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Synthesis and characterization of some transition metal phosphinates and their complexes Du, Jing-Long 1991

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SYNTHESIS A N D CHARACTERIZATION OF SOME TRANSITION M E T A L PHOSPHINATES A N D THEIR COMPLEXES by JING-LONG D U B.Sc , Nankai University, People's Republic of China, 1975 M.Sc., The University of British Columbia, 1987 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE F A C U L T Y OF G R A D U A T E STUDIES Department of Chemistry We accept this thesis as confonning to the required standard THE UNIVERSITY OF BRITISH C O L U M B I A August 1991 © Jing-long Du, 1991 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of The University of British Columbia Vancouver, Canada DE-6 (2/88) Abstract A number of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) monophenyl- and diphenylphosphinates have been synthesized and characterized using physical methods such as thermal analysis, X-ray crystallography, vibrational and electronic spectroscopy and magnetic susceptibility measurements. Complexes of some of these metal phosphinates with neutral donor molecules such as formamide, acetamide, methylformamide, monophenylphosphinic acid, pyridine, pyrazine and the aquo ligand have also been prepared and characterized. Studies on the magnetic properties of some manganese(II)-cadmium(II) mixed metal systems are also reported in this thesis. Co[H(C6H5)P02J2 was prepared in three structural forms and indirect evidence supports polymeric chain structures with phosphinate ligands bridging tetrahedral metal centers in all three forms. Two of the forms exhibit antiferromagnetism; the third form exhibits ferromagnetic, field dependent behaviour. The related compounds, M[H(CtsH5)P02]2> where M is Mn(n), Cd(II), Ni(II) and Cu(II) are concluded to have polymeric structures with double phosphinate bridged chains of octahedrally coordinated metal centers cross-linked to form sheet structures. While the manganese and copper compounds are weakly antiferromagnetic the nickel compound exhibits ferromagnetic, field dependent behavior. The binary metal diphenylphosphinates, MlXC^s^PC^h (where M is Mn(II) and Co(II)), were found to exist in two forms, labelled p" and y. Single crystal X-ray crystallography showed that the structures of the y-forms consist of infinite linear chains, formed by metal ions in nearly regular tetrahedral environments, joined by bridging phosphinate ligands. The structural differences (between the (3- and y-forms) are manifested in their thermal, spectral and magnetic properties, making the two forms distinguishable on this basis. The (J- and y-forms of both compounds are antiferromagnetic. Single crystal X-ray diffraction studies on M(HCONH2)2[H(C6H5)P02]2 (where M is Mn(II), Cd(II) and Co(II)) and MnL2[H(C 6H 5)P0 2]2 (where L is C H 3 C O N H 2 and H(C6H5)PC*2H) revealed polymeric structures with metal atoms linked by double phosphinate ii bridges and neutral ligands coordinating in the axial sites, completing a distorted octahedral coordination around each metal. The cobalt and manganese complexes are antiferromagnetic and in the case of the manganese complexes, the magnitude of the exchange coupling has been correlated with structural parameters. Similar phosphinate bridged polymeric structures have been proposed, primarily on the basis of spectroscopic evidence, for the following complexes: M(H20)2[H(C6H5)P02]2 (where M is Mn, Co and Ni), M(pyz)[H(C6H5)P02]2 (where M is Co and Ni), M(py)2[H(C6Hs)P02]2 (where M is Mn, Co and Ni) and Ni(HCONH2)2[H(C6H5)P02]2- Magnetic studies indicate that regardless of the metal involved, the strength of antiferromagnetic coupling in these complexes increases in the order L = py < pyz < H20 < HCONH2. In the course of this work the following mononuclear phosphinate complexes were prepared and structurally characterized by single crystal X-ray diffraction: Co(H20)4[H(C6H5)P02]2, Ni[HCON(CH3)2]2[(C6H5)2P02H]2[(C6H5)2P02]2 and {Ni[HCON(CH3)2]2(H20)4}(H20)2[(C6H5)2P02]2. Magnetic studies indicate no significant magnetic exchange in any of these complexes. The compound Cd(H20)Cl[H(Cf5H5)P02] was also prepared and characterized by single crystal X-ray diffraction. The compound has a sheet structure involving both bridging phosphinate and bridging chloride ligands. To investigate the effects of cadmium doping on magnetic exchange in phosphinate bridged manganese(II) complexes the following mixed metal systems were prepared and studied: Mni.xCdx[H(C6H5)PC>2]2, Mni.xCdx(HCONH2)2[H(C6H5)P02]2 and Mni-xCdx[(n-Ct5Hi3)2P02]2 (where x varies from ~ 0.01 to ~ 0.54). In all three studies the results showed that the effect of Cd doping is to break the polymer chain into finite segments and to generate monomeric impurities in odd numbered segments. As the extent of doping increases the average chain length decreases and the fraction of monomer increases. In addition the exchange coupling constant was found to decrease as the average chain length decreases. iii TABLE OF CONTENTS Abstract. ii Table of Contents iv List of Tables xi List of Figures....... xvi List of Abbreviations and Symbols xxii Acknowledgements xxiv Chapter 1. Introduction 1 1.1. Low-dimensional Materials and Coordination Polymers 1 1.2. Review of Poly(metal phosphinates) 4 1.3. Objectives of This Work 10 1.4. Methods of Compound Characterization 11 1.4.1. X-ray Crystallography 12 1.4.2. Solubility Studies 15 1.4.3. Thermal Properties 16 1.4.4. Infrared Spectroscopy 18 1.4.5. Electronic Spectroscopy 22 1.4.6. Magnetic Properties 24 1.5. Organization of the Thesis 26 Chapter 2. Complexes of Manganese(II) Monophenylphosphinate 28 2.1. Introduction 28 2.2. Results and Discussion 29 2.2.1. Syntheses, Solubilities and Thermal Properties 29 2.2.2. Single Crystal X-ray Diffraction 32 2.2.2.1. Structure of Mn(HCONH2)2[H(C6H5)P02]2 32 iv 2.2.2.2. Structure of Mn(OT^  34 2.2.2.3. SmicmreofMn^^ 36 2.2.3. X-ray Powder Diffraction 38 2.2.4. Infrared Spectroscopy 40 2.2.5. Magnetic Properties 43 2.3. Summary and Conclusions 52 Chapter 3. Cobalt(II) Monophenylphosphinate and Its Complexes 54 3.1. Introduction 54 3.2 Results and Discussion 55 3.2.1. Syntheses, Solubilities and Thermal Properties 55 3.2.2. Single Crystal X-ray Diffraction 62 3.2.2.1. Structure of Co(HCONH2)2[H(C6H5)P02]2. 62 3.2.2.2. Structure of Co(H20)4[H(C6H5)P02]2 64 3.2.3. X-ray Powder Diffraction 66 3.2.4. Infrared Spectroscopy 68 3.2.5. Electronic Spectroscopy 77 3.2.6 Magnetic Properties 81 3.2.6.1. Octahedral Complexes 81 3.2.6.2. Tetrahedral Complexes 100 3.3. Summary and Conclusions 107 Chapter 4. Nickel(U) Monophenylphosphinate and Its Complexes 109 4.1. Introduction 109 4.2. Results and Discussion 109 4.2.1. Syntheses, Solubilities and Thermal Properties 109 4.2.2. X-ray Powder Diffraction 113 4.2.3. Infrared Spectroscopy 115 4.2.4. Electronic Spectroscopy 120 v 4.2.5. Magnetic Properties 123 4.3. Summary and Conclusions 140 Chapter 5. Diphenylphosphinates of Manganese(II), Cobalt(II) and C?admium(II) 141 5.1. Introduction 141 5.2. Results and Discussion 143 5.2.1. Syntheses, Solubilities and Thermal Properties 143 5.2.2. Single Crystal X-ray Diffraction Studies on Y-Mn[(C6H5)2P02]2 and Y-Co[(C6H5)2P02]2 146 5.2.3. X-ray Powder Diffraction 150 5.2.4. Infrared Spectroscopy 152 5.2.5. Electronic Spectroscopy 154 5.2.6. Magnetic Properties 155 5.3. Summary and Conclusions 159 Chapter 6. Mixed Metal Systems—Mni.xCdx[H(C6H5)P02]2, Mni.xCdx(HCONH2)2[H(C6H5)P02]2 and Mni.xCdx[(n-C6Hi3)P02]2 160 6.1. Introduction 160 6.2. Results and Discussion 161 6.2.1. Mn 1. xCd x[H(C 6H 5)P0 2] 2 161 6.2.2. Mn1.xCdx(HCONH2)2[H(C6H5)P02]2 168 6.2.3. Mn 1. xCd x[(n-C 6H 1 3) 2P0 2] 2 173 6.3. Summary and Conclusions 179 Chapter 7. Miscellaneous Compounds 180 7.1. Copper(H) and Zinc(H) Monophenylphosphinates, Cu[H(C6H5)P02]2 and Zn[H(C6H5)P02 180 vi 7.2. Bis(N,N-dimemylformarrude)bis(^ acid)bis(diphenylphosphinato)nickel(II), Ni(DMF)2[(C 6 H5)2P0 2 H]2[(C 6 H5)2P02]2 186 7.3. Tetraaquobis(N,N-dirnemylformarrd dihydrate, {Ni(DMF)2(H 20)4}(H20) 2[(C6H 5)2P02]2 190 7.4. Aquo-u-chloro-u-rnonophenylphosphinatocach^ C d ( H 2 0 ) C l [ H ( C 6 H 5 ) P 0 2 ] 192 Chapter 8. Experimental 198 8.1. Physical Experimental Techniques 198 8.1.1. Elemental Analysis 198 8.1.2. Qualitative Solubility Tests 198 8.1.3. Thermal Studies 199 8.1.4. Infrared Spectroscopy 199 8.1.5. Electronic Spectroscopy 199 8.1.6. X-ray Powder Diffraction 200 8.1.7. Single Crystal X-ray Crystallography 200 8.1.8. Magnetic Susceptibilies 200 8.2. Syntheses 201 8.2.1. General Comments 201 8.2.2. Materials 203 8.2.2.1. Bis(p:-rnonophenylphosphinato)manganese(II), M n [ H ( C 6 H 5 ) P 0 2 ] 2 204 8.2.2.2. Diaquobis(u.-monophenylphosphinato)manganese(II), Mn(H 2 0) 2 [H(C6H5)P02]2 204 8.2.2.3. Bis(forniamide)bisOJ.-rnonophenylphosphinato)-manganese(II), M n ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 205 vii 8.2.2.4. Bis(monophenylphosphinic acid) bis(u.-monophenylphosph^ Mn[H(C6H5)P02H]2[H(C6H5)P02]2 205 8.2.2.5. Bis(N-memylforrnarnide)bis(jx-monoph^  manganese(n), Mn(HCONHCH3)2[H(C6H5)P02]2 206 8.2.2.6. Bis(acetamide)bis(u.-monc^henylphc«prdnato) manganese(n), Mn(CH3CONH2)2[H(C6H5)P02]2 206 8.2.2.7. Bis(pyridine)bis(p:-monophenylphosphinato) manganese(II), Mn(C5H5N)2[H(C6H5)P02]2 206 8.2.2.8. Bis(ii-rnonophenylphosphinato)cobalt(II), Co[H(C 6H 5)P0 2] 2 Form I 207 8.2.2.9. Bis(u.-monophenylphosphinato)cobalt(n), Co[H(C 6H 5)P0 2] 2 Form II 207 8.2.2.10. Bis(p.-monophenylphosphinato)cobalt(II), Co[H(C 6H 5)P0 2] 2 Form III 207 8.2.2.11. Diaquobis(|i-monophenylphosphinato)cobalt(II), Co(H20)2[H(C6H5)P02]2 208 8.2.2.12. Bis(foraiamide)bis(|X-rnonophenylphosphinato) cobalt(II), Co(HCONH2)2[H(C6H5)P02]2 208 8.2.2.13. Bis(pyridine)bis(p:-monophenylphosphinato)cobalt(II), Co(C5H5N)2[H(C6H5)P02]2 208 8.2.2.14. Bis(u,-monophenylphospMnato)iTK3nc<pyrazine) cobalt(II),Co(C4H4N2)[H(C6H5)P02]2 209 8.2.2.15. Tetraaquobis(p:-rrK)nophenylphosphinato) cobalt(II), Co(H20)4[H(C6H5)P02]2 209 viii 8.2.2.16. Bis(^-nK>nophenylphosphinato)nickel(II), N i [ H ( C 6 H 5 ) P 0 2 ] 2 209 8.2.2.17. Diaquobis(p>n^ophenylpto^ Ni(H 20)2[H(C 6H5)P02]2 210 8.2.2.18. Bis(formarmde)bisi^ nickel(H), Ni(HCONH 2) 2 [H(C6H 5)P0 2 ] 2 210 8.2.2.19. Bis(pyridine)bis(ji-monophenylpho^ N i (C 5 H5N) 2 [H (C 6 H 5 )P0 2 ] 2 211 8.2.2.20. Bis(u,-monopheny lphosp Wnato)mono(pyrazine) nickel(II) Ni(C4H 4N 2)[H(C 6H 5)P0 2]2 211 8.2.2.21. Tenaaquobis(monophenylphosphinato)nickel(II), Ni(H 20)4[H(C6H5)P02]2 211 8.2.2.22. Bis ^-dUphenylphosphinato)manganese(II), Mn[(C6H 5)2P0 2]2 (y-form) 212 8.2.2.23. Bis (^-diphenylphosphinato)manganese(II), Mn[(C 6H 5)2P02]2 (p-form) 212 8.2.2.24. Bis (u.-diphenylphosphinato)cobalt(II), Co[ (C 6 H 5 )2P0 2]2 (Y-form) 213 8.2.2.25. Bis (u,-diphenylphosphinato)cobalt(II), Co[ (C 6 H 5 )2P0 2]2 (p-form) 213 8.2.2.26. Bis(u.-dlphenylphosphinato)<^dmium(ir), Cd[(C 6H 5)2P02]2 (Y-form) 214 8.2.2.27. Bis (^ -monophenylphosphmato)cadmium(n), C d [ H ( C 6 H 5 ) P 0 2 ] 2 214 8.2.2.28. M n i . x C d x [ H ( C 6 H 5 ) P 0 2]2 215 8.2.2.29. Bis(fcnmarnide) bisQi-monophenylphospWnato) cadmium(II), Cd(HCONH2)2[H(C6H5)P02]2 216 ix 8.2.2.30. Mni.xCdx(HCONH2)2[H(C6H5)P02]2 216 8.2.2.31. Bis(u^ -di-n-hexylphosphinato)manganese(II), Mn[(n-C6Hi3)2P02]2 217 8.2.2.32. Bis(u--o^ -n-hexylphospMnato)cadWum(II), Cd[(n-C 6H 1 3) 2P0 2] 2 218 8.2.2.33. Mni.xCdx[(n-C6Hi3)2P02]2 218 8.2.2.34. Bis(}X-rjMnophenylphosphinato)copper(II), Cu[H(C6H5)P02]2 219 8.2.2.35. Bis(|i-monophenylphosphinato)zinc(ir), Zn[H(C6H5)P02]2 219 8.2.2.36. Aquo-u.-chloro-u,-monophenylphosphinatocadmium Cd(H20)Cl[H(C6H5)P02]. 220 8.2.2.37. Bis(N,N-dimeAylformarmde)bis(diphenylphosp acid) bis(diphenylphosphinato)nickel(H), Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2 220 8.2.2.38. Tetraaquobis(N,N-dimemylformarrade)nicM diphenylphosphinate dihydrate, {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 221 Chapter 9. Summary, Conclusions and Suggestions for Further Work 222 9.1. Summary and Conclusions 222 9.2. Suggestions for Further Study 227 References 228 Appendix 238 x LIST OF TABLES Table Page 1.1. X-ray structural data for selected polymeric metal phosphinates and adduct polymers 13 2.1. Thermal parameters for M r d ^ H C C g r ^ P O ^ complexes 30 2.2. Bond distances (A) and bond angles for M n ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 33 2.3. Bond distances (A) and bond angles (*) for M n ( C H 3 C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 36 2.4. Bond distances (A) and bond angles (*) for M n [ H ( C 6 H 5 ) P 0 2 H ] 2 [ H ( C 6 H 5 ) P 0 2]2 38 2.5. Selected infrared data (cm"1) for the M n l ^ r H t C g r ^ P O ^ complexes 41 2.6. Magnetic parameters for Mrtf^[H(C6H5)P0 2 ] 2 complexes 47 2.7. J values and some related bonding parameters for M n L 2 [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 51 3.1. Thermal parameters for C o r H C C e r ^ P O ^ and C o L x [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 59 3.2. Bond distances (A) and bond angles (°) for C o ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 62 3.3. Bond distances (A) and bond angles (°) for C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 65 3.4. Selected infrared data (cm"1) for the three forms of C o [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 68 3.5. Selected infrared data (cm"1) for C o L x [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 71 xi 3.6. Electronic spectral data for Co[H(C6H5)P02]2 and C o L x [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 78 3.7. Magnetic parameters for C o I ^ t H X C g r ^ P C ^ h complexes 96 3.8. Magnetic parameters for CoIHCCgH^PC^h complexes 102 4.1. Thermal parameters for Ni[H(C5H5)P(>2]2 and N i L x [ H ( C 6 H 5 ) P 0 2 ] 2 complexes I l l 4.2. Selected infrared data (cm'1) for Ni[H(C 6H5)P0 2]2 and N i L x [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 117 4.3. Electronic spectral data for Ni[H(C 6 H 5 )P0 2 ]2 and N i L x [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 123 4.4. Magnetic parameters for the N i l ^ t H t C g r L j J P C ^ complexes 131 5.1. Thermal parameters for the diphenylphosphinates of manganese(II), cobalt(II) and cadmium(II) 146 5.2. Bond distances (A) and bond angles (°) for Y-Mn[(C 6H 5) 2P02]2 149 5.3. Bond distances (A) and bond angles (°) for y - C o K C g H s k P O ^ 149 5.4. Selected infrared data (cm - 1) for diphenylphosphinates of manganese(II), cobalt(II) and cadmium(II) (cm"1) 154 5.5. Magnetic parameters for M n K C g H ^ P C ^ and C o K C ^ H s k P O ^ 157 6.1. Magnetic parameters for Mni_ x Cd x [H(C6H 5 )P02]2 164 6.2. Magnetic parameters for Mn 1 . x Cd x (HCONH 2 )2 [H(C 6 H 5 )P0 2 ]2 172 6.3. Magnetic parameters for M n ^ C d x I X n - C g H i j ^ P O ^ h 175 7.1. Bond distances (A) and bond angles (°) for N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 188 7.2. Bond distances (A) and bond angles (") for {Ni (DMF)2(H 2 0)4}(H20 )2 [ (C 6 H 5 )2P02] 2 192 7.3. Bond distances (A) and bond angles (*) for C d ( H 2 0 ) C l [ ( C 6 H 5 ) 2 P 0 2 ] • 196 xii 8.1. Reagents, Purities and Suppliers 203 8.2. Elemental analysis for Mn^CdJHCCgHsJPC^h 215 8.3. Elemental analysis for Mn 1. xCd x(HCONH2)2[H(C 6H5)P0 2]2 217 8.4. Elemental analysis for Mn 1 . x Cd x [ (n-C 6 H 1 3 )2P0 2 ]2 219 9.1. Classification of the compounds 223 Appendix I Crystallographic data and X-ray structural parameters 238 Part A : Crystallographic data 238 I-1. Position parameters with standard deviations in parentheses 238 1-2. Crystallographic data for M(HCONH 2)[H(<^H 5)P02]2 complexes, M = Co(II), Cd(II) and Mn(II) 245 1-3. Crystallographic data for y-M[(C6H5)2P02]2 compounds, M = Co(II) and Mn(II) 245 1-4. Crystallographic data for MnL2[H(C6H5)P02]2 compounds, L = C H 3 C O N H 2 and H ( C 6 H 5 ) P 0 2 H 246 1-5. Crystallographic data for other compounds 246 Part B : X-ray structure parameters 248 v 1-6. Selected bond distances (A) with estimated standard deviations in the last significant figure in the parentheses... 248 1-7. Selected bond angles (") with estimated standard deviations in the last significant figure in the parentheses 252 Part C: X-ray powder diffraction data 261 1-8. X-ray powder diffraction data for M[H(C6H5)P02] 2 where M = Co, Cd, M n and N i 261 1-9. X-ray powder diffraction data for M^OteTOCer^ PCbh where M = Mn , Co and N i 261 I-10. X-ray powder diffraction data for M[H(C6Hs)P02]2 where M = Cu and Zn 262 xiii M l . X-ray powder (jiffraction data for M(HCONH2)2[H(C6H5)P02]2 where M = Mn, Co, Ni and Cd 262 1-12. X-ray powder diffraction data for M(py)2[H(C6H5)PC>2]2 where M = Mn, Co and Ni 263 1-13. X-ray powder diffraction data for M(H20)4[H(<^H5)P02]2 where M = Co and Ni 263 1-14. X-ray powder diffraction data for M(pyz)[H(C6H5)P02]2 where M = Co and Ni 263 1-15. X-ray powder diffraction data for p-MKC^HstePC^te where M = Mn and Co 264 1-16. X-ray powder diffraction data for Y-M[(C6H5)2P02]2 where M = Mn, Co and Cd 264 1-17. X-ray powder diffraction data for MnL2[H(C6H5)P02]2 where L = CH3CONH2, HCONHCH3 and H(C6H5)P02H 265 1-18. X-ray powder diffraction data for Mni.xCdx[H(C6H5)P02]2 where x = 0,01, 0.19, 0.26 and 0.41 265 1-19. X-ray powder diffraction data for Mni.xCdx(CONH2)2[H(C6H5)P02]2 where x = 0.01, 0.04, and 0.05 266 1-20. X-ray powder diffraction data for Mni.xCdx(CONH2)2[H(C6H5)P02]2 where x = 0.14, 0.32 and 0.54 266 I- 21. X-ray powder diffraction data for Mni.xCdx[(n-C6Hi3)2P02]2 where x = 0, 0.08, 0.54 and 1.0 267 Appendix II Magnetic susceptibility results 267 II- 1. Magnetic data for NiLx[H(C6H5)P02]2 where L x = (H20)2, (HCONH2)2 and (pyz) 267 x i v II-2. Magnetic a^ m for Nlru^ 2l?i(C6H5)P02]2 where L = H20, HCONH2 and HCONHCH3 268 II-3. Magnetic data for MnL2[H(C6H5)P02]2 where L = GH3CONH2, H(C6H5)P02H and py 269 II-4. Magnetic data for Co[H(C6H5)P02]2 (Form I) 270 II-5. Magnetic data for Co[H(C6H5)P02]2 (Form II and Form HI).272 II-6. Magnetic data for CoLx[H(C6H5)P02]2 where L x = (H20)2, (HCONH2)2 and (pyz) 273 II-7. Magnetic data for Ni[H(C6H5)P02]2 274 II-8. Magnetic data for Mn[(C6H5)2P02]2 275 II-9. Magnetic data for Co[(C6Hs)2P02]2 276 11-10. Magnetic data for Mni.xCdx[H(C6H5)2P02]2 277 II-11. Magnetic data for Mni.xCdx(HCONH2)2[H(C6H5)2P02]2 278 11-12. Magnetic data for Mni.xCdx[(C6Hi3)2P02]2 279 11-13. Magnetic data for Cu[H(C6H5)2P02]2 and Ni(DFM)2[(C6H5)2P02H]2[(C6H5)2P02]2 281 Appendix HI Unassigned infrared absorptions 282 Appendix r V Vibrational assignments for pyridine and its complexes 285 Appendix V Vibrational assignments for pyrazine and its complexes 285 xv LIST OF FIGURES Figure Page 1.1. Structures of: a) Z n K C g H s X n - C ^ P O J * b) C u K C g H ^ k P O ^ and c) P b [ ( C 6 H 5 ) 2 P 0 2 ] 2 6 1.2. A portion of the chain of Mn(HCONH 2 ) [ (C6H5)(CH 3 )P0 2 ] 2 9 1.3. R R ' P 0 2 " bonding modes and possible polymeric structures 20 2.1. Thermogram of M n ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 31 2.2. View of M n ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 showing the numbering scheme and coordination about the manganese atom 33 2.3. Stereoview of a section of M n ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 34 2.4. View of M n ( C H 3 C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 showing the numbering scheme and coordination about the manganese atom.* 35 2.5. Polymeric structure of M n ( C H 3 C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 35 2.6. View of M n [ H ( C 6 H 5 ) P 0 2 H ] 2 [ H ( C 6 H 5 ) P 0 2 ] 2 showing the numbering scheme and coordination about the manganese atom 37 2.7. Stereoview of a section of M n [ H ( C 6 H 5 ) P 0 2 H ] 2 [ H ( C 6 H 5 ) P 0 2 ] 2 37 2.8. X-ray powder diffraction patterns for M n l ^ f H X C g H ^ P O ^ complexes... 39 2.9. Magnetic moment versus temperature plots for MnL 2 [H(C5H5)P0 2 ] 2 complexes 45 2.10. Magnetic susceptibility versus temperature plots for M n L 2 [ H ( C 6 H 5 ) P 0 2 ] 2 complexes 46 2.11. Magnetic susceptibility versus temperature plot for MnL 2[H(C f5H5)P0 2] 2: a) L = H C O N H 2 , b) L=HCONHCH 3 ,c) L = C H 3 C O N H 2 , d) L = H ( C 6 H 5 ) P 0 2 H and e) L = C 5 H 5 N 50 xvi 3.1. Thermograms of: a) Co(H20)2rH(C6H5)P02]2, b) Co(HCONH2)2[H(C6H5)P02l2, c) CoCpy^HCQ^POzh, d) Co(pyz)[H(C6H5)P02]2; e) Form I, f) Form H and g) form IH of CorH(C6H5)P02]2; and h) Co(H20)4[H(C6H5)P02]2 61 3.2. Stereoview of a section of Co(HCONH2)2[H(Ce5H5)P02]2 63 3.3. View of C o 0 H C O N H 2 ) 2 r H ( C 6 H 5 ) P O 2 ] 2 , showing the numbering scheme and coordination about the cobalt atom 63 3.4. A stereoview of the unit cell in Co(H20)4[H(C6H5)P02]2 65 3.5. View of Co(H20)4[H(C6H5)P02]2, showing the numbering scheme and coordination about the cobalt atom 66 3.6. X-ray powder diffraction patterns of a) Form I, b) Form II and c) Form HI of Co[H(C6H5)P02]2; d) Co(H20)2[H(C6H5)P02]2, e) Co(HCONH)2[H(C6H5)P02]2, f) Co(py)2[H(C6H5)P02]2, g) Co(pyz)[H(C6H5)P02]2, and h) Co(H20)4[H(C6H5)P02]2 67 3.7. Infrared spectra of Co[H(C6H5)P02]2: a) Form I, b) Form II and c) Form III 69 3.8. Infrared spectra of a) Co(HCONH2)2rH(C6H5)P02]2, b) Co(py)2[H(C6H5)P02]2 and c) Co(pyz)rH(C6H5)P02]2 75 3.9. Infrared spectra of a) Co(H20)2[H(C6H5)P02]2 and b) Co(H 2 0) 4 [H(C 6 H 5 )P0 2 ] 2 76 3.10. Electronic spectra of CoLx[H(C6H5)P02]2: a) Co(pyz)rH(C6H5)P02]2, b) Co(HCONH2)2[H(C6H5)P02]2, c) Co(H20)2[H(C6H5)P02]2, d) Co(py)2[H(C6H5)P02]2 and e) CoCHzOUfHCC^PO^ 79 3.11. Electronic spectra of Co[H(C6H5)P02]2: a) Form I, b) Form II and c) Form III 80 3.12. Magnetic moment versus temperature plots for Q)La[H(C6H5)P02]2 complexes 82 xvii 3.13. Partial energy level diagram for octahedral cobalt(II) 83 3.14. Magnetic moment versus -kTA plot for Co(H20)4[H(C6H5)P02]2 85 3.15. Magnetic susceptibility versus temperature plot for Co(H20)4[H(C6H5)P02]2 87 3.16. Magnetic moment versus temperature plot for Co(H20)4[H(C6H5)P02]2. 88 3.17. Magnetic moment versus -kTA plot for CoCpy^ tHCCgr^ PC^h 90 3.18. Magnetic susceptibility versus temperature plot for Co(py)2[H(C6H5)P02]2 91 3.19. Magnetic moment versus temperature plot for Co(py)2[H(C6H5)P02]2.... 92 3.20. Magnetic susceptibility versus temperature plot for Co(HCONH 2)2[H(C6H5)P02]2 97 3.21. Magnetic susceptibility versus temperature plot for Co(H 20) 2[H(C 6H 5)P0 2] 2 98 3.22. Magnetic susceptibility versus temperature plot for Co(pyz)[H(C6H5)P02]2 99 3.23. Partial energy level diagram for tetrahedral cobalt(II) 102 3.24. Magnetic moment versus temperature plot at H = 9225 G for the three forms of Co[H(C6H5)P02]2 103 3.25. Magnetic susceptibility versus temperature plot for Form II and Form HI of Co[H(C6H5)P02]2 104 3.26. Magnetic susceptibility versus temperature plot for CorHCCgF^PO^ at different magnetic fields 105 3.27. Magnetic moment versus temperature plot for CtotHCCgHyPO^ at different magnetic fields 106 4.1. Thermograms of a) Ni[H(C6H5)P02]2, b) Ni(HCONH2)2[H(C6H5)P02]2, c) Ni(H20)2[H(C6H5)P02]2, d) Ni(py)2[H(C6H5)P02]2, e) Ni(pyz)[H(C6H5)P02]2 and f) Ni(H20)4[H(C6H5)P02]2 112 xviii 4.2. X-ray powder diffraction patterns for: a) Ni(HCONH 2) 2[H(C 6H5)P02]2, b) Ni(H 2 0)2[H(C 6 H 5 )P0 2 ]2,c) Ni(py)2rH(C 6H5)P02]2, d) Ni[H(C 6 H 5 )P0 2 ]2 > e) Ni(pyz)[H(C 6H5)P0 2]2 and f) N i ( H 2 0)4 [ H ( C 6 H 5 ) P 0 2 ] 2 • 114 4.3. Infrared spectra of a) Ni(HCOrff l 2)2P*(Q H 5) p o2J2. b) N i (H 2 0)2 [H(C 6 H 5 )P02 ] 2 and c) N i C p y ^ H C C ^ P O i h 118 4.4. Infrared spectra of a) Ni[H(C 6H5)P0 2]2» b)Ni(pyz)[H(C 6 H 5 )P0 2 ]2 and c) Ni(H 2 0)4[H(C 6 H5)P0 2]2 119 4.5. Electronic spectra of a) Ni(pyz)[H(CyH5)P02]2, b) Ni(HCONH 2 )2[H(C 6 H 5 )P0 2 ]2, c) N i ^ O h t H C C ^ P O ^ , d) Ni(py)2[H(C 6H 5)P02]2, e) Ni(H 2 0)4[H(C 6 H5)P0 2 ] 2 and f) N i [ H ( C 6 H 5 ) P 0 2 ] 2 • 122 4.6. Partial energy level diagram for octahedral nickel(II) 124 4.7. Magnetic moment versus temperature plots for NiI^[H(C6H5)P0 2] 2 complexes 125 4.8. a) Magnetic susceptibility versus temperature plot, b) magnetic moment versus versus temperature plot for Ni(H20)4[H(C6H5)P0 2] 2 127 4.9. Magnetic susceptibility versus temperature plot for N i ( p y ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 131 4.10. Magnetic susceptibility versus temperature plot for N i ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 132 4.11. Magnetic susceptibility versus temperature plot for N i ( H 2 0 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 133 4.12. Magnetic susceptibility versus temperature plot for N i ( p y z ) [ H ( C 6 H 5 ) P 0 2]2 134 4.13. Magnetic susceptibility versus temperature plot for Ni(pyz)[H(C6H5)P02]2 135 xix 4.14. Magnetic susceptibility versus temperature plots for NitHXCgHsJPC^ at different magnetic fields 138 4.15. Magnetic moment versus temperature plot for Ni[H(Ct3H5)P02]2 at different magnetic fields 139 5.1. Thermograms of a) p-Mn[(C6H5)2P02]2, b) y-Mn[(Q>H5)2P02]2, c) |3-Co[(C6H5)2P02]2, d) Y-Co[(C6H5)2P02]2 and e) Y-Cd[(C6H5)2P02]2 145 5.2. Stereoview of the Y-MntCQHstePC^h structure showing a section of the linear double phosphinate bridged chain structure 148 5.3. Stereoview of a symmetric unit of the Y'MnlXCisHstePC^k structure showing atom labelling and the coordination about the metal atom 148 5.4. X-ray powder diffraction patterns for: a) P-Mn[(C6H5)2PC>2]2, b) Y-Mn[(C6H5)2P02]2, c) P-Co[(C6H5)2P02]2, d) Y-Co[(C6H5)2P02]2 and e) Y-Cd[(C6H5)2P02]2. 151 5.5. Infrared spectra of a) a) p-Mn[(C6H5)2PC>2]2, b) Y-Mn[(C6H5)2P02]2, c) P-Co[(C6H5)2P02]2, d) Y-Co[(C6H5)2P02]2 and e) Y-Cd[(C6H5)2P02]2 153 5.6. Electronic spectra of Co[(C6H5)2P02]2: a) y-form and b) p-form 155 5.7. Magnetic susceptibility versus temperature plots for MKQjHs^PO^ : a) Y-Mn, b) P-Mn, c) y-Co, d) p-Co 158 6.1. Magnetic susceptibility versus temperature data for M n i . x C d x [ H ( C 6 H 5 ) P 0 2 ] 2 165 6.2. Magnetic moment versus temperature data for Mni_xCdx[H(QH5)P02]2- • 166 6.3. Magnetic susceptibility versus temperature plots for Mn i _xCtf xJHCCgHs^O^. 167 6.4. Magnetic susceptibility versus temperature data for M n 1 . x C d x ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 • 169 xx 6.5. Magnetic moment versus temperature data for M n 1 . x C d x ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 170 6.6. Magnetic susceptibility versus temperature plots for Mnl.xCdx(HCONH2)2[H(C6U5)P02h 171 6.7. X-ray powder diffraction patterns of a) Mn[(n-C6Hi3) 2P0 2] 2; b) Mno.46Cdo.54[(n-C6Hi 3) 2P0 2] 2 and c) CM[(n -QiHi 3 ) 2 P0 2 ] 2 . 174 6.8. Magnetic susceptibility versus temperature data for M n i . x C d x [ ( n - C 6 H 1 3 ) 2 P 0 2 ] 2 176 6.9. Magnetic moment versus temperature data for M n i T X C d x [ ( n - C 6 H 1 3 ) 2 P 0 2 ] 2 177 6.10. Magnetic susceptibility versus temperature plots for M n i . x C d x [ ( n - C 6 H 1 3 ) 2 P 0 2 ] 2 178 7.1. X-ray powder diffraction patterns for a) Cu[H(C6H5)P02]2 and b) Z n [ H ( C 6 H 5 ) P 0 2 ] 2 182 7.2. Infrared spectra of a) Cu[H(C6Hs)P0 2 ] 2 and b) Zn[H(C6Hs)P02]2 183 7.3. Magnetic moment versus temperature plot for Cu[H(C6H5)PC*2]2 184 7.4. Magnetic susceptibility versus temperature plot for Cu[H(C6H5)P02] 2.... 185 7.5. View of N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 showing the atom numbering scheme and coordination about the nickel atom 187 7.6. Magnetic susceptibility versus temperature plot for N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 189 7.7. A view of the unit cell in { N i ( D M F ) 2 ( H 2 0 ) 4 } ( H 2 0 ) 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 191 7.8. View of {Ni(DMF) 2 (H 2 0) 4 } ( H 2 0 ) 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 showing the atom numbering scheme and coordination about the nickel atom 191 7.9. A stereoview of the unit cell in raCH^CllTICCgr^PC^] 194 7.10. View of Cd(H 2 0)Cl[H(C 6 H 5 )P0 2 ] showing the atom numbering scheme and coordination about the cadmium atom 195 xxi LIST OF ABBREVIATIONS AND SYMBOLS A Angstrom Anal. Analysis and. antisymmetric br. broad B.M. Bohr Magneton °C degree Celsius Calcd. Calculated DMF Dimemylfc^ mamide 2,2-DMP 2,2-Dimethoxypropane DSC Differential scanning calorimetry cm"1 reciprocal centimeter ESR Electron Spin Resonance g Lande splitting factor, gram(s) k Boltzmann's constant XM Molar magnetic susceptibility HB Bohr Magneton Hen- Effective magnetic moment ri hour(s) J Exchange coupling constant m. medium min minute(s) ml milliliter(s) mmol millimole(s) mol mole(s) N Avogadro's number xxii nm nanometer(s) NMR Nuclear Magnetic Resonance Obs. Observed ppm parts per million py pyridine pyz pyrazine s. strong sh. shoulder sym. symmetric TGA Thermal Gravimetric Analysis T. I. P. Temperature Independent Paramagnetism w. weak vs. very strong vw. very weak U.B.C. University of British Columbia ZFS Zero-Field Splitting ~ approximately < less than > greater than A difference between, reflux AH Change in enthalpy u, bridging v Infrared stretching frequency xxiii ACKNOWLEDGMENTS I would like to express sincerest thanks to my supervisor Dr. R. C. Thompson for the support, encouragement and guidance he provided during the course of this work. I am extremely grateful to Professor H. Z. Tian for her technical assistance in the syntheses of some cobalt and nickel compounds. Thanks go to my guidance committee, Dr. A. Storr, Dr. J. R. Sams and Dr. D. E. McGreer for their constructive remarks during the final preparation of this thesis. The research described in this thesis would have been rendered painstakingly slow if it were not for the technical expertise of the mechanical, electronic and glassblowing shops. Many thanks go to Dr. S. J. Rettig for the crystal structure determinations, Mr. P. Borda for his microanalytical services and to Miss K. Hull, Dr. K. W. Oliver, Mr. T. Otieno, and Mr. M. Ehlert for their assistance in this work and for proof-reading of this thesis. I would like to express a special thanks to my wife, Jiuxue Song, and my daughter, Zhimin Du, whose many words of encouragement make this thesis possible. xxiv Chapter 1 Introduction 1.1. Low-dimensional Materials and Coordination Polymers In the past few years there has been considerable interest in the chemical and physical properties of low-dimensional materials, particularly in their magnetic and optical as well as structural and chemical properties!1"4]. The compounds which have been studied range from those of an organic nature to inorganic polymers. The use of a wide range of physical techniques has permitted structure-property relationships to be examined in attempts to provide rational approaches to the design of new materials having specific properties^2'3]. This work has had a significant impact on concepts utilized in chemistry and in solid state physics^. Interest in the structures and properties of low-dimensional metal complexes was stimulated by the work of Krogmann in the late 1960sf5]. However, the compounds which aroused so much interest then have a much longer history. Indeed many of the compounds that were studied intendy in the 1970s were first prepared in the middle of the 19th century although the true nature of the materials was to remain a mystery for over a hundred years. For example, K2Pt(CN)4Cln.3xH20 was synthesized in 1842t6J and was later found to possess a high conductivity; in 1968 it was confirmed to be a linear chain polymer by X-ray structure determination!7]. More recently, low-dimensional metal complexes have been prepared from a wide range of transition metals and ligands; for instance, transition-metal complexes of porphyrins, phthalocyanines and glyoximes have been found to exhibit interesting electrical and optical, as well as magnetic, propertiest8]. Inorganic coordination polymers which form a sub-branch of low-dimensional materials have also been investigated since the early 1960s!9]. A common feature of these compounds is that metal ions are bridged by intervening groups and are much more 1 closely spaced in some directions than others. Where metals in paramagnetic ground states are involved, these intervening groups are found to influence the magnetic properties of the complex, and often give rise to magnetic exchange via a so-called superexchange mechanism. At the present time, there is considerable interest in compounds which exhibit magnetic exchange phenomena. Dimeric copperQT) carboxylatesf10'11! were among the first complexes to be investigated extensively because of their "abnormal" magnetic properties. In recent years, researchers have correlated exchange coupling with bond lengths and angles in a variety of dimers, trimers and small clusters, as well as in polymeric materials. Crawford et al. t 1 2 l , for example, investigated a series of planar bis-p:-hydroxo copper(II) dimers. In their work it was demonstrated that the exchange constant, J, varies linearly with the Cu-OCu angle and the exchange shifts from ferromagnetic to antiferromagnetic as the bridging angle is increased. Other factors, such as the stereochemistry around the metal and the nature of non-bridging ligands, have also been shown to play an important role in deterrnining the nature and magnitude of exchange interactions in such materials. Extensive research carried out in our laboratory over the past ten years on a series of transition-metal pyridine, pyrazine, sulfonate, pyrazolate, and phosphinate compounds^1 3"2 4! has focused on attempts to correlate structure with magnetic properties. A brief overview of some of this work follows. It was found that in complexes of stoichiometry ML4(RS03)2 (where M is Fe, Cu, or N i , L is pyridine, pyrazine or 2-methylpyrazine and R is CF3, CH3 or P-CH3C6H4) the neutral ligands as well as the RSO3" groups adopt a unidentate mode of coordination^ 1 4 ' 1 5^. For several of these complexes, X-ray crystallography revealed a square-planar array of neutral ligands around the central metal, with anions coordinated in a unidentate mode above and below this plane. A mononuclear molecular structure results in which the paramagnetic centers are well isolated from each other giving rise to magnetically-dilute species. In complexes of stoichiometry M(pyz)2X2 ( where M is Fe, Cu, or N i , X " is CF3S03", CH3S03", C l" , Br", I", CIO4" or N C S ' and pyz = pyrazine, C4H4N2), pyrazine was found to coordinate 2 through both nitrogen donor atoms and inorganic coordination polymers are produced, many of which exhibit magnetic concentration effects. X-ray crystallography revealed a two-dimensional lattice in Cu(pyz)2(CH3S03>2 with two distinct kinds of bridging pyrazine groups and monodentate sulfonate anions. Fe(pyz)2(NCS>2 is thought to have an analogous structure with pyrazine ligands bridging in two dimensions and six coordination about the iron completed by terminal thiocyanate ligands. Magnetic studies on both Cu(pyz)2(CH3S03)2 and Fe(pyz)2(NCS)2 revealed the antiferromagnetic nature of both of these materials with Xmax at temperatures of 7.0 and 8.0 K, respectively! 1 4 l In the case of nickel(II) complexes of this kind, however, it has been observed that the presence of a bridging network does not necessarily lead to measurable magnetic concentration^ 5]. It has been suggested that transition-metal sulfonate compounds, M(RS03)2, adopt polymeric two-dimensional layered structures, as been found for Ca(CH3S03)2!25]. A series of anhydrous iron(II) sulfonates, Fe(RSC>3)2, where R is F, CF3, C H 3 or J 3-CH3C6H4 was characterized by means of infrared, Mossbauer and electronic spectroscopy. A distorted FeC<6 chromophobe with each sulfonate anion bridging to three different metal centers resulting in a two-dimensional lattice was proposed for these compounds. Two structural forms were found to exist for Fe(CH3SC»3)2: the P-isomer was shown by Mossbauer spectroscopy to undergo a transition to an antiferromagnetically-ordered state at 22 K while the a-form was found to be magnetically dilute!14'16 .^ Another class of inorganic coordination polymers studied in our laboratory consists of the binary metal pyrazolate ( and substituted pyrazolate) compounds in which the pyrazolate anion serves as the link between metal centers. In [Cu(pz)2]x. where pz = pyrazolate, C3H3N2" , X-ray crystallography reveals an infinite double-bridged polymeric chain in which each Cu atom has a D2, distorted tetrahedral coordination geometry. Magnetic susceptibility studies (4.2 to 299K) on this material reveal very strong antiferromagnetic exchange between Cu(II) centers in the extended linear chain with J=-78cm-! and g=2.12117]. 3 Inorganic coordination polymers involving phosphorus containing ligands have been extensively studied in our laboratory and elsewhere!13'19-23'26-49!. Anionic phosphorus containing ligands have included mononegative phosphinates R2PO2", R(H)PC»2", and X 2 P 0 2 " (where X is F, CI or Br), and the hypophosphite anion, H 2 P0 2 " [13,19-23,26-35]. m e phosphates (RO)(R)P02" and phosphonates!36*42!. Some dinegative and trinegative ligands such as RPO3 2" and PO4 3 ' have also been investigated!43-49]. Phosphinate ligands are studied in the current work. Their ability to form inorganic coordination polymers!50!, which are stable and have plastic properties that might be of some commercial use!28!, has been recognized for some time. Earlier work on phosphinate bridged coordination polymers is reviewed in more detail in the next section. Several conclusions may be drawn from these earlier studies which are applicable to this thesis. The combination of X-ray structure determinations and magnetic susceptibility measurements is important if meaningful conclusions are to be drawn concerning the nature of the bridging ligand and metal chromophore, and the effects of these on magnetic properties. Also, magnetic susceptibility measurements have to be made at low temperatures in order to probe the weak exchange interactions often observed in coordination polymers incorporating multi-atom bridges between metal centers. 1.2. Review of Poly(metal phosphinates) The first metal phosphinate compounds were reported in the late 1800's!51!, but their polymeric nature was not confirmed until 1959, when preliminary viscosity data for U02[(n-C4H9)2P02]2 were published!52!. Since that time and up to the late 1970's, researchers concentrated on modifying the properties of phosphinate polymers by changing the substituents on the phosphorus and employing different metals!27"29'53"57!. In this way it was possible to alter properties such as crystallinity, glass transition temperature, melting and decomposition temperatures, viscosity, solubility and molecular weight!58!. At the same time, the classification of these compounds by structural type and the correlation of 4 « structures with the nature of the R groups on phosphorus were also undertaken! 2 6 ' 5 3 - 5 7]. A knowledge of structures was expected to aid in understanding the properties of these materials. Initially, structural characterization was achieved solely by indirect methods involving solubility, viscosity, thermal analysis, spectral techniques and, at times, magnetic susceptibility measurements! 5 4" 5 7 ' 5 9 - 6 1!. Giordano et a/.! 6 2* 6 7! characterized a number of zinc(II), cobalt(II) and beryllium(II) phosphinates and investigated polymer structure by means of single crystal X-ray diffraction, X-ray fiber and powder diffraction studies. In the case of the zinc(II) phosphinate, Zn[(C6H5)(n-C4H9)P02]2> these authors found, using X-ray fiber studies, a linear chain structure involving a bridging system in which chains of zinc atoms are linked alternately by single and triple phosphinate anion bridges!64" 6 5 J . The structure of this compound is shown in Figure 1.1 a). In 1976, Colamarino et a/. [68] fu- s t confirmed the existence of the double phosphinate bridged structure among phosphinate compounds with their report of the crystal structure of Pb[(C6H5)2P02]2- The polymeric structure of this is also shown in Figure 1.1c). Karayannis and his coworkers!36^ reported the subnormal room temperature magnetic moments for complexes containing a wide variety of metals and they explained the phenomenon as being due to superexchange via the O-P-0 bridging units. Thereafter, interest in the investigation of the possibility of magnetic exchange effects in these materials using techniques such as 3 1 P NMR, ESR, specific heat and variable temperature magnetic susceptibility measurements was awakened! 8 ' 6 9" 7 6!. One notable early study along these lines is the work of Scott and his coworkers on a number of phosphinate complexes of Mn, Fe, Co, N i and C u ! 6 9 ' 7 1 ! . Since the late 1970's, several copper(II) phosphinates have been synthesized and characterized in our own laboratory! 1 3 ' 2 0" 2 3^. In this work it was found, in the case of the linear chain copper(II) dialkylphosphinates, that distortion of the MO4 chromophore plays an important role in determining the nature of magnetic exchange interactions. Single 5 crystal X-ray diffraction studies on the complexes, Cu(R2P02)2, where R is ethyl, butyl and hexyl have been reported!20'21'77!. A portion of the chain in Cu[(C6Hi3)2P02]2 is shown in Figure 1.1b). The X-ray studies revealed two structural forms, a- for the ethyl and pV for the butyl and hexyl derivatives. Both forms exhibit structures involving chains of fused eight-membered rings formed by two bridging phosphinate ligands and two copper ions. Structural differences between the a- and P-forms were found to mainly involve different degrees of distortion of the Q1O4 chromophore from regular tetrahedral geometry. For the complexes where R is n-octyl, n-decyl and n-dodecyl, both a- and In-forms were isolated for each and identified on the basis of their magnetic and other propertiest22!. Figure 1.1. Structures of: a) ZnKCsHsXn-C^PC^h, b) Cu[(C6Hi3)2P02]2 and c) Pb[(C6H5>2P02]2. Taken from references 21,64 and 68. 6 Both a- and {J-forms of these copper phosphinates were found to be magnetically concentrated. The a-isomers exhibit antiferromagnetic exchange with values of the exchange parameter, J, ranging from ~ -1 to ~ -30 cm"1 in different compounds, while the -^isomers show weak ferromagnetic coupling with J approximately 2 cm"1- Oliver!131 first synthesized and characterized a powder sample of Cu[(C6H5)2P02]2- On the basis of its electronic spectrum, she speculated that the compound has a cross-linked structure with a relatively flattened Cu04 chromophore. Recently, Bino and Sismant78! prepared the compound in a crystalline form and determined its structure by X-ray diffraction. The compound was found to have the same basic double phosphinate bridged infinite chain structure as the other copper(II) phosphinates; however, in this case the Q1O4 chromophore is square planar. Magnetic susceptibility studies down to 2.0 K were made on this compound soon after its structure was reported and this work revealed the presence of weak ferromagnetic exchange in the compound!23!. Recent reports on the preparation and characterization of transition-metal phosphinates other than those of copper are relatively few. Scott et al. ! 6 9 » 7 1 1 reported the characterization of a series of complexes of composition M(R2P02)2, where M=Mn, Fe, Co, Ni, or Cu and R= alkyl or aryl. While some correlations between magnetic properties and the nature of the phosphinate were obtained in this work, the characterization of the complexes was not complete. In 1978, Cookson and coworkers!79! synthesized a series of manganese(H) diakylphosphonates and diarylphosphinates and characterized them using electron spin resonance (ESR) spectroscopy. The diversity of the spectra observed showed that the manganese(II) ion is sensitive to structural changes resulting from the effects of different organic substituents on the phosphonate or phosphinate ligands; however, no specific structural conclusions were obtained from this work other than that the compounds are probably polymeric. Work carried out in our laboratory!80! described the synthesis and magnetic properties of the dimethylphosphinate of manganese(II), Mn[(CH3)2P02]2, and its dihydrate. Magnetic susceptibility studies on the dihydrate at temperatures from 300 to 7 4.2K revealed a magnetic moment of ~ 5.9 \IR over most of the range studied and gave no evidence for significant magnetic exchange. Conversely, the anhydrous compounds showed relatively strong antiferromagnetic exchange effects. An X-ray structure determination of the dihydrate revealed a double phosphinate bridged chain structure with a strong hydrogen bonding network linking the chains together. It was suggested that the interchain interaction effectively dampens the magnetic exchange in this material. Other work on phosphinates of manganese(II) carried out in our laboratory including a study of doping cadmium into the polymeric structure of manganese(II) monophenylphosphinatef81!. It was found that the incorporation of diamagnetic cadmium atoms into the polymer chain has the effect of breaking the infinite chain into finite segments and generating paramagnetic impurities in odd numbered segments. As the extent of doping is increased the average chain length decreases and the fraction of paramagnetic impurity increases. In addition, the value of IJI was found to decrease (from 3.00 to 2.00 cm"1) as the average chain length decreases. One other recent report on a metal phosphinate polymer is worth mentioning. Shieh et a/.t82l published the crystal structure of Zn[H(C6Hs)P02]2- They found that the coordination geometry around Zn is tetrahedral and that the basic structure is similar to that found for most other metal phosphinates. The zinc ions are linked in chains by double phosphinate bridges. Polymeric materials of the type [ML2(R2P0 2 ) 2 ] X in which phosphinate bridged metal ions have their coordination spheres increased by the binding of neutral donor molecules, L, such as H 2 0, or HCONH2 may be termed "adduct polymers"!83,84 .^ In 1988, Betz et al. t 8 5! first reported the preparation and characterization of a novel series of such complexes, the series of formamide adducts of metal phosphinates with the composition of M0HCONH2)[(CH3)(C^5)PO2]2HCONH2, where M=Mn, Cu and Co. Structural studies showed these compounds to consist of polymeric chains in which phosphinate groups form double bridges between metal centers and formamide oxygen 8 atoms form \i-0 bridges between metal atoms. The crystal structure of Mn(HCONH2)[(CH3)(C6H5)P02]2-HCONH2 is given in Figure 1.2. The introduction of the fi-O group into the chain causes a substantial decrease in the metal-metal separation from about 5 A in polymers such as M(R 2 P02)2 t 0 a b ° u t 4 A (Table 1.1). The geometry about the metal atom is octahedral with four oxygen atoms from four different phosphinate groups and two shared oxygen atoms from the coordinated formamide ligands forming the M 0 6 chromophore. Betz et al. also reported the crystal structures of Cu[(CH3)(C6H5)P02]2(DMF)t8« and of Mn[(DMF)(C6H5)2P02]2-(DMF)[83]. Figure 1.2. A portion of the chain of Mn[(C6H5)(CH3)P02](HCX)NH2); Taken from reference 85. 9 In the case of Cu[(CH3)(C6H5)P02]2(DMF), the structure consists of infinite chains of fused centrosymmetric eight-membered rings formed by two metal atoms bridged by two phosphinate groups. Each copper atom is bonded to five oxygen atoms, four of which come from four different phosphinate groups and the fifth from the molecule of dimethylformamide, completing a square pyramidal coordination geometry. The chain structure of Mn[(DMF)(C6H5)2P02]2(DMF) involves fused centrosymmetric eight-membered rings as for the above compounds. Each manganese atom is coordinated to four oxygen atoms from four different phosphinate groups and to one DMF oxygen atom. The geometry around the metal atom in this compound is nearly that of a trigonal bipyramid. The second molecule of DMF in the compound is a molecule of solvation. A class of compounds with the formula, M(DMF)2[(C6H5)2P02H] 2 [(C6H 5 ) 2 P02]2, where M = Mn or Co, has also been structurally characterized by Bino et al. t83]. T n these compounds, the metal atom is coordinated to two phosphinate ions, to two phosphinic acid molecules and to two DMF molecules forming a MC«6 chromophore. These compounds are mononuclear. Two very strong intramolecular hydrogen bonds are formed between the P-OH groups of the phosphinic acid ligands and the P-0 group of the phosphinate ligands. The existence of the two very strong hydrogen bonds in these compounds is thought to contribute to the stability of these species. 1.3. Objectives of This Work The objectives of this work were: (i) to extend the earlier work in our laboratory on copper (II) phosphinates to other metals such as Mn, Co, Ni, and Cd, (ii) to extend the study of "adduct polymers" using a range of neutral ligands such as H2O, HCONH2, HCONHCH3, CH 3CONH2, pyridine, pyrazine and phosphinic acid and (iii) to investigate further our earlier doping experiments, involving phosphinates of Mn and Cd, specifically to improve the method of synthesis and to extend the work to doping in an "adduct 10 polymer". The bridging ligands that were used in this work are mainly mono- and diphenylphosphinate. The monophenylphosphinate ligand was particularly appropriate for this study because the acid is available commercially, but also, because the few previous studies that had been done utilizing this ligand indicated that the reduced steric crowding in the phosphinate/metal backbone due to the presence of the small H substituent increases the chance of forming stable "adduct polymers". 1.4. Methods of Compound Characterization Magneto-structural correlations in poly(metal phosphinates) were the main focus of this study. Determination of precise structures, where possible by single crystal X-ray diffraction methods, is particularly important in such work. This technique provides precise details of bond lengths and angles, and establishes the exact nature of the bridging system. However, since more commonly materials are only obtained in microcrystalline powder form there is also a need for X-ray powder diffraction studies. Powder diffraction studies are useful in identifying polymorphism and establishing isomorphism. Also, for magneto-structural correlation studies a range of spectroscopic tools are usefully employed. Electronic spectroscopy in the visible region has been used for the Co(II), Ni(II), and Cu(II) complexes in this study as a means of probing the ligand-field environment of the central metal ion. Infrared spectroscopy was also employed to provide information on the nature of the coordination of neutral and anionic ligands through the analysis of diagnostic bands. DSC ( Differential Scanning Calorimetry ) combined with TGA (Thermal Gravimetric Analysis) play an important role in investigating the thermal properties of the compounds studied here yielding information on enthalpies of thermal processes, energies of melting, polymorphism, phase transitions, and decomposition pathways. The measurement of magnetic susceptibilities of the compounds down to cryogenic temperatures, together with the information obtained from X-ray crystallography, 11 spectroscopic methods, and thermal studies made the correlation of magnetic properties and structure possible. In the remainder of this chapter a brief introduction to each technique mentioned above is given. Only limited explanations of each technique are presented; instead, attention is focused on the kind of information that each method provides and where possible, examples where the particular technique has been utilized in early work are given. 1.4.1. X-ray Crystallography The evolution of our understanding of magneto-structural correlations has relied heavily upon the structural information obtained from a wide range of physical methods. Spectroscopic methods have played an important role, of course, but the most definitive structural data has largely been acquired using single crystal X-ray diffraction methodsf87a' 8 7 b t Some of the early work on metal phosphinates also involved the interpretation of X-ray diffraction photographs from oriented fibers and/or from powdersf62'63'66'67*870-88'89'903!. It can be difficult to obtain single crystals of polymeric metal phosphinates, so only relatively few structural determinations have been reported. Some of the metal phosphinate compounds for which X-ray structural data were available prior to the current work are listed in Table 1.1. 12 Table 1.1. X-ray structural data for selected polymeric metal phosphinates and adduct polymers. Compound Type of Bridge Geometry3 M-M(A)b Reference Zn[(n-QH9)2P02 (n-QdinhPOd Single-Triple distorted tetrahedral 9.90c 62d Zn[(n-C4H9)2P02]2 Single-Triple distorted tetrahedral 9.90c 63d Zn[(n-C4H9)(C6H5)P02]2 Single-Triple distorted tetrahedral 10.16* 64d Zn[(CH3)(QH9)P02]2 double distorted tetrahedral 4.58 67 Cu[(n-C4H9)2P02]2 double compressed tetrahedral 4.938 77 Cu[(C2H5)2P02]2 double compressed tetrahedral 4.956 ~ 5.025 20 Cu[(C6Hi3)2P02]2 double compressed tetrahedral 4.928-4.931 21 ZnrH(C6H5)2P02]2 double tetrahedral 82 Pb[(C6H5)2P02]2 double trigonal bipyramidal 68 Cu[(C6H5)2P02]2 double squar planar 5.081 78 Y-Co[(C6H5)2P02]2 double tetrahedral 4.329 - 4.363 e Y-Mn[(C6H5)2P02]2 double tetrahedral 4.417 - 4.446 e Table continued Table 1.1.(continued) Compound Type of Bridge Geometry3 M-M(A)b Reference Co(HCONH2)2[(H(C6H5)P02]2 double distorted octahedral 5.539 e Cd(HCONH2)2[(H(C6H5)P02]2 double distorted octahedral 5.761 e Mn(HCONH2)2[(H(C6H5)P02]2 double distorted octahedral 5.650 e {Mn(DMF)[(C6H5)2P02]2} DMF double trigonal bipyrarnidal 4.583 83 Cu[(CH3)(C6H5)P02]2(DMF) double square pyramidal 5.184-5.199 86 Mn(HCONH2)[(CH3)(C6H5)P02]2 double distorted octahedral, formamide oxygen atom forms a \i-0 bridge 4.020 85 Co(HCONH2)[(CH3)(C6H5)P02]2 double distorted octahedral, formamide oxygen atom forms a p>0 bridge 3.947 85 Cu(HCONH2)[(CH3)(C6H5)P02]2 double distorted octahedral, formamide oxygen atom forms a |i-0 bridge 4.056 85 a Coordination geometry around metal center. b Intrachain metal-metal separations. c Sum of M-M single and triple bridge separations. d Fiber X-ray diffraction. e This work. The X-ray powder diffraction pattern of a microcrystalline compound provides a convenient and characteristic fingerprint which can be used in qualitative analysis!901*' It permits one to identify isomorphous compounds. For example, the similarities in the X-ray powder diffraction patterns exhibited by Mn[H(C6H5)P02]2 and Cd[H(C6H5)P02]2 identified these as isomorphous and, likely, isostructural compounds!81!. One particular property that has been investigated using X-ray powder diffraction is polymorphism. This is common in many of the bivalent metal phosphinate polymers. For instance!89,91!, two distinct powder diffraction patterns were repeatedly observed for Zn[(RR'P02]2» where R=R'=C6H5- and for Co[(RR'P02]2, R=CH3- and for R'=C6H5-. These were assigned t to P- and y- polymorphs of these materials. 1.4.2. Solubil i ty Studies Solubility tests in polymer studies can provide some insight into the nature of the polymer, for example, whether it is predominantly a linear polymer and therefore expected to show some solubility in non-coordinating solvents, or whether it is a cross-linked, sheet polymer and therefore expected to be insoluble in non-coordinating solvents. Gillman and Eichelberger! 5 6 ! concluded on this basis that the zinc(II) and cobalt(II) methylbutylphosphinates are linear polymers, while the di-t-butyl and diphenyl analogues are cross-linked. Similarly, Flagg and Schmidt!92! characterized a variety of aluminum tris(phosphinates) by solubility studies in THF and concluded that these complexes are essentially linear polymers with perhaps a small amount of cross-linking. On the other hand, Gillman and his coworkers!93! suggested on the basis of solubility studies, that the amount of cross-linking is large in the chromium(III) hydroxo-bridged bisphosphinates, Cr[RR'P02]2(OH), (R=methyl and R'=phenyl or R=R*=n-octyl). Structural conclusions, drawn from solubility studies must, however, be considered very tentative. It was suggested for example, that because of its low solubility, Cu[(C6H5)2P02]2 might have a cross-linked sheet structure!13!. It was later shown that it is a chain polymer!78!. The cross-15 linked structure proposed for Co[(C6H5)2P02]2 on the basis of solubility propertiest56! is proven to be incorrect by work described in Chapter 5 of this thesis. 1.4.3. Thermal Properties The thermal properties of materials can be studied by Differential Scanning Calorimetry (DSC). This technique, when applied to coordination polymers, provides a means of determining thermal stabilities. In addition, enthalpy changes and temperatures at which chemical decomposition and physical changes (e.g. melting, fusion, glass transition, and crystallinity) occur can be established quantitatively by such measurements. The use of DSC combined with thermogravimetric analysis (TGA) allows the thermal changes (thermolysis) to be monitored not only by changes in enthalpy but also by the weight changes associated with the thermolysis reaction. Studies of solubilities and thermal properties also show a close correlation between the two techniques. For example, while the zinc(II) and cobalt(II) dimethyl- and diphenylphosphinates are high melting (the methyl derivatives melt at approximately 340 °C) or infusible (the diphenyl derivatives are infusible to above 450 °C), insoluble polymers, the methylphenylphosphinates are soluble in benzene and chloroform and soften or melt at low temperatures (90 °C and 120 °C, for the zinc and cobalt compounds, respectivelyE89*91]). DSC and T G A can be used to examine the stabilities of polymeric materials. Nannelli et al. t 3 °! found the stability of the metal phosphinates to be gready reduced by the introduction of phosphinates containing long chain alkyl groups. For example, Cr[(CH3)(C6H5)P02l3 undergoes a major weight loss due to thermal decomposition at 480 °C, but replacing one methylphenyl ligand with a di-n-hexylphosphinate reduces that temperature to 265 °C . This phenomenon has been attributed to the greater ease of oxidation of the longer alkyl chains. Aryl groups on the other hand lead to high temperature stability. Rose and Blockt 8 9 » 9 1 l investigated some bivalent metal diphenylphosphinates by T G A and found that both the zinc(II) and cobalt(II) compounds show thermal stability up 16 to a temperature of just under 500 °C. Such properties as the melting point and the glass transition temperature (studied by DSC) can also be varied, for a given metal complex, by changing the substituents on the phosphinate ligand. This has been attributed, partially, to the ability of the longer alkyl chains to shield the polymer backbone from polar interchain mteractionsl30'62'88,903'94] more effectively than groups such as methyl.or phenytf63!. In addition, Wunderlichl95] has described the melting of extended chain systems in terms of their DSC melting curves and concluded that broadness or sharpness of the melting curve may be interpreted in terms of the distribution of molecular weights present in a given system; the narrower the distribution, the sharper the melting curve and vice versa. DSC provides important information in the investigation of polymorphism, a phenomenon which seems common in many of the bivalent metal phosphinate polymerst 2 7 , 5 5" 5 7 , 6 2 , 6 5 , 6 8 , 8 8 , 8 9 , 9 1]. Different polymorphs of the same compound typically exhibit different DSC thermograms and where conversion of one polymorph into another can be achieved thermally, the process is readily studied by DSC. There are different factors which may cause a given polymer to exist in different forms, for example, i) the compound crystallizes in slighdy different ways, yielding the same basic polymer structure but a different unit celtf65], ii) there may be differences in the orientations of the organic groups attached to phosphorus yielding different polymer structures^57*62,68'88'89,91] and iii) there may be a difference in the coordination number or geometry of the metal from one form to another. Normally, by heating and/or dissolving in an appropriate solvent, one form can be converted into another form either reversibly or irreversibly. For example, Gillman and Eichelbergert56! isolated the nickel(II) di-n-butyl- and di-n-octylphosphinates from preparative mixtures as octahedral compounds containing unsymmetrically bridging phosphinate ligands; however, upon melting and re-solidifying, both compounds are obtained as polymers containing tetrahedral metal centres and symmetric phosphinate bridging ligands. At times, different preparative routes yield different forms for a given 17 polymer! 5 4 ' 8 9 ' 9 1 ! . In the preparation of cobalt(H) methylphenylphosphinate, for example, Rose and Blockf 8 9 ] found that when using ethanol as solvent, a crystalline solid, (fJ-Co[(CH3)(C6H5)P02]2 )»is obtained. This compound is insoluble in common organic solvents and has a melting point of 210-211 °C . Using benzene as the solvent, these authors prepared another crystalline solid y-Co[(CH3)(C6Hs)P02]2- This form of the compound is also insoluble, however, it melts at a higher temperature (226 - 227 °C). 1.4.4. Infrared Spectroscopy Infrared spectroscopy can provide information about the coordination mode(s) of the ligands in complexes, the stereochemistry around the metal, and the strength of metal-ligand interactions! 9 6' 9 7]. For ligands with high symmetry in the non-coordinated ("free") state, infrared spectroscopy can, in some cases, distinguish between possible coordination modes based on the appearance of infrared inactive bands and/or the splitting of degenerate vibrations, due to the lowering of ligand symmetry upon coordination. A typical example of this is sulfate!9 8!, which has Td symmetry when it is in a non-coordinated state. Monodentate coordination reduces the symmetry to C 3 v and bidentate coordination reduces it to C2v- These two bonding modes are distinguishable on the basis of the number of bands present in the infrared spectrum. In the case, for example, of carboxylate or phosphinate ligands, where the maximum free-ion symmetry is low (C2v or Cs), structural inferences must come from the positions, rather than the number of bands. Information on the strength of the metal-ligand interaction can also be obtained by comparing the number and the frequencies of infrared absorptions of the ligand in the "free" and coordinating states!""101!. The phosphinate ligands considered in this work have a maximum free-ion symmetry of Cs or C2v- For RRTO2" (C2v» when R=R'), nine fundamentals are expected (4Ai , 1A 2 , 2 B i , 2B 2 ) for the C2PO2" part of the ligand, none of which are degenerate and only one of which, the A 2 (torsion) mode, is infrared inactive. In the case of HRPO2" (C$ 18 symmetry), nine fundamentals are again expected, 6A1 and 3A", of which none are degenerate, and all are infrared active!102]. Clearly, if any structural information can be obtained from the infrared spectra of metal phosphinates it must come from an analysis of band positions. Oldham^103! examined the shifts of CO2 stretching frequencies in carboxylates upon coordination and, with reference to this work, Gillman and Eichelbergert55'56] correlated the frequency shifts observed for the antisymmetric and symmetric PO2 stretches in phosphinates with the coordination mode of the phosphinate and hence with the geometry about the metal. The manner in which the phosphinate ligand binds will depend on a number of factors such as: i) the preferred coordination number and stereochemistry of the metal involved and, ii) the substituents on phosphorus. The substituents can introduce steric restrictions on the type of phosphinate bonding possible. Some of the possible symmetric and unsymmetric binding modes of phosphinates are shown in Figure 1.3[56,57,104,105] Types I-IV are symmetric bonding types (each oxygen of the phosphinate ligand is bonded to the metal in an equivalent manner resulting in two equivalent PO bonds). Based on the work of Gillman and Eichelbergert55*56], these are expected to have smaller separations between the antisymmetric and symmetric PO2 stretching modes (Av = VP0 2 anti.- VP0 2 sym.) than the unsymmetric bonding types (types V-VIII) which involve non-equivalent PO bonds. Structures IX, X, XII, and XIV show possible chain polymer structures involving symmetric and unsymmetric bonding modes with tetrahedral or octahedral metal centres. Types XI, XIII, XV, and XVI show possible sheet polymer structures involving symmetric (XI and XIII) and unsymmetric (XV and XVI) bridging coordination. For types IX and X, examples of which have been confirmed by X-ray crystallography, A is around 70 cm"! and the antisymmetric and symmetric PO2 stretching frequencies are in the range, 1150-1100 and 1065-1025 cm"*, respectively. In types XII and XIII there are two distinct RR'PO"2 groups, suggesting the possibility of four PO2 stretching modes for both of these structural types. 19 Examples of symmetric PO2 bonding > o;V> 9 X 9 p f ^ A X A M fvl iCl M M M MM MM i 11 in iv Examples of unsymmetric P02 bonding = w \ / \ / \ / o'p*o yo'Pxo o'Pxov cTPvo M M M M M M M M V VI VII VIII Possible polymer structures^ Symmetric Figure 1.3. RR'P02" bonding modes and possible polymeric structures. Taken from references 56,57,104 and 105. 20 XIII Unsymmetric: i XVI Figure 1.3 (continued). RR'POi* bonding modes and possible polymeric Structures. Taken from references 56,57,104 and 105. 21 1.4.5. Electronic Spectroscopy The coordination geometry of transition metal complexes can often be determined from their ultraviolet, visible and near-infrared region electronic spectra. Studies of the electronic spectra of complexes are also important when the nature of the chromophore has been determined by X-ray crystallography; the results obtained for complexes of known structure can then be extended to probe the nature of the chromophores in compounds where detailed structure determination by X-ray crystallography is not possible. At the present time, the published electronic spectral data on metal phosphinates is sparse and, where reported, the spectra have rarely been assigned or interpreted. We have met with some success in the present work in determining structural information from examining the visible region electronic spectra of cobalt, nickel and copper phosphinate complexes. What follows is a very brief overview of aspects of the electronic spectra of manganese(II), cobalt(II), nickel(II) and copper(n) complexes relevant to this work. The spectra of octahedrally or tetrahedrally coordinated spin-free manganese(II) complexes differ from those of many other transition metal ions. The bands in these compounds are very low in intensity (apart from any charge transfer bands). Hence, colors of these complexes are very pale, usually pink for octahedral and green for tetrahedral. Finely ground solids appear white. The explanation stems from the fact that any electronic d-d transition involving a high-spin d5 configuration must of necessity involve the pairing of some electron spins. It follows that such transitions are spin-forbidden and the absorptions are low in intensity. This makes the examination of the electronic spectra of manganese(II) complexes difficult particularly when dealing with solid state powders as in the present work. No electronic spectra are obtained for the manganese complexes studied here. Cobalt(II) is a common d7 ion and because of its stereochemical diversity the spectra of its complexes have been widely studied^106'107]. In either an octahedral or a tetrahedral ligand field, three spin-allowed electronic transitions are expected. 22 Quantitatively, the two cases differ considerably, as might be inferred from the simple observation that octahedral complexes are typically pink, whereas many common tetrahedral ones are an intense blue. In both stereochemistries the visible spectrum is dominated by the highest energy transition, 4 Ti(P)<- 4 A 2 for tetrahedral and 4Tig(P)<—4Tig(F) for octahedral complexes. In octahedral systems there is a 4 A 2 g level close to the 4Ti g(P) level. Since the 4 A 2 g state is derived from a t 2g 3e g 4 electron configuration, and the 4Ti g(F) ground state is derived mainly from a t 2 g 5e g 2 configuration, the 4A2g<— 4Tig(F) transition is essentially a two-electron process and is often not observed. Thus it is weaker by about a factor of ~ 100 than the other transitions and hence a total of only two bands is normally seen in octahedral complexes. In tetrahedral systems, the visible transition is generally about an order of magnitude more intense and displaced to lower energies compared to the corresponding band in octahedral complexes. The assignment of stereochemistry in cobalt(H) complexes is often more reliably based on color intensity than on simple color. It is known, for instance^07!, that octahedral CoCl2 has an "anomalous" blue color which arises from the fact that 6 CI" ions generate such a weak crystal field that the main band in its spectrum is at an unusually low energy, extending into the red region (hence giving a blue color). An example of the use of electronic spectroscopy in previous studies on poly(metalphosphinate) comes from the work of Gillmant54]. The two forms of cobalt(II) dioctylphosphinate were assigned to octahedral and tetrahedral geometries based on a detailed analysis of their electronic spectra. As for cobalt(II), octahedral and tetrahedral spin-free nickel(II) complexes (d8 configuration) exhibit three spin-allowed bands in their electronic spectra. In an octahedral field the bands, in order of decreasing energy, are assigned as: 3Tig(P)<—, 3Tig(F)<- and 3 T 2 g <- 3 A 2 g . Quite often there is also evidence for a weak spin-forbidden (i.e. spin triplet-*singlet) absorption giving rise to shoulder on the 3Ti g(P)<- 3A 2 g band. For d 8 ions in tetrahedral fields the splitting of the free-ion 3 F ground term is the inverse of its splitting in an octahedral field, so that the 3Ti(F) term lies lowest. In practice the spectra 23 are a good deal more intense than those of octahedral complexes and the bands are often split by spin-orbit coupling to such an extent that unambiguous assignment is difficult. The copper(II) ion (d9 configuration), by virtue of the Jahn-Teller effect, is typically found in low symmetry environments (i.e., less than cubic), making detailed interpretation of the spectra somewhat complicated, even though one is dealing with the equivalent of a one-electron system. Virtually all complexes are blue or green, the color arising from the presence of an absorption band typically in the 600 ~ 900 nm region of the spectrum. The envelopes of these bands are generally unsymmetrical, seeming to encompass several overlapping transitions. 1.4.6. Magnetic Susceptibility The magnetic properties of transition metal compounds, when recorded as a function of temperature, provide information on the nature of the ground state of the metal[108-114] Several factors influence the magnetic properties of paramagnetic systems including d-orbital configuration, ligand-field symmetry, spin-orbit coupling and electron-delocalisation effects. In addition, the magnetic properties may be measurably affected by magnetic exchange interactions of various types.Two important examples of this are where the electrons in neighboring paramagnetic centres align either parallel or opposed to each other, resulting in ferromagnetism or antiferromagnetism, respectively. The theory of magnetic susceptibility of transition-metal complexes is well covered^108"120! and theoretical aspects of the mechanisms of exchange and the models used to interpret and fit the experimental data have been the subject of extensive investigationst108"114!. In the present work the magnetic studies are not usually employed to obtain structural information as such. Instead, the work is aimed at obtaining correlations between structure and magnetism in magnetically concentrated systems, specifically systems in which transition metal ions in paramagnetic ground states are bridged by phosphinate ligands. In this work, the structural information comes from the application of a variety of 24 other techniques as described above. A brief description of the magnetic properties to be expected of complexes of manganese(II), cobalt(n), nickel(II) and copperQT) follows. The spin-free manganese (II) ion has an odd number of electrons, with 6 Ai as the electronic ground state in octahedral or tetrahedral geometry. The g value is isotropic at about 2.00. Zero-field splitting is usually small and the ground state is well-isolated from higher energy levels. In a magnetically dilute system, the magnetic moment is the spin-only value of 5.92 pis and is independent of temperature. Any deviation from this (except possibly at very low temperatures) is indicative of magnetic coupling. Cobalt(II) has a d7 configuration. For the high-spin situation, the ground state for an octahedral crystal field is 4 T i g and an important orbital contribution to the magnetic moment is expected. The moment at room temperature is typically around 5.2 UB» falling as the temperature decreases. This temperature dependence makes the identification and interpretation of magnetic exchange effects in octahedral complexes rather difficult. This matter is dealt with in more detail at appropriate points later in this thesis. In a tetrahedral ligand field, a 4 A 2 ground state results. Since there is no orbital angular momentum associated with this term to first order, the moment is expected to be close to but slightly higher than spin-only and to be temperature independent except possibly at low temperatures where zero-field splitting effects become important. In octahedral ligand fields, the ground term of nickel(II) complexes is 3 A 2 g and, as for tetrahedral cobalt(II) described above, the magnetic moment is expected to be close to but slightly higher than the spin-only value and to be temperature independent except possibly at low temperatures. In tetrahedral ligand fields, the nickel(II) ion has a 3 Ti ground state and would be expected to exhibit temperature dependent magnetic moments as described above for octahedral cobalt(II). No tetrahedral nickel(II) complexes were obtained in this work and hence the magnetic properties of such systems are not discussed further here. The copper(II) ion has a d9 configuration and, typically, exhibits paramagnetism 25 corresponding to one unpaired electron. Octahedral coppenTI) complexes would have an 2 E g ground state and would be expected to have moments close to but slightly higher than the spin-only value and independent of temperature. Tetrahedral compounds, if regular, would have a 2 T 2 ground state, which would be expected to yield an orbital contribution to the moment. Copper(TJ) complexes tend to be distorted and generally exhibit temperature independent moments slighdy larger than the spin-only value. A temperature dependent moment usually indicates the presence of magnetic exchange in copper complexes. 1.5. Organization of the Thesis A general introduction which includes a description of the historical development of metal phosphinate chemistry is given in this chapter, along with a description of how a variety of physical techniques may be used to characterize coordination polymers. Adducts of transition-metal monophenylphosphinates with the general formula of ML2[H(C6H5)P02]2, where M = Mn, Ni, Co and Cd and L = H20, H(C6H5)P02H, HCONH2, HCONHCH3, C H 3 C O N H 2 , HCON(CH3)2, pyridine, and pyrazine were prepared in the present study. Chapters 2, 3 and 4 are organized to discuss the complexes of manganese, cobalt and nickel respectively. Each chapter begins with a description of the experimental procedures used for the preparation of the compounds. Following this, the results of compound characterization studies are presented and interpreted. In some cases the structures were clearly identified by X-ray crystal structure determinations; in the absence of such conclusive evidence, the proposed structures were based upon spectroscopic evidence and X-ray powder diffraction studies. In all cases the magnetic properties were investigated over the temperature range of - 4 to ~80 K (sometimes studies were done down to 2.2 K) and magneto-structural correlations are discussed. Studies on the preparation, structural and magnetic characterization of three metal diphenylphosphinates, those of Mn, Co and Cd are described in Chapter 5. In Chapter 6, studies on some mixed metal manganese/cadmium phosphinate systems are presented and 26 discussed. Some miscellaneous compounds are discussed in Chapter 7, while experimental details are presented in Chapter 8. A summary, with general conclusions and suggestions for further study are presented in Chapter 9. 27 Chapter 2 Complexes of Manganese(II) Monophenylphosphinate 2.1. Introduction The synthesis and characterization of complexes of manganese(II) monophenylphosphinate with the general formula, MnL2[H(C6H5)P02], where L = H 2 0 , HCONH2, HCONHCH3, CH3CONH2, H(C6H5)P02H and C5H5N, are described in this chapter. Three of the compounds, M n ( H C O N H 2 > 2 [ H ( C 6 H s ) P 0 2 ] 2 , Mn[H(C6H 5 )P02H]2[H(C6H 5 )P0 2 ]2 and Mn(CH3CONH2)2[H(C 6 H5)P0 2 ]2 were obtained in crystalline form suitable for single crystal X-ray diffraction studies. These studies, which showed all these compounds to have polymeric structure, provided an excellent opportunity to investigate relationships between structural parameters and magnetic properties. Structural studies on the other manganese compounds described here, using indirect methods, indicated that they also have chain structures, thus permitting then-inclusion in this general study of the effects of neutral donor ligands on magnetic exchange in poly(manganese phosphinates). The crystal structure of Mn(HCONH2)2[H(C6H5)P02]2 described in this chapter is the work of A . Bino and P. Betzt 1 2 1 ! at the Hebrew University of Jerusalem. These authors also reported to us single crystal X-ray diffraction studies on Mn[H(C6H5)P02H]2[H(C6H5)P02]2 although there were problems with their study S. Rettig of the X-ray Crystallography Laboratory at the University of British Columbia completed the structure determination on this compound. This work and all other studies reported in this chapter were completed at U.B.C. 28 2.2. Results and Discussion 2.2.1. Syntheses, Solubilities and Thermal Properties Detailed descriptions of the synthetic procedures used to obtain the manganese complexes are given in Chapter 8. All compounds were obtained as precipitates from solution and the routes used are summarized by the equations below. H 2 0 2H(C6H5)P02H + K2CO3 + M n S 0 4 H2O »• Mn(H20)2[H(C^H5)P02]2 + K 2 S0 4 + C02 [2.1] Acetone 2H(C6H5)P02H + Mn(C104)2-6H20 + 4HCONH2 Mn(HCONH2)2[H(C6H5)P02]2 + 2HCONH2HC104 + 6H20 [2.2] H 2 0 2H(C6H5)P02H + 2H(C6H5)P02Na + Mn(C104)2 -6H20 Mn[H(C6H5)P02H]2[H(C6H5)P02]2 + 2NaC104 + 6 H 2 0 [2.3] HCONHCH3 Mn[H(C6H5)P02]2 + 2HCONHCH3 ^ Mn(HCONHCH3)2[H(C6H5)P02]2 [2.4] Acetone 2H(C6H5)P02H + 4CH3CONH2 + MnCl2-4H20 Mn(CH3CONH2)2[H(C6H5)P02]2 + 2CH3CONH2HCl + 4 H 2 0 [2.5] Pyridine Mn[H(C6H5)P02]2 + 2C5H5N > Mn(C5H5N)2[H(C6H5)P02]2 [2.6] The compounds are relatively soluble in H2O and CH3OR and insoluble or only slighdy soluble in CH3CH 2 OH, CHCI3, C6H6, CCLj and CH2CI2. It would appear that strongly polar, hydrogen bonding, solvents are needed to dissolve these polymeric materials. These solvents would be expected to solvate strongly phosphinate groups and, in so doing, break up any interchain interactions present and/or the intrachain phosphinate bridges. The pyridine complex as judged by its microanalysis (Chapter 8) and the presence 29 of a weak broad band centered around 3300 cnr 1 contains a trace amount of lattice water (less than 0.5 mol). The results of the DSC (Differential Scanning Calorimetry) analyses are given in Table 2.1 and the DSC thermogram for Mn(HCONH2)2[H(C6H5)Pb 2]2 is shown in Figure 2.1. As shown in the Table, a l l of the compounds except Mn(HC0^2 ) 2 [H (C6H5 )P02 ]2 exhibit a single endothermic event at around 120 to 140 °C. Mn(HCONH2)2[H(C6H5)P0 2]2 exhibits a second event at 189 °C. The weight loss measurements indicate these events corresponding to loss of both neutral ligands; in the case of the formamide complex this takes place in two separate steps. Exothermic decomposition for all the compounds is noted in the temperature range of 220-240 °C. This corresponds to the decomposition temperature of 220 °C observed for Mn[H(Cf5H5)P02]2-There is no evidence for phase transitions over the range from room temperature to the decomposition temperature for any of the compounds. Table 2.1. Thermal parameters for MnL2[H(C6H5)PC>2]2 complexes. L Peak Temp CC) A H (kJ mol"1) % Weight Loss Calcd 3. Obs. H 2 0 130 108 10 10 240 b H C O N H 2 140 21 22 189 35 233 b H C O N H C H 3 131 60 25 26 230 b C H 3 C O N H 2 131 48 13 13 220 b H ( C 6 H 5 ) P 0 2 H 140 93 200 b C 5 H 5 N 123 116 33 28 221 b a Calculated for loss of all neutral ligands. b Onset of oxidative decomposition. A l l other events are endothermic. 30 Figure 2.1. Thermogram of Mn(H(X>NH2)2[H((^ 5)P02]2. 31 2.2.2. Single Crystal X-ray Diffraction The structure of Mn(HCONH2)2[H(<^ H5)PC>2]2 was determined by Bino and Betz at the Hebrew University of Jerusalem while the other two structures reported here were determined by S. Rettig in the X-ray crystallography laboratory at the University of British Columbia. 2.2.2.1. Structure of Mn(HCONH2)2[H(C6H5)P02]2 Crystallographic data for Mn(HCONH2)2[H(C6Hs)P02]2 are given in the Appendix and some bond distances and angles are given in Table 2.2. Figure 2.2 shows the atom numbering scheme and Figure 2.3 shows a stereoscopic view of a section of the polymeric chain of this compound. The structure of Mn(HCONH2)2[H(C6H5)P02l2 consists of polymeric chains, propagating along the crystallographic b axis, in which two phosphinate ligands form double O-P-0 bridges between adjacent metal atoms. Two formamide molecules are coordinated via oxygen to each metal atom, completing a distorted octahedral geometry around the metal. The intrachain distance between metal atoms in this compound is 5.650 (1) A. Intramolecular hydrogen bonds between the NH2 group of the coordinated formamide ligand and an oxygen atom of a bridging phosphinate group exist with N—0(2) separations of about 2.9 A. The second NH2 hydrogen atom on each formamide ligand is involved in a hydrogen bond with a phosphinate oxygen of a neighboring chain with an N—0(1) distance of about 2.9 A. An important feature of this structure, which will be reported on later, is that the Mn-O-P-O-Mn bridges involve relatively symmetrical O-P-0 unit (P—O(l) and P—0(2) distances of 1.519(4) and 1.511 (4)A , respectively). The total Mn-O-P-O-Mn distance (sum of bond lengths), an important feature in relation to the discussion of magnetism to follow, is 7.38 (1) A. 32 Table 2.2. Bond distances (A) and bond angles (*) for Mn(HC0NH2)2[H(C6H5)PO2]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond Distances(A) AnglesO Mn—0(1) 2.149(3) Mn—0(2)' 2.201(3) Mn—0(3) 2.241(3) P-O(l) 1.519(4) --0(2) 1.511(4) O(l)—Mn—0(2)' 89.8(1) —0(2)" 90.2(1) - 0 ( 3 ) 92.1(1) - 0 ( 3 ) ' 87.9(1) 0(2)'—Mn—0(3) 91.8(1) - 0(3)' 88.2(1) © 0 3 -Figure 2.2. View of Mn(HCONH2)2[H(C6H5)P02]2 showing the numbering scheme and coordination about the manganese atom. 33 Figure 2.3. Stereoview of a section of Mn(HCONH2>2lH(C^5)P02]2-2.2.2.2. Structure of M n ( C H 3 C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 The structure of Mn(CH3CONH2)2[H(C6H5)PC>2]2 shows many similarities with the structure of the formamide complex discussed above; however, some significant differences are also noted. A view of a portion of the polymeric chain and the atom numbering scheme of Mn(CH3CONH2)2[H(C6H5)P02]2 is shown in Figures 2.4 and 2.5 and selected intramolecular bond distances and angles are given in Table 2.3. A complete compilation of X-ray structural data is give in the Appendix. As found for the formamide complex, the coordination sphere around manganese consists of a square-planar array of oxygen atoms from four different phosphinate groups with axial coordination sites occupied by oxygen atoms from coordinated amide molecules. Both interchain and intrachain hydrogen bonding interaction are present here also resulting in N—0(2) and N—0(1) separation of about 2.982(2) A and 3.074(2) A respectively. Like the situation in the formamide complex, the P-O distances are similar (P—O(l) and P—(2) distances of 1.510(1) and 1.512(1) A , respectively). The total Mn-O-P-O-Mn distance of 7.428(4) A , in this case, greater than that in the formamide complex. 34 Figure 2.4. View of Mn(CH3CX)NH2)2[H(C6H5)P02]2 showing the numbering scheme and crjordination about the manganese atom. Figure 2.5. Polymeric structure of Mn(CH3CONH2)2[H(C6H5)P02]2-35 Table 2.3. Bond distances (A) and bond angles (') for Mn(CH3CONH2)2[H(C6H5)P02]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond Distances(A) AnglesO Mn—0(1) 2.232(1) Mn—0(2)'* 2.174(1) Mn—0(3) 2.182(1) P—0(1) 1.510(1) —0(2) 1.512(1) 0(2)'—Mn—0(3) 90.35(5) —0(2)* 89.65(5) —0(1) 92.11(5) —0(1)* 87.89(5) 0(3)—Mn—O(l) 89.88(5) 0(3)*—Mn—0(1) 90.12(5) a Here the symbols ' and * refer to the symmetry operations: 1+x, y, z and 1-x, 1-y, 1-z. 2.2.2.3. Structure of Mn[H(C6H5)P02H]2[H(C6H5)P02]2 The atom numbering scheme and a stereoscopic view of a section of the polymeric chain of Mn[H(C6H5)P02H]2[H(C6H5)P02]2 are shown in Figures 2.6 and 2.7. Selected intermolecular bond distances and angles are given in Table 2.4 and a complete compilation of the structural parameters is given in the Appendix. The structural analysis shows that the structure of Mn[H(C6H5)P02H]2[H(C6H5)P02]2 is similar to that shown by the formamide and acetamide complexes with, in this case, neutral acid molecules occupying the axial positions. A major difference here is the presence of intrachain hydrogen bonding only and no interchain hydrogen bonding. This results in an unsymmetrical O-P-0 bridging unit with P—0(1) and P—0(2) distances of 1.500(2) and 1.524(2) A , respectively. This makes the bridging unit in this complex the most unsymmetrical among all the three 36 complexes discussed in this section. The Mn-O-P-O-Mn distance here (7.43(1) A) is the same as that in the acetamide complex. Figure 2.6. View of MnrH(C^5)P02H]2[H((^ H5)P02]2 showing the numbering scheme and coonlination about the manganese atom. Figure 2.7. Stereoview of a section of Mn[H(C6Hs)P02H]2lH(C^5)P02]2. 37 Table 2.4. Bond distances (A) and bond angles (") for Mn[H((^5)P02H]2[H(C6H5)P02]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond Distances(A) AnglesO Mn—0(1) 2.165(2) Mn—0(2)'* 2.175(2) Mn—0(3) 2.243(2) P-O( l ) 1.500(2) -0(2) 1.524(2) O(l)—Mn—0(3) . 85.68(7) —0(3)" 94.32(7) -0(2)' 90.75(7) —0(2)* 89.25(7) 0(3)—Mn—0(2)' 88.32(7) —0(2)* 91.68(7) a Here the symbol'," and * refer to symmetry operations: 1+x, y, z; -x, 1-y, 1-z; 1-x, 1-y, 1-z ; and x-1, y, z; respectively. 2.2.3. X-ray Powder Diffraction Diffraction patterns for all the compounds studied in this Chapter are given in Figure 2.8 and the d-spacings and intensities are listed in the Appendix. Although these complexes are considered to have similar polymeric chain structures, as has indeed been proven in the case of the HCONH2, CH3CONH2 and H(C6Hs)P02H complexes, they are not isomorphous as shown by the unique X-ray patterns exhibited by each. 38 (A "E 3 L. c 9 O U J . - J J U L A . IJULILLI *LOLL 10.0 20.0 30.0 40.0 50.0 60.0 26 Figure 2.8. X-ray powder diffraction patterns for MnL2[H(C6H5)P02]2 complexes: a) L= HCONH 2 , b) L= H(C 6 H 5 )P0 2 H, c) CH 3 CONH 2 , d) L= py, e) L= HCONHCH3 and f) L= H 2 0 . 39 2.2.4. Infrared Spectroscopy Infrared spectroscopy was routinely used in this work as the initial test of product purity. Infrared bands observed for all of the complexes over the 4000 to 250 cm"1 range are given in the Appendix. We will concentrated here on the PO2 and PH stretches of the bridging ligand and the NH and OH vibrations of the neutral amide and acid ligands. The infrared data for these vibrations are listed in Table 2.5. The absorptions appearing in the 1200-950 cm"1 region are readily assigned to the antisymmetric and symmetric PO2 stretches of the coordinated phosphinate groups. The frequencies and A values (A = VP02 anti. - VP02 sym.)[31>55>56] for the compounds studied here are given in the Table. The A values observed range from 80 to 120 cnr1 suggesting that the P-O bond type may range from equivalent P-0 bonds as in Mn(HCONH2)2[H(C6Hs)P02]2 and Mn(CH3CONH2)2[H(C6H5)P02]2 to unequivalent P-0 bonds as in Mn[H(C6H5)P02]2[H(C6H5)P02]2 (results of X-ray structure). The results here are consistent with those of X-ray single crystal diffraction studies since the two compounds which have symmetrical O-P-0 bridge show A values of 84 and 89 cm"1 while the one with unsymmetrical O-P-0 bridge exhibits a value of 118 cm"1. Although there are no crystal structure data available for the H2O, HCONHCH3 and C5H5N adduct complexes, it may be inferred from the infrared data that the H2O complex has a rather symmetrical O-P-0 bridging unit while the HCONHCH3 and C5H5N complexes likely have unsymmetrical O-P-O units. The spectra for all of the compounds include numerous shoulders, of lesser intensity, on the strong PO2 stretching absorptions. This has been observed in the infrared spectra of a number of transition metal phosphinatest56-57]. Shoulders have been described as due to one of three possibilities such as overtones, combination bands, or PO2 stretching frequencies caused by phosphinate structures not predorninant in the bulk polymer. One of these may be the explanation in the present case; however, the bands seen here are of medium to strong intensity and perhaps another explanation is that they arise from 40 vibrational coupling between adjacent rings!3 ^ and/or from such effects as factor group splitting!96], giving rise to fairly intense absorptions. Table 2.5. Selected infrared data (cm"1) for MnL2[H(C6H 5)P02]2 complexes8. L V P02 anti. v P 0 2 s y m . A vp -H VN -H v o - H VCO H 2 0 1144 vs. 1060 s. 84 2357 m. 3318 s.br. 1697 m. H C O N H 2 1130 vs. 1046 s. 84 2380 m. 3250 m.br. 1674 s 3128 m.br. 1698 m.sh HCONHCH3 1162 vs. 1048 s. 114 2379 m. 3224 m.br. 1657 vs. CH3CONH2 1134 vs. 1045 s. 89 2380.m. 3360 m.br. 1653 vs. 3160m.br. H(C6H 5)P02H 1144 vs. 1026 s. 118 2398 m. 3360 w.br. 3181 w.br. C5H5N 1192 vs. 1070 s. 122 2310 m. 2280 m. Here and elsewhere in this thesis: vs., very strong; s., strong; m., medium; w., weak; vw., very weak; sh., shoulder and br., broad. It is apparent from the single crystal X-ray diffraction studies that all the amide ligands are bonded to the metal through the oxygen, therefore, a lower carbonyl stretching frequency (compared to that in the free state) is expected. The following shifts are observed: (i) for HCONH2 from 1680 (free)! 1 2 2! to 1674 cm" 1 (coordinated), (ii) for HCONHCH3 from 1663 (free) to 1657 cm" 1 (coordinated) and (iii) for CH3CONH2 from 1680 (free) to 1653 cm" 1 (coordinated). The effect on the NH2 vibration of the hydrogen bonding in these complexes is also seen. In the formamide complex for example the NH2 41 stretching vibrations are observed at 3250 and 3128 cm -1, considerably shifted from the frequency of ~ 3310 cnr1 observed in the free amidet122t But in contrast, the NH2 stretching vibrations in the acetamide complex appear to be unshifted in view of the frequencies of 3370 and 3163 cm -1 in the free amidet123] and 3360 and 3160 cm"1 observed in the complex. Only one NH stretching vibration is observed at 3224 cm"1 in the methylformamide complex. No shift has been observed as compared with 3220 cm*1 in the free amide stated 1 2 3 l As shown by the single crystal X-ray diffraction studies the formamide and acetamide ligands are involved in intra- and interchain hydrogen bonding in their compounds. The phosphinic acid adduct complex exhibits intrachain hydrogen bonding only. We note the effect of hydrogen bonding interactions on the OH stretching vibration of the diaquo complex also. The spectrum of Mn(H20)2[H(C6H5)P02]2 exhibits a strong broad band around 3322 cm - 1 which is about 300 cm"1 lower than the corresponding absorption of H2O in the gasous stated. The absorptions appearing in the 2200-2500 cm"1 region are readily assigned to P-H stretching vibrations^35'45'124"128]. It is interesting to note here that the absorptions in this region for the HCONHCH3, CH3CONH2, HCONH2 and H(C6Hs)P02H complexes are at higher frequencies than for the H2O and C5H5N complexes. The shift to higher frequencies may occur as a result of the phosphorus atom attempting to compensate for electron density lost through donation from oxygen to the metal, i.e., the P-H bond is somewhat strengthened. Such shifts have been observed and accounted for in this way previously^13]. This is analogous to the increase in vp-F seen upon the coordination of F7PO2" to a metatf129]. The implication in this analysis is that since the vP-H vibration is at a lower frequency in the H2O and C5H5N complexes, these complexes must have weaker phosphinate oxygen to metal bonds than do the other complexes. The band assignments due to pyridine for Mn(C5H5N)2[H(C6H5)P02]2 are given in the Appendix. It has been previously reported that there are considerable frequency shifts 42 in the infrared absorptions of coordinated pyridine relative to uncomplexed pyridine! 1 3 °1, with the 8a, 6a and 16b vibrations in particular showing a more pronounced coordination dependence. The results obtained for this compound are consistent with these observations, with the 6a, and 16b bands appearing at about 624 and 424 cm*1, respectively, as has been reported for other pyridine complexes! 130-132] 2.2.5. Magnetic Properties Magnetic susceptibility and magnetic moment data for MnL2[H(C6Hs)P02]2 complexes are given in the Appendix. All of the compounds studied here exhibit antiferromagnetic behavior as shown by the magnetic moment versus temperature plots. The value of u^ ff decreases with temperature for all six complexes (Figure 2.9). Three of the complexes, where L=HCONH2 , HCONHCH3, and CH3CONH2, exhibit maxima in their %M versus temperature plots at ~ 6.0, 3.5 and 3.2 K, respectively (Figure 2.10). This behavior is typical of antiferromagnetic complexes. For the other three complexes the susceptibility maxima are assumed to occur below the temperature range accessible to our equipment. Three of the MnL2[H(C6H5)P02]2 complexes are proven by X-ray diffraction studies to have extended structure (Section 2.3) and, assuming the other three complexes have similar structures, we have analyzed the magnetic properties of all six according to the same theoretical models. Two models are available for the theoretical analysis of antiferromagnetic exchange in linear chain manganese (II) compounds. According to the Wagner-Friedberg model!133!, the magnetic susceptibility, XM. is given by the following equation; Ng^SCS+l) i + • XM= 3fcf l - u [ 1 ] t In this equation, U = Coth(K-l/K) and K = 2JS(S + l)/kT, where U\R is the Bohr magneton, k the Boltzman constant, T the temperature in Kelvin, g the Lande splitting 43 f a c t o r , J t h e c o u p l i n g c o n s t a n t a n d S i s 5 / 2 f o r m a n g a n e s e Q I ) . I n t h e s e c o n d m o d e l , H i l l e r et a / J 1 3 4 l h a v e g e n e r a t e d a s e r i e s o f c o e f f i c i e n t s t o r e p r o d u c e W e n g ' s n u m e r i c a l r e s u l t s t 1 3 5 ] f o r t h e m a g n e t i c s u s c e p t i b i l i t i e s . A c c o r d i n g t o t h i s m o d e l ; w h i c h w e r e f e r t o a s W e n g m o d e l : m kT [ 1 + C X + D X 3 ] U J I n t h i s e q u a t i o n , f o r S = 5 / 2 , A = 2 . 9 1 6 7 , B = 2 0 8 . 0 4 , C = 1 5 . 5 4 3 , D = 2 7 0 7 . 2 a n d X = J / k T . O u r e x p e r i m e n t a l r e s u l t s w e r e a n a l y z e d u s i n g b o t h m o d e l s w i t h f i t s m a d e t o t h e s u s c e p t i b i l i t y d a t a a n d w i t h J a s a v a r i a b l e p a r a m e t e r a n d g f i x e d a t 2 . 0 0 . T h e b e s t f i t t o t h e e x p e r i m e n t a l s u s c e p t i b i l i t y d a t a w a s o b t a i n e d b y a d j u s t i n g J u n t i l t h e f u n c t i o n , F , d e f i n e d b e l o w , w a s m i n i m i z e d . V I n /Y;calc.. y-obs.\2 I n e q u a t i o n [ 3 ] , X i c a l c " i s t h e c a l c u l a t e d m o l a r s u s c e p t i b i l i t y , X i o b s - t n e o b s e r v e d s u s c e p t i b i l i t y a n d n t h e n u m b e r o f d a t a p o i n t s . 4 4 ca B © & CB s 100 Temperature (K) Figure 2.9. Magnetic moment versus temperature plots for MnL2|H(C6H5)P02]2 complexes: a) L= py, b) L= H(C6H5)P02H, c) L= HCONHCH3, d) L= CH3CONH, e) L= H 20 andf)L= HCONH2. 45 700 •00-o 400-Legend o 600-1 • • • o b D C o d a • • f 300-1 \ ^ O 200-1 ^ £ # um£% • o ! i i ' i i • • i • i i ' i ' • i • ' i ' i ' ' ' ' 20 40 60 80 100 Temperature (K) Figure 2.10. Magnetic susceptibility versus temperature plots for MnL2[H(C6H5)P02]2 complexes: (a) L= py, b) i=H(C 6 H 5 )P0 2 H, c) L= HCONHCH3d) L= CH 3 CONH, e) L= H 2 0 and f) L= HCONH^. 46 Representative plots are shown in Figure 2.11, the points are experimental and the lines are theoretical, calculated using the best fit values of J obtained from the model. The magnetic parameters for all the compounds studied here are listed in Table 2.6. Table 2.6. Magnetic parameters a « b for MnL2[H(C6H5)P02]2 complexes. L -J (cm- 1^ F d HCONH2 0.507 0.0436 (0.473) (0.0402) H 2 0 0.327 0.0200 (0.311) (0.0153) CH3CONH2 0.300 0.0085 (0.281) (0.0205) HCONHCH3 0.284 0.0322 (0.267) (0.0426) H(C6H 5)P02H 0.132 0.0092 (0.122) (0.0102) C5H5N 0.056 0.01925 (0.051) (0.0238) a The data inside the brackets are obtained using the Weng model! 1 3 4 " 1 3 5 ] and those outside the brackets are obtained using the Wagner-Friedberg model! 1 3 3 1 . b g is fixed at 2.00. c The value of J is considered accurate to ± 5%. d The function F is defined in equation [3]. Both theoretical models reproduce the experimental magnetic data reasonably well, although the Wagner-Friedberg model reproduces the temperature of the susceptibility 47 maximum better for all complexes except the one where L= HCONH2. Either or both of the following factors could account for differences observed between calculated and experimental magnetic susceptibilities. Both models ignore zero-field splitting effects and although these should be small in the case of manganese(II), they may have a measurable contribution at low temperatures. Also, interchain interactions are ignored in both models and small effects of this nature could affect the magnetic data at low temperatures. As the data in Table 2.6 show, the exchange perameter IJI, is significantly smaller in all of the complexes than the value previously reported for Mn[H(C6H5)P02l2- (2.78 cm-1 for the Weng and 3.00 for the Wagner-Friedberg models)!81 .^ A possible explanation for this is that coordination of the neutral molecules in the complexes results in a decrease in Lewis acidity of the metal with the net effect of weakening the phosphinate-manganese bonds. This leads to poorer orbital overlap and weaker intrachain exchange. In addition, the structures of the L=HCONH2, CH3CONH2 and H(C6Hs)P02H complexes reveal strong hydrogen bonding between the neutral ligands and the bridging phosphinate groups. Such interactions should have the effect of reducing the Lewis basicity of the bridging phosphinates resulting in weaker metal-phosphinate interactions and weaker exchange. Such hydrogen bonding interactions are also likely to be present in the L= H2O and HCONHCH3 complexes although they are not possible in the L=CsH5N complex. We turn now to a more detailed discussion of the exchange observed in the six MnL2[H(C6H5)P02]2 complexes starting first with a comparison of the three complexes, where L= HCONH2, CH3CONH2 and H(C6Hs)P02H, for which detailed structural information is available. For these complexes the exchange coupling was found to decrease in the order HCONH2 > CH3CONH2 > H(C6Hs)P02H. This order can be understood if it is assumed that the magnetic exchange increases with decreasing length of the Mn-O-P-O-Mn pathway and, moreover, is favored by a symmetrical O-P-0 unit The latter would imply good rc-delocalisation over the phosphinate bridge and should result in an effective 7t-pathway for exchange. It has been suggested for some time that the rc-pathway 48 for exchange is important in antiferromagnetic coupling between metal centers in phosphinate bridged compounds^ 20!. Refering to the data in Table 2.7, it can be seen that the L=HCONH2 complex, which exhibits the largest IJI, has a symmetrical O-P-0 unit and the shortest Mn-O-P-O-Mn pathway of the three compounds studied. In contrast, the L=H(C6H5)P02H compound, which exhibits the smallest value of IJI has unsymmetrical O-P-0 units and a significandy longer exchange pathway. The L=CH3CONH2 which has a intermediate IJI has a symmetrical O-P-0 bridge but a long exchange pathway. Possible reasons for the structural differences in the exchange pathway discussed above are worth considering. The relatively short Mn-O-P-O-Mn pathway for the HCONH2 compound arises primarily from relatively short Mn-O(bridge) bonds. These in turn seem to be related to relatively weakly coordinating HCONH2 groups as indicated by relatively long Mn-O (terminal) bonds in this compound. The unsymmetrical O-P-0 unit exhibited by the L=H(C6H5)P02H compound is related to the nature of the hydrogen bonding interactions. In this complex only intrachain hydrogen bonding occurs resulting in only one of the two oxygens in each O-P-0 bridge being involved in hydrogen bonding. This oxygen forms a longer O-P bond than does the other oxygen and hence the O—P—O unit is unsymmetrical. In the other two complexes there are both inter- and intrachain hydrogen bonds and hence both oxygens of each O-P-0 unit are affected resulting in symmetrical bridges. 49 Temperature (K) Temperature (K) Figure 2.11. Magnetic susceptibility versus temperature plot for MnL2[H(C6H5)P02]2: a) L= HCONH 2 , b) L= C5H5N, c) L= HCONHCH3 and d) L= CH3CONH2. Lines are calculated using the Wagner-Friedberg model and the parameters are given in Table 2.6. 50 Table 2.7. J values and some related bonding parameters for MnL2[H(C6H5)P02]2 complexes3 with estimated standard deviations in the last significant figure in the parentheses. - T \ / Q 1 11£>>C OrtH TJfvTlH PafQiYi^t^fC L J V d lUCa oJlU .DUIIU r d l d l 11CLCI o H C O N H 2 CH3CONH2 H(C6H 5)P02H -J (cm-l) 0.507 0.300 0.132 2P-0(A) 3.038(8) 3.022(2) 3.024(4) AP-0 (A) 0.008(8) 0.002(2) 0.024(4) l M n - 0 (bridge) (A) 4.350(6) 4.406(2) 4.408(4) AMn-0 (bridge) (A) 0.052(6) 0.058(2) 0.078(4) Mn-O (terminal) (A) 2.241(3) 2.182(1) 2.175(2) Mn-O-P-O-Mn (A) 7.38(1) 7.43(1) 7.43(1) a J obtained from fit to the Wagner-Friedberg model. Detailed magneto-structural correlation studies on the three MnL2[H(C6H5)PC>2]2 complexes, where L=H20, HCONHCH3 and C 5 H 5 N are not possible due to the lack of single crystal X-ray determined structures. The L=HCONHCH3 compound should exhibit only intrachain hydrogen bonding and this may be the primary reason that IJ I for this compound is less than that found for the formamide complex. The value of IJ I for the pyridine complex is very low and, since there is no possibility of hydrogen bonding here, we concluded that the relatively higher basicity of the neutral ligand in this case may lead to relatively weaker manganese-bridging phosphinate bonding and therefore weaken the exchange. There is no obvious explanation for the position of the aquo complex in terms of IJI values between the L = H C O N H 2 and HCONHCH3 complexes. 51 2.3. Summary and Conclusions Complexes of MnL2[H(C 6H 5)P0 2]2 where L= HCONH 2 , H 2 0 , HCONHCH3, CH3CONH2, C 5 H 5 N and H(C6H 5)P0 2H have been prepared and characterized, all of which are considered to have pseudo-octahedral structures. M n ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 , M n ( C H 3 C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 and Mn|Tl(C6H5)P02H]2[H(C6H5)P02]2 are found by single crystal X-ray diffraction to have a polymeric structure with two phosphinate ligands forrning double O-P-0 bridges between the adjacent metal atoms. The compounds are antiferromagnetic and the magnetic susceptibility data was analyzed by employing one-dimensional Heisenberg models. The best fitting parameters were obtained for these compounds by employing a spin, S= 5/2, Wagner-Friedberg model, which give -J= 0.51 cm"1 (F= 0.0436) for L= HCONH 2 , -J= 0.33 cm" 1 (F= 0.0200) for L= H 2 0 and -J= 0.13 cm' 1 (F= 0.0093) for L= HCCgl^PC^H. Detailed magneto-structural correlations have been made for these three compounds in terms of Mn-O-P-O-Mn distances, symmetry of the O-P-0 unit and hydrogen bonding interactions. It has been shown that the L= HCONH 2 complex exhibits the largest IJI, a symmetrical O-P-0 unit and the shortest Mn-O-P-O-Mn pathway of the three compounds studied. In contrast, the L= H(C6H5)P02H compound, which exhibits the smallest value of IJI has a symmetrical O-P-0 unit and a significandy longer exchange pathway. The L= C H 3 C O N H 2 and L= H X Q H ^ P O ^ have the same pathway, but the coupling constant, IJI of the L= H(C6H5)P02H complex is less than one-half of that the former compound. The interpretation for this is that L= CH3CONH 2 has a phosphinate bridge which is more symmetrical than that of the L= H(C6H5)P02H compound. M n ( H 2 0 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 , M n ( H C O N H C H 3 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 and Mn(py)2[H(C5H5)P02]2 are considered to have a polymeric structure analogous to those of L=HCONH 2 , CH3CONH 2 and H(C6H5)P02H complexes in which manganese ions are linked in chains by double bridges with neutral ligands occupying the axial sites around 52 each manganese. The magnetic properties of these compounds show antiferromagnetic coupling interaction with -J values (Wagner-Friedberg model) of 0.31 cm"1 (F= 0.0153) for L= H20, 0.28 cm"1 (F= 0.0322) for L= HCONHCH3 and 0.06 cm"1 (F= 0.01925) for L=py. 53 Chapter 3 Cobalt(II) Monophenylphosphinate and Its Complexes 3.1. Introduction The formamide complex of cobalt(II) monophenylphosphinate, Co(HCONH2)2[H(C6H5)P02]2» was studied by single crystal X-ray diffraction by A. Bino and P. Betz at the Hebrew University of Jerusalem and found to be isomorphous and isostructural with the manganese analogue discussed in Chapter 2. In this chapter we will describe the structure, spectroscopic characterization and magnetic properties of this cobalt(II) chain polymer as well as the synthesis and characterization of the related complexes, CoL2[H(Cr5H5)P02]2, where L = H2O and C5H5N (pyridine). Our studies have indicated that these latter complexes have chain structures analogous to that of the formamide complex. In addition, we synthesized and characterized a complex of composition Co(C4H 4N 2)[H(C6H5)P02] 2 (where C4H4N2 = pyrazine). We were particularly interested in such a compound since the neutral pyz (pyrazine) ligand has the potential of bridging metal-phosphinate chains, thus forming a two-dimensional polymer. Also, in the course of our synthetic work, we isolated Co(H20)4[H(C6H5)P02]2 hi a form suitable for single crystal X-ray diffraction studies. The X-ray determined structure, reported here, shows the compound to be mononuclear. Comparison of the spectroscopic and magnetic properties exhibited by this compound with those of the polymeric materials studied here permitted a useful evaluation of the effects of phosphinate bridging on the properties of cobalt complexes. Since no previous studies had been reported on cobalt(U) monophenylphosphinate itself, we studied this compound in detail. Unexpectedly, we discovered that the properties, particularly magnetic properties, of this compound are dependent on the method of 54 preparation. The material appears to exhibit polymorphism and aspects of this were explored in the present work. 3.2. Results and Discussion 3.2.1. Syntheses, Solubilities and Thermal Properties Cobalt(II) monophenylphosphinate was prepared in three different ways, each giving a form with unique magnetic properties. Each preparation was repeated at least once to verify the reproducibility of obtaining the different forms. The synthetic routes are surnmarized by the equations below. Experimental details are given in Chapter 8. H 2 0 CoCl2-6H20 + 2H(C6H5)P02Na > Co[H(C6H5)P02]2- xH2Oi+ 2NaCl 120° Co[H(C6H5)P02]2- xH20 (s) >C0[H(C6H5)PO2]2 (Form I) + xH2Ot In Vacuo [3.1] 145° Co(acac)2 (s) + 2H(C6H5)P02H (s) v Co[H(C6H5)P02]2 (s) (Form II) + In Vacuo 2Hacact [3.2] 95% EtOH Co(CH3C02)24H20+2H(C6H5)P02H > Co(H20)2[H(C6H5)P02]2l+ 2 CH3COOH + 2H20 [3.3] 85° Co(H20)2[H(C6H5)P02]2 > Co[H(C6H5)P02]2 (Form IH) + 2H20t In Vacuo [3.4] The general methods used to synthesize the complexes of composition C o L 2 [ H ( C 6 H 5 ) P 0 2 ] 2 (where L = H 2 0 , HCONH 2 and C5H5N (pyridine)), Co(pyz)[H(C6H5)P02]2 and Co(H20)4[H(C6Hs)P02]2 are summarized by the reactions below. Experimental details are given in Chapter 8. 55 95% EtOH 2H(QsH5)P02H + Co(CH3C02)2-4H20 ^Co(H20)2[H(C6H5)P02]2i+ 2CH3COOH + 2 H 2 0 [3.5] Acetone 2H(C6H5)P02H + CoCl2- 6H20 + 4 HCONH2 Co(HCONH2)2[H(C6H5)P02]2i + 2 HCONH2HCl + 6H20 [3.6] pyridine Co[H(C6H5)P02]2 (Form I) + 2C5H5N ^ Co(C5H5N)2[H(C6H5)P02]2i [3.7] 2,2-DMP/pyrazine Co[H(C6H5)P02]2 (Form I) + C4H4N2 ^ Co(C4H4N2)[H(C6H5)P02]2i [3.8] H20 2H(C6H5)P02Na + CoCl2- 6H20 > Co(H20)4|H(C6H5)P02]24 + 2H20 + 2NaCl [ 3.9] The results of qualitative solubility tests on the CoL2[H(C6H5)PC>2]2 complexes, where L = HCONH2, H2O and py, were approximately the same as those found for the manganese analogues (Chapter 2). Co(H20)4[H(C6H5)P02]2 is mononuclear and soluble in both polar and non-polar solvents. All three forms of Co[H(C6H5)PC>2]2 and the pyrazine complex were found to be soluble in polar solvents (i.e., CH3OH, H2O) and insoluble or only very slightly soluble in the non-polar or slightly polar solvents (i.e., CH3CH2OH, CHCI3, Cf5H6, CCI4, CH2CI2). As discussed in Chapter 2, the low solubility in non-polar or slightly polar solvents is consistent with polymeric structures for these compounds. The thermal parameters for the three forms of cobalt(II) monophenylphosphinate and the various complexes are given in Table 3.1 and the DSC curves for these compounds are shown in Figure 3.1. Thermal analysis by DSC revealed all three forms of Co[H(C6H5)P02]2 to undergo a series of endothermic transitions before the onset of exothermic decomposition at about 300 'C. The events at ~ 231 and 242 °C for Form I, at 236 and 241 °C for Form II and at 220 and 229 °C for Form III appear to be due to 56 melting. The relatively weak and broad endothermic events which occur at 116 °C and 214 °C in Form II and 112 *C in Form HI compounds suggest structural phase changes occuring in these materials. The thermal properties of Co(HCONH2)2[H(C6H5)P02]2 were reported earlier!84] (Betz et al.). The compound studied in the earlier work was prepared by a colleague in this laboratory!136] and the D S C thermogram reported for that compound differed somewhat from that reported here. Whereas, in the earlier work, a sharp endothermic event at 137 "C followed by a broad endothermic event extending from ~ 140 to 170 °C was observed, the compound studied in this work has relatively sharp events at 132 and 152 "C with a broader event centered around 190 "C. Melting of the compound was seen as a single endothermic event at 232 °C in the earlier work while the compound prepared here shows some structure on the melting event with a shoulder at 231 *C and the main peak at 238 °C. The onset of exothermic decomposition was seen at 265 °C in the compound made earlier and at 310 °C in the compound studied here. In summary, the compound prepared here exhibits sharper events in the D S C thermogram with greater resolution (more structure to the bands ). This we believe arises from a greater degree of crystallinity in the sample studied in this work. Weight loss measurements confirm that heating the sample above 190 °C results in loss of two moles of formamide as reported in the earlier study!84]. Co(H20)2[H(C6H5)P02]2 undergoes loss of two aquo ligands at 135 °C, melting at 231 °C and the onset of exothermic decomposition at about 310 *C. Co(CsH5N)2[H(C6H5)P02]2 shows loss of two moles of pyridine at about 139 °C followed by three endothermic events at 215, 234 and 242 *C and the onset of decomposition at about 320°C. The peak at 215 °C appears to be outside the normal melting range for Co[H(C6H5)P02l2 and is likely due to a structural phase change. The events at 234 "C and 242 °C would appear to be associated with melting. In the case of Co(C4H4N2)[H(C6H5)P02]2 . two endothermic events were observed at 123 and 192 °C before melting at 232 °C. The weight loss of 1 9 % obtained by heating a sample of the 57 compound to 200 *C compares favorably with the value of 22% expected for the loss of one mole of pyrazine. The presence of two events associated with the loss of one pyrazine molecule suggests the formation of an intermediate complex before the loss of all pyrazine ligands. Exothermic decomposition of this compound begins at 310 °C. Co(H20)4[H(C6H5)P02]2 shows a sharp endothermic peak at 69 "C followed immediately by a broad endothermic event extending from about 73 to 85 *C, centered at 80 °C (weight loss measurements confirm the loss of two moles of H2O). A third endothermic event occurs at 143 °C, which indicates loss of another two moles of H2O. The last endothermic event observed at 233 °C is due to melting. Onset of exothermic decomposition occurs at 320 °C. In summary, on heating, the CoLx[H(C6H5)P02]2 complexes lose all the neutral ligands by ~ 200 "C. The Co[H(C6H5)P02]2 which remains then melts in the range -230 to 240 °C, the detailed melting behavior differing for different compounds. The appearance of more than one endothermic event in this region for most of the compounds studied suggests some structural rearrangement just prior to melting. 58 Table 3.1. Thermal parameters for Co[H(C6H5)P02]2 and CoLx[H(C6H5)P02]2 Complexes. Compound Peak Temp. AH %Weight Loss (*C) (kJmoH) Calcd.3 Obs. Co[H(C6H 5)P02]2 (Form I ) Co[H(C6H 5)P02] 2 (Form II) Co[H(C6H 5)P02]2 (Form III) Co(HCONH2)2[H(C6H5)P02]2 231 242 320b 116 214 236 "j 241J 300b 112 220 229 300b 132 152 190 2311 23b 310b 52 15 6 33 too weak to be integrated 32 38-46' 28 21 19 Table continued-59 Table 3.1 (continued) Compound Peak Temp. CO AH (kJmol-1) %Weight Loss Calcd.3 Obs. Co(H20)2[H(C^5)P02]2 135 102 10 11 231 36 310b Co(py)2rH(C6H5)P02]2 139 148 32 33 215 ^ 234 | 40 242 J 320b Co(pyz)[H(C6H5)P02]2 123") 81 19 22 192 ) 232 39 310b Co(H20)4[H(C6H5)P02]2 691 74 9 8 80 J 143 102 9 9 233 38 320b 3 Calculated for loss of all neutral ligands. b Onset of exothermic decomposition (°C). All other events are endothermic. 60 3.2.2. Single Crystal X-ray Diffraction Two of the complexes discussed in this chapter, Co(HCONH2)2[H(C6Hs)P02]2 and Co(H20)4[H(C6H5)P02]2. were obtained in crystalline form suitable for single crystal X-ray diffraction studies. The structure of Co(HCONH2)2[H(C6H5)P02]2 was determined by A . Bino and P. Betz at the Hebrew University of Jerusalem while the structure of Co(H20)4[H(C6H5)P02]2 was determined by S.J. Rettig in the X-ray crystallography laboratory at the University of British Columbia. 3.2.2.1. Structure of Co(HCONH2)2[H(C6H5)P02]2 This compound is isomorphous with Mn(HCONH2)2[H(C6H5)P02]2- Its structure consists of polymeric chains with two phosphinate ligands forming double O-P-0 bridges between adjacent metal atoms. The bridging phosphinates form square planar C0O4 units and six-coordination about the metal is achieved by axially O-bonded formamide ligands. The stereoscopic view of a section of the polymeric chain is shown in Figure 3.2. The atom numbering scheme is shown in Figure 3.3. Table 3.2 gives important bond distances and angles. The intrachain distance between metal atoms in this compound is 5.539 A. Table 3.2. Bond distances (A) and bond angles (°) for Co(HCONH2)2[H(C6H5)P02]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond Distances (A) Angles (°) Co—0(1) Co—0(2)' Co—0(3) 2.079(3) 2.128(3) 2.179(3) 0(1)- -Co—0(2)' 90.2(1) 89.8(1) 92.0(1) 88.0(1) 92.7(1) 87.3(1) - 0 ( 2 ) ' - 0 ( 3 ) - o ( 3 y 0(2)'- -Co—0(3) - 0 ( 3 ) ' 62 Figure 3.2. Stereoview of a section of Co(HCONH2)2[H(Cr3H5)P02]2. Figure 3.3. View of Co(HCXDNH2)2[H(C6H5)P02]2 showing the numbering scheme and coordination about the cobalt atom. 63 Like the manganese counterpart, the intramolecular hydrogen bond involving the NH2 group of the coordinated formamide and an oxygen atom of a bridging phosphinate results in an N—0(2) separation of about 2.9A. The second NH2 hydrogen atom on each formamide ligand is involved in an interchain hydrogen bond with a phosphinate oxygen of a neighboring chain resulting in an N—0(1) distance also of about 2.9A. 3.2.2.2. Structure of Co(H20)4[H(C6Hs)P02]2 A stereoview of the unit cell is given in Figure 3.4 and a view of the molecular structure of Co(H20)4[H(C6H5)P02]2 with the atom numbering scheme is shown in Figure 3.5. Selected intramolecular bond distances and angles are given in Table 3.3 and a complete compilation of structural parameters is provided in the Appendix. The coordination sphere around cobalt consists of an approximately square array of four aquo ligands with axial coordination sites occupied by oxygen atoms from trans-coordinated unidentate monophenylphosphinate groups. Each phosphinate oxygen involved in coordination to the metal is also involved in one hydrogen bonding interaction with a water molecule on a neighboring molecule while each phosphinate oxygen not involved in coordination to the metal is involved in a total of three such hydrogen bonding interactions. The net result is an extended two-dimensional lattice structure propagating in the A-B plane. 64 T a b l e 3 . 3 . B o n d d i s t a n c e s (A) a n d b o n d a n g l e s ( ' ) f o r C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 w i t h e s t i m a t e d s t a n d a r d d e v i a t i o n s i n t h e l a s t s i g n i f i c a n t f i g u r e i n t h e p a r e n t h e s e s . S t r u c t u r e B o n d D i s t a n c e s ( A ) A n g l e s O C o O ) - - O ( l ) 2 . 0 5 8 ( 1 ) C o ( l ) - 0 ( 3 ) 2 . 0 6 9 ( 1 ) C o ( l ) ~ 0 ( 4 ) 2 . 1 6 6 ( 2 ) P ( l ) - - C K l ) 1 . 5 1 2 ( 1 ) P ( l ) ~ - 0 ( 2 ) 1 . 5 0 9 ( 1 ) O ( l ) — C o ( l ) — 0 ( l ) ' a 1 8 0 - 0 ( 3 ) 8 8 . 4 7 ( 6 ) - 0 ( 3 ) ' 9 1 . 5 3 ( 6 ) - 0 ( 4 ) 9 3 . 9 2 ( 6 ) - 0 ( 4 ) ' 8 6 . 0 8 ( 6 ) 0 ( l ) - P ( l ) - - 0 ( 2 ) 1 1 7 . 0 6 ( 8 ) 0 ( 1 ) - P ( 1 ) — C ( l ) 1 0 6 . 7 7 ) 8 ) a H e r e t h e s y m b o l ' r e f e r s t o t h e s y m m e t r y o p e r a t i o n : x , - y , 1 - z . F i g u r e 3 . 4 . A s t e r e o v i e w o f t h e u n i t c e l l i n C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 -6 5 F i g u r e 3.5. V i e w o f C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 s h o w i n g t h e a t o m n u m b e r i n g s c h e m e a n d c o o r d i n a t i o n a b o u t t h e c o b a l t a t o m . 3.2.3. X - r a y P o w d e r D i f f r a c t i o n T h e X - r a y p o w d e r d i f f r a c t i o n p a t t e r n s o f t h e t h r e e f o r m s o f C o [ H ( C 6 H 5 ) P 0 2 ] 2 a r e p r e s e n t e d i n F i g u r e 3.6 a n d t h e d i f f r a c t i o n d a t a a r e r e c o r d e d i n t h e A p p e n d i x . T h e d i f f r a c t i o n p a t t e r n s o f t h e t h r e e f o r m s a r e d i s t i n c t i n d i c a t i n g a u n i q u e c r y s t a l l i n e f o r m f o r e a c h . N o n e o f t h e f o r m s a p p e a r t o b e i s o m o r p h o u s w i t h M n [ H ( C 6 H s ) P 0 2 ] 2 ( S e c t i o n 2.2.3). T h e X - r a y p o w d e r d i f f r a c t i o n p a t t e r n s o f C o ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 , C o ( H 2 0 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 C o ( p y ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 a n d C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 a r e a l s o s h o w n i n F i g u r e 3.6 a n d t h e d i f f r a c t i o n d a t a f o r t h e s e a r e a l s o p r e s e n t e d i n t h e A p p e n d i x . A c o m p a r i s o n o f t h e p o w d e r p a t t e r n s o f t h e s e c o m p l e x e s w i t h t h o s e o f t h e a n a l o g o u s m a n g a n e s e c o m p l e x e s ( S e c t i o n 2.2.3) r e v e a l s t h a t t h e c o r r e s p o n d i n g c o m p l e x e s a r e i s o m o r p h o u s . T h e X - r a y p o w d e r d i f f r a c t i o n p a t t e r n o b t a i n e d f o r t h e p y r a z i n e c o m p l e x , C o ( p y z ) [ H ( C 6 H s ) P 0 2 ] 2 , ( F i g u r e 3.6), r e v e a l s a s e x p e c t e d t h a t t h i s c o m p l e x i s n o t i s o m o r p h o u s w i t h a n y o f t h e o t h e r c o b a l t c o m p l e x e s s t u d i e d h e r e . 66 26 26 Figure 3.6. X-ray powder diffraction patterns of a) Form I, b) Form n and c) Form UI of Co[H(C6H5)P02]2; d) Co(H20)2[H(< 5^)P02]2, e) CoCHCONH^CCsHs)^]^!) Co(py)2[H(Q#5)P02]2, g) Co(pyz)[H(C6H5)P02]2 and h) Co(H20)4[H(C6H5)P02]2 67 3.2.4. Infrared Spectroscopy Infrared spectra over the range of 400 ~ 1600 cnr1 for the three forms of Co[H(C6H5)P02]2 are shown in Figure 3.7. Selected infrared frequencies with tentative assignments are given in Table 3.4. The antisymmetric PO2 stretching vibration in both Form I and Form U of Co[H(C6H5)P02]2 appears at 1140 cnr1 (with shoulders at ~ 1128 and 1129 cm-1, respectively). This is almost the same frequency as found for the corresponding absorption in copper(II) monophenylphosphinate (1141 cm"1)^ 13]. The antisymmetric PO2 stretching vibration in the Form JJI compound is shifted to slightly higher frequency (1155 cm*1), with a shoulder at 1140 cm"1. One feature of this series of compounds is the difference in the intensities of the symmetric PO2 stretching vibrations. Both Form II and Form III compounds show relatively intense absorptions at about 1050 and 1051 cm"1, respectively, while Form I shows a relatively weak absorption at 1040 cm-1. Table 3.4. Selected infrared data (cm"1) for the three forms of Co[H(C6H5)P02]2 complexes. vP02anti. v P02sym. A1 VP-H Form I 1140 vs. 1128 s.sh. 1040 w. 100 2377 w.sh. 2340 w. Form II 1140 vs. 1129 s.sh. 1051 m. 89 2390 w. 2358 w. Form UI 1155 vs. 1140 s.sh. 1050 s. 105 2386 w. 2354 w. lA = VP02 anti.- VP0 2 sym.. 68 J I I I I I I 1 6 0 0 H 0 0 1200 1000 BOO 6 0 0 4 0 0 WAVENUMBER /cm-1 Figure 3.7. Infrared spectra of CoHCCsHsJPCsh: a) Form I, b) Form E and c) Form HI. 69 The three Co[H(C6Hs)P02]2 compounds studied here show A values (A = VPC>2 and. - V P 0 2 sym.) of ~ 100 cm"1, consistent with relatively symmetrically bridging P 0 2 groupst55*56!. Although it seems likely that the phosphinate groups are all bridging in these complexes some evidence for two slightly different phosphinates is seen in the spectra of the Co[H(C6H5)P02]2 compounds. All three forms show a splitting of the bands assigned to the antisymmetric PO2 stretching and the P-H stretching vibrations (Table 3.4). The spectra of the CoLx[H(C6H5)P02]2 complexes are shown in Figures 3.8 and 3.9 and selected frequencies with tentative assignments are given in Table 3.5. These complexes show bands in the infrared region which may be assigned separately to the neutral ligands and to the monophenylphosphinate ligands. Co(HCONH2)2[H(C6H5)P02]2 exhibits a broad, medium intensity, structured absorption centered around 3180 cm"1 (maxima at ~ 3240 and 3120 cm"1) due to NH2 stretching and a strong broad band at 1670 cm"1 (shoulder at ~ 1690 cm*1) due to C O stretching. This compares to corresponding bands at approximately 3310 and 1680 cm"1 in pure HCONH2^  1 2 21 and the smaller shift in the v(CO) frequency on coordination shows that, in spite of the fact that formamide is coordinated through oxygen, a greater perturbation is caused by the hydrogen bonding involving the NH2 groups. The P 0 2 antisymmetric stretching vibration appears as a strong broad band at 1130 cm"1 and the symmetric stretching mode is of medium intensity at 1040 cm"1. These band frequencies are comparable to those of the dialkylphosphinates of copper(IT)[13l and are consistent with the relatively symmetrical phosphinate bridging in this compound. A relatively sharp medium intensity band ascribed to the P-H stretching vibration occurs at 2402 cm"1. The spectra of the diaquo and tetraaquo compounds over the 400 ~ 1600 cm"1 region are shown in Figure 3.9. Outside of this region, strong broad absorptions are also seen between 3100 and 3400 cm"1 in these compounds and are assigned as the antisymmetric and symmetric vibrations of coordinated water molecules. Other strong 70 Table 3.5. Selected infrared data (cnr 1 ) for CoLxfHCCfcrtyPC^h complexes. Lx vP02anri. V P 0 2 sym. A> V P _ H v 0 - H V N _ H V C = Q (H 2 0)2 1140 vs. 1056 s. 84 2382 w. 3321 m. 1703 w. (HCONH 2)2 (py)2 1130 vs. 1188 s. 1040 ms. 1039 m. 90 149 2402 m. 2316 m. 2276 m. 3240 m. 3120 w. 1690 m.sh. 1670 s. (pyz) 1171 vs. 1045 m. 126 2313 m. (H 20) 4 1143 vs. 1049 s. 94 2408 s. 3380 s.br. 3120 s.br. 1649 m. 'A^PChant i . -vpC^ sym.. absorptions which occur between 1650 and 1700 cm-1 are tentatively assigned as the bending mode of H2O in these compounds. Some similarities are obvious in the PO2 stretching region for both compounds. The antisymmetric PO2 stretching frequencies are at v 1140 cm*1 for the diaquo compound and 1143 cm-1 for the tetraaquo derivative, while the symmetric PO2 stretching frequencies appear at 1056 and 1049 cm"1 for the diaquo and tetraaquo compounds, respectively. Such similarities in band frequencies were unexpected since the X-ray structure determination of the tetraaquo species shows the phosphinate ligand to be monodentate in that compound while the phosphinate ligand is proposed to be bridging in the diaquo species. The A values are 84 and 94 cm"1, respectively, for the diaaquo and tetraaquo complexes. These values are, in fact, consistent with symmetrical O-P-0 groups in both compounds. Such a symmetrical group is expected for bridging O-P-O as proposed for the diaquo compound but unexpected in a compound where the phosphinate group is monodentate as in the tetraaquo complex. The crystal structure of the latter, however, confirmed that the P-0 bonds are almost identical in this compound (P(l)—O(l) = 1.512(1) A; P(l)—0(2) = 1.509(1) A). Clearly, the hydrogen bonding interactions involving the uncoordinated oxygen atom of the phosphinate ligand are sufficiently strong to render the bond-order of the P-0 bond involving it almost the same as the bond-order of the P-0 bond involving the coordinated oxygen atom. In addition, the P-H bands observed for these compounds are not split, consistent with only one type of phosphinate ligand - a fact confirmed by the X-ray structure determination on the tetraaquo complex. The pyridine complex shows bands in the infrared spectra which may be assigned separately to the pyridine and phosphinate ligands. The spectrum of this compound is shown in Figure 3.8. Previous research has shown that each band in the infrared spectrum of pyridine is usually reproduced in pyridine complexes with minor shifts or splittings! 1 2 8 J . Such 1:1 correspondence is also observed in this study and has allowed the coordinated pyridine vibrations to be ascertained by a direct comparison with the spectrum of the 72 uncomplexed base. The assignments of the normal vibrational modes of liquid pyridine, made by Kline and Turkevicht137] and the more recent assignment of overtonest138! are given in the Appendix. Upon coordination of pyridine, most bands shift in frequency by up to 10 cm"1. As observed previously^130], the 8a, 6a and 16b vibrations show a pronounced coordination dependence and shift by 20 to 30 cm"1 to higher frequency upon coordination. Some of the pyridine bands in the complex studied here exhibit small splittings which, in this and earlier studies, are attributed to interactions between adjacent pyridine ringsf13!]. The band assigned to the antisymmetric PO2 stretching vibration for this compound is a strong absorption at 1188 cm"1 An absorption band at 1039 cm"1 is tentatively assigned as due to the symmetric PO2 stretching vibration. With these assignments the value of A is 149 cm"1, a value indicative of monodentate or highly un symmetrically bridging phosphinate groups.The observation of a doublet in the P-H stretching region also suggests the presence of two non-equivalent phosphinate groups in this compound. The pyrazine compound may be considered as unique among the adduct polymers studied here because pyrazine may coordinate in a uni- or bidentate mode^139"141]. Goldstein et al. H 4 2 " 1 4 3 ! were able to unambiguously determine the coordination mode of pyrazine in a series of pyrazine complexes by using a combination of infrared and Raman spectroscopy. Their approach considered the different symmetries of unidentate and bidentate pyrazine groups and the effect of ligand symmetry on the infrared and Raman spectra of pyrazine complexes. The uncomplexed pyrazine is planar and is D2h in point group representation. When both nitrogen atoms of pyrazine coordinate equivalendy to the metal centers in a bridging mode, then the symmetry remains the same as in the uncomplexed ligand and a mutual exclusion of infrared and Raman bands occurs. When pyrazine coordinates through only one nitrogen atom, in a unidentate mode, the symmetry is reduced at least to C 2 v and vibration bands formally forbidden in E^ h symmetry become active in the infrared spectrum of the complex. The infrared spectra of complexes containing unidentate pyrazine groups and the Raman spectrum of free pyrazinet144] exhibit 73 bands at approximately 1230,920 and 750 cm*1. The infrared spectrum of the compound studied here shows no absorption bands in these regions, indicating that the pyrazine ligand retains D2h symmetry upon complex formation by acting as a bidentate bridge between metal centers. As shown in Table 3.5 , the spectrum of the pyrazine complex in the PO2 stretching region is similar to those of other the adduct polymers studied here, consisting of a band at 1171 cm"1 assigned to the antisymmetric PO2 stretching vibration and a band at 1045 cm-1 assigned to the symmetric stretching vibration. With these assignments the A value is 126 cm-1 significantly greater than in the formamide complex, suggestive of monodentate or unsymmetrically bridging phosphinate groups. In addition, we note there is no splitting of the band assigned to P-H stretching and therefore presumably as in the formamide complex there is only one type of phosphinate present. The P-H stretching vibrations of all the compounds show only one band except for the pyridine complex which exhibits split bands in this region. Both pyridine and pyrazine complexes show low values of vP-H compared to other complexes in this study. This could be accounted for by a weaker bonding between the oxygen of phosphinate and the metal in these compounds. 74 Figure 3.8. Infrared spectra of a ) Co(HaDNH 2)2[H(C^5)P02J2, b) Co(py)2lH(C6H5)P02]2 and c) Co(pyr)rH(C6H5)P02]2. 75 T J 1 1 I I I | _ 1600 U00 1200 1000 600 600 400 WAVENUMBER / c n r 1 Figure 3.9. Infrared spectra of a) Co(H20)2rH(CfjH5)P02]2 and b) Co(H20)4[H(C6H5)P02]2. 76 3.2.5. Electronic Spectroscopy All three forms of Co[H(C6Hs)P02]2 are blue in color while the CoLx[H(C6H5)P02]2 complexes are all pink. These colors are consistent with the former group of compounds having tetrahedral or distorted tetrahedral structures and the latter having octahedral or distorted octahedral structurest97l. The X-ray crystal structure determinations of Co(HCONH2)2[H(C6H5)P02]2 and Co(H20)4[H(<^ 5)P02]2 (Section 3.2.2) confirmed distorted octahedral CoC*6 chromophores for these compounds. The similarities in the spectra (Figure 3.10) of the CoLx[H(C6H5)P02]2 complexes suggest similar Co06 chromophores in all four compounds. The spectra of the three forms of Co[H(C6H5)P02]2 which are similar to each other (Figure 3.11), are distinctly different from those of the CoLx[H(C6H5)PC>2]2 complexes supporting a different, presumably pseudo-tetrahedral C0O4 chromophore for the former group of compounds. Further support of this is the observation that the spectra of the Co[H(C6H5)P02]2 complexes are almost identical to that of Co[(C6H5)2P02]2 (Chapter 5), a compound shown by X-ray diffraction studies to have a tetrahedral, C0O4 chromophore. Band frequencies with approximate assignment 1 4 51 are given in Table 3.6 for all the compounds discussed in this Chapter. 77 Table 3.6. Electronic spectra data for Co[H(C6H5)P02]2 and CoLx[H(C^H5)P02]2 complexes. Compound Band Position (KPcm*1) Assignment3 Co[H(C6H5)P02]2(FormI) 17.3 s. 18.7 m.sh. 4T 1(P)f- 4A 2 20.0 sh. Co[H(C6H5)P02]2 (Form U) 15.8 s. 17.2 m.sh. 4T!(P)«-4A 2 • 20.1 sh. Co[H(C6H5)P02]2 (Form ffl) 15.9 s. 18.8 m.sh. 4T-(P)<-4A2 20.8 sh. Co(H20)2rH(C6H5)P02]2 15.9 m. 4 A 2 g <- 4 Ti g (F) 18.8 vs. 4Tig(P)<-4Tig(F) 20.8 sh. b Co(H20)4[H(C6H5)P02]2 15.9 m. 4A2g<-4Tig(F) 18.9 vs. 4Ti g(P)<- 4Ti g(F) 20.8 sh. b Co(HCONH2)2[H(Cf3H5)P02]2 15.6 m. 4 A 2 g « - 4 T l g ( F ) 17.2 vs. 4Ti g(P)<- 4T l g(F) 21.0 sh. b Co(py)2[H(C6H5)P02]2 15.7 m. 4 A 2 g <- 4 T l g (F) 19.3 vs. 4Tlg(P)<-4Tig(F) 20.0 sh. b 21.1 sh. b Co(pyz)[H(C6H5)P02]2 16.7 m. 4 A 2 g <- 4 Ti g (F) 19.2 vs. 4Tlg(P)<-4Tig(F) 20.8 sh. b 3 Based on (approximate) tetrahedral and octahedral symmetries. b possibly due to a spin-forbidden transitiont145!. 78 , I I I I I I I I I I I ' • I • I I I I I I I I I 400 *60 5A0 600 660 700 nm Figure 3.10. Electronic spectra of C^rH(C^5)P02]2: a) Co(pyz)rH(C6H5)P02]2, b) Co(HCX>rffl2)2[H(C^5)POri2. c) Co(H20)2[H(C6H5)P02]2, d) Co(py)2[H(C6H5)P02]2 and e)C0(H2O)4[H(C6H5)PO2]2. 79 nm Figure 3.11. Electronic spectra of Co[H((^ 5)POil2: a) Form I, b) Form JJ and c) Form HI. 80 3.2.6. Magnetic Properties T h e d i s c u s s i o n o f m a g n e t i c p r o p e r t i e s i s d i v i d e d i n t o t w o s e c t i o n s . O n e c o n s i d e r s t h e C o L x [ H ( C 6 H 5 ) P 0 2 ] 2 c o m p l e x e s , w h e r e U = ( H C O N r f e t e , (HlOh, ( p y ) 2 , ( p y z ) a n d (H20>4, a l l o f w h i c h a r e c o n s i d e r e d t o h a v e p s e u d o - o c t a h e d r a l s t r u c t u r e s . T h e s e c o n d s e c t i o n w i l l b e d e v o t e d t o t h e t h r e e f o r m s o f C o [ H ( C 6 H 5 ) P 0 2 ] 2 » a l l t h r e e o f w h i c h a r e c o n s i d e r e d t o b e p s e u d o - t e t r a h e d r a l . 3.2.6.1. Octahedral Complexes T h e C o L x [ H ( C 6 H 5 ) P 0 2 ] 2 c o m p l e x e s a r e p r o p o s e d t o b e s i x - c o o r d i n a t e w i t h d i s t o r t e d o c t a h e d r a l s t r u c t u r e s . T h i s h a s b e e n c o n f i r m e d f o r C o ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 a n d C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 b y s i n g l e c r y s t a l X - r a y d i f f r a c t i o n s t u d i e s ( S e c t i o n 3 . 2 . 2 ) a n d h a s b e e n s u p p o r t e d f o r t h e o t h e r c o m p l e x e s b y t h e n -e l e c t r o n i c s p e c t r a ( S e c t i o n 3 . 2 . 5 ) . M a g n e t i c s u s c e p t i b i l i t y a n d m a g n e t i c m o m e n t d a t a f o r t h e s e c o m p o u n d s a r e r e c o r d e d i n t h e A p p e n d i x a n d p l o t s o f m a g n e t i c m o m e n t v e r s u s t e m p e r a t u r e a r e g i v e n i n F i g u r e 3 . 1 2 . T h e g r o u n d s t a t e f o r h i g h - s p i n c o b a l t ( I I ) i n a n o c t a h e d r a l e n v i r o n m e n t i s 4 T i g . T h i s s t a t e i s s p l i t i n a n a x i a l f i e l d t o y i e l d , f o r a x i a l e l o n g a t i o n , a 4 A 2 g g r o u n d s t a t e . T h i s i s s h o w n i n F i g u r e 3 . 1 3 , w h e r e t h e e f f e c t o f z e r o - f i e l d s p l i t t i n g o n t h e 4 A 2 g s t a t e i s a l s o d e p i c t e d t 1 4 6 ^. T h e a n a l y s i s o f t h e m a g n e t i c p r o p e r t i e s o f a n i s o l a t e d c o b a l t ( I I ) i o n t h e n , i n a n a x i a l l y d i s t o r t e d o c t a h e d r a l f i e l d c a n b e e x p e c t e d t o b e c o m p l e x a s t h e p r o p e r t i e s a r e a f f e c t e d b y a n u m b e r o f f a c t o r s i n c l u d i n g e l e c t r o n d e l o c a l i z a t i o n , s p i n - o r b i t c o u p l i n g , e x t e n t o f d i s t o r t i o n a n d m i x i n g o f e x c i t e d s t a t e s i n t o t h e g r o u n d s t a t e ^ 1 4 6 ! T h e s e f a c t o r s m a y b e t e r m e d " s i n g l e i o n e f f e c t s " . M a n y o f t h e c o m p l e x e s s t u d i e d i n t h e c u r r e n t w o r k a r e p o l y m e r i c l e a d i n g t o t h e p o s s i b i l i t y t h a t t h e c o b a l t i o n s a r e n o t i s o l a t e d b u t a r e , i n f a c t , m a g n e t i c a l l y c o n c e n t r a t e d . W h i l e a m a j o r o b j e c t i v e o f t h i s w o r k i s t o s t u d y m a g n e t i c e x c h a n g e e f f e c t s i n t h e s e c o m p l e x e s i t i s c l e a r t h a t t h e i n t e r p r e t a t i o n o f s u c h e f f e c t s i n 8 1 6 4.6-4-f£ 3.6-B V E o • 3- 8 • o • O D O D O o A O o • o t D 2 * • D 2-1.6-S A Legend • • o b o c o d A e 60 20 40 Temperature (K) 80 100 Figure 3.12. Magnetic moment versus temperature plots for CoLx[H(C6H5)P02]2 complexes: a) L*= (py)2, b) L*= (H 2 0) 4 , c) L*= (pyz), d) L*= (H 2 0) 2 and e) 1^ = ( H C O N H ^ . 82 octahedral cobalt (II) complexes is made somewhat difficult because of the single ion effects just mentioned. i i i i i i \ Free ion Octahedral Axial field Zero field field splitting Figure 3.13. Partial energy level diagram for octahedral cobalt(U). Co(H20)4[H(C6H5)P02]2 Of the complexes studied here only this one is known from X-ray studies to have a mononuclear structure. The tetraaquo complex of cobalt(U) monophenylphosphinate consists of Co(H20)4[H(C6H5)P02]2 molecules linked only by hydrogen bonding interactions to form an extended sheet structure (section 3.2.2.2). The paramagnetic centers are well isolated from each other and there are no phosphinate O-P-0 bridges between metal ions in this structure; hence any magnetic exchange effects would be expected to be very weak. The magnetic moment for this complex decreases smoothly with decreasing temperature to about 10 K where a more pronounced decrease with temperature is observed (Figure 3.12). For the most part, this behavior may be accounted for on the basis of single ion effects only as oudined below. 83 T h e m a g n e t i c m o m e n t d a t a f o r C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 w e r e a n a l y z e d b y t h e m e t h o d o f F i g g i s et a / J 1 1 8 ] w h i c h t a k e s i n t o a c c o u n t s i m u l t a n e o u s p e r t u r b a t i o n b y s p i n -o r b i t c o u p l i n g a n d a n a x i a l l y s y m m e t r i c l i g a n d f i e l d . T h e a n a l y s i s i s i n t e r m s o f f o u r p a r a m e t e r s , A , X , k a n d A . T h e a x i a l d i s t o r t i o n p a r a m e t e r A i s t h e s e p a r a t i o n b e t w e e n t h e 4 A 2 g a n d 4 E g s t a t e s d e r i v e d f r o m t h e s p l i t 4 T - g ( F ) s t a t e ( F i g u r e 3 . 1 3 ) . A p o s i t i v e v a l u e o f A c o r r e s p o n d s t o t h e o r b i t a l l y n o n - d e g e n e r a t e 4 A 2 g s t a t e l y i n g l o w e s t . T h e s p i n - o r b i t c o u p l i n g c o n s t a n t , X , i s t h e s e c o n d p a r a m e t e r a n d , i n c o m p l e x e s , i t s v a l u e i s e x p e c t e d t o b e r e d u c e d s o m e w h a t b e l o w t h e f r e e - i o n v a l u e . T h e t h i r d p a r a m e t e r i s t h e o r b i t a l r e d u c t i o n f a c t o r , k . T h e f o u r t h p a r a m e t e r , A , a l l o w s f o r t h e a d m i x t u r e o f t h e h i g h e r l y i n g 4 T i g ( P ) t e r m i n t o t h e g r o u n d 4 T i g ( F ) t e r m b y t h e p r i m a r y c u b i c f i e l d . T h e f o l l o w i n g m e t h o d w a s u s e d t o f i t t h e m a g n e t i c m o m e n t d a t a f o r t h e C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 c o m p l e x . F i g g i s etalS11® h a v e t a b u l a t e d m a g n e t i c m o m e n t d a t a a s a f u n c t i o n o f A A , k a n d A . T h e v a l u e A w a s s e t a t 1 . 4 f o r C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 » t h i s v a l u e c h o s e n b y c o m p a r i s o n w i t h v a l u e s d e t e r m i n e d f o r o t h e r c o m p o u n d s w i t h r e l a t e d CoC>6 c h r o m o p h o r e s f 1 1 8 ! . F i g g i s ' t a b u l a t e d d a t a ( f o r A = 1 . 4 ) w e r e u s e d t o p r o d u c e p l o t s o f | i e f f a s a f u n c t i o n o f k T A - T h e s e p l o t s w e r e t h e n c o m p a r e d v i s u a l l y w i t h p l o t s o f e x p e r i m e n t a l ( l e f f v a l u e s v e r s u s k T A ( f o r d i f f e r e n t v a l u e s o f X). F r o m t h e s i n g l e c r y s t a l X - r a y s t r u c t u r e d e t e r m i n a t i o n s t u d i e s o f C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 , i t i s s e e n t h a t t h e C0O6 c h r o m o p h o r e i s t e t r a g o n a l l y e l o n g a t e d ( T a b l e 3 . 3 ) a n d t h i s w o u l d g i v e t h e o r b i t a l s i n g l e t 4 A 2 g a s t h e g r o u n d s t a t e . T h i s r e s t r i c t s o u r a n a l y s i s t o p o s i t i v e v a l u e s o f A . W e w e r e u n a b l e t o g e t g o o d a g r e e m e n t b e t w e e n e x p e r i m e n t a n d t h e o r y o v e r t h e e n t i r e t e m p e r a t u r e r a n g e s t u d i e d . H o w e v e r , c o n s i d e r i n g t h a t t h e F i g g i s m o d e l h a s b e e n a p p l i e d w i t h s o m e s u c c e s s p r e v i o u s l y ^ 1 4 7 " 1 4 8 ] o n l y i n t h e h i g h e r t e m p e r a t u r e r e g i o n s ( t y p i c a l l y 8 0 ~ 3 0 0 K ) , w e e x a m i n e d t h e b e s t fits t o t h e m o d e l a t t h e h i g h e r t e m p e r a t u r e s s t u d i e d . A s s h o w n i n F i g u r e 3 . 1 4 r e a s o n a b l e fits a r e o b t a i n e d o v e r t h e r a n g e o f ~ 4 0 - 8 0 K w i t h t h e p a r a m e t e r s A = 1 . 4 , k = 1 . 0 , A = 3 9 0 c m " 1 a n d X = - 1 3 0 c m " 1 . 8 4 o o 3 4 l_ 1 1 1 1 1 1 . 1 1 0.0 0.1 0.2 0.3 0.4 0 k T • • • " Figure 3.14. Magnetic moment versus - k T A plot for Co(H20)4rH(C6H5)P02]2-Experimental points are plotted assuming -k = 130 cm - 1. Solid line is calculated using the Figgis's model with A =1.40, k = 1.00 and v= AA= -3.0. 85 In order to analyze the magnetic data for Co(H20)4[H(C6H5)P02]2 further, we considered a second model in which thermal population of the zero-field split 4A 2g state only (Figure 3.13 ) is considered. This is the zero-field spurting model. Equations relating the magnetic susceptibility to temperature in terms of the zero-field splitting parameter D and g , for S=3/2, have been givent109]: J+9e-2x_ . 4+(3/x)(l-e--*) *» 4(l+e-2*) ' *± 4(l+2e-2*) where x = D/kT, C = Ng2P2/kT and the powder magnetic susceptibility is %p= (% + 2xx)/3. Fits of experimental susceptibilities to calculated values based on these equations with the best fit parameters, D = 27 cm-1 and g = 2.41 are shown in Figure 3.15. A comparison between theory (ZFS model) and experiment for the Ueff versus temperature plot is given in Figure 3.16. There is reasonably good agreement between experiment and theory over most of the temperature range using this model; however, as seen in Figure 3.16, the very sharp decrease in magnetic moment below 10 K is not modelled any better by the ZFS model than it was by Figgis's model. This may indicate the presence of very weak antiferromagnetic coupling or simply the limitations of the models. 86 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 3.15. Magnetic susceptibility versus temperature plot for Qj<H20)4[H(C6H5)PO2]2. Solid line is calculated employing the zero-field sphtting model with D=27 cnr1 and g=2.41. 87 "1 I I I I I I I I 1 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 3.16. Magnetic moment versus temperature plot for Co(H20)4[H(C6H5)P02]2.Solid line is calculated employing the rero-field splitting model with D=27 cm - 1 and g=2.41. 88 Co(py)2[H(C6H5)P02]2 The magnetic moment data obtained for the pyridine complex Co(py)2[H(C6H5)P02]2 are very similar to those of Co(H20)4[H(C6H5)P02]2 (Figure 3.12) and although we proposed a polymeric structure for the pyridine compound on the basis of spectroscopic evidence, it would appear that there is very little, if any, magnetic coupling in this compound. Accordingly, we analyzed the magnetic data for this compound in the same way as described above for Co(H20)4[H(C6H5)P02]2 • The best fit of the magnetic moment data to the Figgis model employing the parameters A = 1.4, k = 1.0 , v = -3 cm"1 and X = -130 is shown in Figure 3.17. Best fits of magnetic susceptibility and magnetic moment to the zero-field splitting model employing the parameters D = 39 cm"1 and g = 2.41 (F = 0.0361) are shown in Figures 3.18 and 3.19, respectively. This analysis again shows that both models provide reasonable fits to the magnetic data above 10 K but the sharp drop in u\eff below 10 K is not modelled and may be the result of very weak antiferromagnetic exchange. 89 4J3 ^ I i I i I i l i l i 0.0 0.1 0.2 0.3 0.4 0.5 k T F i g u r e 3 . 1 7 . M a g n e t i c m o m e n t v e r s u s - k T A p l o t f o r C o ( p y ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 . E x p e r i m e n t a l p o i n t s a r e p l o t t e d a s s u m i n g - X = 1 3 0 c m * 1 . S o l i d l i n e i s c a l c u l a t e d u s i n g F i g g i s ' s m o d e l w i t h A = 1 . 4 0 , k = 1 . 0 0 a n d v = A A = - 3 . 0 . 9 0 o ©_. 00 Figure 3.18. Magnetic susceptibility versus temperature plot for Co(py)2[H(C^5)P02]2. Solid line is calculated employing the zero-field splitting model with D=39 cm"1 and g=2.41. 91 F i g u r e 3 . 1 9 . M a g n e t i c m o m e n t v e r s u s t e m p e r a t u r e p l o t f o r f o r Co(py)2[H(C^H5)PQ2]2. S o l i d l i n e i s c a l c u l a t e d e m p l o y i n g t h e z e r o - f i e l d s p l i t t i n g m o d e l w i t h D = 3 9 c m - 1 a n d g = 2 . 4 1 . 9 2 Co(HCONH 2 )2 [H(C6H 5 )P0 2 ]2 The magnetic properties of Cc<HCONH2)2[H(C6H5)P02]2 differ from those of the complexes just discussed in that there is a more pronounced decrease in magnetic moment with temperature over the temperature range studied (Figure 3.12). More importantly, the magnetic susceptibility versus temperature plot exhibits a maximum at about 6 K indicative of significant antiferromagnetic exchange in this complex. The structure of this compound, as determined by single crystal X-ray diffraction (Section 3.2.2.1), consists of extended chains of cobalt ions linked by double phosphinate bridges and, accordingly, we have attempted to analyze the magnetic data using one-dimensional exchange models. The problem of analyzing for antiferromagnetic coupling in the presence of the other factors affecting the magnetic properties of pseudo-octahedral cobalt(II) complexes, discussed above, is simplified if the assumption is made that the distortion from Oh symmetry is sufficiendy strong that the splitting of the 4 T i g term leaves a well isolated 4 A 2 g orbital singlet as the ground statet146!. Thermal population of excited states is ignored in this case. Under this assumption the magnetic properties of this compound may be analyzed according to the Wagner-Friedberg model with S = 3/2^  3 31 or according to the Weng model with the coefficients generated by Hiller et al. [!34,135] for S = 3/2. The best fit parameters utilizing these models are given in Table 3.7. The Wagner-Friedberg model reproduced the position of the maximum in the susceptibility better for Co(HCONH2)2[H(C6H5)P02]2 and gave an overall better fit than the Weng model. The best fit curve using the Wagner-Friedberg model is shown in Figure 3.20. There is a discrepancy between the general shapes of the experimental and calculated curves; moreover the deviation of the g value (~ 2.40) from the spin-only value (2.002) shows the orbital contribution to the susceptibility cannot be totally 'quenched' as is assumed by the model. An alternative approach to the interpretation of the magnetic data for six-coordinate Co(II), particularly at low temperatures, is to consider that spin-orbit coupling splits the 93 4 T i g term in such a way that the lowest level, a Kramers' doublet, is the only thermally occupied level. Under this assumption one needs to consider an effective spin, S' = ipllllh The best-fit parameters using the Wagner-Friedberg and Weng models for S' =1/2 are given in Table 3.6. As indicated by the F values the fits are no better than for the S = 3/2 models. Both the Weng and the Wagner-Friedberg models employ the isotropic Heisenberg Hamiltonian. We have also analyzed the magnetic data employing the anisotropic Ising model of Fishert149! for S = 1/2 (best fit parameters are given in Table 3.7). This gives even poorer agreement with experiment In treating this cobalt system as an effective spin S' = 1/2, thermal population of the excited states above the ground Kramers doublet is ignored, hence the model would be expected to work best at the lowest temperatures. We therefore examined fits to the low temperature data only (2 ~ 30 K) using all three S = 1/2 models. The fits over this limited temperature range are better for all three with the best fit obtained for the Weng model. As the temperature increases above 30 K the experimental susceptibilities become increasing greater than the calculated ones in all cases; comparison of experiment with theory for the Weng S = 1/2 model is illustrated in Figure 3 .20. Co(H20)2[H(C 6H5)P02]2 This complex like that of the formamide analogue, shows a maximum in its X M versus temperature plot. The data have been analyzed as for Co(HCONH2)2[H(C6H5)P02]2 and the corresponding parameters are given in Table 3.7. Plots of X M versus temperature for the diaaquo complex are compared with theory in Figure 3.21. In this case agreement between experiment and theory appears to be best for the low temperature data fitted to the Wagner-Friedberg S' = 1/2 model. The magnetic exchange in this compound appears to be weaker (as judged by -J values) than that in 9 4 Co(HCONH2)2[H(Ce>H5)P02]2- T h e c l e a r p r e s e n c e o f e x c h a n g e h o w e v e r s u p p o r t s t h e c o n c l u s i o n t h a t t h e c o m p l e x h a s a c h a i n s t r u c t u r e s i m i l a r t o t h a t o f t h e f o r m a m i d e c o m p l e x . C o ( p y z ) [ H ( C 6 H 5 ) P 0 2 ] 2 T h e r e i s n o c l e a r m a x i m u m i n t h e X m v e r s u s t e m p e r a t u r e p l o t f o r t h i s c o m p l e x b u t t h e d a t a c l e a r l y s h o w a n i n c i p i e n t m a x i m u m a t a b o u t 3 K . A n a l y s i s o f t h e m a g n e t i c d a t a a s f o r t h e a b o v e t w o c o m p l e x e s y i e l d s t h e p a r a m e t e r s l i s t e d i n T a b l e 3 . 7 . T h e b e s t a g r e e m e n t b e t w e e n e x p e r i m e n t a n d t h e o r y , a s f o r t h e d i a a q u o c o m p l e x , a p p e a r s t o b e w i t h t h e l o w t e m p e r a t u r e d a t a f i t t e d t o t h e W a g n e r - F r i e d b e r g S ' = 1/2 m o d e l . P l o t s o f X M v e r s u s t e m p e r a t u r e f o r t h i s c o m p l e x a r e c o m p a r e d w i t h t h e o r y i n F i g u r e 3 . 2 2 . T h e e x c h a n g e h e r e i s c l e a r l y w e a k e r t h a n f o r e i t h e r C o ( H C O N H 2 ) 2 [ H ( C 6 H s ) P 0 2 ] 2 o r Co(H20)2[H(C6H5)P02]2. A c c o r d i n g t o t h e p r o p o s e d s t r u c t u r e f o r t h e p y r a z i n e c o m p l e x , t h e r e a r e t w o c o n c e i v a b l e p a t h w a y s f o r e x c h a n g e i n t h i s c o m p l e x , v i a b r i d g i n g p h o s p h i n a t e o r v i a b r i d g i n g p y r a z i n e l i g a n d s . W i t h t h e d a t a a v a i l a b l e , w e a r e u n a b l e t o d e t e r m i n e w h i c h p r o v i d e s t h e m o r e f a c i l e p a t h w a y f o r e x c h a n g e . I n v i e w o f t h e c o m p l e x i t i e s i n v o l v e d i n a n a l y z i n g t h e m a g n e t i c p r o p e r t i e s o f d i s t o r t e d o c t a h e d r a l c o b a l t ( U ) s y s t e m s l i k e t h e s e w h e r e t h e r e i s m a g n e t i c e x c h a n g e p r e s e n t , o n e s h o u l d n o t p l a c e t o o m u c h r e l i a n c e o n t h e s i g n i f i c a n c e o f t h e a c t u a l v a l u e s o f t h e e x c h a n g e c o n s t a n t s . A r e l a t i v e o r d e r o f m a g n i t u d e o f e x c h a n g e i n t h e p h o s p h i n a t e b r i d g e d c o m p l e x e s s t u d i e d h e r e d o e s a p p e a r t o b e e s t a b l i s h e d b y t h i s w o r k , h o w e v e r . E x c h a n g e c o u p l i n g a p p e a r s t o i n c r e a s e i n t h e o r d e r L = p y < p y z < H2O < HCONH2; a s i m i l a r o r d e r w a s o b s e r v e d f o r t h e a n a l o g o u s m a n g a n e s e c o m p l e x e s ( S e c t i o n 2 . 5 ) . U n f o r t u n a t e l y w e a r e u n a b l e t o c o r r e l a t e t h i s o r d e r f o r t h e c o b a l t c o m p l e x e s w i t h d e t a i l e d s t r u c t u r a l p a r a m e t e r s , s i n c e s t r u c t u r a l p a r a m e t e r s f o r o n l y o n e o f t h e s e c o m p l e x e s , t h e f o r m a m i d e c o m p l e x , a r e k n o w n . W e n o t e h o w e v e r t h a t t h e N - b o n d e d b a s e s y i e l d c o m p l e x e s w i t h w e a k e r e x c h a n g e t h a n d o t h e O b o n d e d b a s e s . I t s e e m s r e a s o n a b l e t o a s s u m e t h a t t h e b a s i c i t y o f p y r i d i n e a n d p y r a z i n e t o w a r d s c o b a l t i s g r e a t e r t h a n t h a t o f e i t h e r H2O o r HCONH2. T h e s t r o n g e r C o - L b o n d s p r e s e n t i n t h e p y r i d i n e a n d p y r a z i n e c o m p l e x e s m a y r e s u l t i n w e a k e r b o n d i n g 9 5 b e t w e e n c o b a l t a n d t h e b r i d g i n g p h o s p h i n a t e l i g a n d s a n d h e n c e i n w e a k e r e x c h a n g e v i a t h e s e b r i d g e s i n t h e s e c o m p l e x e s . W e n o t e a l s o t h a t t h e a n a l y s i s o f t h e i n f r a r e d s p e c t r a o f t h e p y r i d i n e a n d p y r a z i n e c o m p l e x e s i n d i c a t e d u n s y m m e t r i c a l l y b r i d g i n g p h o s p h i n a t e g r o u p s . T h i s m a y b e a c o n s e q u e n c e o f t h e r e l a t i v e l y w e a k e r c o b a l t - p h o s p h i n a t e b o n d s a n d w o u l d a l s o a c c o u n t f o r w e a k e r m a g n e t i c e x c h a n g e . T a b l e 3 . 7 . M a g n e t i c p a r a m e t e r s f o r C b L * [ H ( C 6 H 5 ) P 0 2 ] 2 c o m p l e x e s . M o d e l a Lx W W - F W W - F I W b W - F b I b ( H C O N H 2 ) 2 s 3 / 2 3 / 2 1/2 1/2 1/2 1/2 1/2 1/2 gc 2 . 3 9 2 . 4 1 7 . 1 1 5 . 4 0 5 . 1 0 4 . 8 7 5 . 1 9 4 . 5 9 -JCcm-1^ 1 . 3 0 1 . 5 2 3 . 6 7 7 . 6 2 6 . 6 9 4 . 2 8 7 . 0 5 5 . 5 3 Fd 0 . 0 4 8 2 0 . 0 4 6 4 0 . 0 5 2 9 0 . 0 4 6 4 0 . 0 6 9 9 0 . 0 1 6 9 0 . 0 4 3 9 0 . 0 2 7 7 ( H 2 0 ) 2 s 3 / 2 3 / 2 1/2 1/2 1/2 1/2 1/2 1/2 gc 2 . 3 2 2 . 3 1 5 . 1 6 5 . 2 0 5 . 0 2 4 . 7 4 4 . 8 6 4 . 5 4 -JCcm-1)0 0 . 6 9 0 . 7 7 2 . 7 1 3 . 8 7 3 . 7 7 2 . 2 9 3 . 3 3 3 . 1 0 Fd .\ 0 . 0 6 5 7 0 . 0 5 6 6 0 . 0 7 3 7 0 . 0 5 6 6 0 . 0 9 0 4 0 . 0 2 8 4 0 . 0 1 0 0 0 . 0 4 3 8 •) S 3 / 2 3 / 2 1/2 1/2 1/2 1/2 1/2 1/2 gc 2 . 1 5 2 . 1 4 4 . 7 6 4 . 7 9 4 . 6 4 4 . 3 9 4 . 4 5 4 . 2 3 -JCcm-1)^  0 . 5 4 0 . 5 9 2 . 1 4 2 . 9 7 3 . 0 3 1 . 7 7 2 . 4 6 2 . 4 6 Fd 0 . 0 7 5 8 0 . 0 6 8 6 0 . 0 8 2 6 0 . 0 6 8 6 0 . 1 0 0 8 0 . 0 3 1 8 0 . 0 1 7 6 0 . 0 4 3 7 a w= W e n g ( r e f e r e n c e s 1 3 4 a n d 1 3 5 ) ; W - F = W a g n e r - F r i e d b e r g ( r e f e r e n c e 1 3 3 ) a n d 1 = I s i n g ( r e f e r e n c e 1 4 9 ) . b D a t a f i t t e d o v e r r a n g e 2 - 3 0 K o n l y . c T h e v a l u e s o f J a n d g a r e b o t h c o n s i d e r e d a c c u r a t e t o ± 1 % . d F = f i t t i n g f u n c t i o n d e f i n e d i n C h a p t e r 2 . 9 6 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 3.20. Magnetic susceptibility versus temperature plot for C o ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 : A, line is best fit over the entire temperature range to the Wagner-Friedberg S = 3/2 model; B, line is best fit to the Weng S = 1/2 model with the data fitted over the 2 - 30 K range only. 97 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 3.21. Magnetic susceptibility versus temperature plot for Co(H20)2[H(C6H5)P02]2: A, line is best fit over the entire temperature range to the Wagner-Friedberg S = 3/2 model; B, line is best fit to the Wagner-Friedberg S = 1/2 model with the data fitted over the 2 ~ 30 K range only. 98 o l 1 i 1 I I I I I 1 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 3.22 Magnetic susceptibility versus temperature plot for Co(pyz)[H(C6H5)P02]2: A, line is best fit over the entire temperature range to the Wagner-Friedberg S = 3/2 model; B, line is best fit to the Wagner-Friedberg S = 1/2 model with the data fitted over the 2 - 30 K range only. 99 3.2.6.2. Tetrahedral Complexes Magnetic susceptibilities measured over the temperature range of 82K to 2.2K for the three forms of Co[H(C6H5)P02]2 are given in the Appendix, together with calculated values of u^ ff. Magnetic moment versus temperature plots at H = 9225 G for these compounds are shown in Figure 3.24. When the cobalt(U) ion is in a tetrahedral environment, even in a distorted one, the ground state will be a orbital singlet. The energy level diagram for spin-free tetrahedral cobalt(II) is shown in Figure 3.23. This figure also shows the effect of zero-field splitting on the ground 4 A2 state. The magnetic moments of tetrahedral cobalt(II) complexes are expected to be temperature independent over a wide range of temperature with possibly some decrease in moment with temperature at the lowest temperatures due to zero-field splitting effects. The strong temperature dependence of p^ ff shown by all three forms of Co[H(C6H5)P02]2 suggests the presence of magnetic exchange interactions, antiferromagnetic for the Form II and III compounds and ferromagnetic in the case of the Form I compound. Consider first the Form II and Form III compounds of Co[H(C6H5)PC«2]2. Attempts to fit the magnetic data for these complexes to the zero-field splitting model for S = 3/2 failed to produce reasonable agreement with experiment. The data cannot be accounted for on the basis of zero-field splitting alone. Assuming the temperature variation of the moment arises primarily from antiferromagnetic coupling, the data were fitted to the Weng and Wagner-Friedberg, S = 3/2 models!133-135]. There is litde difference in the quality of fit between the two models, the fit being reasonable for both. Values of the magnetic parameters are given in Table 3.8 and the best fit magnetic susceptibility curves using the Wagner-Friedberg model are shown in Figure 3.25. Form I of Co[H(C6Hs)P02]2 shows rather unique magnetic properties (Figure 3.24). In an applied field of 9225 G, the magnetic moment remains almost constant as the temperature is decreased to about 20 K, around which temperature it increases to a 100 maximum value at ~ 8 K and then falls sharply at lower temperatures. The magnetic properties are also field dependent below ~ 8 K. Magnetic moment versus temperature plots and magnetic susceptibility versus temperature plots are shown in Figures 3.26 and 3.27 respectively for applied fields ranging from 100 to 9225 G. The increasing magnetic moment with decreasing temperature indicates ferromagnetic exchange. The magnetic susceptibilities show an increasing tendency on increasing the field to level out as the temperature is lowered (Figure 3.27). This has the effect of shifting the maximum in the Heff versus temperature plot to lower temperatures as the field strength is reduced. This behavior is consistent with magnetic saturation effects. It is also possible that this compound is exhibiting metamagnetismt111-150] in which there is weak interchain annferromagnetism combined with intrachain ferromagnetism. Without detailed structural information on the three forms of Co[H(C6H5)P02]2, it is difficult to speculate on the sources of the different magnetic properties of these materials. We do note however, that extensive studies on phosphinate bridged copper(II) complexest13'20"23! have shown that in those complexes the nature of the magnetic exchange is influenced significantly by structure. Both antiferromagnetic and ferromagnetic copper phosphinates have been studied and their magnetic properties correlated with the detailed geometry of the Cu04 chromophore. In essence, changing the geometry alters the efficiency of o- and n- pathways for exchange and hence alters both the magnitude and sign of the coupling^ 22]. Similar effects could be operative in these cobalt phosphinate polymers. 101 \ N _ J _ M,=+l/2 Free ion Tetrahedral Axial Zero field field field splitting Figure 3.23. Partial energy level diagram for tetrahedral cobalt(n). Table 3.8. Magnetic Parameters for Co[H(C6H5)P02]2 complexes. Model3 Compound Wagner-Friedberg Weng -Kcm-1)^ g b F c -Kcnr1)*' g b F FormH 0.37 2.29 0.0380 0.34 2.30 0.0386 Formm 0.97 2.31 0.0323 0.87 2.31 0.0492 a W= Weng (references 134 and 135); W-F= Wagner-Friedberg (reference 133). b The values of J and g are considered accurate to ± 1% and ±1% respectively. c F= fitting function defined in Chapter 2. 102 e-l so =1 i 44 "5 c OD es o o o o o • O D § ° o 8 • • • o • o o o o o o n D D D Legend • F O R M I o F O R M II O F O R M III 1+-0 20 — r -eo 40 Temperature (K) eo 100 Figure 3.24. Magnetic moment versus temperature plot at H=9225 G for the three forms of Co[H(C6H5)P02]2. 103 6 - l 1 . 1 , 1 T— 0.0 ?0.0 «3 C *° ' c ' Temperature (K) Figure 3.25. Magnetic susceptibility versus temperature plots for a) Form II and b) Form UI of CorH(C6H5)P02]2. Solid lines are best fit to the Wagner-Friedberg, S = 3/2, model. 104 3600-1 3000-o ^ 2600-m E o JO »* a CA 3 CA 4} 1000 1600-es 600-© © Legend • A © o B © a C © D © a> • • % • • * • m m m 20 40 60 Temperature (K) 80 100 F i g u r e 3 . 2 6 . M a g n e t i c s u s c e p t i b i l i t y v e r s u s t e m p e r a t u r e p l o t s f o r C o [ H ( C 6 H 5 ) P 0 2 l 2 a t d i f f e r e n t m a g n e t i c fields. F i e l d s t r e n g t h ( G ) : A = 9 2 2 5 , B = 7 5 0 1 , C = 2 5 4 9 a n d D = 1 0 0 . 1 0 5 8 7.5 7-ca it E o • - 6.5-re 4.5 4-3.6 o o © o n 0 OQ O o Legend • A o B o C o D © © © © © 9 • A? » 9 © © 9 © © § 20 40 - T -60 80 100 Temperature (K) F i g u r e 3 . 2 7 . M a g n e t i c m o m e n t v e r s u s t e m p e r a t u r e p l o t s f o r C o t H C C g r y P C ^ h a t d i f f e r e n t m a g n e t i c f i e l d s . F i e l d s t r e n g t h ( G ) : A = 9 2 2 5 , B = 7 5 0 1 , C = 2 5 4 9 a n d D = 1 0 0 . 1 0 6 3.3. Summary and conclusions Complexes of the general formula CoLx[H(C6H5)P02]2 where Lx = (HCONH2>2, (H2CO2, (py)2. (pyz) and (H20)4 have been synthesized and characterized in this work. Evidence indicates that all five of these complexes have pseudo-octahedral structures. A single crystal X-ray diffraction study of Q)(H20)4[H(C6H5)P02]2 showed the complex to be mononuclear with water molecules forming a square planar array about cobalt and monodentate phosphinate ligands binding in axial position. The molecules are joined in sheets by hydrogen bonding interactions. The magnetic properties of this compound have been interpreted on the basis of single ion effects, there being no clear evidence for magnetic exchange. Although no single crystal structure data are available for Co(py) 2[H(C6H 5)P02]2, analogous to Co(HCONH2)2[H(C6Hs)P02]2 (see below) the compound is assigned to be magnetically dilute. Evidence for magnetic exchange interaction was found for three of the complexes. Co(HCONH2)2[H(C6H5)PC>2]2 is shown by single crystal diffraction to have a polymeric structure with two phosphinate ligands forming double O-P-0 bridges between adjacent metal atoms. The compound is antiferromagnetic and the magnetic susceptibility data were analyzed employing a number of models for antiferromagnetically coupled chains of cobalt ions. Co(H20)2[H(C6H5)P02]2 and Co(pyz)[H(C6H5)P02]2 are considered to be have polymeric structures analogous to that of Co(HCONH2)[H(CfjH5)P02]2 in which cobalt ions are linked in chains by double phosphinate bridges with neutral H2O or pyz molecules occupying the 5th and 6th coordination sites around each cobalt In the case of the pyrazine complex the pyz ligand cross-links the cobalt-phosphinate chains to form a two-dimensional structure. These structural conclusions are supported, primarily, by analyses of vibrational and electronic spectra of the complexes. The magnetic properties of the aquo and pyrazine complexes show the presence of antiferromagnetism. The strength of exchange coupling in the MLx[H(Cf5H5)P02]2 cobalt complexes which contain bridging phosphinate groups appears to increase in the order L= py <pyz < H2O < H C O N H 2 . The 107 relative positions of the complexes containing N-bonded ligands versus those containing O-bonded ligands may be explained oh the basis of relative basicities towards cobalt. The greater basicity of pyridine and pyrazine towards cobalt may result in weaker bonding between cobalt and the bridging phosphinate ligands in these complexes and hence in weaker exchange. Co[H(C6H5)P02]2 has been obtained in three structural forms each with distinct magnetic properties. While we were unable to obtain single crystals for X-ray studies for any of three forms, spectroscopic data indicates that the cobalt is tetrahedral in all three forms. All three forms are considered to be polymeric since all show significant magnetic concentration effects. Form II and Form III are antiferromagnetic while Form I exhibits ferromagnetic properties. 108 Chapter 4 Nickel(II) Monophenylphosphinate and Its Complexes 4.1. Introduction One of the aims of the present work was to extend the investigation of the adduct poly(metal phosphinates) of the type MLx[H(C6H5)P02]2 to include nickel(U) complexes. We describe here the synthesis and characterization of several complexes, where L x = (HCONH 2) 2 , (H20)2, (py)2, (pyz) and (H20)4. These complexes, which are analogues of the cobalt complexes described in the last chapter, were expected to be octahedral. Since octahedral nickel(U) has a 3 A 2 g ground stated146^ it was anticipated that the interpretation of the magnetic properties of these nickel complexes would be more straightforward than was the case with the analogous cobalt systems. Finally, since Ni[H(C6H5)P02]2 itself has not been studied previously, we prepared and characterized it also. 4.2. Results and Discussions 4.2.1. Syntheses, Solubilities and Thermal Properties Detailed synthesis procedures are given in Chapter 8. The general methods of preparing the complexes described in this chapter may be summarized by the following equations. H 2 0 NiS0 4-6H 20 + 2H(C6H5)P02Na > Ni[H(C 6H5)P0 2] 2xH 20| + Na 2S0 4 200 °C Ni[H(C 6H 5)P0 2] 2xH 20 > Ni[H(C6H5)P02]2 + xH 2 0 [4.1] H 2 0 NiS0 4-6H 20 + 2H(C6H5)P02Na Ni(H 20) 2[H(C6H 5)P0 2] 2i + 4H 2 0 + Na 2S0 4 [4.2] 109 Acetone Ni(C104)2-6H20-r2H(C6H5)P02H+4HCONH2 »• Ni(HCONH2)2[H(C6H5)P02]2i +2HCONH2HC104 + 6H20 [4.3] C5H5N Ni[H(C6H5)P02]2 + 2C5H5N ^ Ni(C5H5N)2[H(C6H5)P02]24 [4.4] C4H4N2 Ni[H(C6H5)P02]2 + C4H4N2 *• Ni(C4H4N2)[H(C6H5)P02]24 [4.5] 2,2-DMP H20 NiCl2-6H20 + 2H(C6H5)P02Na > Ni(H20)4[H(C6H5)P02]2 + 2H20 + 2NaCl [4.6] The thermal parameters for nickel(U) monophenylphosphinate and its complexes are given in Table 4.1 and the thermograms for these compounds are shown in Figure 4.1. The DSC curve for Ni[H(C6Hs)P02]2 exhibits an event corresponding to exothermic, oxidative decomposition in the range of ~250 to ~370 °C. No other thermal events are observed. In the case of Ni(HCONH2>2[H(C6H5)P02]2, a sharp endothermic event is observed at 145 °C followed immediately by another two endothermic events at about 180 and 205 "C. The weight loss of 24% obtained by heating a sample of the compound to the end of the three endothermic events compares favorably with the value of 25% expected for the loss of the two moles of HCONH2. Onset of decomposition occurs at about 280 °C. Ni(H20)2[H(C6H5)P02]2 undergoes the loss of two aquo ligands at 185 °C and onset of decomposition occurs at ~280 °C for this compound. The onset of thermal decomposition is at about 250 °C for Ni(py)2[H(C6Hs)P02]2 following the loss of two moles of pyridine at about 186 "C. The DSC curve for Ni(pyz)[H(C6H5)P02]2 shows two endothermic events at 153 and 257 °C. The former event is very weak and the latter is strong and broad ranging from -200 to ~260 °C. The weight loss of 18% obtained by heating the sample of the compound to 260 °C is in agreement with the value of 19% expected for the loss of one mole of pyrazine. Exothermic decomposition of this compound begins at 260 °C. Ni(H20)4[H(C6H5)P02]2, unlike the cobalt analogue (Chapter 3), shows only one endothermic peak at 139 °C. The weight loss measurement confirms the 110 loss of four moles of H2O associated with this event. Exothermic decomposition begins at -280 *C. All of the NiLx[H(C6H5)P02]2 complexes appear to lose their neutral ligands on heating ( at temperature ranging from 140 to -260 *C) forming the non-ligated Ni[H(C6H5)PC>2]2 compound. Further heating results in oxidative decomposition, the onset of which varies slightly for each compound but is generally observed to begin somewhere in the 250 to 280 'C range. Ni[H(C6H5)P02]2 itself exhibits only exothermic • decomposition beginning at about 260 'C. For all of these compounds there is a single exothermic peak generated by oxidative decomposition and this occurs over the narrow temperature range of 309 to 329 *C. Table 4.1. Thermal parameters for Ni[H(C6H5)P02]2 and the NiL x[H(C6H5)P02]2 complexes. Compound Peak Temp. CC) AH (kJmoH) %Weight Loss Calcd.3 Obs. Ni[H(C6H5)P02]2 260b Ni(HCONH2)2[H(C6H5)P02]2 145f 180 V 205 J 280b 200 25 24 Ni(H20)2[H(C6H5)P02]2 185 280b 99 11 10 Ni(py)2[H(C6H5)P02]2 186 250b 122 32 31 Ni(pyz)[H(C6H5)P02]2 156 257 260b 2 63 19 18 Ni(H20)4[H(C6H5)PO2l2 139 280b 203 17 16 * Calculated for loss of all neutral ligands. b Onset of exothermic decomposition (*C). All other events are endothermic. I l l I o K I d 1 1 i 1 1 1 1 i 1 0 0 2 0 0 3 0 0 Temperature (*C) Figure 4.1. Thermograms of a) Ni[H(Ct5H5)P02]2. b) Ni(HCONH2)2[H(C6H 5)P02]2, c) Ni(H20)2[H(Q>H5)P02]2, d) Ni(py)2[H(C6H5)P02]2, c) Ni(pyz)[H(C6H5)P02]2 and 0Ni(H2O)4[H(C6H5)PO2]2. 112 4.2.2. X-ray Powder Diffraction The X-ray powder diffraction patterns of Ni[H(C6Hs)P02]2 and the NiLx[H(C6H5)P02]2 complexes are shown in Figure 4.2. The diffraction data for all the compounds studied here are presented in the Appendix. A comparison of the diffraction data indicates isomorphism of the NiL x [H(C6Hs)P02]2 complexes, where L x = (HCONH2)2 and (H2CO2 with the corresponding manganese and cobalt compounds and where Lx = (py)2, (pyz) and (H2CO4 with the corresponding cobalt compounds. The diffraction pattern of Ni[H(C6H5)P02]2 shows broad peaks indicating poor crystallinity. This makes it difficult to draw useful comparisons with the cobalt and manganese analogues, however, it seems unlikely from these results that this compound is isomorphous with the other metal monophenylphosphinates. 113 JuiLliMLJLu. W5 es tm JO u < c S o U 'i i i i * 10.0 20.0 30.0 40.0 50.0 60.0 Figure 4 . 2 . 26 X-ray powder diffraction patterns for: a) N i ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 3 2 , b ) N i ( H 2 0 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 , c) N i ( p y ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 , d) N i r H ( C 6 H 5 ) P 0 2 ] 2 , e) Ni(pyz)[H(C6H 5 )P0 2 ]2 and f) N i ( H 2 0 ) 4 [ H ( < ^ H 5 ) P 0 2 ] 2 . 114 4.2.3. Infrared Spectroscopy Complete infrared data over the 4000 ~ 250 cm*1 range for the nickel compounds are given in the Appendix and the spectra from 1600 to 400 cm-1 are shown in Figures 4.3 and 4.4. We will discuss here some selected vibrational frequencies listed in Table 4.2. For Ni(HCONH2)2[H(C6H5)P02]2 and Ni(H20)2[H(C6H5)P02]2 the P 0 2 stretching vibrations yield A values (A = VPC*2 anti. - VP(>2 sym.) of 85 and 82 cm-1 respectively. Such A values are consistent with relatively symmetrical O-P-0 bridging unitst56!. In contrast, the A values for Ni(pyz)[H(C6H5)P02l2 and Ni(py)2[H(C6H5)P02]2 (123 and 143 cm-1 respectively) suggest rather unsymmetric O-P-0 units in these compounds. The A value of 92 cm"1 for Ni(H20)4[H(C6Hs)P02]2 suggests relatively symmetrical O-P-0 units in this compound. While this is somewhat surprising since the compound likely has a mononuclear structure with monodentate phosphinate groups, the explanation probably lies in hydrogen bonding effects as discussed in Chapter 3 for the cobalt analogue. It is difficult to comment on the nature of the PO2 groups in Ni[H(C6H5)P02]2 other than to note that a splitting of the V P02 anti. band may indicate the presence of two structurally inequivalent phosphinate groups in this compound Ni(HCONH2)2[H(C6H5)P02]2 exhibits broad, medium intensity, structured absorptions centered around 3185 cm-1 (maxima at -3238 and 3132 cnr1) due to NH2 stretching and a strong broad band at 1654 cnr1 (shoulder at -1702 cm-1) due to CO stretching. The corresponding bands appear at approximately 3310 and 1680 cm-1 in pure H C O N H 2 [ 1 2 2 l . The smaller shift in v(CO), compared to that in v(NH2) (as in the case Co(HCONH2)2[H(C6H5)P02]2) shows that, in spite of the fact that the formamide ligand is almost certainly coordinated through oxygen as it is in the cobalt analogues, the perturbation of the ligand caused by the hydrogen bonding interaction involving the NH2 groups is greater than the perturbation caused by coordination through oxygen. All the nickel complexes studied in this section show only one band due to the P-H stretching vibration. This implies the existence of only one type of phosphinate ligand in 115 these compounds although as suggested above there is evidence for non-equivalent phosphinates in Ni[H(Cf5H5)P02]2- The bands assigned to py and pyz vibrations in the Ni(py)2[H(C6H5)P02]2 and Ni(pyz)[H(C6H5)P02]2 complexes are given in the Appendix. The bands due to pyridine show a coordination dependence with the 6a and 16b bands, in particular, showing significant shifts to 632 and 441 cm -1, respectively. The infrared spectrum of Ni(pyz)[H(C6Hs)P02]2 shows no bands at approximately 1230, 920 and 750 cm -1, indicating as discussed in Section 3.2.4 that the pyrazine ligand is acting as a bidentate bridge between the metal centers^  1 4 4 X In summary, the infrared spectra are consistent with symmetrical bridging phosphinate groups in the Ni(HCONH2)2[H(C6H5)P02]2 and Ni(H20)2[H(C6H5)PC>2]2 complexes, with relatively unsymmetrically bridging or monodentate phosphinate groups in Ni(py)2[H(C6H5)P02]2 and Ni(pyz)rH(< 5^)P02]2. The spectrum of NirH(C6H5)P02j2 suggests the presence of more than one type of phosphinate group in this compound. 116 Table 4.2. Selected infrared data (cm1) for Ni[H(C6H5)P02l2 and NiLxtH(C6H5)P02]2 complexes. Compound vP02anti. vP02sym. A 1 V P - H v O-H v N-H VC=0 Ni[H(C6H5)P02]2 1144 vs. 1015 m. 1115 vs. Ni(HCONH2)2[H(C6H5)P02]2 1130 vs. 1045ms. 2380 w. 115a 85 2404 m. 3238 s 3132 s. 1702s.sh. 1654 s. Ni(H20h[H(C6H5)P02h 1140 vs. 1058 s. 82 2391 w. 3310 m. 1710 w. Ni(py)2fH(C6H5)P02]2 1185 vs. 1042 m. 143 2318 w. Ni(pyz)rH(C6H5)P02h 1174 vs. 1051m. 123 2318 w. Ni(H20)4tH(C6H5)P02]2 1141 vs. 1049 s. 92 2412 m. 3350 s.br. 3100 s.br. 1650 m. »A = V P02 anti.- vp()2sym.. 8 A value calculated by averaging the two ^ 0 2 anti. peaks. WAVENUMBER /cnr1 Figure 4.3. Infrared spectra of a) Ni(HCONH2)2[H(C6H5)P02]2, b) Ni(H20)2[H(C6H5)P02]2 and c) Ni(py)2[H(C6H5)P02]2. 118 j I i v i I 1 L_ 1600 H 0 0 1200 1000 8 0 0 6 0 0 4 0 0 WAVENUMBER /cnr1 Figure 4.4. Infrared spectra of a) Ni[H(C^5)P02J2. b)Ni(py2)rH(C6H5)P02]2 and c) Ni(H20)4lH(<^5)P02]2. 119 4.2.4. Electronic Spectroscopy Ni[H(C6H5)P02]2 is yellow in color while Ni(HCONH2)2[H(C6H5)P02]2 , Ni(H20)2[H(C6H5)P02]2 , Ni(py)2H(C6H5)P02]2, Ni(pyz)[H(C6H5)P02]2, and Ni(H20)4[H(C6H5)P02]2 are all light green. The electronic spectra of the complexes over the range 300 nm to 900 nm are shown in Figure 4.5 and band position assignments are given in Table 4.3. For nickel(II) octahedral complexes, three spin-allowed transitions are expected. We interpret the bands observed here as arising from transitions from the ground 3 A 2 g state to excited 3 Ti g (P) , V 3 , and 3 Ti g (F) , V 2 , states in octahedral symmetrytLU6]. T h e complexes are clearly not regular octahedral, however, the spectra show no clear evidence of symmetry lowering except possibly for the feature occuring at -15,000 cm"1 in some of the spectra which may arise from a splitting of the 3Ti g(F) state. It is also possible that this feature is a spin forbidden band which has gained intensity from mixing of singlet and triplet states. Evidence of band splitting due to symmetry lowering is seen in Ni(pyz)[H(C6H5)PC*2]2 where the v 2 band is broad and split. It is important to note that the X-ray powder diffraction patterns of Ni(HCONH2)2[H(C6H5)P02]2 and Ni(H20)4[H(C6Hs)P02]2 indicate these compound are isomorphous and probably isostructural with the cobalt analogues and that the latter compounds have been determined by single crystal X-ray diffraction to have pseudo-octahedral structures (Section 3.2.2). This gives strong support to our assignment of the spectra of these nickel complexes, shown in Figure 4.5, to pseudo-octahedral stereochemistry. The similarity in the spectra of Ni[H(C6Hs )P02]2 , N i ( H 2 0 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 and N i ( p y ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 with those of Ni(HCONH2)2[H(C6H5)P02]2 and Ni(H20)4[H(C^H5)P02]2 supports pseudo-octahedral stereochemistry for all five complexes. The difference in the spectrum of the Ni(pyz)[H(C6H5)P02]2 complex compared to those of the other complexes suggests that 120 the pyz complex may have a greater degree of distortion from regular octahedral symmetry than exhibited by the other complexes. The conclusion based on the electronic spectra (Figure 4.5) that Ni[H(Cf5H5)PC>2]2 is pseudo-octahedral is significant in that this would require a structure for this compound in which two of the phosphinate oxygens in the Ni[H(C6H5)P02]2 unit must be bidentate. Possible structures for this compound will be considered in a later section. This conclusion that Ni[H(Cf3H5)P02]2 involves octahedral metal centers is consistent with the conclusion from X-ray powder diffraction studies that this compound is not isomorphous with any of the forms of Co[H(C6H5)P02]2 which involve tetrahedral metal centers. 121 300 400 600 600 900 nm Figure 4.5. Electronic spectra of a) Ni(pyz)[H(C£H5)P02]2. b) Ni(HCONH2)2rH(C6H5)P02]2 , c) Ni(H20)2rH(C6H5)P02]2 , d) Ni(py)2rH(C6H5)P02]2. e) Ni(H20)4[H(C6H5)P02]2 and f) NirH(C 6H 5)P0 2] 2. 1 2 2 Table 4.3. Electronic spectral data for Ni[H(C 5^)P02]2 and NiLx[H(C6H5)PC>2]2 complexes. Compound Band Position (103 cnr1) Assignment Ni[H(C6H5)P02]2 12.5 m. 3Tig(F) <- 3 A 2 g 14.3 m.sh. 23.1s. 3Tig(P) <- 3A 2 g Ni(HCONH 2)2[H(C6H 5)P02]2 12.5 s. 3 T i g ( F ) <- 3 A 2 g 14.6 m.sh. 23.8 s. 3 T i g ( P ) < - 3 A 2 g Ni(H 20)2[H(C6H 5)P02]2 13.3 s. 3 T i g ( F ) <- 3 A 2 g 14.8 m.sh. 24.3 v.s. 3 T i g ( P ) <- 3 A 2 g Ni(py)2[H(C6H 5)P0 2]2 13.4 s. 3 T i g ( F ) <- 3 A 2 g 14.6 s.sh. 24.2 v.s. 3 T i g ( P ) <- 3 A 2 g Ni(pyz)[H(C6H5)P02]2 13.5 w.br. 3 T i g ( F ) <- 3 A 2 g 15.0 25.3 v.s. 3 T i g ( P ) <- 3 A 2 g Ni(H 20)4[H(C6H 5)P02]2 13.5 s. 3 T i g ( F ) <- 3 A 2 g 15.0 m.sh. 24.3 s. 3 T i g ( P ) <- 3 A 2 g 4.2.5. Magnetic Properties An octahedral nickel(U) ion possesses a 3A2g ground term. This has spin (S = 1), but no orbital angular momentum associated with it to first order. The presence of lower symmetry ligand fields has no direct effect on the ground term. Spin-orbit coupling, however, partially lifts the threefold spin degeneracy of the ground term (Figure 4.6) with 123 a zero-field splitting of a few cm-1 and also causes the g value to deviate measurably from the free spin value to values typically in the neighborhood of 2.25. The net result is that octahedral nickel(IT) complexes exhibit magnetic moments in excess of the spin-only value, typically in the range 2.9 to 3.3 p:B In addition, the magnetic moments are temperature independent at higher temperatures but not at very low temperatures (typically below 10 K) where the zero-field splitting causes a decrease in moment with decreasing temperaturef109-111]. Values of magnetic moments and magnetic susceptibilities at various temperatures for all of the nickel complexes studied here are given in the Appendix and plots of magnetic moment versus temperature for the NiLx[H(C6H5)P02]2 complexes are shown in Figure 4.7. 3 T -ig \ — — — — — "" " "V . . - " - f - n w - 1 ms = 0 Free ion Octahedral Axial field Zero-field field splitting Figure 4.6. Partial energy level diagram for octahedral nickel(U). 124 3.6 ca ov E o 2 z.s ov e ex n 2 2 -1.6-• o o o o 0 • O ° O D D D 9 O D O n * 5 i llilli © ° A * A rt D © _ © o e * 0 A © ° • A Legend • a © o b o c © o A • A * • i i • i • , , 1 1 20 4 0 eo Temperature (K) 60 100 Figure 4.7. Magnetic moment versus temperature plots for h^rH(C^5)PC>2]2 complexes: a) L*= (py)2, b) 1^ = (H20)4, c) L,= (pyz), d) Lx= (H20)2 and e) 1^ = (HCONH2)2-125 Ni(H 2 0)4[H(C6H5)P0 2 ]2 As discussed previously this complex is probably mononuclear and is unlikely to show significant magnetic exchange effects. The magnetic moment (Figure 4.7) is about 3.1 H B over the range ~ 80 to ~ 10 K and decreases with temperature below 10 K. The temperature dependence of its magnetic moment at low temperatures may be attributed to zero-field splitting effects, consequendy, it was deemed appropriate to analyze the susceptibility data of this compound by a model which considers this phenomenon. The axial zero-field splitting parameter D and the g values were found by a least-squares fit of the temperature dependence of the molar magnetic susceptibility to the following expression forS = ltl09]: 2 e x (2/x) (1 -e*) X | | = l + 2 e " x 5 X j = C 1 + 2e-* [4.8] where x = D/kT, C = Ng2(52/kT and the powder magnetic susceptibility is Xp= (X|(+ 2Xj)/3. The best fit magnetic susceptibility and magnetic moment versus temperature curves to the zero-field splitting model for this compound are shown in Figure 4.8. The best fit parameters obtained from this model are D = 5.3 cm-1 and g = 2.233 (F = 0.0269). 126 Figure 4.8. a) Magnetic susceptibility versus temperature plot, b) magnetic moment versus temperature plot for Ni(H20)4[H(C6H5)P02]2. Lines are calculated using the zero-field splitting, S =1, model. 127 Ni(py)2[H(C6Hs)P0 2J2 The magnetic moment of the bis(pyricUne) complex (Figure 4.7) is about ~3.25 pig at 82 K , reaches a value of 3.16 HB a t ~ 10 K and then decreases slighdy below 10 K . The magnetic behavior of this compound is similar to that of the tetraaquo complex suggesting that although it has bridging phosphinates there is little or no measurable magnetic exchange. Accordingly, the magnetic susceptibility data were fitted to the zero-field splitting model. The best fit curve is shown in Figure 4.9. The best fit parameters obtained are: D = 4.1 cm-1 and g = 2.278 Q? = 0.0183), comparable values to those obtained for Ni(Ff20)4[H(C6H5)P02]2- The fit is even better than that obtained for the tetraaquo complex leading to the conclusion that the magnetic properties of this compound can be accounted for by single-ion effects alone and there is no evidence for magnetic exchange. Ni(HCONH2)2[H(C6H5)P02]2 Ni0HCONH2)2[H(C^ H5)PO2]2 exhibits a strongly temperature-dependent magnetic moment, with values decreasing from approximately 2.97 pig at ~ 82 K to about 1.01 0.3 at ~ 4.7 K, a behavior characteristic of an antiferromagnetically coupled nickel(II) system. The effect of magnetic concentration in Ni(HC0^ 2)2|H(C6H5)P02]2 is more clearly seen in the variation of its magnetic susceptibility with temperature. XM exhibits a maximum at ~11 K. In accordance with the proposed polymeric structure of this compound, the magnetic data were analyzed according to one-dimensional Wagner-Friedberg and Weng chain models for S = 1 systems! 1 3 3 _ 1 3 5 J . The parameters obtained from the best fit of the magnetic susceptibility data for Ni(HCONH2)2[H(C6H5)P02]2 to the two one-dimensional models are given in Table 4.4. Excellent agreement between experimental and calculated susceptibilities were obtained for both models. The susceptibility data are plotted in Figure 4.10 where the solid line is calculated from the Wagner-Friedberg model using the best fit parameters. 128 Ni(H 20)2[H(C 6H5)P02]2 The magnetic behavior of this compound is similar to that of Ni(HCONH2)2[H(C6H5>P02]2. A temperature dependence of the magnetic moment is also exhibited in this system with moment values decreasing from 3.13 Hn at ~ 82 K to 1.01 pig at ~ 5 K (Figure 4.7). This again suggests the presence of strong antiferromagnetic exchange interactions. The parameters obtained from the best fit of magnetic susceptibility to theory calculated using the two one-dimensional models are given in Table 4.4. Excellent agreement between experimental and calculated susceptibilities were obtained for both models. Figure 4.11 shows the agreement between experiment and theory using the Wagner-Friedberg model and the best fit parameters. Ni(pyz)[H(C6H5)P02]2 Ni(pyz)[H(C6H5)P02]2 also exhibits a temperature dependent magnetic moment over the temperature range studied. The magnetic moment ranges from 3.17 HR at ~ 82 K to 2.07 pig at ~ 2.9 K (Figure 4.7). In this case there is no susceptibility maximum and any exchange present is clearly weaker than in the case of Ni(H20)2[H(C6Hs)P02]2 or Ni(HCONH2)2[H(C6H5)P02]2- The susceptibility data for Ni(pyz)[H(C6H5)P02]2 were analyzed using the two one-dimensional models and the magnetic parameters obtained by the best fit to theory are given in Table 4.4. Again there is good agreement between experiment and theory for both models. The agreement between experiment and theory can be seen in Figure 4.12 where the solid line is calculated using the Wagner-Friedberg model and the best fit parameters from Table 4.4. Infrared spectroscopy results (Section 4.2.4) suggest that Ni(pyz)[H(Ct5H5)P02]2 contains bridging pyrazine as well as bridging phosphinate ligands resulting in a sheet structure. Accordingly, Lines' two-dimensional model was also used to fit the magnetic susceptibility^!]. In using this model, the assumption is made that two exchange pathways are present and the exchange coupling constant is the same for both. The solid 129 line through the data points (Figure 4.13) represents the best fit using the following parameter values: J = - 0.74 cm - 1 and g = 2.267 (F = 0.0157). The good agreement may reflect the two-dimensional nature of the exchange interaction in Ni(pyz)[H(C6H5)P02]2. However, the agreement between experiment and theory is no better than for the one-dimensional models. It seems the exchange in this system is too weak to enable one to determine unambiguously whether the exchange is via both bridging units or only one. In summary, the Ni(H20)4[H(C6H5)P02]2 and Ni(py)2[H(C6H5)P02]2 complexes, like their cobalt analogues, give no clear evidence for magnetic exchange over the temperature range studied. The magnetic behavior of these compounds is dominated by single-ion effects. In contrast, Ni(HCONH2)2[H(C6H5)P02]2, Ni(H20)2[H(C6H5)P02]2 and Ni(pyz)[H(C6H5)P02]2 show antiferromagnetic exchange interactions. The magnitude of exchange in these phosphinate bridged complexes appears to increase in the order L = py < pyz < H2O < HCONH2- It seems that the same conclusion can be made here for the nickel(II) complexes as was made for the cobalt analogues. The N-bonded bases yield complexes with weaker exchange than do O-bonded bases. This is because the basicities of pyridine and pyrazine are greater than either H2O or HCONH2. The resulting strong bonds between nickel and these N-bonded ligands results in relatively weaker nickel-phosphinate bonds (compared to the strength of the nickel-phosphinate bonds in the complexes with O-bonded ligands) and hence weaker magnetic exchange. One difference, however, between the cobalt and nickel complexes concerns the pyrazine complexes. In the case of cobalt, there was no measurable exchange while for the nickel complex there is weak but measurable exchange. It is possible that in this case the exchange is actually via the pyrazine rather than the phosphinate bridges. 130 Table 4.4. Magnetic parameters for NiI^ rH(Ce5H5)P02]2 complexes. One-dimensional model3 Wagner-Friedberg Weng -J (cnr1)b g b F c -J (cnr1^ pc ( H C O N H 2 ) 2 4.52 2.34 0.023 3.60 2.30 0.019 (H20)2 1.89 2.32 0.012 1.67 2.32 0.018 (pyz) 0.69 2.26 0.016 0.63 2.27 0.013 8 W= Weng (references 134 and 135); W-F= Wagner-Friedberg (reference 133). b The values of J and g are both considered accurate to ± 1%. c F= fitting function defined in Chapter 2. Figure 4.9. Magnetic susceptibility versus temperature plot for Ni(py)2[H(C6H5)PC>2]2- Line is calculated using the zero-field splitting, S = 1, model. 131 1 1 1 1 1 1 1 1 1 — 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 4.10. Magnetic susceptibility versus temperature for Ni(HCONH2)2[H(C6H5)P02]2- Line is calculated using the Wagner-Friedberg, S = 1, model. 132 1 1 1 1 1 1 1 r 0.0 20.0 40.0 60.0 80. Temperature (K) F i g u r e 4 . 1 1 . M a g n e t i c s u s c e p t i b i l i t y v e r s u s t e m p e r a t u r e p l o t f o r N i ( H 2 0 ) 2 [ H ( C c j H 5 ) P 0 2 ] 2 . L i n e i s c a l c u l a t e d u s i n g t h e W a g n e r - F r i e d b e r g , S = 1, m o d e l . 1 3 3 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 4.12. Magnetic susceptibility versus temperature plot for Ni(pyz)[H(C6H5)P02]2. Line is calculated using the Wagner-Friedberg, S = 1, model. 134 • O O o E2-E • © w o a u 3 JH ° '•M O . (U ID s o 0.0 20 .0 40.0 Temperature (K) 60.0 80.0 F i g u r e 4 . 1 3 . M a g n e t i c s u s c e p t i b i l i t y v e r s u s t e m p e r a t u r e p l o t f o r Ni(pyz)[H(CrjH5)P02]2- L i n e i s c a l c u l a t e d u s i n g t h e L i n e s ' t w o -d i m e n s i o n a l m o d e l . 1 3 5 Ni[H(C 6 H 5 )P0 2 ]2 The magnetic properties of Ni[H(C6H5)PC>2]2 are unique amongst the nickel complexes studied here. The magnetic moment increases with decreasing temperature and at low temperatures is field dependent. This indicates ferromagnetic behavior. Both magnetic susceptibility and moment data at magnetic fields of 2549,7501, and 9225 G are presented in the Appendix. The plots of susceptibility versus temperature and magnetic moment versus temperature are shown in Figures 4.14 and 4.15. As illustrated in Figure 4.15, at all magnetic fields applied in this study the magnetic moment rises with decreasing temperature down to ~ 5 K. The moment then maximizes at 3.08, 5.08, and 5.32 K at fields of 2549, 7501 and 9225 G respectively. The moment then decreases with further decrease in temperature. We interpret the magnetic behavior of Ni[H(C6H5)P02]2 as follows. The compound is proposed to have or may have a sheet structure with double phosphinate bridged chains cross-linked as show below: 136 The dominant magnetic interaction is ferromagnetic. This causes the magnetic moment at the higher temperatures, to lie above the range 2.9 ~ 3.3 pig normally observed for octahedral nickel(II) and causes the moment to increase with decreasing temperature. Whether this interaction is via the O-P-0 bridges or the single oxygen bridges (between the chains) or involves both pathways is not possible to determine from our work. The maximum in Heff which is observed at low temperature arises from the leveling off of the magnetic susceptibility at these temperatures (Figure 4.14). The field dependence of this effect whereby there is a greater depression of the susceptibilities for higher fields suggests this is due largely to saturation effects. The presence of some antiferromagnetic coupling between ferromagnetic coupled chains or sheets as is seen in metamagnetic materials!109'150] cannot be discounted and may contribute to the suppression of the moment at low temperatures. 137 2000-1 ieoo-^ uoo 1 E «? P 1200 ™ 1000 OJ o e o o s Vi v e o o e e c a S 400 200 Legend • 2649 o 7501 D 9226 ft T -20 —P" eo m m 4 0 Temperature (K) 8 0 100 F i g u r e 4.14. M a g n e t i c s u s c e p t i b i l i t y v e r s u s t e m p e r a t u r e p l o t s f o r N i [ H ( C 6 H 5 ) P 0 2 ] 2 a t d i f f e r e n t m a g n e t i c f i e l d s . F i e l d s t r e n g t h ( G ) : 2 5 4 9 , 7 5 0 1 , 9 2 2 5 . 138 e.6-66 H E o ov c n 4.6-4H o o D § o o • Legend • 2649 o 7601 • 9226 3.6^ i f •••••• ° ° o e • e —r— 20 80 40 eo Temperature (K) 100 Figure 4.15. Magnetic moment versus temperature plots for Ni[H(C6H5)P02]2 a t different magnetic fields. Field strength(G): 2549,7501,9225. 1 3 9 4.3. S u m m a r y a n d C o n c l u s i o n s Complexes of the general formula NiLx[H(C6H5)P02]2 where L* = (HCONH2)2> (H2CO2, (py)2» (pyz) and (H2CO4 have been synthesized and characterized in this work. All five of these compounds are considered to have pseudo-octahedral structures. Ni(HCONH2)2[H(C6H5)P02]2, Ni(H20)2[H(C6H5)P02]2, Ni(py)2[H(C6H5)P02]2 and Ni(pyz)[H(C6H5)P02l2 are proposed to have polymeric structures analogous to that of Co(HCONH2)2[H(CgH5)P02]2 in which nickel atoms are connected in the chains by double phosphinate bridges with neutral HCONH.2> H2O, py or pyz ligands coordinating the 5th and 6th coordination site around each nickel. Like the cobalt analogue, in Ni(pyz)(H(Cf3H5)P02l2> the pyz ligand cross-links the nickel-phosphinate chains to form a two dimensional structure. These structural conclusions are supported, primarily, by analyses of vibrational and electronic spectra of the complexes. The magnetic properties of the formamide, aquo and pyrazine complexes show the presence of antiferromagnetism. The magnitude of exchange in these phosphinate bridged complexes appears to increase in the order L= py < pyz < H2O < HCONH2. The same conclusions have been made here as were made for the cobalt analogues. Ni[H(C6H5)P02]2 is postulated to have a sheet structure with double phosphinate bridged chains cross-linked as shown on page 136. The dominant magnetic interaction of this compound is ferromagnetic. The magnetic moment increases with decreasing temperature and at low temperature is field dependent. The magnetic behavior can be explained in terms of either saturation effects or metamagnetism. 140 Chapter 5 Diphenylphosphinates of Manganese(II), Cobalt(II) and Cadmium(II) 5.1. Introduction Block and Barth-Werenalpt5°] first showed that the diphenylphosphinate ion can serve as a bridging group between two metal ions, and can thus lead to polymer formation. They reported the reactions of (hphenylphosphinic acid with beryllium(H) acetylacetonate and chromium(iri) acetylacetonate. In each case, the reaction led to dimer formation in which two diphenylphosphinate groups serve to bind the metal ions together and the acetylacetonate (acac) groups act as terminal ligands. In their subsequent studies on this subject, they showed that polymeric substances can be formed by replacing the terminal acac groups with bridging groups. Coates and Golightlyf61] first described the preparation of cobalt(II) diphenylphosphinate, Co[(C6H5)2P02]2, and on the basis of its solubility and color they suggested a polymeric structure with tetrahedrally coordinated cobalt(II) ions linked in chains by double phosphinate bridges. Interestingly Gillman and Eichelberger fourteen years later proposed a cross-linked structure for this compound .^ Rose and Block meanwhile reported X-ray powder diffraction and thermogravimetric studies on Co[(C6H5)2P02]2 in 1966 and their work supported the original structure proposed in 1962. Moreover, these authors showed the compound to be isomorphous with the P-crystalline modification of zinc(II) diphenylphosphinatet89]. Although a second, y-modification of the zinc compound had been reported t 9 1l, no evidence for the y modification of Co[(C6Hs)2P02]2 was found in this earlier work. Giancotti et al J 6 2 ! had suggested that due to the reduction in conformational freedom of the chain backbone owing to the buUtiness of phenyl groups the zinc(II) and Be(II) diphenylphosphinate polymers contain tetrahedral centers and most likely possess alternate single and triple phosphinate bridges rather than double phosphinate bridges between metal centers. These authors went 141 on to suggest that all metal phosphinates which have tetrahedral metal centers will have alternate single and triple phosphinate bridges. This is clearly not the case as shown by the recently reported single crystal X-ray structure determination of zinc(II) monophenylphosphinate!82] which has tetrahedral metal centers and double phosphinate bridges. One other recent study on a metal diphenylphosphinate concerns the copper(II) compound. Bino and Sismant78! prepared Cu[(Cf5H5)2P02]2 hi a crystalline form and determined its structure by X-ray diffraction. The compound was found to be polymeric and to have the same basic double phosphinate bridged infinite chain structure as the other copper(II) phosphinates. However, while copper(II) dialkylphosphinates have generally been found to have structures in which the Q1O4 chromophore is compressed tetrahedral, in the case of the diphenylphosphinate compound the chromophore is square planar. Magnetic susceptibility studies at low temperatures were made on this compound soon after its structure was reported and this work showed the presence of weak ferromagnetic exchange in the compound!23 .^ In the present work we describe the synthesis and characterization of the diphenylphosphinates of manganese(II), cobalt(II) and cadmium(II). Whereas only one form of the cadmium compound was isolated, two forms of each of the manganese and cobalt compounds, the so-called (3- and y-forms were isolated. The y-forms were obtained in crystalline form suitable for single crystal X-ray diffraction studies. These studies revealed tetrahedral metal centers with double phosphinate bridges. Magnetic susceptibility studies to cryogenic temperatures have revealed weak but significant magnetic exchange interactions in all forms of the manganese and cobalt compounds. Evidence from irifrared spectroscopy and X-ray powder diffraction studies indicates the cadmium compound is isomorphous with the y-forms of Co[(C6H5)2P02]2 and Mn[(C6Hs)2P02]2. 142 5.2. Results and Discussion 5.2.1. Syntheses, Solubilities and Thermal Properties The general methods used to synthesize the diphenylphosphinates of manganese(n), cobalt(IT) and cadmium (IT) are summarized below. Experimental details are given in Chapter 8. The manganese(TI) and cobalt(II) diphenylphosphinates were each prepared in two different ways giving P- and y-forms of each with unique thermal and magnetic properties. DMF MnCl2-4H20 + 2(C6H5)2P02H + 2(CH3CH2)3N >-p-Mn[(C6H5)2P02]2 + 2(CH3CH2)3NHC1+ 4H20 [5.1] H20/CH3OH MnS04H20 + 2K[(C6H5)2P02] >- Y-Mn[(C6H5)2P02]2+ K 2S0 4 (3:1, v/v) +H20 [5.2] H20 (1) CoCl2-6H20 + 2Na[(C6H5)2P02] P*-Co[(C6H5)2P02]2 + 2NaCl + 6H20 [5.3] CH3CH2OH (2) Co(CH3C02)2-4H20 + 2(C6H5)2P02H > P-Co[(C6H5)2P02]2 2CH3C02H + 4H20 [5.4] DMF CoCl2-6H20 + 2(C6H5)2P02H + 2(CH3CH2)3N y-Co[(C6H5)2P02]2 + 2(CH3CH2)3NHC1 + 6H20 [5.5] The cadmium compound was prepared by the following route: H20/CH3OH CdS04-8H20 + 2K(C6H5)2P02 y-Cd[(C6H5)2P02]2 + K 2S0 4 3:1 v/v +8H20 [5.6] Solubility tests show that all the compounds studied in this section are insoluble or only slighdy soluble in polar solvents (water, ethanol, methanol and acetone). This can be understood in terms of the polymeric nature of these compounds and the inaccessibility of polar solvent molecules to the inorganic backbone, which has been shielded by the bulky 143 p h e n y l g r o u p s . T h e r e s u l t s o f t h e D S C a n a l y s e s a r e g i v e n i n T a b l e 5.1. T h e D S C t h e r m o g r a m s o f t h e p V f o r m s o f b o t h c o m p o u n d s s h o w j u s t o n e e n d o t h e r m i c p e a k w h i c h f o r t h e m a n g a n e s e c o m p o u n d i s a t 3 5 7 ° C a n d f o r t h e c o b a l t c o m p o u n d i s a t 3 6 6 ° C . T h e Y - f o r m s o f t h e c o b a l t a n d t h e m a n g a n e s e c o m p o u n d s e x h i b i t c o r r e s p o n d i n g e n d o t h e r m i c e v e n t s a t 3 6 8 a n d 3 5 6 * C r e s p e c t i v e l y . T h e s e e n d o t h e r m i c e v e n t s w h i c h o c c u r i n t h e 3 5 6 t o 3 6 8 * C t e m p e r a t u r e r a n g e c o r r e s p o n d c l o s e l y t o t h e |3—•£ ( p a r a c r y s t a l l i n e p h a s e ) t r a n s i t i o n r e p o r t e d f o r Zn[(C6Hs)2P02]2 ( 3 4 5 'Qfi® a n d m a y b e a s s i g n e d t o a s i m i l a r e v e n t i n t h e c o b a l t a n d m a n g a n e s e c o m p o u n d s . T h e D S C t h e r m o g r a m o f t h e y - f o r m o f Mn[(C6H.5)2P02]2 e x h i b i t s t w o a d d i t i o n a l e n d o t h e r m i c p e a k s , a m a j o r e n d o t h e r m i c e v e n t a t 2 1 3 * C a n d a m i n o r e v e n t a t 2 3 8 ° C . O n c o o l i n g t h e s a m p l e f r o m t h e p a r a c r y s t a l l i n e p h a s e t o 3 5 * C a n d r e h e a t i n g , t h e e v e n t a t 2 1 3 * C d i s a p p e a r s w h i l e t h e w e a k p e a k a t 2 3 8 ° C a n d t h e 3 5 6 * C e v e n t a r e r e t a i n e d . A p o s s i b l e e x p l a n a t i o n f o r t h e s e o b s e r v a t i o n s i s t h a t t h e Y - f o r m c o n v e r t s i r r e v e r s i b l y t o a t h i r d f o r m a t 2 1 3 * C w h i c h i n t u r n c o n v e r t s t o t h e | } - f o r m a t 2 3 8 * C . T h e t r a n s i t i o n from {$- t o t h e p a r a c r y s t a l l i n e p h a s e t h e n o c c u r s a t 3 5 6 * C a s o b s e r v e d f o r a n i n d e p e n d e n d y p r e p a r e d s a m p l e o f p V M n[(QH5)2P02] 2. C o m p l e x t h e r m a l b e h a v i o r o f t h i s t y p e i s n o t u n c o m m o n f o r m e t a l p h o s p h i n a t e p o l y m e r s ; i t i s i n t e r e s t i n g t h o u g h t h a t i t i s s e e n i n Y-Mn[(C6Hs)2P02]2 b u t n o t i n a n y o f t h e o t h e r c o m p o u n d s s t u d i e d h e r e . H e a t i n g t h e c o b a l t a n d m a n g a n e s e s a m p l e s t o 4 0 0 " C s h o w s n o f u r t h e r t h e r m a l e v e n t s . C d [ ( C 6 H s ) 2 P 0 2 ] 2 s h o w s n o t h e r m a l e v e n t s a t a l l f r o m 3 5 * C t o 4 0 0 * C . T h e r m a l d e c o m p o s i t i o n m u s t o c c u r a b o v e 4 0 0 * C f o r a l l o f t h e d i p h e n y l p h o s p h i n a t e s s t u d i e d h e r e . 1 4 4 b e ' i * * * 1 1 ' i ' 1 1 ' • 1 • 1 1 1 1 1 i) 1 1111111 1111 1 0 0 2 0 0 3 0 0 Temperature CC) Figure 5.1. Thermograms of a) jJ-Mn[(C6H5)2P02]2. *>) Y-MnKCeHshPO;^, c) P-Co[(C6H5)2P02]2, d) Y-Co[(C6H5)2P02]2 and e)Y-Cd[(C6H5)2P02]2. 145 Table 5.1. Thermal parameters for the diphenylphosphinates of manganese(n), cobalt(II) and cadmium(II). Compound Peak Temp. a C C ) AH (kJmol-1) P-Mn[(C6H5)2P02]2 357 12 Y-Mn[(C6H5)2P02]2 213 14 238 2 356 13 P-Co[(C6H5)2PC>2]2 366 11 Y-Co[(C6H5)2P02]2 368 9 Y-Cd[(C6H5)2P02]2 — — a A l l events are endothermic. 5.2.2. Single Crystal X-ray Diffraction Studies on Y-Mn[(C6H5)2P02]2 and Y-Co[(C6H5)2P02]2 The crystal and molecular structures of y-Mn[(C6H5)2PC>2]2 and Y-Co[(C6H5)2PC»2]2 were determined in this Department by S. J. Rettig. The crystal structures of the y-forms of the diphenylphosphinates of manganese(II) and cobalt(II) consist of well separated infinite chains of centrosymmetric fused eight-membered rings, each of which is made up to two metal atoms bridged by two phosphinate groups. In each compound, the conformations of the two crystallographically independent rings are similar and slighdy distorted. These polymeric structures are illustrated in Figure 5.2 and are different from those found for lead(II) diphenylphosphinatet68] a n d copper(II) diphenylphosphinatet78!. Crystallographic data for the two compounds are given in Table 5.2 and a complete compilation of structural parameters is provided in the Appendix. 146 The atom numbering scheme and the coordination around the metal atoms, for each compound, are illustrated in Figure 5.3. The coordination about each metal is approximately tetrahedral with O-M-0 bond angles ranging from 103.2(1) to 114.7(1)° for Y-Mn[(C6H5)2P02]2 and from 104.81(8) to 117.77(9)° for Y-Co[(C6H5)2P02]2. These contrast with the situation for the diakylphosphinates of copper(II) where the CuC>4 chromophore is a compressed tetrahedron (O-Cu-0 bond angles range from 97.75(5) to 149.85(6)° in the diethylphosphinate, for example^20!) and for copper(II) diphenylphosphinate where the coordination about the metal is square-planar. In the case of lead(U) diphenylphosphinate, the coordination around the lead atom has been described as a distorted trigonal bipyramid with two oxygen atoms in the axial positions and another two oxygen atoms and a lone pair of electrons in the equatorial planet68 .^ The mean M-0 distances for the diphenylphosphinates of manganese(II) and cobalt(II) are 2.023(3) and 1.954(2) A respectively. These distances are shorter than the corresponding ones of lead(II) diphenylphosphinate (2.334 A) and longer than those of copper(II) diphenylphosphinate (1.914 A). There is nothing remarkable about the internal phosphinate geometry in these compounds with bond angles and distances being typical for metal phosphinate compounds. A unique feature of the present structures, however, involves the conformation of the M-O-P-O-M unit. Here, the two bridged metals are on the opposite sides of the plane formed by the O-P-0 atoms and, as a consequence, the eight-membered rings are linked in a folded or stepped fashion along the direction of the chain. In the copper(II) diphenylphosphinate and dialkylphosphinate structures the bridged copper atoms are on the same side of the plane formed by the bridging O-P-O atoms and a more extended linear chain structure results. The M-M distances along the chain in the compounds studied here are 4.471(1) and 4.446(1) A for Mn-Mn and 4.329(1) and 4.363(1) A for Co—Co. This compares with M—M distances of 4.9277(8) and 4.9310(8) A for copper(II) di-n-hexylphosphinatet21]. 147 F i g u r e 5 . 2 . S t e r e o v i e w o f Y * M n [ ( C ^ 5 ) 2 P 0 2 ] 2 , s t r u c t u r e s h o w i n g a s e c t i o n o f t h e l i n e a r d o u b l e p h o s p h i n a t e b r i d g e d c h a i n s t r u c t u r e . Y - C o [ ( C r 5 H 5 ) 2 P 0 2 ] 2 i s i s o m o r p h o u s a n d i s o s t r u c t u r a l . F i g u r e 5 . 3 . S t e r e o v i e w o f t h e a s y m m e t r i c u n i t o f t h e Y-Mn[(C6H5)2P0232. s t r u c t u r e s h o w i n g a t o m l a b e l l i n g a n d t h e c o o r d i n a t i o n a b o u t t h e m e t a l a t o m . Y - C o [ ( C 6 H 5 ) 2 P 0 2 ] 2 i s i s o m o r p h o u s a n d i s o s t r u c t u r a l . 148 Table 5.2. Bond distances (A) and bond angles (") for Y-Mn[(C6H5)2P02]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond Distances(A) Angles(") Mn(l)—0(1) 2.032(3) Mn(l)—0(2)"a 2.033(3) Mn(l)—0(3) 2.028(3) Mn(l)—0(4)' 2.016(3) P(l)-0(1) 1.508(3) P(l)-0(2) 1.511(3) O(l)—Mn(l)—0(2)" 108.0(1) 0(3)—Mn(l)—0(2)" 104.7(1) 0(3)—Mn(l)—0(1) 114.7(1) 0(4)'—Mn(l)—0(2)" 112.4(1) 0(4)'—Mn(l)—0(1) 103.2(1) 0(4)'—Mn(l)—0(3) 114.0(1) a Here symbols ' and " refer to the symmetry operations: 1-x, 1-y, -z and -x, 1-y, -z. Table 5.3. Bond distances (A) and bond angles (") for Y-Co[(C6H5)2P02]2 with standard deviations in the last significant figure in the parentheses. Structure Bond Distances(A) Angles(°) Co(l)-0(l) 1.952(2) Co(l)—0(2)'a 1.963(2) Co(l)—0(3) 1.951(2) Co(l)—0(4)" 1.950(2) P(l)--OO) 1.510(2) P(D-0(2) 1.511(2) 0(1)—Co(l)—0(2)' 107.60(8) 0(l)-Co(l)-CK3) 117.77(9) 0(1)—Co(l)—0(4)" 104.83(9) 0(2)'—Co(l)—0(3) 104.81(8) 0(2)'—Co(l)—0(4)" 109.51(8) 0(3)—Co(l)—0(4)" 112.13(9) a Here symbols ' and" refer to the symmetry operations: 1-x, 1-y, 1-z and -x, 1-y, 1-z. 149 5.2.3. X- ray Powder Diffraction The diffraction patterns for all the compounds studied in this section are shown in Figure 5.4 and the diffraction data are recorded in the Appendix. Based on their X-ray powder diffraction patterns, the two crystalline modifications of Co[(C6Hs)2P02]2 prepared in the present work appear to be isomorphous with the (3- and y-modifications of Zn[(C6H5)2PO2]2t89,90]. For this reason they have been labelled (5- and y- here. The (3-form of the cobalt compound was reported previously by Rose and Block!80] who used a different synthetic route from that employed here, the latter being similar to that described by Coates and Golightly!61!. The powder patterns we observed for our (3-samples show broad line features at the higher 6 values suggesting a lower degree of crystallinity than in the y-samples. Comparison of X-ray powder diffraction patterns (Figure 5.4) indicates the two forms of Mn[(C6Hs)2P02]2 prepared here are isomorphous with the f3- and y-forms of Co[(C6H5)2P02]2 just described. The X-ray powder diffraction pattern obtained for Cd[(C6H5)2P02]2 indicates it is isomorphous with the y-forms of Mn[(C6H5)2P02]2 and Co[(C6H5)2P02]2. 150 e >K ii i iiiit 5.0 JO 15 20 25 30 35 40 45 50 55 60 26 Figure 5.4. X-ray powder diffraction patterns for: (a) p-Mn[(Q5H5)2PC>2]2, (b) y-Mn[(C^5)2P02]2. (c) P-Co[(C6H5)2P02]2, (d) Y-Co[(C6H 5)2P02]2 and (e)Y-Cd[(C6H5)2P0 2]2. 151 5.2.4. Infrared Spectroscopy The manganese(U), cobalt(II) and cadmium(II) diphenylphosphinate compounds are characterized by relatively simple infrared spectra, as illustrated for the f3- and y-forms of manganese(U) diphenylphosphinate in Figure 5.5. As can be seen the spectra of the two forms are very similar. In addition, there is very little difference between the spectra of the |3-forms of the cobalt and manganese compounds or between the spectra of the y-forms of the cobalt and manganese compounds reflecting, no doubt, httle difference in the structures of corresponding cobalt and manganese complexes. One minor difference appears to involve the antisymmetric PO2 stretching vibration which appears as a split band in both forms of the manganese complex and only a single band in the the cobalt analogues.The most distinctive feature in the infrared spectra which distinguishes the |3- and y-forms is a band at about 1210 cm*1 which is moderately strong in the y-form and appears only very weakly in the (J-form. y-Cd[(C6H5)2P02]2 also shows a strong band at 1210 cm-1. There are also some differences in the weak bands which occur below 500 cm-1 and which may be ascribed to M-0 or lattice vibrations. Values of the antisymmetric and symmetric PO2 stretching frequencies are listed in Table 5.4 together with the corresponding A CPO2 anti. - VP02 sym.) values. These A values, in the range of 82 to 94 cm-1, are consistent with relatively symmetric phosphinate bridging groups as confirmed by the X-ray structure determinations of the y-forms. 152 J I I I I 1 , I 1600 H00 UOO 1000 600 600 400 WAVENUMBER / c m " 1 Figure 5.5. Infrared spectra of (a) Y-Mn[(C6H5)2P02]2, (b) P-Mn[(C6H5)2P02]2, (c) Y-Co[(C6H5)2P02]2, (d) P-Co[(C6H5)2P02l2 and (e) Y-Cd[(C6H5)2P02]2. 153 Table 5.4. Selected infrared data (cm-1) for diphenylphosphinates of manganese(H), cobalt(H) and cadmium(II). Compound VP(>2 anti. VPC»2 sym. A* P-Mn[(C6H5)2P02]2 (1152, 1140) vs. 1060 vs. 86 Y-Mn[(C6H5)2P02]2 (1150, 1143) vs. 1053 vs. 94 P-Co[(C6H5)2P02]2 1138 vs. 1056 vs. 82 Y-Co[(C6H5)2P02]2 1135 vs. 1049 vs. 86 Y-Cd[(C6H5)2P02]2 1134 vs. 1045 vs. 89 1A = VPC»2 anti.- V P02 sym.. An average V P02 anti. was taken in calculating the A values for the manganese compounds. 5.2.5. Electronic Spectroscopy Electronic spectra over the frequency range 300 ~ 900 nm were recorded for the two forms of Co[(Cf3H5)2P02]2, and are shown in Figure 5.6. The spectra are dominated by the highest energy transition, 4Ti(P)<—4A2(F), which is centered around 600 nm. The spectra are almost identical indicating very little difference in the C0O4 chromophores of the (3- and y-forms. Both the |3- and y-forms of Mn[(C6H5)2P02]2.were obtained as fine white powders. The y-form was also obtained as pale-green crystals by allowing crystallization to take place over a few months. No solid state electronic spectroscopic studies were attempted on these manganese compounds which should show only spin-forbidden d-d transitions. 154 . •• . I . • • • I • • I — I — I — I — I — 1 — I — 1 — — I — I — I — • ' I • 350 400 500 600 700 600 900 F i g u r e 5.6. E l e c t r o n i c s p e c t r a o f C b [ ( C 6 H 5 ) 2 P 0 2 ] 2 : ( a ) Y - f o r m , 0>) p-form. 5.2.6. M a g n e t i c P r o p e r t i e s T h e m a g n e t i c s u s c e p t i b i l i t y v e r s u s t e m p e r a t u r e p l o t s f o r b o t h f o r m s o f M n [ ( C 6 H 5 ) 2 P 0 2 ] 2 a n d C o [ ( C 6 H 5 ) 2 P 0 2 ] 2 a r e s h o w n i n F i g u r e 5.7. T e t r a h e d r a l m a n g a n e s e ( I I ) c o m p l e x e s , b y v i r t u e o f 6 A i g r o u n d s t a t e , s h o u l d i n t h e a b s e n c e o f m a g n e t i c e x c h a n g e , e x h i b i t a t e m p e r a t u r e i n d e p e n d e n t s p i n - o n l y m a g n e t i c m o m e n t o f 5.92 WJ> w i t h p o s s i b l y s m a l l d e v i a t i o n s a t t h e l o w e s t t e m p e r a t u r e s d u e t o w e a k z e r o - f i e l d s p l i t t i n g ( Z F S ) e f f e c t s . B o t h f o r m s o f M n [ ( C 6 H 5 ) 2 P 0 2 ] 2 e x h i b i t l o w e r t h a n s p i n - o n l y m o m e n t s o v e r t h e e n t i r e t e m p e r a t u r e r a n g e s t u d i e d a n d , m o r e o v e r , t h e m o m e n t s d e c r e a s e s i g n i f i c a n t l y w i t h t e m p e r a t u r e ( s e e A p p e n d i x ) , t h u s i n d i c a t i n g t h e p r e s e n c e o f a n t i f e r r o m a g n e t i c c o u p l i n g . T h e c o u p l i n g a p p e a r s t o b e g r e a t e r i n t h e c a s e o f t h e p-form w h e r e t h e o n s e t o f a m a x i m u m i n t h e s u s c e p t i b i l i t y i s o b s e r v e d a t t h e l o w e s t t e m p e r a t u r e s s t u d i e d . F i t s t o t h e W a g n e r -F r i e d b e r g n 3 3 ] a n ( j >y e ng[134,i35] m o d e l s f o r S=5/2 w e r e o b t a i n e d a n d t h e b e s t f i t 155 parameters are given in Table 5.5. For these manganese compounds a better fit between experiment and theory is obtained if allowance is made for paramagnetic impurity as was described in an earlier study on manganese(II) monophenylphosphinate!8 1]. The improvement in fit is particularly noticeable near the susceptibility maximum in P-Mn[(C6H5>2P02]2. The best fit parameters, including allowance for paramagnetic impurity are also given in Table 5.5 and the theoretical curves obtained from the Weng model and employing these parameters are compared with experiment in Figure 5.7. The magnetic moment of cobaluTf) ( 4 A 2 ground state in Td) in a regular or distorted tetrahedral environment is expected to be temperature independent except possibly at very low temperatures where zero-field splitting (ZFS) effects may impart some temperature dependence! 1 0 9 ' 1 1 1]. The magnetic moments for both ($- and y-forms of Co[(C6H5)2PC>2]2 decrease significantiy with decreasing temperature (see Appendix). Attempts to fit the experimental magnetic susceptibilities calculated assuming zero-field splitting shows that ZFS alone can not account for the magnetic properties of these materials. The susceptibility data for the y-form pass through a maximum at 3.6 K indicative of antiferromagnetic behavior. Although the fi-form of Co[(CtsH5)2PC>2]2 does not exhibit a susceptibility maximum the data for both it and the y-form were analyzed according to the S=3/2 antiferromagnetic Wagner-Friedberg t 1 3 3 l and Wengt 1 3 4 * 1 3 5 ! models. The magnetic parameters generated for the best fits between experiment and theory are given in Table 5.5. For the y-form, the Weng model reproduced the position of the maximum in the susceptibility better and gave an overall better fit than the other model. The best fit curves for both the f and P-forms using the Weng model are shown in Figure 5.7. The exchange is clearly weaker in p-CoKQHstePC^te than in Y-Co[(C6H5)2P02]2. This differs from the situation with Mn[(C6H5)2P02]2 where the exchange is stronger in the case of the P-form compared to that of the y-form. 156 Table 5.5. Magnetic parameters for Mn[(C6Hs)2P02]2 and CoKC^HstePC^h-Metal Form Model3 S g b -JCcnr1)15 %pc F d p W 5/2 2.00 0.34 — 0.0442 W 5/2 2.00 0.45 4.0 0.0154 W-F 5/2 2.00 0.36 — 0.0335 W-F 5/2 2.00 0.41 3.1 0.0132 Y W 5/2 2.00 0.17 — 0.0125 W 5/2 2.00 0.19 8.1 0.0047 W-F 5/2 2.00 0.17 — 0.0169 W-F 5/2 2.00 0.19 6.5 0.0127 P W 3/2 2.29 0.25 — 0.0250 W-F 3/2 2.28 0.26 — 0.0263 Y W 3/2 2.32 0.55 — 0.0112 W-F 3/2 2.31 0.60 0.0229 aw = Weng[l34.135]; W-F = Wagner-Friedbergt133! model. bg value set at 2.00 for S = 5/2 and allowed to vary for S = 3/2. The values of J are considered to accurate to ± 2% for the manganese compounds and values of J and g are both considered accurate to ± 1 % for the cobalt compounds. c%p = % paramagnetic component set at zero where no value indicated. <*F = fitting function defined in Chapter 2. 157 Figure 5.7. Magnetic susceptibility versus temperature plots for M[(C6H5)2P02]2: (a) p*-Mn, (b) y-Mn, (c) p-Co, (d) y-Co. Circles are experimental data and solid lines are calculated as described in the text. 158 5.3. Summary and Conclusions In summary, 0- and y-forms of both Co[(C6Hs)2P02]2 and Mn[(C6H5)2PC»2]2 have been synthesized and characterized. All four materials show antiferromagnetic behavior which can be analyzed according to Heisenberg models for linear chains. Single crystal X-ray diffraction studies on the y-forms confirm the presence of extended chains in which tetrahedrally coordinated metal atoms are linked by double phosphinate bridges. The magnetic exchange which likely occurs by a superexchange mechanism via the bridging O-P-O groups is of the same order of magnitude in the y-forms of the cobalt and manganese compounds, which is perhaps not too surprising considering the similarities in the structural parameters in the two compounds. On the other hand, it is interesting to note that, whereas the exchange coupling is greater for the y-form of Co[(C6H5)2P02]2 compared to its P-form, the opposite is true for the Mn[(C6Hs)2P02]2 pair. Whether such a finding is a result of differences in the detailed structures of the two P-forms or a consequence of the different metal ion electron configurations and therefore magnetic orbitals involved is something which is difficult to answer without a detailed knowledge of the structures of the P-forms. Finally we isolated and characterized only one form of Cd[(CsH5)2P02]2- On the basis of a comparison between infrared spectra and X-ray powder diffraction patterns the cadmium compound appears to be isomorphous and probably isostructural with the y-forms of the cobalt and manganese compounds. 159 Chapter 6 Mixed Metal Systems - Mni . x Cd x [H(C6H 5 )P0 2 ] 2 , Mn 1 . xCd x(HCONH 2)2[H(C 6H 5)P02]2 and Mni. x Cd x [(C 6 H 1 3 )2P02] 2 6.1. Introduction Bridging phosphinates are capable of transmitting magnetic exchange effects between paramagnetic centers via a superexchange mechanism; examples of both ferromagnetic and antiferromagnetic coupling have been observed^ 22]. It has been pointed out that in the formation of extended polymers of the poly (metal phosphinate) type the incorporation of random defects in the polymer would effectively break it into finite segments and this may have a significant effect on the magnetic properties^ . Two recent studies along these lines have been carried out in our laboratory. In one study, material of composition Cuo.9Nio.i[(n-CsHi7)2P02]2 was prepared and characterized^152!. It was found that the whole system adopts the structure of pure copper(II) di-n-octylphosphinate (ferromagnetic form) with about 10% of the metal sites occupied by spin-paired nickel(II) ions. In the second study, the magnetic properties of samples of Mn[H(C6H5)P02]2 doped with varying amounts of cadmium ions (materials of composition Mni.xCdx[H(C6H5)P02]2 where x varies from 0.01 to 1.0) were investigated. This study showed that the effect of cadmium doping was to break the infinite manganese(II) monophenylphosphinate chains into finite segments generating what is in effect paramagnetic impurities in odd numbered segments!81'105]. This study showed that as the extent of doping increases, the average chain length decreases and in addition, the exchange coupling constant, J, decreases!81,105]. In the current study, described in this chapter, we have repeated the earlier work on the Mni.xCdx[H(C6H5)P02]2 system with one important change. In preparing the mixed metal samples, rather than using simple dropping funnels to manually add solutions of the 160 c a d m i u m a n d m a n g a n e s e a c e t a t e s i n a p p r o p r i a t e r e l a t i v e p r o p o r t i o n s t o a s t i r r i n g s o l u t i o n o f m o n o p h e n y l p h o s p h i n i c a c i d ( a s w a s d o n e i n t h e e a r l i e r w o r k t 8 ^ 1 0 5 ] ) , w e e m p l o y e d a p e r i s t a l t i c p u m p i n o r d e r t o c o n t r o l b e t t e r t h e c o n d i t i o n s o f p r e c i p i t a t i o n . W e w e r e i n t e r e s t e d i n s e e i n g w h e t h e r s a m p l e s p r e p a r e d u n d e r t h e s e m o r e c o n t r o l l e d c o n d i t i o n s w o u l d d i f f e r i n t h e i r p r o p e r t i e s f r o m t h e s a m p l e s s t u d i e d e a r l i e r . I n a d d i t i o n , i n o r d e r t o f u r t h e r i n v e s t i g a t e t h e e f f e c t s o f c a d m i u m d o p i n g , a n o t h e r t w o s e r i e s o f c o m p o u n d s o f c o m p o s i t i o n M n i . x C d x ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 , ( x = 0 t o 1 . 0 0 ) a n d M n i . x C d x [ ( C 6 H i 3 ) 2 P 0 2 ] 2 , ( x = 0 t o 1 ) w e r e p r e p a r e d a n d c h a r a c t e r i z e d . 6.2. R e s u l t s a n d D i s c u s s i o n 6.2.1. M n i . x C d x [ H ( C 6 H 5 ) P 0 2 ] 2 A s d e s c r i b e d i n t h e l i t e r a t u r e l 8 1 . 1 0 5 ! M n [ H ( C 6 H 5 ) P 0 2 ] 2 a n d C d [ H ( C 6 H 5 ) P 0 2 ] 2 a r e i s o m o r p h o u s m a k i n g t h e p r e p a r a t i o n o f a r a n g e o f s a m p l e s o f c o m p o s i t i o n M n i . x C d x [ H ( C 6 H 5 ) P 0 2 ] 2 , w h e r e x v a r i e s f r o m 1 t o z e r o , r e l a t i v e l y s t r a i g h t f o r w a r d . T h e d e t a i l s o f t h e s y n t h e t i c p r o c e d u r e s u s e d h e r e i n v o l v i n g a s y r i n g e p u m p a r e d e s c r i b e d i n C h a p t e r 8 . S a m p l e s w i t h t h e f o l l o w i n g v a l u e s o f x w e r e p r e p a r e d i n t h i s w o r k : 0 . 0 1 , 0 . 1 9 , 0 . 2 6 a n d 0 . 4 1 . I n a d d i t i o n t o e l e m e n t a l a n a l y s i s ( C h a p t e r 8 ) a l l s a m p l e s w e r e s u b j e c t e d t o a n a l y s i s b y X - r a y p o w d e r d i f f r a c t i o n , D S C a n d i n f r a r e d s p e c t r o s c o p y . A s o b s e r v e d i n t h e e a r l i e r s t u d y ! 8 1 - 1 0 5 ! , w e f o u n d t h a t t h e i n f r a r e d s p e c t r a a n d p o w d e r d i f f r a c t i o n p a t t e r n s w e r e v i r t u a l l y i n d i s t i n g u i s h a b l e f r o m t h o s e o f t h e p u r e m a n g a n e s e c o m p o u n d . I n a d d i t i o n , l i k e t h e p u r e m a n g a n e s e c o m p o u n d , a l l s a m p l e s s h o w e d t h e o n s e t o f t h e r m a l d e c o m p o s i t i o n n e a r 2 0 0 ° C i n t h e D S C t h e r m o g r a m s . N o e v i d e n c e o f a c e t a t e , w a t e r , o r o t h e r i m p u r i t i e s w e r e f o u n d i n a n y o f t h e s a m p l e s . P r o o f t h a t t h e s e a r e s i n g l e p h a s e m a t e r i a l s a n d n o t p h y s i c a l m i x t u r e s o f t h e m a n g a n e s e a n d c a d m i u m c o m p o u n d s c o m e s f r o m t h e m a g n e t i c s u s c e p t i b i l i t y s t u d i e s . P l o t s o f m a g n e t i c s u s c e p t i b i l i t y ( p e r m o l o f M n ) a n d t h e e f f e c t i v e m a g n e t i c m o m e n t 1 6 1 of manganese versus temperature (2.1 to 82 K) are given in Figures 6.1 and 6.2. At all temperatures both the susceptibility and the moment increase as the fraction of manganese decreases in the sample. In a physical mixture, of course, neither would be expected to change. As the proportion of manganese decreases the maximum in susceptibility appears to shift to lower temperatures and the susceptibility increase is greatest at the lowest temperatures. We have chosen to analyze our data with Wagner-Friedbergt133] and Wengl 1 3 4 - 1 3 5 ! S=5/2 models as described previously (Chapter 2). In the fits to these mixed metal systems we set g= 2.00 and allowed J and % monomer to vary. The best fits to the susceptibility are shown in Figure 6.3. The fitting parameters for these systems are given in Table 6.1. It is assumed in fitting the susceptibility data of the mixed metal systems that a fraction of the manganese atoms is behaving as a normal paramagnet, a paramagnetic component p, uncoupled to other metal centers in the chain. Hence calculated susceptibilities were obtained from Xcalc.= (1 -p)Xchain + P Xpara. [6.1 ] where Xchain is the susceptibility calculated according to either chain model, Xpara. is the susceptibility for magnetically dilute manganese(II) and p is the fraction of manganese making up the paramagnetic component. The paramagnetic component, p, is assumed to follow Curie Law given by Ng2p|S(S+l) Xpara = — where g is assumed to have the same value as in the bulk of the polymer. It is clear from the data analysis that the change in magnetic properties with Cd doping is accounted for primarily by the incorporation of the paramagnetic component which increases with increasing Cd content. Such an effect can be rationalized if we 162 consider the "random defect" model of de Jonght2!. According to this model any chain system will suffer from a certain concentration of defects which, in turn, will break the magnetic chain into finite segments. Half of these finite segments will contain an odd number of magnetic atoms and coupled antiferromagnetically, these odd numbered segments will have a net spin at low temperatures. This net spin will be very weakly coupled along the chain, since the effective magnetic interaction will have to transverse the defects, and will therefore be much smaller than the nearest neighbor intrachain interaction. In our case, cadmium acts as a defect and breaks up the chain and creates smaller isolated finite chains. For example, consider the case where x=0.19. For a random distribution of Cd atoms we might expect the average chain of Mn atoms to be ~4 atoms long. This will result in a distribution of chain lengths about this average and one half of the chains will be odd numbered and effectively contain one Mn atom which is uncoupled (the net spin referred to in the random defect model). If we assume that uncoupled centeres behave as magnetically dilute Mn, then one out of ~8 Mn atoms are magnetically dilute representing about 12% paramagnetic impurity. This compares with ~9% obtained by the fit to the susceptibility data (Table 6.1). This analysis works reasonably well for all systems although it is probably realistic only for the systems with small values of x, since as x increases the probability of formation of clusters of Cd atoms increases. The result of clustering will be to decrease the number of paramagnetic centers from the values predicted on the basis of totally random doping. In fact the value of 100 p obtained for all of the fits is lower than that predicted as was illustrated above for the x=0.19 system. Another important observation here is that the value of IJI decreases as x increases(see Table 6.1). The fact that I J I decreases with increasing Cd doping and hence, presumably with decreasing average chain length suggests that the exchange is not limited to nearest neighbor interactions in the chain but that longer range intrachain as well as interchain effects may be important. Alternatively, the effect may result from weaker coupling between manganese neighbors when one of the metals is adjacent to a cadmium ion or may 163 simply reflect the limitations of an analysis which involves fitting a system of random-length chains to an infinite-chain model. Comparing our results here on the Mni.xCdx[H(C6H5)P02]2 system with those published earlier f81l we find that the main conclusions of the earlier work are confirmed. As x increases the fraction of paramagnetic component and, consequendy, the average chain length of contiguous manganese atoms decreases. The reduction in IJ I with decreasing chain length is also confirmed. Within experimental error the value of IJI for given doping levels are the same in the two studies. An important difference between the current results and those reported earlier is that for given values of x we observed smaller paramagnetic components in the current study. As discussed above, smaller paramagnetic components are the result of clustering; hence, surprisingly the syringe pump used in the present work appears to have actually led to greater clustering during doping of Cd into the manganese phosphinate chains. It is also possible that the lower percentage of p in the current systems is due, at least partly, to a lower content of natural defects in these materials resulting from the longer period of time allowed for reagent mixing when using the syringe pump. Table 6.1. Magnetic parameters for Mni-xCdx[H(C6H5)P02]2-X Weng model3 Wagner-Friedberg model3 -Kcnr1)15 100pb>c F d -J(cnr1)b 100pb.c F d 0.01 2.61e 1.17 0.0202 2.75 0.85 0.0054 0.19 2.12 9.26 0.0226 2.20 8.91 0.0190 0.26 1.95 12.13 0.0266 2.02 11.72 0.0236 0.41 1.87 18.57 0.0231 1.93 18.17 0.0215 3 see Chapter 2 for description of these models. b The values of J and lOOp are considered accurate to ± 3%. c100p = % paramagnetic component. d F = function nimimized in obtaining the best fit, defined in Chapter 2. e The best fitting parameters are taken by fitting the susceptibility data over the temperature range of 4.2 to 82.0 K. 164 260 . 200 O E E cv I o w 150 03 = 100 c eve a 60 B D O o CO V o D 8 O O D D O D O o D O © D O Legend • X-0.01 o x-0.19 • x-0.26 © x-0.41 • • - - S f S 2 20 40 eo Temperature (K) eo 100 Figure 6.1. Magnetic susceptibility versus temperature data for Mni.xCdx[H(C6H5)P02l2. 165 7 6-^ 8" cs 3. C CU E o S e DC « D 0 D O v D ° D o ° • O D O o • • o © D O © o o © • o D O • S 8 S o ° Legend • x - 0 . 0 1 o x - 0 . 1 8 • x - 0 . 2 6 © x - 0 . 4 1 0 —T— eo 80 20 40 Temperature (K) 100 Figure 6.2. Magnetic moment versus temperature data for Mni.xCdx[H(C6H5)P02]2. 166 H 1 ' 1 I I ' 1 ' ' • + T 1 1 1 1 1 1 0 . 0 2 0 . 0 4 0 . 0 4 0 . 0 tO.O • Q . O J O . O 4 0 . 0 4 0 . 0 tO.O Temperature ( K ) Temperature ( K ) Figure 6.3. Magnetic susceptibility versus temperature plots for Mni.xCdx[H(C6H5)P02]2 (x= 0.01,0.19, 0.26 and 0.41 for a, b, c and d respectively). Solid lines represent the best fit to the Wagner -Friedberg model. 167 6.2.2. Mni. xCd x(HCONH 2)2[H(C6H5)P0 2]2 The detailed procedures used to prepare Cd(HCONH2)2[H(C6H5)P02]2 and Mni.xCdx(HCONH2)2[H(C6H5)P02]2 systems are given in Chapter 8. The DSC thermograms of all samples studied in this section are virtually identical. The thermograms exhibit a sharp endothermic peak at about 140 "C followed immediately by a broad endothermic event extending from ~145 to -195 *C (AH total for both events are in the range of -85 to ~195 kJ/mol). The weight loss measurements confirm loss of two moles of HCONH2 in these compounds on heating to the end of the endothermic events. The onset of thermal decomposition for all compounds is at about 200 *C. The infrared spectra of the Mni.xCdx(HC01SfH2)2[H(C6H5)P02]2 complexes with x=0.01, 0.04, 0.05, 0.14, 0.32 and 0.54 are all virtually identical and agree well with the spectrum of Mn(HCONH2)2[H(C6H5)P02]2 described in Chapter 2. X-ray powder diffraction data for all the compounds are recorded in the Appendix. X-ray powder diffraction data indicate that all of the compounds are isomorphous with each other and isomorphous with the pure Mn(HCONH2)2[H(C6H5)P02]2 and Cd(HCONH2)2[H(C6H5)P02]2 complexes. Plots of magnetic susceptibility (per mol of Mn) and the effective magnetic moment of manganese versus temperature (2.1 to 82 K) are given in Figures 6.4 and 6.5. The susceptibility and moment values increase as the fraction of manganese decreases in all the mixed metal Mni.x(Tdx(HCONH2)2[H(C6H5)P02]2 complexes at all temperatures studied. The magnetic susceptibility data for the Mni.xCdx(HCONH2)2[H(C6H5)P02]2 complexes were analyzed using the Wagner-Friedberg!133] and Weng!134'135] S=5/2 models as described previously (Chapter 2). As in the case of the Mni.xCdx[H(Cf5H5)P02]2 compounds, when fitting to the linear chain models, allowance was made for a paramagnetic component p. Fits were made to the susceptibility data with g fixed at 2.00 and with J and p as fitting parameters. Best fit values of J and p are given in Table 6.2. The observed susceptibilities are compared with calculated for the Wagner-Friedberg model for some of the materials in Figure 6.6. 168 600 460-—s400-O E r i E w <T5 360-t B *B *B A 5 3 0°-260-a cv 9 C a 200-160-100-© • B I Legend • 1 - 0 . 0 1 o x - 0 . 0 4 D x - 0 . 0 5 c x - 0 . 1 4 A x-0.32 B x - 0 . 6 4 60- « • • « 0 + 20 T * 40 —r™ 60 60 Temperature (K) 100 Figure 6.4. Magnetic susceptibility versus temperature data for Mni.xCdx(HCONH2)2[H(C6H5)P02]2. 169 e .B-3. c cu E © JU «» ex es 6.6-4.6-J2 4-o 1 A © I O B o 9 3.5-2.6-Legend • x-0.01 o x-0.04 D x-0.05 © x-0.14 A x-0.32 • x-0.64 1.6-20 4 0 eo Temperature (K) 80 100 Figure 6.5. Magnetic moment versus temperature data for Mni.xCdx(HCONH2)2[H(C6H5)P02]2. 170 '0.0 20.0 40.0 40.0 Temperature (K) •0.0 '0.0 20.0 40.0 60.0 Temperature (K) 80.0 Figure 6.6. Magnetic susceptibility versus temperature plots for Mni.xCdx(HCONH2)2[H(C6H5)PO2]2.(x=0.01,0.05, 0.14 and 0.54 for a, b, c and d respectively). Solid lines are the best fits to the Wagner -Friedberg model. 171 Table 6.2. Magnetic parameters for Mni.xCdx(HCONH2)2[H(C6H5)P02]2 Weng model3 Wagner-Friedberg model3 x -J(cm-1)b 100pb.c F d -J(cnr1)b 100pb-c F d 0.01 0.46 1.48 0.0110 0.48 0.74 0.0115 0.04 0.45 2.80 0.0126 0.47 2.03 0.0115 0.05 0.45 3.33 0.0120 0.47 2.52 0.0108 0.14 0.41 5.08 0.0154 0.43 4.43 0.0094 0.32 0.38 14.43 0.0148 0.40 13.68 0.0141 0.54 0.34 28.64 0.0103 0.35 28.05 0.0082 3 see Chapter 2 for description of these models. b The values of J and lOOp are considered accurate to ± 2%. and ± 4% respectively. c100p = % paramagnetic component. dF = function minimized in obtaining the best fit, defined in Chapter 2. Unlike the situation with the Mni.xCdx[H(C6H5)P02l2 systems, the structures of the Mni.xCdx(HCONH2)2[H(C6H5)P02l2 complexes are known, in detail, from single crystal X-ray diffraction studies (Section 2.2.3). There is no doubt that these complexes are linear chain polymers. The effects of increasing the Cd content in this system are completely analogous to those described above for the Mni.xCdx[H(C6H5)P02]2 system. Not only does the % paramagnetic component increase as x increases but the value of I J I decreases as x increases as observed previously. The interpretation of these results is described in the previous section (6.2.1). In particular, we note that for the random defect model, at low values of x where there is likely little clustering of Cd atoms, the value of p (fraction of paramagnetic impurity) should be approximately one half the value of x (fraction of Cd atom). This relationship between p and x is roughly followed for x=0.04 to 0.32. The data for x=0.01 is affected by the fact that p includes natural defects which contribute significandy at low doping levels. 172 6.2.3. Mni.xCdx[n-C6Hi3)2P02]2 Detailed procedures for the preparation of Cd[(n-C6Hi3)2P02l2 and the Mni-xCdx[(n-C6Hi3)2P02]2 materials in this section are given in Chapter 8. The DSC thermogram shows Mn[(n-C6Hi3)2P02]2 to exhibit an endothermic event at 129 °C (AH=52 kJ/mol). Onset of exothermic decomposition occurs at about 180 *C. Cd[(n-C6Hi3>2P02]2 shows an endothermic event at 155 °C (AH=7 kJ/mol) and there follows a sharp endothermic event followed immediately by the onset of exothermic decomposition at about 180 *C. The Mni.xCdx[(n-C6Hi3)2P02]2 mixed metal materials studied here exhibit an endothermic event in the 138 to 160 °C temperature range with AH values ranging from 47 to 52 kJ/mol. Onset of exothermic decomposition for these compounds normally occurs with a sharp peak at about 180 °C and a weak, broad exothermic peak at about 200 °C. X-ray powder diffraction data for all the compounds, recorded in the Appendix, indicate that they are isomorphous with each other and isomorphous with pure Mn[(n-C6Hi3)2P02]2 and Cd[(n-C6Hi3)2P02]2- The X-ray powder diffraction patterns of the pure manganese and cadmium compounds and one of the mixed metal materials is shown in Figure 6.7. The infrared spectra for the Mni.xCdx[(n-C6Hi3)2P02]2 complexes are all virtually indistinguishable. Spectral frequencies for the pure manganese and cadmium compounds are given in the Appendix. The infrared spectra in the 1200-1000 cm-1 region (corresponding to PO2 stretching vibrations) show one very strong and two additional weaker but still relatively strong bands. As described before (Chapter 1), for the phosphinate anion with either C2v or C s symmetry, only two strong PO2 stretching bands are expected. The existence of more than two bands suggests that the two phosphinate ligands are non-equivalent, and therefore, four different PO2 absorption bands should be present in the infrared spectrum. A possible explanation to there being only three bands observed is that there is some overlap of absorptions. 173 l ' | M M M M ' ) M M M M ' | M M M ' l ' | M M M ' l ' | M ' 1 M ' l l [ M M M l l , ; ' l M l I M l | M M l I M l | ' T ; y F y p f f T * T , ^ * F f ^ 5. 10. 15. 20. 25. 30. 35. 40. 45. 50. 55. 60 26 Figure 6.7. X-ray powder diffraction patterns of a) Mn[(n-C^Hi3)2P02]2, b) Mno.46Cdo.54[(n-C6Hi3)2P02]2 and c) (^[(n-QjHnhPC^h. 174 Plots of magnetic susceptibility (per mol of Mn) and the effective magnetic moment of manganese versus temperature (2.1 to 82 K) are given in Figures 6.8 and 6.9. The susceptibility and the moment increase as the fraction of manganese decreases in all the mixed metal Mni.xCdx[(n-C6Hi3)2P02]2 complexes at all temperatures studied. The data were analyzed as described above for the Mni.xCdx[H(C6Hs)P02]2 and Mni-xCdx(HCONH2)2[H(C6H5)P02]2 complexes and best fit values of J and p are given in Table 6.3. Comparison of observed susceptibilities with theoretical curves are made in Figure 6.10. Table 6.3. Magnetic parameters for Mni.xCtfx[(n-QHi3)2P02]2-Weng model3 Wagner-Friedberg model3 x -Kern-1)1* 100pb F c -J(cm-l)b lOOpb F c 0 0.29 d 0.0210 0.32 d 0.0332 0.08 0.28 7.12 0.0112 0.29 5.79 0.0204 0.33 0.25 17.70 0.0127 0.25 16.33 0.0203 0.54 0.20 26.66 0.0147 0.20 25.89 0.0214 3 see Chapter 2. DThe values of J and lOOp are considered accurate to ± 3% and ± 5% respectively. lOOp = % paramagnetic component CF = function minimized in obtaining the best fit; defined in Chapter 2. d100p set to zero. The measured susceptibilities at the lowest temperatures are lower than predicted by the model and including p as a variable parameter here generates an unrealistic negative value. Only three mixed metal compounds were studied in this case; however, the study is extensive enough to confirm the general nature of the findings in 6.2.1 and 6.2.2. Increasing the level of cadmium doping increases the % paramagnetic impurity to a level consistent with chain fragmentation and the generation of random defects in odd numbered fragments. The reduction in the magnitude of J with decreasing, average chain length is confirmed in this work. 175 •00-700- O t eoo-600-1 DO a 400-300-200-B V-*=• • o D o • o • Legend • x-o.oo o x-O.OB o x-0.33 o xB0.64 100 i •* 0 • 0 20 40 e'o 80 i< Temperature (K) Figure 6.8. Magnetic susceptibility versus temperature data far Mni.xCdx[(n-C6Hi3)2P02]2. 176 7 e.6-1 6.6 ea S 6 E o 4.6-1 tw B DJD 3.5 2.6 © o • 8D 0 © • o © © D ° D O o 8 S 6 8 4 » O 2-1-0 Legend • x-0.00 o x-o.oe • x-0.33 © x-0.64 —r-20 40 —I— eo 80 100 Temperature (K) Figure 6.9. Magnetic moment versus temperature data for Mni.xCdx[(n-C6Hi3)2P02]2. 177 1 1 1 1 ) 1 1 i , 1 1 1 1 1 i ' 1 0.0 20.0 40.0 40.• »0.0 0.0 20.0 40.0 40.0 80.0 Temperature (K) Temperature (K) Figure 6.10. Magnetic susceptibility versus temperature plots for Mni.xCdx[(n-C6Hi3)2P02]2 (x=0.0,0.08, 0.33 and 0.54 for a, b, c and d respectively). Solid lines represented the best fit to the Wagner Friedberg model. 178 6.3. Summary and Conclusions In order to investigate the effect of cadmium doping, three series of compounds of composition Mni.xCdx[H(C6H5)P02]2, Mni-xCdx(HCONH2)2[H(C6H5)P02]2 and Mni.xCdx[(n-C6Hi3)2P02]2 were synthesized and characterized. The pure Mn[H(C6H5)P02]2, Mn(HCONH2)2[H(C6H5)P02]2 and Mn[(n-C6Hi3)2P02]2 compounds are antiferromagnetic and their susceptibility versus temperature behaviors may be reasonably modeled according to infinite chains of coupled manganese ions. Incorporation of diamagnetic Cd ions into these polymers fragments the magnetic chains resulting in the formation of a significant paramagnetic component arising from the net spins associated with odd numbered fragments. Natural defects can also fragment the chains and lead to a paramagnetic component. As x varies from O.Olto 0.41 in the M n i _ x C d x [ H ( C 6 H 5)P02]2 samples, from 0.01 to 0.54 in the Mni. xCd x(HCONH 2) 2[H(C6H5)P0 2] 2 samples and from 0 to 0.54 in the Mni.xCdx[(n-C6Hi3)2P02]2 samples, the average number of contiguous Mn atoms is considered to go from greater than 100 to presumably two or three atoms at most in a chain. This is accompanied by an apparent decrease of about 30% in the absolute value of the exchange coupling constant J. This result suggests that factors other than nearest neighbor intrachain interactions such as longer range intrachain and interchain exchange may also be affecting the magnetic properties of these materials. 179 Chapter 7 Miscellaneous Compounds 7.1. Copper(II) and Zinc(II) Monophenylphosphinates, Cu[H(C6H5)P02]2 and Zn[H(C6H5)P02]2 A number of copper(TJ) phosphinates have been synthesized and characterized in our laboratory^13.20-23] and elsewhere! 7 7 , 7 81. Structural determinations have confirmed a compressed tetrahedral geometry for some of these compounds! 2 0- 2 1 ' 7 7! and magnetic studies have revealed that many of the compounds are magnetically concentrated with exchange constants, J, ranging from -30 to +3 c m - 1 . With this in mind, we considered carrying out doping experiments, of the type described in the previous chapter, involving copper(II) phosphinate doped with a diamagnetic metal ion. Zinc(II) was chosen as the diamagnetic ion because it commonly forms four coordinate compounds with tetrahedral geometry[97,107] yje began by examining the monophenylphosphinate compounds. Subsequent characterization revealed that the copper(II) and zinc(II) monophenylphosphinates are not isomorphous and for this reason doping experiments were not persued. Nonetheless, we did characterize these compounds and these results are reported here. Subsequent to our completing our studies, the structure of Z n [ H ( C 6 H 5 ) P 0 2 ] 2 was reported in the literature!8 2^. Some characterization of Cu[H(C6H5)P0 2] 2 has been reported previously! 1 3 1 . The syntheses of Zn[H(C6Hs )P0 2 ] 2 and Cu[H(C6Hs )P0 2 ] 2 are described in Chapter 8. Infrared data and X-ray powder diffraction data for the two compounds as well as magnetic data for the copper compound are recorded in the Appendix. Recendy, Shieh et a/.! 8 2! reported the single crystal structure of Zn[H(C6H5)P(D2]2. The structure consists of isolated {Zn[H(C6H5)P0 2] 2} x chains in which tetrahedral zinc ions are linked by double phosphinate bridges. The X-ray powder diffraction patterns of 180 Zn[H(C6H5)P02]2 and Cu[H(C6H5)P02]2, shown in Figure 7.1, are different and indicate the compounds are not isomorphous. It seems likely that in the case of the copper compound the MO4 chromophore is compressed, possibly even square planar. This would * make the copper-phosphinate polymer backbone more accessible for cross-linking of chains in the solid state and for coordination by polar solvents in solution. This could account for the observation that Cu[H(C6H5)P02]2 is slightly soluble in water!13! while 21n[H(C6H5)P02]2 is insoluble in wide range of solvents including water. There are important differences in the thermal properties of these compounds also. While Cu[H(C6H5)P02]2 shows the onset of thermal decomposition at 130 "C^13!, Zn[H(C6Hs)P02]2 was found in the present work to melt at ~240 °C and to be stable to oxidative decomposition up to 320 *C. Differences are also apparent in the infrared spectra of these compounds (Figure 7.2). The spectrum of Cu[H(C6Hs)P02]2 is in reasonable agreement with that reported earlier^  1 3 l Important differences between the spectra of the two compounds involve the following: (i) Zn[H(C6H5)P02]2 shows a single band assigned to VPC>2 anti. at 1145 cm"1 while Cu[H(C6H5)P02]2 exhibits a split band at 1185 and 1141 cnr1!13!, (ii) The VP02 sym. band occurs at 1064 cm'1 and at 1047 cm-1 in the zinc and copper compounds respectively and (iii) while Cu[H(C6H5)P02l2 shows a split band assigned to vPH (2398, 2362 cm-1), a single unsplit band assigned to this vibration occurs at 2400 cm"1 for the zinc compound. The magnetic moment data obtained for Cu[H(C6H5)P02]2 are plotted versus temperature in Figure 7.3.The decrease in moment with decreasing temperature suggests antiferromagnetic exchange, and accordingly we analyzed the magnetic susceptibility data using the Bonner and Fisher isotropic Heisenberg model for exchange coupled chains with S = l/2t153!. According this model the susceptibility is given by the expression: Ng 2p 2r 0.250 + 0.14995 x-1 + 0 . 3 0 0 9 X - 2 i X m kT J- 1 + 1.9862 x-1 + 0.6885 x"2 + 6.0626 x"3 J 1 J 181 where x = kT/J. The best fit of magnetic susceptibility versus temperature using this model is shown in Figure 7.4. The fit is poor, visually, and as indicated by the fitting parameters (-J = 22.6 cm'1 and g = 2.567 (F • 0.1532)). This suggests that the complex may not involve a chain structure. Attempts were made to fit the susceptibility data for this complex to Lines' two dimensional modelt151! but the fit here was also very poor. a c CS va s 3 © Figure 7.1. X-ray powder diffraction patterns for a) Cu[H(C6H5)P02]2 and b) Zn[H(C6H5)P02]2. 182 J I I I I 1 L_ 1600 U 0 0 1200 1000 800 600 400 WAVENUMBER /cnr1 Figure 7.2. Infrared spectra of a) Cu[H((^H5)P02]2 and b) Zn[H(C6H5)PC>2]2. 183 6 3 3.6-cv B e S 3-UD 2 M 2H 1.6-20 — i — 40 eo Temperature (K) —i— 80 100 Figure 7.3. Magnetic moment versus temperature plot for Cu[H(C6H5)P02]2. 184 1 1 1 1 l I i r ~ 0.0 20.0 40.0 60.0 80.0 Temperature (K) Figure 7.4. Magnetic susceptibility versus temperature plot for CurH(C6H5)P02]2. The line is calculated using the Bonner and Fisher model (see text) with the best fit parameters -J = 22.6 cm*1, g = 2.567 (F= 0.1532). 185 7.2. Bis(N,N-dimethylformamide)bis(diphenylphosphinic acid)bis(diphenylphosphinato)nickel(II), Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2 P.Betz and A . B i n o f 8 3 ! reported the syntheses and crystal structures of M(DMF) 2 [ (C6H5) 2 P0 2 H] 2 [ (C6H5) 2 P0 2 ] 2 (where M= Mn and Co). These authors found that these compounds are mononuclear and isostructural but crystallize in different space groups. This led us to attempt to synthesize and characterize the nickel analogue. The preparation of Ni (DMF) 2 [ (C6Hs) 2 P0 2 H] 2 [ (C^H5) 2 P0 2 ] 2 is described in Chapter 8. A s ing le c r y s t a l X - r a y structure de te rmina t ion shows that N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 is isomorphous and isostructural with the cobalt analogue. A stereoview of the unit cell is given in Figure 7.5 and a view of the molecular structure with the atom numbering scheme is shown in Figure 7.6. Selected intramolecular bond distances and angles are given in Table 7.1 and a complete compilation of X-ray structural data is given in the Appendix. Structural analysis shows that each nickel ion is coordinated to two phosphinate anions and two phosphinic acid groups in approximately trans- square planar geometry. Two dimethylformamide molecules are coordinated to nickel via oxygen completing an all trans distorted octahedral geometry. Two intramolecular hydrogen bonds between phosphinic acid P-OH groups and the phosphinate P-0 groups, exist in the complex. The O—O separations of 2.42(4) A indicates a relatively strong hydrogen bond. The corresponding separation in the manganese and cobalt analogues are 2.444(3) and 2.422(4) A respectively. 186 Figure 7.5. View of Ni(DMF)2[(<^ 5)2P02Hh[(C6H5)2P02]2 showing the atom numbering scheme and coordination about the nickel atom 187 Table 7.1. Bond distances (A) and bond angles(°) for Ni(DMF)2[(C6H5)2PC^ H]2[(C6H5)2P02]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond distances(A) anglesf) Ni 0(1) 2.075(2) Ni 0(3) 2.043(2) Ni 0(5) 2.056(1) P(l)--0(1) 1.494(2) P(l)--0(2) 1.533(2) P(2)--0(3) 1.487(2) P(2)--0(4) 1.520(2) 0(l)-P(l)-0(2) 117.8(1) 0(3)-P(2)-0(4) 118.4(1) 0(1)—Ni—0(1) 180 0(3)—Ni—0(3) 180 0(3)—Ni—0(5) 89.19(6) 0(3)—Ni—0(5) 90.81(6) 0(3)—Ni—0(1) 91.88(6) 0(3)—Ni—O(l) 88.12(6) 0(5)—Ni—0(5) 180 0(5)—Ni—O(l) 90.73(6) 0(5)—Ni—O(l) 89.27(6) The infrared spectrum (tabulated in the Appendix) of this compound shows intense bands at 1200 cm-1 (with a shoulder at 1180 cm"1) and 1129 cm"1 (with a shoulder at 1110 cnr1) and a medium intensity band at 1070 cm-1. These bands are assigned as arising from PO2 vibrations. The multiplicity of bands arises because of the presence of both neutral 188 phosphinic acid molecules and anionic phosphinate groups. A strong, broad band between -770 to 1000 cm-1 may be due to a strong HOH hydrogen bonding interactionf154!. Since the single crystal X-ray studies on Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2 reveal a mononuclear structure, the compound is expected to be magnetically dilute. Magnetic susceptibility and moment data are given in . the Appendix. At approximately 82 K the complex has a magnetic moment of 3.36 Jin and drops to ~ 3.07 \LB at 5 K. The magnetic susceptibility data were analyzed using the zero-field splitting model as described in Chapter 4. The analysis yields a value of 5.6 cm-1 for D and 2.29 for g (F=0.0400). The experimental values are compared with theory in Figure 7.6. The agreement is quite good and, as expected, there is no evidence for significant magnetic exchange in this compound over the temperature range studied. c O-T 1 i 1 1 1 1 1 r— 0 0 70 0 « 0 60 0 . 00 0 Temperature (K) Figure 7.6. Magnetic susceptibility versus temperature plot for Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2. The line is calculated using the ZFS model and the best fit parameters: D=5.6 cm"1 and g = 2.29. 189 7.3. Tetraaquobis(N,N-dimethylformamide)nickel(II) diphenylphosphinate dihydrate, {Ni(DMF) 2(H20)4}(H20)2[(C 6H5)2P0 2]2 One of the objectives of this work was to synthesize and characterize poly(metal phosphinate) in crystalline form suitable for X-ray diffraction studies. While we were successful in obtaining crystals of manganese(II) and cobalt(II) diphenylphosphinate (Chapter 5) our attempts to obtain crystals of Ni[(C6H5)2P02]2 led instead to the material described here. The details of the preparation procedure are given in Chapter 8. The green crystals of {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02J2 were found to be stable when keep moist with the solvent from which they are obtained (moist DMF). A stereoview of the unit cell is given in Figure 7.8 and a view of the molecular structure of {Ni(DMF)2(H20)4}(H20)4[(C6H5)2P02]2 with the atom numbering scheme is shown in Figure 7.9. Important bond distances and bond angles are listed in Table 7.2. Each nickel atom is coordinated to four water molecules in a square planar array and to two DMF molecules bonded in axial positions. Two of the water molecules coordinated to each nickel are hydrogen bonded to two diphenylphosphinate ligands. The phosphinate anions are each hydrogen-bonded to four water molecules: two molecules from one nickel, a third from a second nickel and a fourth non-coordinated water molecule. In each {Ni(DMF)2(H20)4)(H20)2[(C6H5)2P02]2 molecule then, four water molecules are coordinated to the nickel and two more water molecules are non-coordinated. Because the diphenylphosphinate ligands are not coordinated to the metal ions in this complex, the two P—O distances in a given anion might be expected to be equal. In fact (Table 7.2) they are equal. These bond distances are slighdy shorter than the average P—O bond distance of 1.51 A in Y-Co[(C6H5)2P02l2 and Y-Mn[[C6Hs)2P02]2- The Ni-0(DMF) bond distance of 2.065(2) A is comparable to the value 2.056(1) A in Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2. 190 Figure 7.7. A view of the unit cell in {Ni(DMF)2(H20)4} (H20)2[(C6H5)2P02]2. Table 7.2. Bond distances (A) and bond angles(°) for {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 with estimated standard deviations in the last significant figure in the parentheses. Structure Bond distances(A) anglesO N i(l)- 0(1) 2.065(2) N i(l)- 0(2) 2.070(2) N i ( l ) - - 0 ( 3 ) 2.052(2) P ( l ) - - 0 ( 4 ) 1.499(2) P ( l ) - - 0 ( 5 ) 1.502(2) O ( l ) — N i ( l ) — 0 ( l ) ' a 180 0 ( l ) - N i ( l ) - 0 ( 2 ) 90.3(1) 0 ( l ) ~ N i ( l ) ~ 0 ( 2 ) ' 89.7(1) 0 ( l ) - N i ( l ) - 0 ( 3 ) 89.2(1) 0 ( l ) - N i ( l ) - 0 ( 3 y 90.8(1) 0 ( 2 ) — N i ( l ) — 0 ( 2 ) 180 0 ( 2 ) - N i ( l ) - 0 ( 3 ) 89.5(1) 0 ( 2 ) — N i ( l ) — 0 ( 3 ) ' 90.5(1) 0 ( 3 ) — N i ( l ) — 0 ( 3 ) ' 180 a The symbol' refers to symmetry operation: 1-x, 1-y, 1-z. 7.4. Aquo-)i-chloro-u-monophenylphosphinatocadmium(II), Cd(H20)Cl[H(C6Hs)P02] The synthesis and characterization of monophenylphosphinates of the type, M[H(C6H5)P02]2 where M=Mn, Cd, Co, N i , Cu and Zn, have long been persued in our own laboratory[13,81,105] and elsewhere!82! but only limited crystal structure data are available for these compounds. In fact, only Zn[H(C6H5)P02]2 has been characterized by using single crystal X-ray diffraction^ 2 !. We attempted to obtain crystals of 192 Cd[H(C6H5)P02]2 suitable for single crystal X-ray study by following the procedures for the preparation of ZnfH(C6H5)P02]2 described by Shieh et a/J8 2l. Doing this, we obtained colorless crystals which from elemental analysis and X-ray diffraction studies, have the empirical formula Cd(H20)arH(C!6H5)P02]- The details of the preparation of this compound are described in Chapter 8. A stereoview of the unit cell is given in Figure 7.9 and a view of Cd(H20)Cl[H(C6H5)P02] with the atom numbering scheme is shown in Figure 7.10. The crystal structure shows three independent cadmium atoms, all three of which are six-coordinate. Cd(l) coordinates to four different monophenylphosphinate ligands in a square-planar array and to two chlorine atoms above and below the plane. This cadmium is linked in chains by double phosphinate bridges along the c-crystallographical axis. There are only minor differences between Cd(2) and Cd(3). These cadmiums are bonded to two trans-chloro ligands which in turn are bonded to Cd(l) atoms thus forming Cl-Cd(2,3)-Cl bridges along the b-crystallographical axis between the cadmium-phosphinate chains. In addition each Cd(2) and Cd(3) atom is bonded to two trans-aquo ligands and to two oxygen atoms which come from different phosphinates on adjacent cadmium-phosphinate chains. This latter interaction gives rise to Cd-O-Cd-0 chains propagating along the b-crystallographic axis and an overall two-dimension sheet structure. One of the most interesting points about the structure of this compound is that while the phosphinate anions bridge metal ions in the M-O-P-O-M fashion, now recognized as common for poly(metal phosphinate), one of the oxygen in each O-P-0 unit is bonded to a second metal. This type of phosphinate bonding in which one oxygen is monodentate and the second bidentate has been suggested as a possibility for some time (see Chapter 1, Section 1.1), however it has never been demonstrated by a single crystal X-ray diffraction study until this work. This type of bonding was suggested for the two-dimensional structure proposed for Ni[H(C6H5)P02]2 in Chapter 4. 193 The DSC thermogram of this compound shows an endothermic peak at 197 *C (with a shoulder at ~210 *C). The onset of exothermic decomposition occurs at about 280 *C. The infrared spectrum shows a strong split band at 1140 and 1100 cm*1 assigned to the VPC»2 anti. stretching vibration and a strong band at 1027 cm*1 assigned to the symmetric PO2 stretching vibration. A value (A = VPC^  anti.- VPC»2 sym.) of - 100 cm*1 is in the range expected for fairly symmetrical PO2 groups. This is somewhat surprising since the structure involves PO2 groups where one oxygen is monodentate and the other bidentate. Nonetheless we note that the X-ray structure shows that the differences in the PO bond length are, in fact, not very large, being 0.01(2) A for one phosphinate and 0.006(2) A for the other (Table 7.1). Figure 7.9. A stereoview of the unit cell in Cd(H20)QrH(C6H5)P02]. 194 H U Figure 7.10. View of Cd(H20)a[H(C6H5)PQ2] showing the atom numbering scheme and coordination about the cadmium atom. 195 Table 7.3. Bond distances (A) and bond anglesf) for Cd(H20)Cl[H(C6H5)PO2] with estimated standard deviations in the last significant figure in the parentheses. Structure Bond distances(A) anglesO Cd(l)- Cl(l) 2.5816(5) Cd(l) ci(2) 2.5819(5) Cd(l) 0(1) 2.382(1) Cd(l) 0(2)*a 2.291(1) Cd(l)- 0(3) 2.384(1) Cd(l) 0(4)* 2.289(1) Cd(2) Cl(l) 2.6429(5) Cd(2)- O(l) 2.367(1) Cd(2) 0(5) 2.253(1) Cd(3) Cl(2) 2.6432(6) Cd(3) 0(3) 2.366(1) Cd(3) 0(6) 2.252(1) P ( l ) . o(l) 1.528(1) P(l)--~0(2) 1.518(1) P(2)---0(3) 1.526(1) P(2)--0(4) 1.520(1) Cl(l)—Cd(l)—Cl(2) 175.44(1) Cl(l)—Cd(l)—O(l) 80.58(3) Cl(l)—Cd(l)—0(2)* 87.58(4) Cl(l)—Cd(l)—0(3) 96.22(3) Cl(l)—Cd(l)—0(4)* 95.77(4) Cl(2)—Cd(l)—O(l) 96.19(3) Cl(2)—Cd(l)—0(2)* 95.69(4) Cl(2)—Cd(l)—0(3) 80.57(3) Cl(2)~-Cd(l)—0(4)* 87.53(3) Table continued 196 Table 7.3.(continued) Bond distances (A) and bond angles(°) for Cd(H20)Cl[H(C6H5)P02] with estimated standard deviations in the last significant figure in the parentheses. Structure Bond distances(A) anglesf) O(l)—Cd(l)—0(2)* 90.62(4) 0(l)-Cd(l)-0(3) 90.97(4) 0(l)-Cd(l)-0(4)* 176.13(4) 0(2)*—Cd(l)—0(3) 176.08(4) 0(2)*—Cd(l)—0(4)* 87.97(4) Cl(l)~-Cd(2)—O(l)' 180.00 Cl(l)—Cd(2)—O(l) 79.58(3) Cl(l)—Cd(2)—0(1)' 100.42(3) Cl(l)—Cd(2)—0(5) 91.45(4) Cl(l)—Cd(2)—0(5)' 88.55(4) O(l)—Cd(2)—O(l)' 180.00 0(1)—Cd(2)—0(5) 83.84(5) O(l)—Cd(2)—0(5)' 96.16(5) 0(5)—Cd(2)~-0(5)* 180.00 Cl(2)—Cd(3)—Cl(2)" 180.00 Cl(2)—Cd(3)—0(3) 79.63(3) Cl(2)—Cd(3)—0(3)" 100.37(3) Cl(2)-~ Cd(3)—0(6) 91.42(4) Cl(2)—Cd(3)—0(6)" 88.58(4) Cl(2)—Cd(3)—0(3) 79.63(3) 0(3)—Cd(3)—0(3)" 180.00 0(3)—Cd(3)—0(6) 84.11(5) 0(3)—Cd(3)—0(6)" 95.89(5) 0(6)—Cd(3)—0(6)" 180.00 Cd(l)—Cl(l)—Cd(2) 90.96(2) Cd(l)—Cl(2)—Cd(3) 90.93(2) a The symbols *,' and" 1-x, 1-y, 1-z. refer to the symmetry operations; x, y, z-1; -x, -y, -z and 197 Chapter 8 Experimental 8.1. Physical Experimental Techniques 8.1.1. Elemental Analysis A l l carbon, hydrogen and nitrogen analyses were performed by Mr. Peter Borda of this Department. Metal content was determined using Varian A A 5 and Perkin Elmer 305 Atomic Absorption Spectrophotometers. Sample solutions for A . A . were prepared by dissolving a known amount (20 to 70 mg) of the metal phosphinate in 15 ml of 37% H C l . This solution was heated gentiy until all the solids were dissolved, and was diluted with distilled water to about 3 ppm in concentration. The metal standard solutions (1-5 ppm) were made using spectral grade metal nitrates. 8.1.2. Qualitative Solubility Test Qualitative solubility tests, as applied to the compounds mentioned in this work, were undertaken at room temperature using the following solvents: petroleum ether, benzene, CCLj, HCCI3, H2CCI2, acetone, ethanol, methanol and distilled water. Where ~ 0.1 g or more of a compound was found to give a clear solution in 100 ml of solvent the compound was considered be soluble. Where - 0.01 g to 0.1 g was found to give a clear solution in 100 ml of solvent the compound was considered to be slightly soluble. Where a clear solution could not be obtained for ~ 0.01 g or less of a compound per 100 ml of solution the compound was considered to be insoluble. 198 8.1.3. Thermal Studies Differential Scanning Calorimetry (DSC) was performed utilizing a Mettler TA3000 system, consisting of a Metder DSC 20 standard cell, a Mettler TC 10 TA processor and a Print Swiss Matrix RO-80 printer/plotter. Finely powdered samples of approximately 5-10 mg were accurately weighed into aluminum crucibles and the samples were heated from 35 °C to 450 °C at a rate of 4 degrees per minute. The temperature was calibrated over the entire temperature range with a standard sample containing exactly known quantities of indium, zinc and lead. Heat flow calibration was achieved using accurately weighed samples of indium. Both calibrations were checked periodically, particularly after periods of instrument disuse. The temperature and enthalpy of a particular thermal event were obtained from the maximum (or minimum) in the DSC curve and the integrated area underneath the curve respectively. Temperature and enthalpy values are considered accurate to ± 5 degrees and ±5% respectively. Thermogravimetric analysis was determined by weighing the aluminum crucible on an analytical balance prior to and following a thermal event The weight changes were small and the accuracy of the weight loss figure is estimated to be ± 5%. 8.1.4. Infrared Spectroscopy Infrared spectra, over the range 4000 cm-1 to 250 cm1, were recorded on samples mulled in Nujol sandwiched between KRS-5 plates (58% Til, 42% TlBr, Harshaw Chemical Co.). A Perkin Elmer model 598 spectrophotometer was used. All spectra were calibrated using a polystyrene film (907 and 1601 cm1). Tabulated frequencies are considered accurate to ± 5 cm"1 for broad bands and ± 2 cnr1 for sharp bands. 8.1.5. Electronic Spectroscopy Solid-state electronic spectra were obtained at room temperature using Nujol mulls supported on filter paper. A Shimadzu UV-2100 Spectrophotometer was used over the 199 frequency range of 28000 ~ 12000 cm -1. Due to the broad nature of these absorptions, electronic spectral frequencies quoted are considered accurate to ± 200 cm-1. 8.1.6. X-ray Powder Diffraction X-ray powder diffraction patterns were recorded on a Rigaku Rotating Anode X-ray Powder Diffractometer, operating in line focus with 12 kW maximum operating power. Cu K a target radiation was detected through a 20 urn Ni filter. The peak finding program was provided by Rigaku. Samples were prepared by dispersing the specimen by grinding under alcohol in an agate mortar. The sample slurry was mounted on a glass slide and allowed to dry. 8.1.7. Single Crystal X-ray Crystallography The structures of the complexes M(HCONH2)2[H(C6H5)PC>2]2 where M is Mn, Co and Cd were determined by P. Betz and A. Bino at the Hebrew University of Jerusalum. All other X-ray structure determinations were performed by Dr. S. J. Rettig of this department. Crystals suitable for X-ray analysis were obtained as described in the relevant experimental sections. Complete descriptions of the structural analyses are given elsewhere. Structural parameters are given either in relevant experimental sections or in the Appendix. 8.1.8. Magnetic Susceptibilities Magnetic susceptibility measurements over the temperature range ~2 K to -80 K were obtained using a Princeton Applied Research Model 155 Vibrating Sample Magnetometer!21!. Magnetic fields from 100 Gauss to 9225 Gauss were employed. Magnetic fields were set to an accuracy of 0.5% and measured using a F. W. Bell model 620 gaussmeter. Accurately weighed samples of approximately 90 mg, contained either in gelatin capsules or in Kel-F capsules (whenever the sample was air and moisture sensitive) 200 were attached to a Kel-F holder with an epoxy resin. Corrections were made for the diamagnetic background of the holder. Ultrapure nickel metal was used to calibrate the instrument. Temperature measurement was achieved with a chromel versus Au-0.02% Fe thermocouple!155! located in the sample holder immediately above the sample. The thermocouple was calibrated using the known susceptibility versus temperature behavior of tetramethylethyldiammonium tetrachlorocuprate(II) and checked with mercury(II) tetrathiocyanatocobalate(n)t156!. The temperature was estimated to be accurate to ±1% over the range studied. The accuracy of the magnetic susceptibility values as measured by this technique is estimated to be in the ±1 to 2% range. The measurements were normally obtained with one field, i.e. 7501 Gauss for manganese compounds and 9225 Gauss for cobalt, nickel, and copper compounds. Checks for field dependence of the magnetic susceptibilities were made using several of the following values: 100, 2549, 7501, and 9225 Gauss and unless otherwise noted in this thesis no field dependence was observed. Magnetic susceptibilities were corrected for the diamagnetism of all atoms and temperature independent paramagnetism for copper, octahedral nickel(II) and tetrahedral cobalt(II) complexes!108"111,1141. The diamagnetic corrections were (in 10"6 cm3 mol"1): Mn+ 2, -14; Cd+2, -22; Co+2' -12; Ni+2, -11; Cu+2, -11; (n-QjHnhPOr, -166; (C6H5)(H)P02-, -78; (C6H5)2P02-, -127; H(C6H5)P02H, -78; HCONH2, -15; HCONHCH3, -36; HCON(CH3)2, -32; CH3CONH2, -26; H20, -12; pyridine, -49; pyrazine, -45. T.I.P. corrections used were 560, 230, and 60 x 10"6 cm3 mol"1 for cobalt, nickel and copper respectively. 8.2. Syntheses 8.2.1. General Comments Many methods for the synthesis of metal phosphinate complexes have been described in the literature, including some novel and exotic preparations. Block et a/J1 5 7! 201 synthesized zinc(II) diphenylphosphinate through the interfacial polymerization of an aqueous solution of zinc(II) acetate with a benzene solution of the phosphinic acid. Mikulski et alP® prepared metal methylphenylphosphinates, in near quantative yields, through the high temperature reaction of the appropriate metal halide with an excess of methyl methylphenylphosphinate: A MXn + n(CH3)(C6H5)P(0)(OCH3) _^M[(CH3)(C6H5)P02]n + nCH3X [8.1] However, the more conventional syntheses generally involve the reaction between a metal salt and either the acid or a salt of the acid, in an appropriate solvent, e.g., M(CH3C02)2xH20 + 2R2PO2H ^ M(R2P02)2 + 2CH3CO2H + xH20 [8.2] M S 0 4 x H 2 0 + 2R 2 P0 2 K » M(R2P02)2 + K 2 S 0 4 + xH20 [8.3] Most of the copper(ir) complexes prepared previously have employed one or other of the above methodst13'20-23'78!. One aim of our synthetic work was to investigate the applicability of these reactions to the synthesis of other metal phosphinate polymers and, by extension, to the preparation of adduct polymers by addition of certain neutral ligands to the polymer. All of the complexes prepared in this work, with the exception of those containing pyrazine, are air stable and the preparative reaction could be performed in open beakers or flasks The pyrazine complexes, Co(pyz)rH(C6H5)P02]2 and Ni(pyz)[H(C6H5)P02]2 are moisture sensitive and hence care was taken to avoid their exposure to the atmosphere. Standard vacuum-line techniques for the manipulation of air-sensitive compounds were used; in addition, the compounds were handled in an inert nitrogen atmosphere dry box (D. L. Herring Corporation Dri-Lab (Model He-43)) equipped with a dry-train (Model He-93). The yields in these synthetic reactions varied from nearly quantitative to -20% of theory, as given later. 202 8.2.2. Materials A l l chemicals used in these preparations were commercially available reagent grade and were used as received. Di-n-hexylphosphinic acid was synthesized according to literature methods^13]. The chemicals used, their purities and suppliers are given in Table 8.1. Table 8.1. Reagents, Purities and Suppliers. Compound (commercial name) Stated Purity Suppliers N,N-dimemylformamide 99.9 Aldrich Chem.Co., Inc. N-methylformamide 99% Aldrich Chem.Co., Inc. Diphenylphosphinic acid 99% Aldrich Chem.Co., Inc. Phenylphosphinic acid 97% Aldrich Chem.Co., Inc. Cadmium Perchlorate Reagent Grade Alfa Products Cobalt(II) 2,4-Pentanedionate 97% Alfa Products Manganese Perchlorate Reagent Grade Alfa Inorganics Cobaltous Acetate Reagent Grade Allied Chemical Manganese Chloride Reagent Grade B D H Laboratory Reagent Potassium Carbonate 99% B D H Laboratory Reagent Sodium Hydroxide 98% B D H Laboratory Reagent Acetamide Reagent Grade B D H Laboratory Reagent Cupric Chloride Reagent Grade B D H Laboratory Reagent Cupric Nitrate Reagent Grade B D H Laboratory Reagent Nickel Chloride 97% B D H Laboratory Reagent Formamide Reagent Grade Eastman Kodak Co. Cadmium Chloride 96% Fisher Scientific Co. Cadmium Acetate Reagent Grade Fisher Scientific Co. Zinc Acetate Reagent Grade Fisher Scientific Co. Cobalt Chloride 99.5% J.T.Baker Chemical Table continued 203 Table 8.1.(continued) Nickelous Acetate 97.2 J.T.Baker Chemical Manganese Acetate Manganese Sulfate Reagent Grade Reagent Grade Matheson Coleman &Bell Matheson Coleman & Bell Cadmium Sulfate Reagent Grade Mallinckrodt Chemical Works Ethanol 95% Chemistry store supply Methanol Chemistry store supply Distilled Water Chemistry store supply Acetone Chemistry store supply Nitrogen (gas) Union Carbide 8.2.2.1. Bis(|i-monophenylphosphinato)manganese(II), Mn[H(C6H5)P02]2 Monophosphinic acid (1.99 g, 14.0 mmol) was dissolved in 200 ml of ethanol. A manganese(II) acetate tetrahydrate solution was prepared by dissolving 1.47 g (6.01 mmol) of the salt in 150 ml of ethanol. The salt solution was added dropwise with stirring to the acid solution. The reaction mixture became cloudy after about 1/2 of the salt solution was added. The mixture was stirred for a further 24 h., then allowed to stand for another 5 days. The precipitate was collected on a sintered glass funnel, washed with ethanol and air-dried between pieces of filter paper. The dried product is a pale-pink, fine powder, (yield 73%). Anal, calcd. for MnCi2Hi2C>4P2: C 42.76, H 3.59; found: C 42.90, H 3.70. 8.2.2.2. Diaquobis(p>monophenylphosphinito)manganese(II), Mn(H20)2[H(C6H5)P02]2 Monophenylphosphinic acid (2.84 g, 20.0 mmol) was neutralized with potassium carbonate (1.39 g, 10.0 mmol) in 50 ml of aqueous methanol solution (50:50 by volume). Manganese(II) sulfate monohydrate (1.69 g, 10.0 mmol) was dissolved in 50 ml of 204 distilled water and then added dropwise with stirring to the potassium monophenylphosphinate solution. The reaction mixture became cloudy after about 6 ml of the sulfate solution was added, then became clear until most of the mixing was complete, becorning cloudy again once both solutions were completely mixed. The white precipitate was isolated by filtration on a sintered glass funnel, washed with aqueous methanol and then air dried between pieces of filter paper, (yield 61%). Anal, calcd. for MnCi2Hi60(>P2: C 38.63, H 4.32; found: C 38.55, H 4.30. 8.2.2.3. Bis(formamide)bis(p>monophenylphosphinato)manganese(II), Mn(HCONH2)2[H(C6H5)P02]2 Monophenylphosphinic acid (0.926 g, 6.52 mmol) and manganese perchlorate hexahydrate (0.832 g, 2.30 mmol) were mixed and dissolved in a solution of 135 ml of acetone containing 13.5 ml of formamide. The solution was stirred in a open beaker for about 20 h and the precipitate which formed was washed with acetone and air-dried overnight, (yield 72%). Anal, calcd. for MnCi4Hi8C>6N2P2: C 39.36, H 4.25, N 6.56; found: C 39.20, H 4.42, N 6.78. 8.2.2.4. Bis(monophenyIphosphinic acid)bis(|i-monophenylphosphinato) manganese(II), Mn[H(C6H5)P02H]2[H(C6H5)P02]2 Monophenylphosphinic acid (3.13 g, 22.0 mmol) was partially neutralized with sodium hydroxide (0.179 g, 4.48 mmol) in 70 ml of distilled water. The resulting solution was added dropwise to a manganese salt solution prepared by dissolving manganese perchlorate hexahydrate (1.62 g, 4.47 mmol) in 10 ml of distilled water. The resulting solution became cloudy after stirring for about 40 minutes. Stirring of the solution was continued for nearly 18 h. The product was collected by filtration and washed with distilled water. The white powder was left to air-dry for 2 days.(yield 44%) Anal, calcd. for MnC24H260gP4: C 46.40, H 4.22; found: C 46.48, H 4.25. 205 8 .2 .2 .5 . Bis(N-methylformamide)bis(p:-inonophenylphosphinato) manganese(II), Mn(HCONHCH3)2[H(C6H5)P02]2 Manganese(H) monophenylphosphinate (~1 g, ~3 mmol) was dissolved in 20 ml of N-methylformamide. A white powder was obtained after the solvent had been removed under vacuum. The powder was washed with acetone, then left to air-dry between pieces of filter paper.(yield ~ 70%). Anal, calcd. for MnCi6H2206N2P2: C 42.21, H 4.87, N, 6.15; found: C 41.95, H 4.90, N 6.05. 8 .2 .2 .6 . Bis(acetamide)bis(|i-monophenylphosphinato))manganese(II), Mn(CH 3CONH 2)2[H(C 6H5)P0 2l 2 Manganese(TJ) dichloride tetrahydrate (0.501 g, 2.53 mmol) was dissolved in 40 ml of acetone. This solution was added to an acid solution prepared by dissolving acetamide (1.82 g) and monophenylphosphinic acid (0.712 g, 5.00 mmol) in 50 ml of acetone. The colorless crystals were collected by filtration, washed with acetone and air-dried, (yield 98%). Anal, calcd. for M n C i 6 H 2 2 0 6 N 2 P 2 : C 42.21, H 4.87, N 6.15; found: C 42.30, H 4.89, N 6.10. 8.2.2.7. Bis(|i-monophenylphosphinato)bis(pyridine)manganese(II), Mn(C5H5N)2[H(C6Hs)P02]2 Manganese(II) monophenylphosphinate (~1.00 g, ~ 3.00 mmol) was mixed with 40 ml of pyridine and 10 ml of 2^ -dimethoxypropane (2,2-DMP). The mixture was refluxed for 8 h, then filtered on a sintered glass funnel, washed with a small portion of diethyl ether and then dried under vacuum at room temperature for about 2 h. (yield ~ 70%) Anal, calcd. for MnC22H2 04N2P2: C 53.34, H 4.48, N 5.66; found: C 52.54, H 4.42, N 5.31. This compound appears to contain a small amount of lattice water (approximately 0.5 mole) as evidenced by the microanalysis and the presence of a weak band centered around 3300 cm*1 in the infrared spectrum. 206 8.2.2.8. Bis(u-monophenyIphosphinato)cobalt(II), Co[H(C6H5)P02]2, Form I Cobalt chloride hexahydrate (5.10 g, 21.0 mmol) was dissolved in 50 ml of distilled water. This solution was added dropwise to a solution prepared by dissolving monophenylphosphinic acid (18.3 g, 130 mmol) in 75 ml of distilled water and neutralizing with sodium hydroxide (5.00 g, 125 mmol). A pale red precipitate started to form after several minutes. The solution was stirred for 4 h, then the product was collected by filtration, washed twice with water and air-dried overnight. The product was subsequendy heated at 120 "C under vacuum for 2 days, (yield 31%). Anal, calcd. for C0C12H12O4P2: C 42.25, H 3.55; found: C 42.08, H 3.69. 8.2.2.9. Bis(^ -monophenylphosphinato)cobalt(II), Co[H(C6H5)P02]2, Form II Monophenylphosphinic acid (0.70 g, 4.95 mmol) and cobalt(II) 2,4-Pentanedionate (1.97 g, 7.67 mmol) were mixed as solids and finely ground. The mixture was then heated under vacuum at 145 °C for the first 4 h. The mixture was repeatly ground and heated four more times until the color of the product turned blue. The product was then washed with ethanol and air-dried, (yield 66%). Anal, calcd. for C0C12H12O4P2: C 42.25, H 3.55; found: C 42.54, H 3.80. 8.2.2.10. Bis(|i-monophenylphosphinato)cobalt(II), Co[H(C6H5)P02]2, Form III Cobalt acetate tetrahydrate (1.25 g, 5.02 mmol) was dissolved in 100 ml 95% ethanol solvent. The solution was left to stand overnight, then filtered through a fine sintered glass funnel and the residue washed with ethanol. The light purple filtrate was added to a solution prepared by dissolving monophenylphosphinic acid (0.412 g, 2.90 mmol) in 50 ml ethanol. The resulting solution was stirred for 7 h, during which time a blue precipitate formed. The precipitate was isolated by filtration, washed with ethanol, 207 air-dried overnight and subsequendy dried under vacuum at 84 °C for 9 h.(yield 71%). Anal, calcd. for C0C12H12O4P2: C 42.25, H 3.55; found: C 42.09, H 3.49. 8.2.2.11. Diaquobis(|i-monophenylphosphinato)cobalt(II), Co(H 20)2[H(C 6H5)P02]2 Cobalt acetate tetrahydrate (0.374 g, 1.50 mmol) was dissolved in 120 ml of 95% ethanol, then mixed with a solution prepared by dissolving monophenylphosphinic acid (0.427 g, 3.00 mmol) in 50 ml of 95% ethanol. The mixture was heated to boiling for 30 min. It was then stirred overnight. The pink colored product was collected by filtration, washed with ethanol and air-dried, (yield 65%). Anal, calcd. for C0C12H16O6P2: C 38.22, H 4.28; found: C 38.13, H 4.40. 8.2.2.12. Bis(formamide)bis(u-monophenyIphosphinato)cobalt(II), Co(HCONH2)2[H(C6H5)P02]2 Monophenylphosphinic acid (1.71 g, 12.0 mmol) was added to a solution of cobalt chloride hexahydrate (1.1 lg, 4.67 mmol) in 150 ml of acetone containing 16.6 ml of formamide. The solution was concentrated to approximately 10% of its original volume by evaporation in air over a period of about one week. The light purple powder (with some crystals) was washed with acetone and air-dried, (yield 50%). Anal, calcd. for C 0 C 1 4 H 1 8 O 6 N 2 P 2 : C 39.00, H 4.21, N 6.50; found: C 38.89, H 4.21, N 6.60. 8.2.2.13. Bis(u-monophenyIphosphinato)bis(pyridine)cobalt(II), Co(C5H5N)2[H(C6H5)P02]2 Cobalt monophenylphosphinate (Form I) (0.418 g, 1.33 mmol) was mixed with 8 ml of 2,2-DMP and 10 ml of pyridine. A lavender precipitate which formed turned pale red while refluxing under a nitrogen atmosphere. The mixture was refluxed for almost 24 h. The product was collected by filtration and dried under vacuum at room temperature for 8 208 h. (yield 7 2 % ) . Anal, calcd. for C0C22H22O4N2P2: C 52.92, H 4.44, N 5.61; found: C 52.74, H 4.40 N 5.65. 8.2.2.14. Bis(|i-monophenyIphosphinato)(pyrazine)cobalt(II), Co(C4H4N2)[H(C6H5)P02]2 Cobalt(II) monophenylphosphinate (Form I) (0.612 g, 1.79 mmol) was added to a mixture of 30 ml of 9 5 % ethanol and 20 ml of 2,2-DMP. The mixture was refluxed under a nitrogen atmosphere overnight. The pale red powder was collected by filtration and dried under vacuum at room temperature for 8 h. (yield 6 8 % ) . Anal, calcd. for C0C16H16O4N2P2: C 45.63, H 3.83; N 6.65; found: C 45.43, H 4.00, N 6.80. 8.2.2.15. Tetraaquobis(monophenyIphosphinato)cobalt(II), Co(H20)4[H(C6H5)P02]2 Cobalt chloride hexahydrate (2.55 g, 10.7 mmol) was dissolved in 25 ml of distilled water; this solution was added dropwise to a solution made by dissolving monophenylphosphinic acid (9.16 g, 64.5 mmol) in 40 ml of distilled water, followed by neutralization with sodium hydroxide (2.51 g, 62.8 mmol). The mixture was stirred for 4 h, then filtered in a sintered glass funnel, washed with distilled water and air-dried for 2 days. Slow evaporation of the filtrate yielded the pink product in crystalline form, (yield 33%). Anal, calcd. for C0C12H20O8P2: C 34.88, H 4.88; found: C 34.78, H 4.88. 8.2.2.16. Bis(u-monophenylphosphinato)nickeKII), Ni[H(C6H5)P02]2 Monophenylphosphinic acid (7.33 g, 51.6 mmol) was neutralized with sodium hydroxide (2.00 g, 50.0 mmol) in 30 ml of distilled water. This solution was added dropwise to a solution prepared by dissolving nickel sulfate hexahydrate (2.26 g, 8.60 mmol) in 20 ml of distilled water. The mixture was stirred for 4 h, then filtered in a sintered glass funnel. The solids were washed with distilled water and air-dried for 2 days. 209 The pale green powder was then heated in a furnace at 200 °C for 8 h. (yield 18%). Anal. calcd. for N i C n H n O ^ : C 42.25, H 3.55; found: C 42.50, H 3.50. 8.2.2.17. Diaquobis(|i-monophenylphosphinato)nickel(H), Ni(H20)2[H(C6H5)P02h Monophenylphosphinic acid (3.66 g, 25.7 mmol) was dissolved in 150 ml of distilled water and then neutralized with sodium hydroxide(10.0 g, 25.0 mmol). The neutralized acid solution was added to a solution prepared by dissolving nickel sulfate hexahydrate (1.13 g, 4.30 mmol) in 100 ml of distilled water. The mixture was stirred overnight. During this process, a pale green precipitate formed. The product was isolated by filtration, washed with distilled water and dried under vacuum at room temperature for 12 h. (yield 58%). Anal, calcd. for NiCi2Hi 6 0 6 P2: C 38.24, H 4.28; found: C 38.02, H 4.12. 8.2.2.18. Bis(formamide)bis(u\-monophenylphosphinato)nickel(II), Ni(HCONH2)2[H(C6H5)P02]2 Nickel(II) perchlorate hexahydrate (3.36 g, 23.9 mmol) was dissolved in a solution containing 70 ml of acetone, 10 ml of 2,2-DMP and 33 ml of formamide. The resulting solution was added to a solution prepared by dissolving monophenylphosphinic acid (3.40 g, 23.9 mmol) in 180 ml of acetone. The mixture was allowed to sit overnight and a yellow precipitate was obtained after stirring for two days. The yellow precipitate was collected by filtration, washed with a small amount of acetone and air-dried overnight, (yield 67%). Anal, calcd. for NiCi 4Hi 80 6N2P2: C 38.99, H 4.21, N 6.50; found: C 38.88, H 4.08, N 6.37. 210 8.2.2.19. Bis(p:-monophenyIphosphinato)bis(pyridine)nickel(II), Ni(C 5H5N)2[H(C«H5)P02]2 Nickel(II) monophenylphosphinate (0.413 g, 1.21 mmol) was added to a mixture of 20 ml of pyridine and 15 ml of 2,2-DMP in a round-bottom flask. The mixture was refluxed under nitrogen at 50 *C for 12 h. A greenish powder was isolated by filtration and dried under vacuum at room temperature for 5'h. (yield 9 2 % ) . Anal, calcd. for NiC22H2 04N2P2: C 52.95, H 4.44, N 5.61; found: C 52.87, H 4.29, N 5.69. 8.2.2.20. Bis(|i-monophenylphosphinato)mono(pyrazine)nickel(II), Ni(C 4H4N 2 )[H(C 6H5)P02]2 Nickel(II) monophenylphosphinate (1.04 g, 3.06 mmol) was added to a solution prepared by dissolving pyrazine (0.295 g, 3.69 mmol) in 30 ml of 2,2-DMP. An orange precipitate formed. The total volume of the mixture was then increased to 60 ml by adding ~ 30 ml of 9 5 % ethanol. This mixture was refluxed overnight under nitrogen. The product, which was now green, was isolated by filtration, washed with a small amount of petroleum ether, and dried under vacuum at room temperature for 3 h. (yield 73%). Anal, calcd. for NiCi 6 Hi 6 0 4N2P2: C 45.65, H 43.83, N 6.65; found: C 45.29, 3.84, N 6.75. 8.2.2.21. Tetraaquobis([i-monophenylphosphinato)nickel(II), Ni(H 20) 4[H(C 6H5)P02] 2 Nickel(II) chloride hexahydrate (2.55 g, 10.7 mmol) was dissolved in 25 ml of distilled water and the solution added dropwise to a second solution prepared by dissolving monophenylphosphinic acid (9.16 g, 64.5 mmol) in 40 ml of distilled water and neutralizing with sodium hydroxide (2.58 g, 64.4 mmol). The mixture was stirred for 4 h and filtered using a sintered glass funnel. The greenish solid was then washed with distilled water and air dried for 2 days.(yield 36%). Anal, calcd. for CoCi2H2oC>8P2: C 34.90, H 4.88; found: C 34.77, H 4.77. 211 8.2.2.22. Bis(u-diphen ylphosphinato)manganese(II), Mn[(C6H5)2P02]2 (Y-form ) Diphenylphosphinic acid (2.18 g, 10.00 mmol) was dissolved in 40 ml aqueous methanol (1:3 methanol: water, v/v) and neutralized with potassium carbonate. To this solution, was added dropwise, over about 30 min a solution prepared by dissolving manganese sulfate monohydrate (0.845 g, 5.00 mmol) in 35 ml water. A precipitate in the form of a fine white microcrystalline powder formed and the mixture was stirred for an additional 45 min. The powder was then removed by filtration, washed with a 50:50 methanol:water mixture and then air-dried overnight, (yield 53%). Anal, calcd. for Mn24H2oP204: C 58.91, H 4.12; found: C 59.07, H 4.34. Attempts to prepare a formamide adduct of Mn[(C6Hs)2P02]2 led instead to the synthesis of the y-form of the binary phosphinate in a crystalline form suitable for single crystal X-ray diffraction studies. The neutralized acid and manganese(II) sulfate solutions were prepared as above. These were then mixed and 60 ml of formamide was added immediately before any precipitate formed. Over a period of three months, pale-green crystals were collected, washed with water and dried under vacuum at 60 °C for 6 h. That these crystals are the same compound as the microcrystalline powder sample described in the above paragraph was confirmed by a detailed comparison of the spectroscopic and other physical properties of the two samples. 8.2.2.23. Bis(p>dipheny]phosphinato)manganese(II), Mn[(C6H5)2P02]2 (P-form ) Diphenylphosphinic acid (2.19 g, 10.0 mmol) was dissolved in 70 ml of dimethylformamide and neutralized by the addition of 1.7 ml of triethylamine. To this solution was added dropwise, over about 30 min, a solution of manganese(TI) chloride tetrahydrate (1.00 g, 5.06 mmol) in 50 ml of dimethylformamide. A white precipitate 212 formed and the mixture was left stirring overnight The product was collected by filtration, washed well with acetone and air-dried, (yield 49%). Anal, found: C 58.8, H 4.25. 8.2.2.24. Bis(p>diphenyIphosphinato)cobalt(II), Co[(C6H5)2P02]2(Y-form ) Cobalt(II) chloride hexahydrate (1.19 g, 5.00 mmol) was dissolved in 30 ml of dimethylformamide and this solution was mixed with a solution containing 2.18 g (10.0 mmol) of diphenylphosphinic acid and ~ 1.2 ml of triethylamine dissolved in 50 ml of dimethylformamide. A clear solution was obtained; on standing over three months, blue needle-like crystals formed. The crystals were collected by filtration , washed with acetone and air-dried, (yield 57%). Anal, calcd.for C0C24H20P2O4: C 58.44, H 4.09; found: C 58.26, H 4.05. 8.2.2.25. Bis(p>diphenylphosphinato)cobalt(II), Co[(C 6H 5)2P0 2]2 ( P-form ) The P-form of Co[(C6H5)2PC>2]2 was obtained by two different synthetic routes. One route followed the procedure of Coates and Golightlyt60!. Cobalt(II) chloride hexahydrate (2.67 g, 11.2 mmol) was dissolved in 50 ml of water. The resulting solution was added dropwise with stirring to a solution of sodium diphenylphosphinate which was prepared by neutralizing diphenylphosphinic acid (5.27 g, 24.2 mmol) in 100 ml of water with sodium hydroxide. Initially a red solution formed and as more of the metal salt solution was added a blue precipitate formed. After addition was complete the mixture was heated gently on a hot plate then filtered. The solid which remained was starting material and was discarded. The pink filtrate was heated at 60 °C for two days during which time a product in the form of a blue precipitate formed. This was collected by filtration, washed with warm water, then air-dried. Anal, found: C 58.45, H 4.07. 213 The second route used to prepare P-Co[(C6Hs)2P02]2 followed that of Rose and Block!89!. Cobalt acetate tetrahydrate (1.25 g, 5.00 mmol) was dissolved in 100 ml of ethanol and the resulting solution was added dropwise to a solution prepared by dissolving diphenylphosphinic acid (2.19 g, 10.0 mmol) in 125 ml of ethanol. A blue precipitate formed and the mixture was left stirring for 1.5 h. The product was then collected by filtration, washed extensively with ethanol, and dried under vacuum at 70 °C for 12 h. (yield ~ 70%). Anal, found: C 58.14, H 4.03. 8.2.2.26. Bis(u-diphenylphosphinato)cadmium(II), Cd[(C 6H5)2P02]2 (Y-form) Diphenylphosphinic acid ( 4.36 g, 20.0 mmol) was dissolved in 80 ml of 25:75 mefhanokwater (by volume) solution, then neutralized with potassium carbonate (1.38 g, 10.0 mmol). To the resulting solution, a solution containing cadmium sulfate octahydrate (7.69 g, 10.0 mmol) in 70 ml of water was added dropwise. During addition the solution was heated gendy, and a fine white precipitate formed. After the addition was completed, the mixture was left stirring for another 20 minutes. The white precipitate was collected by filtration, air-dried and further dried under vacuum at 118 °C for a period of 18 h. (yield 49%). Anal, calcd. for CdC24H2oP204: C 52.72, H 3.69; found: C 52.64, H 3.65. 8.2.2.27. Bis(p.-monophenylphosphinato)cadmium(II), Cd[H(C6H5)P02h Cadmium(H) acetate dihydrate (1.33 g, 5.00 mmol) was dissolved in 55 ml of ethanol and the solution was then added dropwise to a solution prepared by dissolving monophenylphosphinic acid (1.42 g, 10.0 mmol) in 150 ml of ethanol. A white product began to precipitate after about 10 ml of the cadmium acetate solution had been added. The precipitate was collected, left to air-dry overnight, then dried under vacuum at 85 °C for 12 h. (yield 62%). Anal, calcd. for CdCi 2Hi2P20 4: C 36.53, H 3.07; found: C 36.64, H 3.10. 214 8.2.2.28. Mni. xCd x[H(C 6H5)P02]2 Manganese(II) acetate tetrahydrate and cadmium(II) acetate dihydrate were separately dissolved in 130 ml of ethanol. These solutions were then added separately via a peristaltic pump (Model 132100, DES AG A, Heidelberg) to an acid solution which had been prepared by dissolving monophenylphosphinic acid in 100 ml of ethanol. For example in the preparation of Mno.74Cdo^6[H(C6H5)P02]2: Monophenylphosphinic acid (1.42 g, 10.0 mmol) was dissolved in 100 ml of ethanol. Manganese(II) acetate tetrahydrate (0.920 g, 3.75 mmol) and cadmium(II) acetate dihydrate (0.334 g, 1.25 mmol) were separately dissolved in 130 ml of ethanol and then added via peristaltic pump with stirring to the acid solution. The remaining procedures for this and other mixed metal compounds of the type of Mni.xCdx[H(C6H5)P02]2 where x= 0.01,0.19, 0.26 and 0.41, where identical to that for the preparation of Mn[H(C6H5)P02]2(section 8.2.2.1). The yield of all the preparations is about 70%. Table 8.1. Elemental analysis1 for Mni.xCdx[H(C6H5)P02]2. Elements Compound C H Mn Cd Mno.99Cdo.Ol[H(C6H5)P02]2 42.68 3.58 (42.33) (3.57) Mno.8iCdo.i9[H(C6H5)P02]2 41.40 3.53 12.79 6.14 (41.35) (3.47) (12.69) (5.99) Mn0.74Cdo.26[H(C6H5)P02]2 40.32 3.35 11.54 8.30 (40.67) (3.58) (11.39) (8.07) Mno.59Cdo.4l[H(C6H5)P02]2 39.79 3.39 8.99 12.78 (40.03) (3.36) (8.67) (12.46) 1The data outside the brackets are calculated and those inside the brackets are experimental. 215 8.2.2.29. Bis(formamide)bis(u-monophenylphosphinato)cadmium(H), Cd(HCONH2)2[H(C6H5)P02]2 Cadmium perchlorate hexahydrate (0.962 g, 2.30 mmol) was dissolved in 75 ml of acetone. This solution was added dropwise with stirring to an acid solution containing monophenylphosphinic acid (0.927 g, 6.52 mmol) in a mixture of 13.5 ml of formamide and 60 ml of acetone. The mixture was stirred for about 19 h. The white product obtained was collected by filtration, washed with acetone and then air-dried, (yield 69%). Anal. calcd. for CdCi4Hi8N206P2: C 34.70, H 3.74, N 5.78; found: C 34.74, H 3.75, N 5.68. 8.2.2.30. Mni.xCdx(HCONH2h[H(C6H5)P02]2 Manganese(II) perchlorate hexahydrate and cadmium(n) perchlorate hexahydrate were dissolved in 75 ml of acetone, then added dropwise with stirring to an acid solution of monophenylphosphinic acid in a mixture of 60 ml of acetone and 13.5 ml of formamide. The mixture was stirred in an open beaker for about 20 h. The white precipitate which formed was collected by filtration, washed with acetone and air-dried overnight. For the preparation of Mno.68Cdo.32(HCONH2)2[H(C6Hs)P02]2: nianganese(n) perchlorate hexahydrate (0.585 g, 1.62 mmol) and cadmium(II) perchlorate hexahydrate (0.291 g, 0.69 mmol) were dissolved in 75 ml of acetone, then added dropwise to a solution prepared by dissolving monophenylphosphinic acid (0.927 g, 6.52 mmol) in a mixture of 60 ml of acetone and 13.5 ml of formamide. The remaining procedures for this and other mixed metal adduct polymers with the composition Mni.xCdx(HCONH2)2[H(C6H5)P02]2, where x=0.01, 0.04, 0.05, 0.14, 0.32 and 0.54, were identical to that of preparation of Mn(HCONH2)2[H(C6Hs)P02]2. The yield of all preparations is about 70%. 216 Table 8.2. Elemental analysis1 for Mni. xCd x(HCONH2)2[H(C6H5)P02]2. Elements C H N Mn Cd Mno.99Co<).oi(HCONH2)2[H(C6H5)P02]2 39.31 4.24 6.55 (39.35) (4.38) (6.63) Mno.%Cdo.04(HCONH2)2[H(C6H5)P02]2 39.15 4.22 6.52 (38.98) (4.23) (6.53) Mno.95Cdo.05(HCONH2)2[H(C6H5)P02]2 39.10 4.22 6.51 (39.19) (4.16) (6.55) Mno.86Cdo.i4(HCONH2)2[H(C6H5)P02]2 38.54 4.39 6.43 10.86 3.62 (38.84) (4.19) (6.30) (10.74) (3.32) Mno.68Cao.32(HCONH2)2[H(C6H5)P02]2 37.56 4.05 6.36 8.25 8.31 (37.84) (4.08) (6.30) (8.22) (8.05) Mno.46Cdo.54(HCONH2)2[H(C6H5)P02]2 36.70 3.95 6.26 5.52 13.24 (36.88) (3.98) (6.14) (5.51) (12.77) 1The data outside the brackets are calculated and those inside the brackets are experimental. 8 . 2 . 2 . 3 1 . Bis( | i-di-n-hexylphosphinato)manganese(II), M n [ ( n - C 6 H i 3 ) 2 P 0 2 ] 2 Manganese(II) sulfate monohydrate (0.171 g, 1.00 mmol) was dissolved in 50 ml of distilled water and the resulting solution was added dropwise to a solution containing di-n-hexylphosphinic acid (0.472 g, 2.00 mmol) in 100 ml of methanol (plus ~ 5 ml of distilled water) neutralized with 0.145 g (1.00 mmol) of potassium carbonate. The solution was stirred for about 2 h and then 100 ml of distilled water was added to the mixture causing a fluffy white precipitate to form immediately. The product was filtered on a sintered glass funnel, washed with distilled water, then air-dried, (yield 77%). Anal, calcd. for MnCi 2 H2604P2: C 55.27, H 10.25;.found: C 55.08, H 10.08. 217 8.2.2.32. Bis(u-di-n-hexylphosphinato)cadmium(II), Cd[(n-C6Hi3)2P02]2 Di-n-dihexylphosphinic acid (0.473 g, 2.00 mmol) was neutralized with potassium carbonate (0.151 g, 1.00 mmol) in 100 ml of methanol (plus ~ 5 ml of distilled water). Cadmium(II) sulfate octahydrate (0.284 g, 1.07 mmol) was dissolved in 50 ml of distilled water and then added dropwise to the potassium di-n-hexylphosphinate solution. The mixture was stirred for about 2 h and then another 100 ml of distilled water was added causing a fluffy white precipitate to form immediately. The precipitate was isolated by filtration on a sintered glass funnel, washed with distilled water, and then left to air-dry. (yield 65%). Anal, calcd. for CdCi2H 2 60 4 P2: C 49.78, H 9.05; found: C 49.71, H 9.00. 8.2.2.33. Mni. xCd x[(n-C 6Hi3)2P0 2] 2 Manganese(II) sulfate monohydrate and cadmium(II) sulfate octahydate were dissolved in 50 ml of distilled water, then added dropwise with stirring to a solution prepared by dissolving di-n-hexylphosphinic acid (0.470 g, ~ 2.00 mmol) in 100 ml of methanol (plus ~ 5 ml of distilled water) neutralized with potassium carbonate. The solution was stirred for another 30 minutes, then another 100 ml of distilled water was added causing a fluffy precipitate to form. After stirring for another 1.5 h, the product was isolated by filtration, washed with distilled water and left to air-dry. Consider the preparation of Mno.46Cdo.54[(C6Hi3)P02]2 as a specific example: manganese(II) sulfate monohydrate (0.085 g, 0.500 mmol) and cadmium(n) sulfate octahydrate (0.128 g, 0.400 mmol) were dissolved in 50 ml of distilled water and then added dropwise to an acid solution of di-n-dihexylphosphinic acid (0.470 g, 2.00 mmol) in 100 ml of methanol (plus ~ 5 ml of distilled water) neutralized with potassium carbonate(0.141 g, 1.00 mmol). The mixture was stirred for 30 minutes and then 100 ml of distilled water was added causing a fluffy precipitate to form. The mixture was left stirring for a further 1.5 h. The product was collected on a sintered glass funnel, washed with distilled water and set aside to air-dry. The preparations of the other compounds of the type Mni . x Cd x [ (n -C6Hi3)P0 2 ] 2 where 218 x=0.08 and 0.33 were carried out in an analogous way. Elemental analyses are given in Table 8.3. The yield of all the preparations is about 70%. Table 8.3 Elemental analysis1 for Mni. xCd x[(n-C6Hi3)P02]2. Compound Elements C H Mn Cd Mno.92Cdo.08[(n-C6Hi3)2P02]2 54.67 9.94 9.61 1.71 (54.43) (9.92) (9.41) (1.62) Mno.67Cdo.33[(n-C6Hi3)2P02]2 53.31 9.74 6.81 6.86 (53.50) (9.73) (6.78) (6.79) Mno.46Cdo.54[(n-C6Hi3)2P02]2 52.34 9.53 4.57 10.98 (52.38) (9.52) (4.47) (11.68) ^ e data outside the brackets are calculated and those inside the brackets are experimental. 8.2.2.34. Bis((i-monophenylphosphinato)copper(II), Cu[H(C6Hs)P02]2 Copper chloride dihydrate (1.83 g, 10.7 mmol) was dissolved in 25 ml of distilled water. The solution was added dropwise with stirring to a solution containing monophenylphosphinic acid (9.12 g, 64.7 mmol) in 40 ml of distilled water, neutralized with sodium hydroxide (2.57 g, 64.3 mmol). The mixture was stirred for 6 h. The greenish precipitate was isolated by filtration and air-dried overnight, (yield 43%). Anal, calcd. for CUC12H12P2O4: C 36.53, H 3.07; found: C 36.64, H 3.10. 8.2.2.35. Bis(|i-monophenylphosphinato)zinc(II), Zn[H(C 6H 5)P0 2]2 Zinc(II) acetate dihydrate (0.420 g, 1.83 mmol) was dissolved in 100 ml of 95% ethanol and then added to an acid solution prepared by dissolving monophenylphosphinic acid (0.543 g, 3.82 mmol) in 50 ml of ethanol. A white precipitate formed immediately. The mixture was left stirring for a further 5 h then the product was isolated by filtration, 219 washed with ethanol and air-dried, (yield 90%). Anal, calcd. for ZnCi2Hi2P2C>4: C 41.47, H 3.48; found: C 41.31, H 3.63. 8.2.2.36. Aquo-u-chloro-|i-monophenylphosphinato)cadmium(II), Cd(H 2 0 )C l [H(C 6 H5)P02] Cadmium dichloride dihydrate (1.14 g, 5.01 mmol) and monophenylphosphinic acid (0.71 g, 5.04 mmol) were mixed and dissolved in 100 ml of distilled water in an open beaker. The beaker was loosely covered and its contents allowed to slowly evaporate. Colorless crystals formed over a period of two weeks. The crystals were collected by filtration and air-dried, (yield 65%). Anal, calcd. for CdC^HgPC^Cl: C 23.47, H 2.63; found: C 23.58, H 2.51. 8.2.2.37. Bis(N,N-dimethylformamide)bis(diphenylphosphinic acid) bis(diphenyIphosphinato)nickel(II), N i [ H C O N ( C H 3 ) 2 ] 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 Diphenylphosphinic acid (1.01 g, 4.63 mmol) was dissolved in 25 ml of dimethylformamide, deprotonated with ~ 0.6 g of triethylamine, and then the solution was mixed with a solution containing nickel(II) chloride hexahydrate (0.469 g, 2.00 mmol) in 15 ml of dimethylformamide. The mixture was placed in a beaker covered with filter paper and let stand for a week. Yellow crystals formed over a period of 5 days. Yellow crystals were collected by filtration and washed with acetone, (yield 38%). Anal, calcd. for NiC3oH56N2P40io: C 60.30, H 5.25, N 2.60; found: C 60.31, H 5.07, N 2.56. 220 8.2.2.38. Tetraaquobis(N,N-dimethylformamide)nickeI(II) diphenylphosphinate dihydrate, {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 Diphenylphosphinic acid (2.18 g, 10.0 mmol) was deprotonated with 1.3 ml of triethylammine in 50 ml of DMF and then the solution was mixed with nickel(II) chloride hexahydrate (1.19 g, 5.00 mmol) in 30 ml of DMF. The mixture was put in a beaker and heated gendy for 30 min and then left to crystallize. Green crystals formed after two weeks.The crystals were found to contain DMF molecules of crystallization (see Figure 7.7.). On grinding to a powder these molecules of crystallization were lost. All characterization (including microanalysis) except for the single crystal X-ray structural determination was done on the powder. Anal, calcd. for NiC3oH46N2P2Oi2: C 48.31, H 6.51, N 5.12; found: C 48.04, H 6.64, N 5.13. 221 Chapter 9 Summary, Conclusions and Suggestions for Further Study 9.1. Summary and Conclusions The present study involved the synthesis and characterization of a number of metal phosphinate compounds most, but not all, of which are polymeric. An extensive investigation of the spectral, magnetic and other properties of these compounds in the solid state was carried out in an attempt to study magneto-structural correlations in these complexes and in so doing, increase our understanding of metal phosphinate chemistry in general. For the purpose of this summary, the compounds studied here have been divided into groups based on elemental composition and structural considerations (Table 9.1). Group 1: M[H(C6Hs)P02]2 compounds The compounds in Group 1 are binary metal phosphinates and are divided into two sub-groups according to structural information. (1A) The complexes in this sub-group are formally considered as having "tetrahedral" metal centers. Recently, Shieh et al.^ reported the single crystal structure of Zn[H(C6H5)P02]2. The structure consists of isolated {Zn[H(C6H5)P02]2}x chains in which tetrahedrally coordinated zinc ions are linked by double phosphinate bridges. Co[H(C6H5)P02]2 has been isolated in three structural forms each with distinct magnetic properties; while we were unable to obtain single crystals for any of the three forms, spectroscopic data indicated that the cobalt is tetrahedral in all three forms. All three forms are considered to be polymeric since all show significant magnetic concentration. Form n and Form III are antiferromagnetic exhibiting values of -J = 2.29 and 2.31 cm"1 respectively (S=3/2, Wagner-Friedberg model). Form I is ferromagnetic and shows field-dependent magnetic properties. 222 Table 9.1. Classification of the compounds. Group 1: M[H(C6H5)P02]2 compounds (IA) C o [ H ( C 6 H 5 ) r o 2 ] 2 ( F o n n L F o n n n a n d F o r m i n ) a n d ZnrH(C6H5)P02]2-(IB) Mn[H(C6H5)P02]2. Cd[H(C6H5)P02]2, Ni[H(C6H5)P02]2 and Cu[H(C6H5)P02]2. Group 2: M I X C g H ^ P C ^ compounds R-Mn[(C6H5)2P02]2, Y-Mn[(C6H5)2P02]2, B - C o K Q J W C ^ , Y-Co[(C6H5)2P02]2and Y-Cd[(C6H5)2P02]2. Group 3: MKn-C^H^^PC^b compounds Mn[(n-C6H13)2P02]2 and CdKn-C^kPO^. Group 4: MLX[H(C6H5)P02]2 complexes. (4A) Lx=(HCONH2)2 with M=Mn(H), Co(II), Ni(II) and Cd(H). (4B) 1^=^0)2 with M=Mn(TI), Coai) and Ni(II). (4C) Lx=(pyz) with M=Co(H) and Ni(H). (4D) Lx=(py)2 with M=Mn(U), Co(IJ) and Ni(II). Group 5: Mixed metal systems Mn1.xCdx[H(C6H5)P02]2 where x=0.01, 0.19, 0.26 and 0.41. Mn1.xCdx(HCONH2)2[H(C6H5)P02]2 where x=0.01, 0.04, 0.05, 0.18, 0.32 and 0.54. Mn1.xCdx[(n-C6H13)2P02]2 where x=0, 0.08, 0.32, 0.54. Group 6: Miscellaneous compounds Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2, Cd(H20)CirH(C6H5)P02], {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2, Co(H20)4[H(C6H5)P02]2 and Ni(H20)4[H(C6H5)P02]2. 223 (IB) T h e c o m p o u n d s i n t h i s s u b - g r o u p a r e c o n s i d e r e d t o h a v e a s h e e t s t r u c t u r e s w i t h d o u b l e p h o s p h i n a t e b r i d g e d c h a i n s c r o s s - l i n k e d as s h o w n o n p a g e 1 3 6 . M n [ H ( C 6 H 5 ) P 0 2 ] 2 a n d C u [ H ( C 6 H 5 ) P 0 2 ] 2 s h o w t y p i c a l a n t i f e r r o m a g n e t i c b e h a v i o r . N i [ H ( C 6 H 5 ) P 0 2 ] 2 e x h i b i t s f e r r o m a g n e t i c a n d f i e l d d e p e n d e n t m a g n e t i c p r o p e r t i e s w h i c h m a y b e a c c o u n t e d f o r o n t h e b a s i s o f e i t h e r s a t u r a t i o n e f f e c t s o r m a g n e t i c c o n c e n t r a t i o n e f f e c t s i n w h i c h f e r r o m a g n e t i c e x c h a n g e i n o n e d i m e n s i o n i s a c c o m p a n i e d b y a n t i f e r r o m a g n e t i c e x c h a n g e i n a s e c o n d d i m e n s i o n . Group 2: MU'CjT^^PO h^ compounds T h e s e b i n a r y d i p h e n y l p h o s p h i n a t e c o m p o u n d s a r e a l l c o n s i d e r e d t o h a v e p o l y m e r i c c h a i n s t r u c t u r e s w i t h t e t r a h e d r a l MO4 c h r o m o p h o r e s . M n f C C g H s ^ P O ^ a n d C o [ ( C 6 H 5 ) 2 P 0 2 ] 2 w e r e f o u n d t o e x i s t i n t w o s t r u c t u r a l f o r m s , p* a n d y . S i n g l e c r y s t a l X - r a y d i f f r a c t i o n s t u d i e s o n t h e y - f o r m s c o n f i r m e d t h e p r e s e n c e o f e x t e n d e d c h a i n s i n w h i c h t e t r a h e d r a l l y c o o r d i n a t e d m e t a l s a r e l i n k e d b y d o u b l e p h o s p h i n a t e b r i d g e s . A l l t h e c o m p o u n d s s h o w a n t i f e r r o m a g n e t i c b e h a v i o r a n d t h e m a g n e t i c d a t a h a v e b e e n a n a l y z e d a c c o r d i n g t o H e i s e n b e r g m o d e l s f o r l i n e a r c h a i n s . It w a s f o u n d t h a t t h e e x c h a n g e c o u p l i n g i s g r e a t e r f o r t h e y - f o r m o f C o K C g H s ^ P C ^ c o m p a r e d t o i t s f 5 - f o r m ; t h e o p p o s i t e i s t r u e f o r t h e M n [ ( C g H 5 ) 2 P 0 2 ] 2 p a i r . T h i s f i n d i n g w a s i n t e r p r e t e d a s a r i s i n g e i t h e r f r o m a d i f f e r e n c e i n t h e d e t a i l e d s t r u c t u r e s o f t h e t w o B - f o r m s o r a s a c o n s e q u e n c e o f t h e d i f f e r e n t m e t a l i o n c o n f i g u r a t i o n s a n d t h e r e f o r e m a g n e t i c o r b i t a l s i n v o l v e d . F i n a l l y , C d K C g H s ^ P C ^ w a s f o u n d t o b e i s o m o r p h o u s a n d p r o b a b l y i s o s t r u c t u r a l w i t h t h e y - f o r m s o f t h e c o b a l t a n d m a n g a n e s e c o m p o u n d s . Group 3: M K n - C ^ H ^ ^ P C ^ h compounds T h e m a n g a n e s e a n d c a d m i u m d i - n - h e x y l p h o s p h i n a t e s a r e i s o m o r p h o u s b a s e d o n X - r a y p o w d e r d i f f r a c t i o n s t u d i e s . T h e m a g n e t i c s u s c e p t i b i l i t y d a t a o f M n K n - C g H ^ ^ P C ^ w e r e a n a l y z e d u s i n g H e i s e n b e r g m o d e l s f o r a n t i f e r r o m a g n e t i c a l l y c o u p l e d l i n e a r c h a i n s . 224 Group 4: M L X [ H ( C 6 H 5 ) P 0 2 J 2 complexes The complexes in this group contain octahedral metal centers with MOg or MO4N2 chromophores. Structural studies on these compounds using single crystal X-ray diffraction and indirect methods show they all have phosphinate bridged chain structures, thus permitting the study of the effects of neutral donor ligands on magnetic exchange in phosphinate bridged chain polymers. (4A) Complexes in this sub-group (except Ni(HCONH2)2[H(C6H5)P02]2) were characterized by single crystal X-ray diffraction. The compounds were found to have polymeric structures with metal atoms linked by double phosphinate bridges in chains and neutral formamide ligands coordinating in the axial sites, thus completing a distorted octahedral coordination around each metal. The nickel complex was shown to be isomorphous with the others by X-ray powder diffraction. For the compounds in this sub-group the magnetic moments show a significant temperature dependence. Al l of the compounds show maxima in their magnetic susceptibility versus temperature data and, hence, relatively strong antiferromagnetic exchange interactions. (4B) Compounds in this sub-catagory are proposed to have similar structures to those in the sub-group (4A). The magnetic exchange is weaker than for the analogous formamide complexes. (4C) The structures of the complexes in this sub-group involve chains of double phosphinate bridged metal ions cross-linked by pyrazine bridges. The structural conclusions are supported, primarily, by the analysis of the vibrational and electronic spectra of the complexes. The magnetic susceptibility data were analyzed by using one- and two-dimensional models. It was not possible to determine whether the antiferromagnetic exchange observed in these complexes is propagated by the phosphinate or the pyrazine (or , both) pathways. 225 (4D) Complexes in this sub-group are also proposed to have "octahedral" metal centers. The magnetic studies indicate litde or no magnetic exchange in any of the three complexes. Group 5: Mixed metal systems Spectral and X-ray powder diffraction studies confirmed the isomorphism of each manganese and cadmium phosphinate pair in the mixed metal systems. The magnetic behavior of each system was analyzed by using one-dimensional Heisenberg models and the magnetic parameters obtained were interpreted according to de Jongh's "random defect" ^  model. It was found for all three systems that incorporation of diamagnetic Cd ions into the polymers results in fragmentation of the magnetic chains resulting in the formation of a significant paramagnetic component arising from the net spins associated with odd numbered fragments. As the fraction of cadmium, x, varies from 0 to ~ 0.50 in these samples the average number of contiguous Mn atoms decreases from greater than 100 to approximately two or three atoms at most in a chain. This is accompanied by an apparent decrease of about 30% in the absolute value of the exchange coupling constant J. This decrease in J suggests that factors other than nearest neighbor intrachain interactions, such as longer range intrachain and interchain exchange, may be affecting the magnetic properties of these materials. Group 6: Miscellaneous complexes Single crystal X-ray diffraction studies on Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2, {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 and Co(H20)4[H(C6H5)P02]2 revealed mononuclear structures. Ni(H20)4[H(C6H5)P02]2 was shown by X-ray powder diffraction studies to be isomorphous with the cobalt compound. All four of these compounds were found to be magnetically dilute. 226 Cd(H20)Cl[H(C6H5)P02] was shown by single crystal X-ray diffraction studies to have a unique sheet structure involving bridging phosphinate and chloride ligands. 9.2. Suggestions for Further Study One area of interest would be the investigation of dinuclear or trinuclear metal phosphinate complexes using chelating agents such as acetylacetonate (acac) as terminal ligands. Of interest would be a comparison of the magnitude of exchange in such low nuclearity complexes with the exchange observed in the infinite chain polymers. Another area of interest would be the synthesis and characterization of metal halophosphinates. As halogen substituents have varying electronegativities, the study of magnetic exchange for a given metal with different halophosphinates may reveal some interesting trends. In addition, extension of the work described here on complexes of metal phosphinates with neutral donor ligands would be useful to more fully explore the effect of the basicity of the donor ligand on magnetic exchange in phosphinate bridged complexes. Studies on mixed metal systems such as Coi_xCdx(HCONH2)2[H(C6H5)P02]2 system may prove interesting in exploring more fully the effects of chain fragmentation on the magnetic properties of exchange coupled systems. Indeed, studies on systems such as Coi_xNix(HCONH2)2[H(C6H5)P02l2 could lead to some interesting ferrimagnetic effects. Single crystal structural studies remain an important goal in this work. 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Stryjewiski and N . Giordano. Advances in Physics. Vol . 26, No.5. 487 (1977). 151. M . E. Lines. J. Phys. Chem. Solids. 31, 101 (1970). 152. J. Peers. B. Sc. Thesis, The University of British Columbia, Vancouver, B . C . , (1987). 153. J. C. Bonner and M . E. Fisher. Phys. Rev. 135, A640 (1964). 154. L . J. Bellamy. The Infrared Spectra of Complex Molecules. Vol . 2. Chapman and Hall, London. (1980). 155. L . L . Sparks, R. L . Powell. J. Res. Natl. Bur. Standards. 76A, 263 (1972). 236 156. D. B . Brown, V . H . Crawford, J. W. Hall, and W. E. Hatfield. J. Phys. Chem. 81, 1303 (1977). 157. B . P. Block. S. H . Rose. C. W. Shaumann, E. S. Roth, and J. Simkin. J. A m . Chem. Soc. 84, 3200 (1962). 237 Appendix I Crystallographic data and X-ray structural parameters. Part A: Crystallographic data. I-1. Position parameters with standard deviations in the last significant figure in the in parentheses. atom x y z B«,(A2)* Mn(CH3CONH2)2[H(C6H5)P02]2 Mn 1/2 1/2 1/2 1.46(1) P -0.01495(7) 0.41447(5) 0.42702(2) 1.51(1) 0(1) 0.2292(2) 0.3417(2) 0.44544(6) 1.99(4) 0(2) -0.2096(2) 0.3624(2) 0.46411(5) 1.89(4) 0(3) 0.4996(2) 0.3006(2) 0.56875(6) 2.62(5) N 0.7200(3) 0.0658(3) 0.54666(9) 2.98(7) C(l) -0.1025(3) 0.3505(2) 0.35282(7) 1.77(6) C(2) -0.3257(3) 0.3981(3) 0.32688(8) 2.41(7) C(3) -0.3969(4) 0.3498(3) 0.27000(9) 2.91(8) C(4) -0.2461(4) 0.2532(3) 0.2386(1) 3.09(8) C(5) -0.258(4) 0.2050(3) 0.2636(1) 3.5(1) C(6) 0.0469(4) 0.2533(3) 0.32030(9) 2.75(7) C(7) 0.5469(3) 0.1395(2) 0.57309(8) 2.15(6) C(8) 0.4081(5) 0.0209(3) 0.6090(1) 3.6(1) Mn[H(C6H5)P02H]2[H(C6H5)PO2]2 Mn 1/4 3/4 1/2 1.97(2) P(l) 0.22827(3) 0.2619(1) 0.40480(3) 2.04(3) P(2) 0.11822(3) 0.5352(1) 0.52320(3) 2.54(3) 0(1) 0.21788(9) 0.5230(3) 0.42181(9) 2.61(8) 0(2) 0.20834(8) 0.0775(3) 0.45508(8) 2.33(7) 0(3) 0.16899(8) 0.6720(4) 0.5477(1) 2.75(8) 0(4) 0.1246(1) 0.2558(4) 0.5189(1) 3.5(1) C(l) 0.1945(1) 0.1915(5) 0.3282(1) 2.1(1) C(2) 0.2000(1) 0.3532(6) 0.2764(1) 2.8(1) 238 C(3) 0.1752(1) 0.3033(6) 0.2166(1) 3.4(1) C(4) 0.1445(1) 0.0918(6) 0.2080(2) 3.6(1) C(5) 0.1386(1) -0.0702(6) 0.2587(2) 3.3(1) C(6) 0.1639(1) -0.0226(5) 0.3190(1) 2.8(1) C(7) 0.0568(1) 0.5709(6) 0.5739(1) 2.7(1) C(8) 0.0230(2) 0.7745(7) 0.5682(2) 4.6(2) C(9) -0.0242(2) 0.8028(8) 0.6089(2) 5.6(2) C(10) -0.0373(2) 0.6353(9) 0.6450(2) 5.0(2) C ( l l ) -0.0044(2) 0.433(1) 0.6592(2) 6.3(2) C(12) 0.0424(2) 0.3999(8) 0.6195(2) 5.2(2) Mn(HCONH 2)2[H(C6H 5)P02]2 Mn 0.000 0.000 0.000 P 0.16134(9) 0.4959(2) 0.05448(7) 0(1) 0.0996(3) 0.2687(6) 0.0836(2) 0(2) 0.1027(3) 0.7235(6) 0.0845(2) 0(3) 0.1564(3) -0.0166(7) -0.0929(2) C ( l ) 0.3306(4) 0.4902(3) 0.0939(3) C(2) 0.4027(5) 0.2941(9) 0.0712(3) C(3) 0.5346(5) 0.290(1) 0.0966(4) C(4) 0.5934(4) 0.477(1) 0.1459(3) C(5) 0.5223(5) 0.667(1) 0.1704(3) C(6) 0.3905(4) 0.6767(9) 0.1423(3) C(7) 0.1577(4) 0.0483(9) -0.1734(3) N 0.0763(5) 0.1933(9) -0.2170(3) H ( l ) 0.157(4) 0.483(9) -0.039(3) H(2) 0.372(5) 0.16(1) 0.038(4) H(3) 0.584(5) 0.16(1) 0.078(4) H(4) 0.684(5) 0.48(1) 0.162(3) H(5) 0.558(5) 0.80(1) 0.205(4) H(6) 0.350(5) 0.81(1) 0.164(4) H(7) 0.224(5) -0.02(1) -0.213(3) H(8) 0.084(5) 0.23(1) -0.269(4) H(9) 0.014(5) 0.26(1) -0.175(4) 239 Co(HCONH2)2[H(C6H5)P02]2 C o 0.000 0.000 0.000 P 0.1585(1) 0.4935(2) 0.05239(7) (XD 0.0970(3) 0.2618(6) 0.0831(2) 0(2) 0.0993(3) 0.7255(6) 0.0816(2) 0(3) 0.1540(3) -0.0184(7) -0.0888(2) C ( l ) 0.3274(4) 0.4873(9) 0.0936(3) C(2) 0.4009(5) 0.2895(9) 0.0705(3) C(3) 0.5334(5) 0.290(1) 0.0957(4) C(4) 0.5917(5) 0.479(1) 0.1451(4) C(5) 0.5195(5) 0.673(1) 0.1702(4) C(6) 0.3873(4) 0.6782(9) 0.1429(3) C(7) 0.1576(4) 0.0464(8) -0.1703(3) N 0.0748(5) 0.190(1) -0.2166(3) H ( l ) 0.158(4) 0.478(9) -0.041(3) H(2) 0.352(4) 0.159(9) 0.036(3) H(3) 0.584(5) 0.15(1) 0.080(4) H(4) 0.689(6) 0.50(1) 0.163(4) H(5) 0.563(6) 0.80(1) 0.204(4) H(6) 0.341(5) 0.83(1) 0.162(3) H(7) 0.226(5) -0.00(1) -0.209(3) ' H(8) 0.088(5) 0.21(1) -0.267(4) H(9) 0.012(5) 0.27(1) -0.189(4) Co[(C6H5)2P02]2 Co ( l ) 0.24621(4) 0.50596(1) 0.43267(3) 1.98(1) P(D 0.45808(8) 0.56285(3) 0.65155(6) 2.21(3) P(2) 0.06473(8) 0.41352(3) 0.60026(6) 2.20(3) CKl) 0.3750(2) 0.55690(8) 0.5339(2) 2.99(9) 0(2) 0.6041(2) 0.52429(8) 0.6793(1) 2.54(8) CK3) 0.1477(2) 0.43902(8) 0.5001(2) 2.91(8) 0(4) -0.0802(2) 0.44552(8) 0.6447(2) 2.87(8) C ( l ) 0.5233(3) 0.6353(1) 0.6707(2) 2.5(1) C(2) 0.4722(5) 0.6779(1) 0.5974(3) 4.6(2) 240 C(3) 0.5180(6) 0.7337(2) 0.6207(4) 6.1(2) C(4) 0.6135(5) 0.7466(2) 0.7168(4) 5.1(2) C(5) 0.6647(5) 0.7044(2) 0.7908(3) 4.4(2) C(6) 0.6207(4) 0.6493(1) 0.7676(3) 3.5(1) C(7) 0.3085(3) 0.5543(1) 0.7575(2) 2.5(1) C(8) 0.1471(4) 0.5710(20 0.7322(3) 5.0(2) C(9) 0.0326(5) 0.5700(2) 0.8152(4) 6.8(3) C(10) 0.0786(5) 0.5540(2) 0.9236(4) 5.4(2) C ( l l ) 0.2371(5) 0.5365(2) 0.9501(3) 4.3(2) C(12) 0.3520(4) 0.5364(1) 0.8674(3) 3.2(1) C(13) -0.0019(3) 0.3425(1) 0.5625(2) 2.6(1) C(14) 0.0573(4) 0.3147(1) 0.4693(3) 3.9(2) C(15) 0.0089(6) 0.2589(2) 0.4456(4) 5.5(2) C(16) -0.0938(6) 0.2315(2) 0.5150(5) 5.6(2) C(17) -0.1534(5) 0.2582(2) 0.6080(4) 5.2(2) C(18) -0.1082(5) 0.3136(2) 0.6304(3) 4.0(2) C(19) 0.2154(3) 0.4038(1) 0.7167(2) 2.4(1) C(20) 0.3838(4) 0.4052(1) 0.6993(3) 3.1(1) C(21) 0.4963(4) 0.3959(1) 0.7910(4) 4.0(2) C(22) 0.4435(5) 0.3844(1) 0.8973(3) 4.2(2) C(23) 0.2769(5) 0.3825(2) 0.9151(3) 4.1(2) C(24) 0.1624(4) 0.3928(1) 0.8262(3) 3.2(1) Mn[(C6H5)2P02]2 Mn(l) 0.24352(8) 0.50589(2) -0.07301(5) 2.51(2) P(D 0.4548(1) 0.56443(4) 0.115479(9) 2.75(4) P(2) 0.06771(1) 0.41106(4) 0.10261(9) 2.73(4) 0(1) 0.3751(4) 0.5571(1) 0.0365(3) 3.6(1) 0(2) 0.6003(3) 0.5270(1) 0.1852(2) 3.1(1) 0(3) 0.1429(4) 0.4379(1) 0.0015(3) 3.7(1) 0(4) -0.0778(4) 0.4415(1) 0.1495(3) 3.5(1) C ( l ) 0.5174(5) 0.6364(2) 0.1729(4) 3.1(2) C(2) 0.4623(7) 0.6786(2) 0.0989(5) 5.4(3) C(3) 0.507(1) 0.7338(2) 0.1222(6) 7.1(4) C(4) 0.6047(8) 0.7473(2) 0.2161(6) 5/7(3) 241 C(5) 0.6585(7) 0.7061(2) 0.2896(5) 5.1(3) C(6) 0.6157(7) 0.6502(2) 0.2683(4) 4.1(2) C(7) 0.3053(5) 0.5562(2) 0.2601(4) 3.1(2) C(8) 0.3461(6) 0.5364(2) 0.3691(4) 3.9(2) C(9) 0.2320(8) 0.5361(3) 0.4503(5) 5.4(3) C(10) 0.0748(9) 0.5550(3) 0.4232(6) 6.5(4) C ( l l ) 0.0310(8) 0.5733(4) 0.3155(7) 7.5(4) C(12) 0.1467(7) 0.5741(3) 0.2344(5) 5.6(3) C(13) 0.0041(5) 0.3408(2) 0.0645(4) 3.1(2) C(14) 0.0632(7) 0.3132(2) -0.0289(4) 4.5(2) C(15) 0.0163(8) 0.2577(2) -0.0530(6) 5.9(3) C(16) -0.0858(8) 0.2299(2) 0.0142(7) 6.2(3) C(17) -0.1450(8) 0.2562(3) 0.1067(6) 5.8(3) C(18) -0.1018(7) 0.3118(2) 0.1328(4) 4.5(2) C(19) 0.2201(5) 0.4023(2) 0.2167(4) 2.9(2) C(20) 0.1711(6) 0.3919(2) 0.3281(4) 3.9(2) C(21) 0.2883(8) 0.3825(2) 0.4155(4) 4.9(3) C(22) 0.4517(8) 0.3848(2) 0.3957(5) 5.2(3) C(23) 0.5023(6) 0.3961(2) 0.2878(5) 4.6(2) C(24) 0.3853(6) 0.4046(2) 0.1983(4) 3.8(2) Co(H20)4[H(C6H 5)P02 ] 2 C o ( l ) 1/2 0 1/2 1.83(1) P ( D 0.33351(4) 0.1389(1) 0.32537(3) 2.01(2) 0(1) 0.4122(1) 0.2270(2) 0.40380(9) 2.33(5) 0(2) 0.2094(1) 0.1385(3) 0.3459(1) 2.75(5) 0(3) 0.3811(1) -0.2944(3) 0.4804(1) 2.50(5) 0(4) 0.4026(1) 0.1346(3) 0.6183(1) 2.85(6) C ( l ) 0.3593(1) 0.3516(4) 0.2265(1) 2.28(6) C(2) 0.2733(2) 0.4297(5) 0.1650(5) 3.27(9) C(3) 0.2952(2) 0.5982(7) 0.0916(2) 4.3(1) C(4) 0.4028(2) 0.6892(6) 0.0774(2) 4.6(1) C(5) 0.4887(2) 0.6128(7) 0.1369(2) 4.6(1) C(6) 0.4674(2) 0.4448(5) 0.2116(2) 3.35(9) 242 {Ni(DMF)2(H20)4} (H 20) 2[(Q>H5)2P02]2 N i ( l ) 1/2 1/2 1/2 2.56(2) P ( D 0.75226(6) 0.7600(1) 0.60528(3) 3.20(4) 0(1) 0.5751(2) 0.3523(2) 0.47115(8) 3.5(1) 0(2) 0.5917(2) 0.6520(2) 0.4877(1) 3.2(1) CK3) 0.5764(2) 0.4624(3) 0.5634(1) 3.4(1) 0(4) 0.7003(2) 0.6624(3) 0.57100(7) 4.1(1) 0(5) 0.8391(2) 0.8190(3) 0.59307(8) 4.1(1) 0(6) 0.9674(3) 0.9979(5) 0.6283(1) 11.0(3) 0(7) 0.941(1) 0.219(2) 0.6841(6) 23(2) N ( l ) 0.6407(2) 0.1407(3) 0.4734(1) 3.8(1) N(2) 1.0000 0.196(1) 3/4 12.4(6) C ( l ) 0.5871(2) 0.2344(4) 0.48478(1) 3.4(1) C(2) , 0.6933(3) 0.1733(4) 0.4368(1) 5.3(2) C(3) 0.6517(4) 0.0031(5) 0.4939(2) 6.9(2) C(4) 0.7767(2) 0.6733(4) 0.6608(1) 3.7(2) C(5) 0.8449(3) 0.7179(5) 0.6947(1) 5.7(2) C(6) 0.8616(4) 0.6547(6) 0.7377(2) 7.3(3) C(7) 0.8097(5) 0.5463(7) 0.7469(2) 8.7(3) C(8) 0.7427(6) 0.4991(7) 0.7148(2) 11.8(4) C(9) 0.7256(4) 0.5626(6) 0.6713(2) 8.6(3) C(10) 0.6784(2) • 0.9023(4) 0.6147(1) 3.7(2) C ( l l ) 0.5857(3) 0.8836(5) 0.6120(2) 6.4(2) C(12) 0.5301(3) 0.9938(8) 0.6182(2) 8.4(3) C(13) 0.56344(4) 1.1225(7) 0.6262(2) 7.5(3) C(14) 0.6548(4) 1.1448(5) 0.6294(2) 7.0(3) C(15) 0.7115(3) 1.0351(4) 0.6239(1) 5.2(2) C(16) 0.977(2) 0.255(2) 0.7161(4) 38(2) C(17) 1.0000 0.019(2) 3/4 20(1) 243 Cd(H20)Cl[H(C6H5)P02] C d ( l ) 0.25001(1) 0.249981(9) 0.02041(2) 1.313(2) Cd(2) 0 0 0 1.562(3) Cd(3) 1/2 1/2 1/2 1.564(3) C l ( l ) 0.19950(3) 0.03914(3) -0.09281(7) 1.761(8) Cl(2) 0.30046(3) 0.46084(3) 0.16849(7) 1.757(8) P ( l ) 0.10740(3) 0.26467(3) 0.45162(6) 1.231(7) P(2) 0.39260(3) 0.23533(3) 0.57957(6) 1.243(7) CKl) 0.1007(1) 0.1952(1) 0.2019(2) 1.55(2) 0(2) 0.1112(1) 0.2098(1) 0.6508(2) 1.87(3) 0(3) 0.3993(1) 0.3049(1) 0.4067(2) 1.58(2) 0(4) 0.3887(1) 0.2903(1) 0.8301(2) 1.85(3) 0(5) -0.0732(1) 0.0491(1) -0.3219(2) 2.30(3) 0(6) 0.5733(1) 0.4515(1) 0.2022(2) 2.33(3) C ( l ) -0.0095(1) 0.3089(1) 0.4202(3) 1.60(3) C(2) -0.0838(2) 0.2948(2) 0.1912(3) 2.13(4) C(3) -0.1663(2) 0.3396(2) 0.1786(4) 2.68(5) C(4) -0.1748(2) 0.3986(2) 0.3947(5) 2.88(6) C(5) -0.1028(2) 0.4109(2) 0.6214(4) 2.84(6) C(6) -0.0195(2) 0.3667(2) 0.6366(3) 2.22(4) C(7) 0.5092(1) 0.1911(1) 0.6207(3) 1.59(3) C(8) 0.5194(2) 0.1329(20 0.7886(3) 2.27(4) C(9) 0.6026(2) 0.0884(2) 0.8125(4) 2.80(5) C(10) 0.6755(2) 0.1016(2) 0.6724(4) 2.89(5) C ( l l ) 0.6666(2) 0.1603(2) 0.5057(4) 2.68(5) C(12) 0.5839(2) 0.2051(2) 0.4803(3) 2.13(4) *Beq = (8/3) TI2 £ 1 Uy & i* Ej* (^ Ej) 244 1-2. Crystallographic data for M(HCONH 2)2[H(C 6H5)P02]2 complexes. Compound M=Co(II) M=Cd(U) M=Mn(TJ) Formula Formula weight Space group a (A) b (A) c (A) C ^ H ^ C o ^ O g P j 431.18 Plilc 10.453(1) 5.539(1) 14.587(2) C w H j g C d ^ O ^ 484.65 i°2i/c 10.490(2) 5.756(1) 14.792(2) C n H ^ M n N z O ^ 427.19 P2i/c 10.456(2) 5.650(1) 14.674(2) PC) 96.472(2) 96.45(2) 96.21(3) V(A3) 839(1) 887(1) 862(1) z 2 2 2 Pcalc (g c m " 3 ) 1.706 1.813 1.646 H (cm"1) 11.68 13.21 9.11 Range of 29 (') 4-55 4-55 4-55 No. of unique data 1889 1980 1987 Data with F 0 2 > 3 a ( F 0 2 ) 1457 1431 1360 R 0.050 0.036 0.047 R w 0.053 0.040 0.049 I- 3. Crystallographic data for y - M K C g H s ^ P C ^ complexes. Compound M=Co(II) M=Mn(II) Formula C24H2oCo04P2 C 24H2oMn0 4P2 Formula weight 493.30 489.31 color, habit blue, prism colorless, prism Crystal system monoclinic monochnic Space group / ^ i / c «(A) 8.080(2) 8.161(1) b(k) 23.550(6) 23.751(1) c(A) 11.726(3) 11.6946(6) PC) 92.88(2) 93.026(8) V(A3) 2229(1) 2263.6(4) Z 4 4 Pcalc (g cn 1" 3) 1.470 1.436 H (cm - 1) 9.36 63.63 No. of unique data 8260 4954 Data with F 0 2 > 3 a ( F Q 2 ) 4041 2878 R 0.039 0.045 R w 0.042 0.056 245 1-4. Crystallographic data for MnJ^fHCCgHsJPO^k compounds. Compound L = C H 3 C O N H 2 L = H ( C 6 H 5 ) P 0 2 H Formula C i ^ M n N z O g P z C 2 4 H 2 6 M n 0 8 P 4 Formula weight 455.25 621.30 Crystal system monoclinic monoclinic Space group P2x/c 5.668(2) 23.281(1) b (A) 7.500(2) 5.508(2) c(k) 23.104(2) 20.5489(6) PC) 95.52(2) 90.424(4) V(A3) 977.4(3) 2635.2(7) z 2 4 Pcalc (g c™" 3) 1.55 1.57 p, (cm"1) 8.43 68.51 Data with F 0 2 > 3 o ( F 0 2 ) 2081 2117 R 0.028 0.035 R w 0.035 0.045 1-5 (1). Crystallographic data for other compounds. Compound N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 Formula C ^ H ^ N i O ^ C 1 2 H 2 0 C o O 8 P 2 Formula weight 1075.64 413.17 Crystal system monoclinic monoclinic Crystal color, habit pink, prism Space group P2i/c P2\fa a (A) 12.541(1) 11.896(2) b (A) 9.893(3) 5.059(2) c(A) 21.463(2) 14.213(2) p O 102.276(8) 90.88(1) Z 2 2 Pcalc (gem" 3) 1-37 1.604 M-tcrn"1) 5.52 12.18 Data with F 0 2 > 3 o ( F 0 2 ) 4699 2454 R 0.038 0.034 R w 0.045 0.041 246 1-5 (2). Crystalllograghic data for other compounds. Compound {Ni(DMF)2(H20)4}(H20)2[(C6H5)2PO2]2 C d ^ O ^ W Q ^ P O z ] Formula 0 3 3 ^ 3 ^ 3 0 ! 3 P 2 CgHgCdC^P Formula weight 820.44 306.96 Crystal color, Habit pale, plate colorless, prism Crystal system monoclinic triclinic Space group C2/c P l A (A) 14.880(2) 12.855(2) fc(A) 9.633(3) 13.501(2) c(A) 29.177(2) 5.8864(6) a C) 102.60(1) p* O 98.73(1) 103.24(1) y(°) 110.235(9) V (A3) 4134(2) 882.3(2) Z 4 4 Pcalc(gcm- 3) 1.318 2.311 p. (cm"1) 6.05 29.13 Data with F 0 2 > 3 a ( F 0 2 ) 6595 9816 R 0.044 0.024 R w 0.050 0.029 247 Part B: X-ray structural parameters. 1-6. Selected bond distances (A) with estimated standard deviations in in the last significant figure in the parentheses. atom atom distance atom atom distance Mn(CH3CONH2 ) 2[H(C 6H 5)P0 2 ] 2 Mn 0 ( 2 ) , a 2.174(1) C(5) C(6) 1.384(3) Mn 0(3) 2.182(1) C(7) C(8) 1.491(3) Mn 0(1) 2.232(1) P H ( l ) 1.33(2) P CKD 1.510(1) N H(3) 0.83(2) P 0(2) 1.512(1) N H(2) 0.97(3) P C ( l ) 1.803(2) C(2) H(4) 0.91(3) 0(3) C(7) 1.240(2) C(3) H(5) 0.99(2) N C(7) 1.325(3) C(4) H(6) 0.91(3) C ( l ) C(6) 1.391(3) C(5) H(7) 0.86(3) C ( l ) C(2) 1.394(2) C(6) H(8) 0.93(2) C(2) C(3) 1.386(3) C(8) H ( l l ) 0.85(3) C(3) C(4) 1.378(3) C(8) H(9) 0.87(4) C(4) C(5) 1.372(3) C(8) H(10) 1.04(3) Here symbol' refer to the symmetry operation: 1+x, y, z. Mn[H(C 6H5)P02H] 2[H(C 6H5)P0 2]2 Mn O(l) 2.165(2) C(3) C(4) 1.377(5) Mn CK3) 2.175(2) C(4) C(5) 1.378(5) Mn 0(2)' 2.243(2) C(5) C(6) 1.394(4) P ( l ) OO) 1.500(2) C(7) C(12) 1.372(5) P(D 0(2) 1.524(2) C(7) C(8) 1.374(5) P(D C ( l ) 1.798(3) C(8) C(9) 1.394(5) P(2) 0(3) 1.487(2) C(9) C(10) 1.345(6) P(2) 0(4) 1.549(2) C(10) C ( l l ) 1.358(6) P(2) C(7) 1.787(3) C ( l l ) C(12) 1.377(5) C ( l ) C(6) 1.389(4) P( l ) H ( l ) 1.35(3) C ( l ) C(2) 1.394(4) P(2) H(2) 1.37(3) C(2) C(3) 1.382(4) 0(4) H(3) 0.93(5) 248 Cof(C6H5)2P02]2b C o d ) 0(1) 1.952(2) C(7) C(8) 1.380(4) C o ( l ) 0(2)' 1.963(2) C(7) C(12) 1.383(4) C o d ) 0(3) 1.951(2) C(8) C(9) 1.376(5) C o d ) 0(4)" 1.950(2) C(9) C(10) 1.360(6) P d ) 0(1) 1.510(2) C(10) C ( l l ) 1.367(6) P d ) 0(2) 1.511(2) C ( l l ) C(12) 1.377(4) P d ) C ( l ) 1.796(3) C(13) C(14) 1.379(4) P d ) C(7) 1.788(3) C(13) C(18) 1.380(4) P(2) 0(3) 1.506(2) C(14) C(15) 1.396(5) P(2) 0(4) 1.508(2) C(15) C(16) 1.355(7) P(2) C(13) 1.806(3) C(16) C(17) 1.369(6) P(2) C(19) 1.798(3) C(17) C(18) 1.377(5) C d ) C(2) 1.372(4) C(19) C(20) 1.386(4) C d ) C(6) 1.389(4) C(19) C(24) 1.399(4) C(2) C(3) 1.388(5) C(20) C(21) 2.390(4) C(3) C(4) 1.367(6) C(21) C(22) 1.366(5) C(4) C(5) 1.370(5) C(22) C(23) 1.373(5) C(5) C(6) 1.369(5) C(23) C(24) 1.380(4) Mn[(QH 5)2P02]2 b Mn(l) 0(4)' 2.016(3) C(7) C(12) 1.380(7) Mn(l) 0(3) 2.028(3) C(7) C(8) 1.383(6) Mn(l) 0(1) 2.032(3) C(8) C(9) 1.364(7) Mn(l) 0 ( 2 ) " 2.033(3) C(9) C(10) 1.380(9) P d ) 0(1) 1.508(3) C(10) C ( l l ) 1.36(1) P d ) (2) 1.511(3) C ( l l ) C(12) 1.373(8) P d ) C(7) 1.789(4) C(13) C(14) 1.382(7) P d ) C ( l ) 1.793(4) C(13) C(18) 1.389(6) P(2) 0(3) 1.505(3) C(14) C(15) 1.398(7) P(2) 0(4) 1.513(3) C(15) C(16) 1.348(9) P(2) C(19) 1.791(4) C(16) C(17) 1.36(1) P(2) C(13) 1.795(4) C(17) C(18) 1.397(8) C ( l ) C(6) 1.380(6) C(19) C(24) 1.378(6) C ( l ) C(2) 1.384(6) C(19) C(20) 1.405(6) C(2) C(3) 1.386(8) C(20) C(21) 1.381(6) 249 C(3) C(4) 1.359(8) C(21) C(22) 1.367(8) C(4) C(5) 1.361(8) C(22) C(23) 1.374(8) C(5) C(6) 1.390(7) C(23) C(24) 1.394(7) D Here the symbols '," and * refer to symmetry operations: 1-x, 1-y, 1-z and -x, 1-y, 1-z for the Co complex and 1-x, 1-y, -z and -x, 1-y, -z for the M n complex. N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 N i 0(3) 2.043(2) C(7) C(8) 1.381(3) N i 0(5) 2.056(1) C(7) C(12) 1.386(3) N i 0(1) 2.075(1) C(8) C(9) 1.382(4) P ( l ) OO) 1.494(2) C(9) C(10) 1.360(5) P ( l ) 0(2) 1.533(2) C(10) C ( l l ) 1.369(5) P(D C(7) 1.799(2) C ( l l ) C(12) 1.390(4) P ( l ) C ( l ) 1.805(2) C(13) C(14) 1.383(4) P(2) 0(3) 1.487(2) C(13) C(18) 1.393(4) P(2) 0(4) 1.520(2) C(14) C(15) 1.401(4) P(2) C(13) 1.799(2) C(15) C(16) 1.362(5) P(2) C(19) 1.810(3) C(16) C(17) 1.377(5) 0(5) C(25) 1.230(3) C(17) C(18) 1.376(4) N C(25) 1.321(3) C(19) C(20) 1.378(3) N C(27) 1.449(3) C(19) C(24) 1.398(3) N C(26) 1.449(3) C(20) C(21) 1.387(4) C ( l ) C(2) 1.380(3) C(21) C(22) 1.370(4) C ( l ) C(6) 1.389(3) C(22) C(23) 1.376(5) C(2) C(3) 1.385(3) C(23) C(24) 1.391(4) C(3) C(4) 1.367(4) CK2) H ( l ) 0.90(4) C(4) C(5) 1.366(4) 0(4) H ( l ) 1.52(4) C(5) C(6) 1.389(4) C o ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 C o ( l ) Oil) 2.058(1) C ( l ) C(2) 1.393(3) C o ( l ) 0(3) 2.069(1) C ( l ) C(6) 1.389(3) C o ( l ) 0(4) 2.166(2) C(2) C(3) 1.375(4) P(D OO) 1.512(1) C(3) C(4) 1.478(4) P ( l ) 0(2) 1.509(1) C(4) C(5) 1.372(4) P ( l ) C ( l ) 1.800(2) C(5) C(6) 1.386(4) 250 Bond length (A) involving hydrogen atoms. P ( l ) H ( l ) 1.28(2) C(2) H(6) 0.97(2) CX3) H(2) 0.83(3) C(3) H(7) 0.81(3) 0(3) H(2) 0.72(3) C(4) H(8) 0.99(3) 0(4) H(4) 0.81(3) C(5) H(9) 0.96(3) 0(4) H(5) 0.78(3) C(6) H(10) 0.90(3) {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 N i ( l ) 0(1) 2.065(2) N(2) C(17) 1.71(2) N i ( l ) 0(2) 2.070(2) C(4) C(5) 1.373(5) N i ( l ) 0(3) 2.052(2) C(4) C(9) 1.372(6) P ( l ) 0(4) 1.499(2) C(5) C(6) 1.385(6) P ( l ) 0(5) 1.502(2) C(6) C(7) 1.349(7) P(D C(4) 1.809(4) C(7) C(8) 1.339(8) P(D C(10) 1.804(4) C(8) C(9) 1.398(7) 0(1) C ( l ) 1.238(4) C(10) C ( l l ) 1.382(5) 0(7) C(16) 1.06(3) C(10) C(15) 1.382(6) N ( l ) C ( l ) 1.315(4) C ( l l ) C(12) 1.373(7) N ( l ) C(2) 1.451(4) C(12) C(13) 1.343(7) N ( l ) C(3) 1.452(5) C(13) C(14) 1.367(7) N(2) C(16) 1.15(2) C(14) C(15) 1.376(6) Cd(H 20)Cl[H ( C 6 H 5)P02] c C d ( l ) C l ( l ) 2.5816(5) P(2) 0(3) 1.526(1) Cd ( l ) Cl(2) 2.5819(5) P(2) 0(4) 1.520(1) Cd(l) 0(1) 2.382(1) P(2) C(7) 1.784(2) Cd ( l ) 0(2)* 2.291(1) C ( l ) C(2) 1.393(2) Cd ( l ) CK3) 2.384(1) C ( l ) C(6) 1.399(2) Cd ( l ) 0(4)* 2.289(1) C(2) C(3) 1.387(3) Cd(2) C l ( l ) 2.6429(5) C(3) C(4) 1.394(3) Cd(2) 0(1) 2.367(1) C(4) C(5) 1.377(4) Cd(2) 0(5) 2.253(1) C(5) C(6) 1.391(3) Cd(3) Cl(2) 2.6432(6) C(7) C(8) 1.401(2) Cd(3) 0(3) 2.366(1) C(7) C(12) 1.395(2) Cd(3) CK6) 2.252(1) C(8) C(9) 1.392(3) P(D OO) 1.528(1) C(9) C(10) 1.374(3) 251 P ( l ) 0(2) 1.518(1) C(10) C ( l l ) 1.399(3) P ( l ) C ( l ) 1.786(2) C ( l l ) C(12) 1.390(3) c Here sumbol * refer to the symmetry operation: x, y, z-1. 1-7. Selected bond anglesf) with estimated standard deviation in the last significant figure in the parentheses. atom atom attorn angle atom atom atom angle Mn(CH3CONH2)2[H(C 6H5)P02] 2 d 0(2)' Mn 0 ( 2 ) " 180.00 P 0(2) Mn# 135.58(7) 0(2)' Mn 0(3) 90.35(5) C(7) 0(3) Mn 135.4(1) 0(2)' Mn 0(3)* 89.65(5) C(6) C ( l ) C(2) 118.5(2) 0(2)' Mn CKD 92.11(5) C(6) C ( l ) P 212.8(1) 0(2)' Mn O ( l ) * 87.89(5) C(2) C ( l ) P 119.7(1) 0(3) Mn 0(3)* 180.00 C(3) C(2) C ( l ) 210.7(2) 0(3) Mn O(l) 89.88(5) C(4) C(3) C(2) 119.8(2) 0(3)* Mn Oil) 90.12(5) C(5) C(4) C(3) 210.2(2) O(l) Mn 0(1)* 180.00 C(4) C(5) C(6) 120.3(2) O(l) P CK2) 116.47(7) C(5) C(6) C ( l ) 120.5(2) O(l) P C ( l ) 109.43(8) 0(3) C(7) N 122.2(2) 0(2) P C ( l ) 108.74(7) 0(3) C(7) C(8) 120.3(2) P 0(1) Mn 121.92(7) N C(7) C(8) 117.5(2) H ( l ) P CKD 109.4(8) H(6) C(4) C(3) 118(2) H ( l ) P 0(2) 108.9(8) H(7) C(5) C(4) 119(2) H ( l ) P C ( l ) 103.0(8) H(7) C(5) C(6) 120(2) H(3) N H(2) 212(2) H(8) C(6) C(5) 118(2) H(3) N C(7) 116(2) H(8) C(6) C ( l ) 122(2) H(2) N C(7) 122(2) H ( l l ) C(8) H(9) 105(3) H(4) C(2) C(3) 120(2) H ( l l ) C(8) H(10) 116(3) H(4) C(2) C ( l ) 119(2) H ( l l ) C(8) C(7) 112(2) H(5) C(3) C(4) 118(1) H(9) C(8) H(10) 100(3) H(5) C(3) C(2) 122(1) H(9) C(8) C(7) 107(2) H(6) C(4) C(5) 122(2) H(10) C(8) C(7) 115(2) a Here symbols ", * and # refer to the symmetry operations: 1+x, y, z; -x, 1-y, 1-z; 1-x, 1-y, 1-z; and x-1, y, z; respectively. 252 MnrH(C6H5)P02H]2rH(C6H5)P02]2e 0(1) Mn O ( l ) " 180.00 P ( l ) 0(1) Mn 132.2(1) 0(1) M n 0(3) 85.68(7) P ( l ) 0(2) Mn# 133.0(1) 0(1) Mn 0 ( 3 ) " 94.32(7) P(2) 0(3) Mn 129.6(1) 0(1) M n 0(2)' 90.75(7) P(2) 0(4) H(3) 117(3) 0(1) Mn 0(2)* 89.25(7) C(6) C ( l ) C(2) 119.3(2) 0(3) Mn 0 ( 3 ) " 180(3) C(6) C ( l ) P(D 121.5(2) 0(3) Mn 0(2)' 88.32(7) C(2) C ( l ) P(D 119.2(2) CK3) Mn 0(2)* 91.68(7) C(3) C(2) C ( l ) 120.7(3) 0(2)' Mn 0(2)* 180(3) C(4) C(3) C(2) 119.7(3) 0(1) P(D 0(2) 115.5(1) C(3) C(4) C(5) 120.4(3) 0(1) P ( l ) C ( l ) 109.9(1) C(4) C(5) C(6) 120.4(3) 0(2) P(D C ( l ) 108.4(1) C ( l ) C(6) C(5) 119.5(3) 0(1) P ( l ) H ( l ) 109(1) C(12) C(7) C(8) 118.4(3) 0(2) P ( l ) H ( l ) 108(1) C(12) C(7) P(2) 121.5(3) C ( l ) P(D H ( l ) 105(1)' C(8) C(7) P(2) 120.0(3) 0(3) P(2) 0(4) 116.5(1) C(7) C(8) C(9) 119.6(3) 0(3) P(2) C(7) 112.6(1) C(10) C(9) C(8) 121.4(4) 0(4) P(2) C(7) 102.7(1) C(9) C(10) C ( l l ) 119.2(3) 0(3) P(2) H(2) 112(1) C(10) C(1I) C(12) 120.6(4) 0(4) P(2) H(2) 109(1) C(7) C(12) C ( l l ) 120.8(4) C(7) P(2) H(2) 102(1) e Here symbols ', ", * and # refer to the symmetry operations: 1+x, y, z; -x, 1-y, 1-z; 1-x, 1-y, 1-z; and x-1, y, z; respectively. C o [ ( C 6 H 5 ) 2 P 0 2 ] 2 f CKD C o ( l ) 0(2)' 107.60(8) C(2) C(3) C(4) 120.4(4) 0(1) C o ( l ) 0(3) 117.77(9) C(3) C(4) C(5) 120.1(4) CKD C o ( l ) 0 ( 4 ) " 104.83(9) C(4) C(5) C(6) 119.6(3) 0(2)' C o ( l ) 0(3) 104.81(8) C ( l ) C(6) C(5) 121.2(3) 0(2)' C o ( l ) 0 ( 4 ) " 109.51(6) P ( l ) C(7) C(8) 118.9(2) 0(3) Co ( l ) 0 ( 4 ) " 112.13(9) P( l ) C(7) C(12) 122.2(2) 0(1) P ( D 0(2) 116.6(1) C(8) C(7) C(12) 118.7(3) 253 CXI) P(D C ( l ) 108.4(1) C(7) C(8) C(9) 120.3(4) CKD P ( l ) C(7) 109.8(1) C(8) C(9) COO) 120.3(4) CX2) P ( l ) C ( l ) 108.8(1) C(9) C(10) C ( l l ) 120.3(4) 0(2) P(D C(7) 109.3(1) C(10 C ( l l ) C(12) 119.9(4) C(D P(D C(7) 102.9(1) C(7) C(12) C ( l l ) 120.5(3) 0(3) P(2) 0(4) 117.0(1) P(2) C(13) C(14) 121.5(2) 0(3) P(2) C(13) 108.5(1) P(2) C(13) C(18) 120.1(2) CK3) P(2) C(19) 109.4(1) C(14) C(13) C(18) 118.4(3) 0(4) P(2) C(13) 108.7(1) C(13) C(14) C(15) 119.9(4) 0(4) P(2) C(19) 108.0(1) C(14) C(15) C(16) 120.2(4) C(13) P(2) C(19) 104.5(1) C(15) C(16) C(17) 120.7(4) Co(D OO) P ( l ) 144.3(1) C(16) C(17) C(18) 119.2(4) Co(D' 0(2) P ( l ) 125.1(1) C(13) C(18) C(17) 121.5(4) Co(D 0(3) P(2) 147.7(1) P(2) C(19) C(20) 121.2(2) Co(D' 0(4) P(2) 131.3(1) P(2) C(19) C(24) 119.6(2) P(D C ( l ) C(2) 122.7(2) C(20 C(19) C(24) 119.2(3) P(D C ( l ) C(6) 118.6(2) C(19) C(20) C(21) 119.4(3) C(2) C ( l ) C(6) 118.6(3) C(20) C(21) C(22) 121.0(3) C(D C(2) C(3) 120.1(3) C(21) C(22) C(23) 120.0(3) C(22) C(23) C(24) 120.3(3) C(19) C(24) C(23) 120.1(3) Mn[(C 6H 5) 2P0 2 ] 2 f 0(4)' Mn(l) 0(3) 114.0(1) C(4) C(3) C(2) 121.3(5) 0(4)' Mn(l) 0(1) 103.2(1) C(3) C(4) C(5) 119.9(5) 0(4)' Mn(l) 0 ( 2 ) " 112.4(1) C(4) C(5) C(6) 120.2(5) 0(3) Mn(l) OO) 114.7(1) C ( l ) C(6) C(5) 120.2(5) 0(3) Mn(l) 0 ( 2 ) " 104.7(1) C(12) C(7) C(8) 118.8(5) 0(1) Mn(l) 0 ( 2 ) " 108.0(1) C(12) C(7) P(D 118.8(4) OO) P(D 0(2) 116.4(2) C(8) C(7) P(D 122.1(3) 0(1) P ( l ) C(7) 110.2(2) C(9) C(8) C(7) 120.2(5) 0(1) P(D C ( l ) 108.9(2) C(8) C(9) C(10) 119.6(6) 0(2) P ( l ) C(7) 109.3(2) C ( l l ) C(10) C(9) 120.8(6) 0(2) P ( l ) C ( l ) 108.5(2) C(10) C ( l l ) C(12) 119.1(6) C(7) P ( l ) C ( l ) 102.9(2) C ( l l ) C(12) C(7) 121.1(6) 0(3) P(2) 0(4) 116.3(2) C(14) C(13) C(18) 118.2(4) 254 0(3) P(2) C(19) 109.6(2) C(14) C(13) P(2) 122.0(4) 0(3) P(2) C(13) 108.9(2) C(18) C(13) P(2) 119.8(4) 0(4) P(2) C(19) 108.3(2) C(13) C(14) C(15) 120.2(5) 0(4) P(2) C(13) 108.3(2) C(16) C(15) C(14) 121.0(6) C(19) P(2) C(13) 104.9(2) C(15) C(16) C(17) 119.7(5) P(D 0(1) Mn(l) 146.6(2) C(16) C(17) C(18) 120.8(6) P ( l ) 0(1) M n ( l ) " 125.9(2) C(13) C(18) C(17) 120.1(5) P(2) 0(3) Mn(l) 150.2(2) C(24) C(19) C(20) 118.8(4) P(2) 0(4) M n ( l ) ' 130.9(2) C(24) C(19) P(2) 121.9(3) C(6) C ( l ) C(2) 119.2(4) C(20) C(19) P(2) 119.3(3) C(6) C ( l ) P ( l ) 118.3(3) C(21) C(20) C(19) 119.7(5) C(2) C ( l ) P ( l ) 122.4(4) C(22) C(21) C(20) 120.8(5) C ( l ) C(2) C(3) 119.3(5) C(21) C(22) C(23) 120.4(5) C(22) C(23) C(24) 119.4(5) C(19) C(24) C(23) 120.9(5) 1 Here and elsewhere the symbols' and " refer to symmetry operations: 1-x, 1-y, 1-z -x, 1-y, 1-z for the Co complex and 1-x, 1-y, -z and -x, 1-y, -z for the M n complex. N i ( D M F ) 2 [ ( C 6 H 5 ) 2 P 0 2 H ] 2 [ ( C 6 H 5 ) 2 P 0 2 ] 2 g 0(3) N i 0(3)* 180.00 C(25) N C(26) 119.9(2) 0(3) N i 0(5) 89.19(6) C(27) N C(26) 117.8(2) 0(3) N i 0(5)* 90.81(6) C(2) C ( l ) C(6) 118.1(2) 0(3) N i 0(1) 91.88(6) C(2) C ( l ) P ( l ) 121.0(2) 0(3) N i O ( l ) * 88.12(6) C(6) C ( l ) P ( l ) 120.8(2) 0(5) N i 0(5)* 180.00 C ( l ) C(2) C(3) 121.0(2) 0(5) N i 0(1) 90.73(6) C(4) C(3) C(2) 120.0(3) 0(5) N i 0(1)* 89.27(6) C(5) C(4) C(3) 120.2(2) Oil) N i O ( l ) * 180.00 C(4) C(5) C(6) 120.0(3) Oil) P(D Oil) 117.8(1) C ( l ) C(6) C(5) 120.6(3) Oil) P ( l ) C(7) 113.7(1) C(8) C(7) C(12) 118.1(2) CKD P ( l ) C ( l ) 107.3(1) C(8) C(7) P ( l ) 120.5(2) 0(2) P ( l ) C(7) 104.1(1) C(12) C(7) P(D 121.3(2) 0(2) P ( l ) C ( l ) 107.6(1) C(7) C(8) C(9) 121.0(3) C(7) P(D C ( l ) 105.5(1) C(10) C(9) C(8) 120.2(3) 0(3) P(2) 0(4) 118.4(1) C(9) C(10) C ( l l ) 120.0(3) 255 CK3) P(2) C(13) 107.8(1) C(10) C ( l l ) C(12) 120.2(3) 0(3) P(2) C(19) 110.5(1) C(7) C ( l l ) C(12) 120.4(3) 0(4) P(2) C(13) 107.0(1) C(14) C(13) C(18) 118.9(2) 0(4) P(2) C(19) 107.8(1) C(14) C(13) P(2) 122.3(2) C(13) P(2) C(19) 104.3(1) C(18) C(13) P(2) 118.8(2) P ( l ) CKD N i 141.6(1) C(13) C(14) C(15) 119.7(3) P ( l ) 0(2) H ( l ) 121(2) C(16) C(15) C(14) 120.3(3) P(2) CK3) N i 144.3(1) C(15) C(16) C(17) 120.4(3) C(25) 0(5) N i 121.6(1) C(18) C(17) C(16) 119.8(3) C(25) N C(27) 122.3(2) C(17) C(18) C(13) 120.8(3) C(20) C(19) C(18) 118.6(2) C(20) C(19) P(2) 120.5(2) C(24) C(19) P(2) 120.8(2) C(19) C(20) C(21) 121.1(2) C(22) C ( 2 D C(20) 120.0(3) C(21) C(22) C(23) 120.0(3) C(22) C(23) C(24) 120.4(3) C(23) C(24) C(19) 119.9(3) 0(5) C(25) N 124.1(2) 0(2) H ( l ) CK4) 174(4) 8 Here sumbol * refer to the symmetry operation: x, y, z-1. Co(H 20)4[H(C6H 5)P02]2 h CKD Co( l ) O ( l ) * 180.00 CK2) P( l ) C ( l ) 109.31(8) 0(1) Co ( l ) 0(3) 88.47(6) C o ( l ) CKD P( l ) 128.89(8) OO) C o ( l ) 0(3)* 91.53(6) P ( D C ( l ) C(2) 121.8(2) 0(1) Co ( l ) 0(4) 93.92(6) P ( D C ( l ) C(6) 119.4(2) 0(1) Co ( l ) 0(4)* 86.08(6) C(2) C ( l ) C(6) 118.7(2) 0(3) C o ( l ) 0(3)* 180.00 C ( l ) C(2) C(3) 120.4(2) 0(3) C o ( l ) 0(4) 87.61(6) C(2) C(3) C(4) 120.4(2) 0(3) C o ( l ) 0(4)* 92.39(6) C(3) C(4) C(5) 120.0(2) CK4) C o ( l ) 0(4)* 180.00 C(4) C(5) C(6) 120.1(2) 0(1) P ( l ) 0(2) 17.06(8) C ( l ) C(6) C(5) 120.3(2) CKD P ( l ) C ( l ) 106.77(8) C ( l ) C(2) H(6) 117(1) CKD P ( l ) H ( l ) 108.0(8) C(3) C(2) H(6) 122(1) CK2) P ( l ) H ( l ) 109.9(8) C(2) C(3) H(7) 123(2) C ( l ) P ( D H(2) 105.1(9) C(4) C(3) H(7) 117(2) C o ( l ) CK3) H(2) 117(2) C(3) C(4) H(8) 119(2) C o ( l ) 0(3) H(3) 124(2) C(5) C(4) H(8) 121(2) H(2) 0(3) H(3) 103(3) C(4) C(5) H(9) 115(2) 256 C o ( l ) 0(4) H(4) 110(2) C(6) C(5) H(9) 125(2) C o ( l ) 0(4) H(5) 129(2) C ( l ) C(6) H(110) 119(2) H(4) 0(4) H(5) 106(3) C(5) C(6) H(10) 121(2) h Here symbol * refer to the symmetry operation: x, -y, 1-z. Intramolecular bond angles(') involving the hydrogen atoms with estimated standard devistion in parentheses. 0(1) P(D H ( l ) 108.0(8) C(3) C(2) H(6) 122(1) 0(2) P ( l ) H ( l ) 109.9(8) C(2) C(3) H(7) 123(2) C ( l ) P d ) H ( l ) 105.1(9) C(4) C(3) H(7) 117(2) Co(D 0(3) H(2) 117(2) C(3) C(4) H(8) 119(2) C o ( l ) 0(3) H(3) 124(2) C(5) C(4) H(8) 212(2) H(2) 0(3) H(3) 103(3) C(4) C(5) H(9) 115(2) C o ( l ) 0(4) H(4) 110(2) C(6) C(5) H(9) 125(2) Co( l ) 0(4) H(5) 129(2) C ( l ) C(6) H(10) 119(2) H(4) CK4) H(5) 106(3) C(5) C(6) H(10) 121(2) C ( l ) C(2) H(6) 117(1) {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 i 0(1) N i ( l ) ooy 180.00 C(16) N(2) C(17) 120(1) 0(1) N i ( l ) 0(2)' 89.7(1) CKD C ( l ) N ( l ) 124.3(3) 0(1) N i ( l ) 0(2)' 89.7(1) P(D C(4) C(5) 121.8(3) 0(1) N i ( l ) CK3) 89.2(1) P(D C(4) C(9) 121.0(3) 0(1) N i ( l ) 0(3)' 90.8(1) C(5) C(4) C(9) 117.1(4) 0(2) N i ( l ) 0(2)' 180.00 C(4) C(5) C(6) 121.9(4) 0(2) N i ( l ) 0(3) 89.5(1) C(5) C(6) C(7) 119.3(5) 0(2) N i ( l ) 0(3)' 90.5(1) C(6) C(7) C(8) 120.9(5) 0(3) N i ( l ) 0(3)' 180.00 C(7) C(8) C(9) 120.0(5) 0(4) P ( l ) CK5) 117.0(1) C(4) C(9) C(8) 120.8(5) CK4) P(D C(4) 108.7(2) P(D C(10) C ( l l ) 121.2(3) 0(4) P ( l ) C(10) 108.3(2) P(D C(10) C(15) 121.8(3) 0(5) P(D C(4) 108.8(2) C ( l l ) C(10) C(15) 117.1(4) 0(5) P ( l ) C(10) 108.3(2) C(10) C ( l l ) C(12) 120.5(5) C(4) P ( l ) C(10) 105.0(2) C ( l l ) C(12) C(13) 121.5(5) N i ( l ) CKD C ( l ) 121.8(2) C(12) C(13) C(14) 119.6(5) C ( l ) N ( l ) C(2) 120.5(3) C913) C(14) C(15) 119.5(5) 257 C ( l ) N ( l ) C(3) 122.1(3) C(10) C(15) C(14) 121.8(4) C(2) N ( l ) C(3) 117.4(3) 0(7) C(16) N(2) 130(3) C(16) N(2) C ( 1 6 ) " 120(2) H(28) C(17) H(29) 109.38 N i ( l ) 0(2) H ( l ) 115(3) C(8) C(7) H(16) 119.57 N i ( l ) 0(2) H(2) 120(3) C(7) C(8) H(17) 120.00 H ( l ) 0(2) H(2) 110(4) C(9) C(8) H(17) 120.02 N i ( l ) 0(3) H(3) 111(3) C(4) C(9) H(18) 119.58 N i ( l ) 0(3) H(4) 108(3) C(8) C(9) H(18) 119.57 H(3) 0(3) H(4) 105(4) C(10) C ( l l ) H(19) 119.76 H(5) 0(6) H(6) 102.05 C(12) C ( l l ) H(19) 119.76 0(1) C ( l ) H(7). 117.83 C ( l l ) C(12) H(20) 119.25 N ( l ) C ( l ) H(7) 117.83 C(13) C(12) H(20) 119.25 N ( l ) C(2) H(8) 109.47 C(12) C(13) H(21) 120.20 N ( l ) C(2) H(9) 109.47 C(14) C ( l 3) H(21) 120.19 N ( l ) C(2) H(10) 109.47 C(13) C(14) H(22) 120.24 H(8) C(2) H(9) 109.47 C(15) C(14) H(22) 120.24 H(8) C(2) H(10) 109.48 C(10) C(15) H(23) 119.09 H(9) C(2) H(10) 109.47 C(14) C(15) H(23) 119.10 N ( l ) C(3) H ( l l ) 109.47 N(2) C(16) H(24) 109.37 N ( l ) C(3) H(12) 109.47 N(2) C ( l 6) H(25) 109.34 N ( l ) C(3) H(13) 109.47 N(2) C ( l 6) H(26) 110.03 H ( l l ) C(3) H(12) 109.47 H(24) C(16) H(25) 108.88 H ( l l ) C(3) H(13) 109.47 H(24) C(16) H(26) 109.63 H(12) C(3) H(13) 109.47 H(25) C(16) H(26) 109.57 C(4) C(5) H(14) 119.08 N(2) C(17) H(27) 109.56 C(6) C(5) H(14) 119.06 N(2) C(17) H(28) 109.56 C(5) C(6) H(15) 120.32 N(2) C(17) H(29) 109.56 C(7) C(6) H(15) 120.34 H(27) C(17) H(28) 109.38 C(6) C(7) H(16) 119.57 H(27) C(17) H(29) 109.38 1 The symbols ' and " refer to symmetry operations: 1-x, 1-y, 1-z; and 2-x, y, 3/2-z; respectively. Cd(H20)CirH(C 6H5)P02} j C l ( l ) C d ( l ) Cl(2) 175.44(1) Cl(2) Cd(3) 0 ( 3 ) " 100.37(3) C l ( l ) C d ( l ) 0(1) 80.58(3) C(2) Cd(3) 0(6) 91.42(4) 258 Cl(l) Cd(l) 0(2)* 87.58(4) Cl(2) Cd(3) 0(6)" 88.58(4) Cl(l) Cd(l) 0(3) 96.22(3) 0(3) Cd(3) 0(3)" 180.00 Cl(l) Cd(l) 0(4)* 95.77(4) 0(3) Cd(3) CK6) 84.11(5) Cl(2) Cd(l) Oil) 96.19(3) 0(3) Cd(3) 0(6)" 95.89(5) Cl(2) Cd(l) Oil)* 95.69(4) 0(6) Cd(3) 0(6)" 180.00 Cl(2) Cd(l) 0(3) 80.57(3) Cd(l) Cl(l) Cd(2) 90.96(2) Cl(2) Cd(l) 0(4)* 87.53(3) Cd(l) Cl(2) Cd(3) 90.93(2) 0(1) Cd(l) 0(2)* 90.62(4) OO) PO) Oil) 115.45(7) 0(1) Cd(l) 0(3) 90.97(4) Oil) P(l) C(l) 111.18(7) CKl) Cd(l) 0(4)* 176,13(4) Oil) P(l) C(l) 109.49(7) 0(2)* Cd(l) 0(30 176.08(4) 00) P(2) 0(4) 115.33(7) 0(2)* Cd(l) 0(4)* 87.97(4) 0(3) P(2) C(7) 111.23(7) 0(3) Cd(l) 0(4) 90.67(4) 0(4) P(2) C(7) 109.54(7) Cl(l) Cd(2) Cl(l)' 180.00 Cd(l) Oil) Cd(2) 103.35(4) Cl(l) Cd(2) Oil) 79.58(3) Cd(l) Oil) PO) 123.35(6) Cl(l) Cd(2) o(iy 100.42(3) Cd(2) Oil) P(D 129.20(6) Cl(l) Cd(2) 0(5) 91.45(4) Cd(l)#0(2) P(l) 133.48(7) Cl(l) Cd(2) 0(5)' 88.55(4) Cd(l) 0(3) Cd(3) 103.28(4) Oil) Cd(2) o(iy 180.00 Cd(l) 0(3) P(2) 123.27(6) Oil) Cd(2) CK5) 83.83(5) Cd(3) 0(3) P(2) 129.40(6) O(l) Cd(2) 0(5)' 96.16(5) Cd(l)#0(4) P(2) 133.47(7) 0(5) Cd(2) 0(5)' 180.00 P(l) C(l) C(2) 122.4(1) Cl(2) Cd(3) Cl(2) 180.00 P(l) C(l) C(6) 117.5(1) Cl(2) Cd(3) 0(3) 79.63(3) C(2) C(l) C96) 119.9(2) C(l) C(2) C(3) 119.8(2) C(2) C(3) C(4) 120.1(2) C(3) C(4) C(5) 120.2(2) C(4) C(5) C(6) 120.3(2) C(l) C(6) C(5) 119.7(2) P(2) C(7) C(8) 117.7(1) P(2) C(7) C(12) 122.6(1) C(8) C(7) C(12) 199.5(2) C(7) C(8) C(9) 120.4(2) C(8) C(9) C(10) 120.4(2) C(9) C(10) C(ll) 120.1(2) C(10) C(ll) C912) 120.1(2) C(7) C(12) C(ll) 119.9(2) J Here the symbols *,'," and # refer to the symmetry operations: x, y, z-1; -x, -y, -z; and x, y, 1+z; respectively. 259 Intramolecular bond angles(') involving the hydrogen atoms with estimated standard devistion in the last significant figure in the parentheses. CKD P ( l ) H ( l ) 109(1) C(3) C(4) H(9) 119.87 0(2) P ( l ) H ( l ) 109(1) C(5) C(4) H(9) 119.89 C ( l ) P ( l ) H ( l ) 102(1) C(4) C(5) H(10) 119.87 0(3) P(2) H(2) 108(1) C(6) C(5) H(10) 119.86 0(4) P(2) H(2) 108(1) C ( l ) C(6) H ( l l ) 120.16 C(7) P(2) H(2) 105(1) C(5) C(6) H ( l l ) 120.16 Cd(2) 0(5) H(3) 111(2) C(7) C(8) H(12) 119.99 Cd(2) 0(5) H(4) 124(2) C(9) C(8) H(12) 119.99 H(3) 0(5) H(4) 104(2) C(8) C(9) H(13) 119.82 Cd(3) 0(6) H(5) 120(2) C(10) C(9) H(13) 119.82 Cd(3) CK6) H(6) 102(2) C(9) C(10) H(14) 119.97 H(5) 0(6) H(6) 98(3) C ( l l ) C(10) H(14) 119.97 C ( l ) C(2) H(7) 120.10 C(10) C ( l l ) H(15) 119.95 C(3) C(2) H(7) 120.10 C(12) C ( l l ) H(15) 119.95 C(2) C(3) H(8) 119.97 C(7) C(12) H(16) 120.04 C(4) C(3) H(8) 119.97 C ( l l ) C(12) H(16) 120.05 260 Part C X-ray powder diffraction data1. 1-8. X-ray powder diffraction data for MIHCQHstePOsh. Co[H(C6H 5)P02]2 Form I Form II Form HI 20 d I 29 d I 29 d I 5.78 15.28 92 5.92 14.92 100 5.78 15.28 100 5.98 14.77 100 7.84 11.27 15 11.62 7.61 9 7.88 11.21 22 12.00 7.37 20 17.52 5.06 19 9.08 9.73 12 17.92 4.95 33 19.80 4.48 14 11.56 7.65 11 18.96 4.68 47 23.50 3.78 12 12.10 7.31 16 24.62 3.61 11 17.38 5.10 12 25.86 3.44 14 18.16 4.88 11 26.06 3.42 14 18.98 4.67 15 Cd [ H ( C 6 H 5 ) P 0 2 ] 2 Mn[H(C6H5)P02]2 Ni[H(C 6H5)P0 2]2 29 d I 29 d I 29 d I 5.58 15.83 63 8.24 10.72 100 6.30 14.02 100 8.18 10.80 100 8.50 10.39 52 9.26 9.54 26 8.39 10.53 49 11.04 8.01 4 11.26 7.85 11 14.62 6.05 8 14.16 6.25 8 16.56 5.35 7 14.50 6.10 10 17.06 5.19 6 16.50 5.37 8 19.14 4.63 28 16.97 5.22 18 19.80 4.48 3 19.04 4.66 14 22.28 3.99 20 25.59 3.48 5 25.82 3.45 3 26.85 3.32 7 27.12 3.29 3 27.60 3.23 6 30.44 2.93 4 1-9. X-ray powder diffraction data for M ( H 2 0 ) 2 [ H ( ( ^ 5 ) P O 2 ] 2 . M=Mn(U) M=Co(II) M=Ni(II) 29 d I 29 d I 29 d I 6.00 14.72 100 6.04 14.62 100 6.06 14.57 100 12.12 7.30 16 12.18 7.26 14 12.18 7.26 11 18.30 4.84 10 18.36 4.83 6 18.38 4.82 5 18.74 4.73 6 19.00 4.67 4 19.14 4.63 2 19.96 4.44 3 22.06 4.03 3 24.56 3.62 7 24.56 3.62 1 1 Here and elsewhere in this thesis 29 is in degree; d is in A and I is relative intensity. 261 1-10. X-ray powder diffraction data for MrH((^H5)2P02]2. M=Cu(TI) M=Zn(U) 26 d I 26 d I 5.72 15.44 100 9.84 8.98 100 11.54 7.66 5 11.84 7.47 7 17.36 5.10 12 15.82 5.60 5 16.50 5.37 5 19.52 4.54 37 19.84 4.47 12 20.82 4.26 9 24.82 3.58 16 25.18 3.53 9 25.52 3.49 7 27.14 3.28 7 27.98 3.19 5 29.98 2.98 3 M l . X-ray powder diffraction data for M C H C O N ^ ^ t H C C ^ P O ^ . M=Mn(II) M=Co(JJ) M=Ni(U) M=Cd(H) 26 d I 26 d I 26 d I 26 d I 6.04 14.62 21 6.06 14.57 100 5.64 15.66 22 8.38 10.54 86 8.44 10.47 100 8.44 14.57 38 8.42 10.48 100 11.30 7.82 4 12.02 7.36 91 12.16 7.27 70 12.22 7.24 , 38 11.98 7.38 60 13.94 6.35 100 14.02 6.31 88 14.08 6.29 31 13.90 6.37 60 15.62 5.67 27 15.66 5.65 7 15.44 5.73 12 16.96 5.22 54 17.00 5.21 83 17.04 5.20 20 16.98 5.22 61 18.38 4.82 19 18.26 4.85 6 19.06 4.65 45 19.12 4.64 17 18.88 4.70 45 19.44 5.56 35 19.52 4.54 32 19.68 4.51 10 19.76 4.49 7 19.82 4.48 32 20.36 4.36 9 21.92 4.05 4 23.80 3.74 10 24.42 3.64 29 24.26 3.67 27 24.86 3.58 88 24.76 3.59 40 24.78 3.59 12 24.72 3.60 39 25.06 3.55 58 25.20 3.53 20 25.60 3.48 14 25.66 3.47 40 26.00 3.42 11 26.22 3.40 10 26.72 3.33 10 27.00 3.29 7 28.00 3.16 20 28.36 3.14 38 28.48 3.13 10 28.06 3.18 14 29.04 3.07 13 29.56 3.02 9 29.60 3.02 11 262 1-12. X-ray powder diffraction data for M(py) 2[H(C 6H5)P02]2. M=Mn(H) M=Co(II) M=Ni(II) 29 d I 29 d I 29 d I 5.72 15.44 5 5.94 14.87 100 7.74 11.41 18 7.66 11.53 9 12.12 7.30 12 9.96 8.87 100 9.96 8.96 100 12.20 7.25 27 14.88 5.95 7 14.76 6.00 5 17.32 5.12 13 15.24 5.81 5 18.74 4.73 7 18.18 4.88 13 16.46 5.38 6 21.78 4.08 31 17.80 5.00 6 28.84 3.09 5 18.18 4.88 5 18.48 4.80 5 18.88 4.70 6 20.06 4.42 4 20.36 4.36 7 21.52 4.13 6 21.96 4.04 19 23.62 3.76 5 28.70 3.11 4 29.06 3.07 3 1-13. X-ray powder diffraction data for M(H20)4[H(C 6H 5)P02]2-M=Co(ID M=Ni(H) 29 d I 29 d I 6.06 14.57 100 6.18 14.29 100 12.20 7.25 16 12.42 7.12 3 18.40 4.82 9 18.66 4.75 2 18.98 4.67 3 24.66 3.61 4 25.00 3.56 2 1-14. X-ray powder diffraction data for M(pyz)[H(C5H5)P02] 2. M=Co(II) M=Ni(H) 29 d I 29 d I 5.92 14.92 100 6.22 14.20 100 12.20 7.25 13 12.56 7.04 22 17.40 5.09 9 17.74 5.00 5 18.14 4.89 9 18.94 4.68 5 20.04 4.21 6 263 1-15. X-ray powder diffraction data for p-M[(C 6H5)2P0 2]2. M=Mn(H) M=Co(II) 29 d I 29 d I 6.66 13.26 27 7.78 11.35 100 7.66 11.53 65 7.86 11.24 100 8.22 10.75 18 8.38 10.54 38 16.34 5.42 15 15.82 5.60 14 21.24 4.18 12 21.02 4.22 20 21.80 4.07 15 23.76 3.74 18 1-16. X-ray powder diffraction data for y -MKCgHs^PO^-M=Mn(U) M= =Co(ir) =Cd(ID 29 d I 29 d I 29 d I 7.36 12.00 66 7.44 11.87 59 7.30 12.10 47 8.32 10.61 100 8.36 10.57 100 8.32 10.62 100 13.42 6.59 3 13.50 6.55 7 13.34 6.63 6 14.94 5.93 8 14.72 6.01 5 16.76 5.29 4 20.08 4.42 4 20.24 4.38 8 19.98 4.44 4 21.24 4.18 7 21.28 4.17 13 21.14 4.20 7 22.36 3.97 5 22.54 3.94 13 23.62 3.76 7 23.82 3.73 18 23.48 3.79 4 27.26 3.27 7 26.96 3.30 3 264 1-17. X-ray powder diffraction data for M n l ^ l T i C C f j I t y P O ^ . L = C H 3 C O N H 2 L = H C O N H ( C H 3 ) L = H ( C 6 H 5 ) P 0 2 H 20 d I 20 d I 20 d I 6.14 14.38 25 5.54 15.94 100 7.46 11.84 97 7.76 11.38 100 11.30 7.82 7 8.48 10.42 100 12.48 7.09 34 14.64 6.05 4 11.36 7.78 20 14.12 6.27 11 17.10 5.18 12 15.10 5.86 19 15.46 5.73 11 22.24 3.99 4 16.42 5.39 13 16.62 5.33 9 22.94 3.87 4 17.34 5.11 37 17.92 4.95 8 18.54 4.78 14 18.42 4.81 13 18.82 4.71 50 18.96 4.68 11 20.12 4.41 10 19.86 4.47 7 20.94 4.24 17 21.74 4.08 8 21.50 4.13 19 22.70 3.91 10 23.06 3.85 41 23.28 3.82 8 24.34 3.65 52 24.14 3.68 10 25.30 3.52 16 25.08 3.55 24 26.34 3.38 16 26.48 3.36 14 26.98 3.30 11 28.40 3.09 10 27.26 3.27 17 28.22 3.16 17 29.38 3.04 10 1-18. X-ray powder diffraction data for M n 1 . x C d x [ H ( C 6 H 5 ) P 0 2 ] 2 . x=0.01 x=0.19 x= =0.26 x= =0.41 20 d I 20 d I 20 d I 20 d I 8.13 10.87 100 8.13 10.87 100 8.07 10.95 100 8.11 10.89 100 8.47 10.43 20 8.49 10.41 42 8.41 10.51 47 8.44 10.47 56 14.00 6.32 7 14.04 6.30 7 14.02 6.31 7 14.58 6.07 4 14.59 6.07 6 14.51 6.10 7 14.54 6.09 9 16.42 5.39 6 16.46 5.38 6 16.39 5.40 8 16.43 5.39 8 16.98 5.22 7 17.01 5.21 6 19.04 4.66 24 19.05 4.66 22 18.99 4.67 23 19.03 4.66 19 19.77 4.49 7 19.64 4.52 5 19.91 4.46 6 22.21 4.00 13 22.22 4.00 14 22.15 4.01 14 22.18 4.00 10 22.61 3.93 7 22.51 3.95 5 22.53 3.94 4 25.69 3.46 4 25.69 3.46 4 27.10 3.29 8 27.01 3.30 7 26.99 3.30 6 29.20 3.06 3 265 1-19. X-ray powder diffraction data for Mn 1. xCd x(HCONH 2)2[H(C 6H5)P02]2-x=0.01 x=0.04 x=0.05 26 d I 26 d I 26 d I 5.91 14.94 4 8.38 10.54 64 8.38 10.54 94 8.40 10.52 86 12.01 7.36 59 12.00 7.37 94 12.02 7.36 87 13.94 6.35 100 13.92 6.36 100 13.94 6.35 100 15.47 5.72 5 16.69 5.31 6 16.93 5.23 51 16.96 5.22 54 16.96 5.22 54 19.07 4.65 40 19.04 4.66 54 19.06 4.65 54 19.75 4.49 4 23.16 3.84 4 24.03 3.70 5 24.40 3.65 19 24.39 3.65 27 24.41 3.64 29 24.86 3.58 62 24.84 3.58 78 24.86 3.58 82 25.30 3.52 4 25.61 3.48 15 25.59 3.48 13 25.62 3.47 14 26.22 3.40 6 26.19 3.40 8 26.22 3.40 7 28.22 3.16 25 28.19 3.16 19 28.21 3.16 19 29.04 3.07 8 29.02 3.07 10 29.04 3.07 11 29.53 3.02 5 1-20. X-ray powder diffraction data for Mn 1 . x Cd x (HCONH 2 )2[H(C 6 H5)P0 2 ]2-x=0.14 x=0.32 x=0.54 29 d I 29 d I 29 d I 5.64 15.66 61 5.60 15.77 69 5.60 15.77 63 8.39 10.53 80 8.33 10.61 81 8.35 10.58 100 12.01 7.36 79 11.96 7.39 92 11.95 7.40 94 13.94 6.35 100 13.88 6.38 100 13.85 6.39 94 15.41 5.75 13 16.96 5.22 52 16.92 5.24 59 16.90 5.24 59 19.06 4.65 48 18.96 4.68 81 18.92 4.69 73 19.67 4.51 11 23.85 3.73 9 24.40 3.65 28 24.32 3.66 48 24.28 3.66 38 24.86 3.58 86 24.78 3.59 93 24.74 3.60 68 25.62 3.47 13 25.56 3.48 7 . 26.21 3.40 10 26.10 3.41 16 26.05 3.42 13 27.15 3.28 8 27.05 3.29 8 28.21 3.16 24 28.13 3.17 27 28.09 3.17 18 29.03 3.07 12 28.92 3.08 14 28.85 3.09 11 29.51 3.21 8 29.33 3.04 7 29.93 2.98 6 266 1-21. X-ray powder diffraction data for M n i . xCd x[n-(C6Hi3)2P02l2-x=0 x= =0.08 x=0.54 x= 1.0 26 d I 26 d I 26 d I 26 d I 4.80 18.39 100 4.86 18.17 100 4.98 17.73 100 4.98 17.73 100 5.15 17.18 96 5.02 17.59 95 5.20 16.98 89 7.10 12.44 24 7.16 12.33 33 7.16 12.34 27 7.00 12.62 18 7.28 12.13 24 9.88 8.95 7 10.50 8.42 9 10.42 8.48 8 10.52 8.40 9 11.34 7.80 14 11.38 7.77 9 11.78 7.51 9 18.32 4.83 10 18.42 4.81 15 18.32 4.84 9 22.74 3.91 10 23.04 3.86 11 23.10 3.85 16 22.94 3.87 8 Ap p e n d i x II Magnetic susceptibility r e s u l t s 1 . II-1 Magnetic data for NiL x r H(C 6H5)P0 2]2 complexes. L x = ( H 2 0 ) 2 =(HCONH 2) 2 L x=(pyz) Temp. XM Meff Temp, XM Meff Temp. XM Meff (K) (K) (K) 5.19 75.0 1.76 5.17 28.8 1.09 2.89 185 2.07 7.22 73.1 2.05 5.99 29.5 1.19 4.39 162 2.39 10.1 66.2 2.31 10.7 33.4 1.69 7.36 122 2.67 15.5 54.1 2.59 15.5 32.8 2.02 8.30 113 2.73 20.5 45.4 2.73 20.5 30.6 2.24 9.29 106 2.81 25.5 38.8 2.81 25.6 28.1 2.40 11.5 88.4 2.85 29.5 35.2 2.88 29.8 26.3 2.50 16.4 65.5 2.93 39.9 27.8 2.98 38.8 22.7 2.65 21.8 51.1 2.99 47.4 24.1 3.02 39.9 22.4 2.67 26.7 42.7 3.02 53.8 21.7 3.06 47.4 20.1 2.76 31.1 37.1 3.04 60.3 19.8 3.09 54.0 18.5 2.82 40.1 29.0 3.05 65.5 18.6 3.12 60.2 17.1 2.87 48.2 24.9 3.10 69.9 17.5 3.13 65.4 16.1 2.90 55.2 22.0 3.12 74.3 16.6 3.14 74.4 14.6 2.95 60.9 20.1 3.13 78.0 15.9 3.15 78.3 14.0 2.96 66.0 18.8 3.15 81.8 15.2 3.16 81.6 13.5 2.97 70.7 17.7 3.17 74.8 16.9 3.18 78.6 16.1 3.18 82.2 15.5 3.19 1 Here and elsewhere in this thesis temperatures are in K; molar susceptibilities (XM) ^ M 10~3 cm 3 mol" 1; magnetic moments (p^ff) ^  m B.M.. 267 II-2. Magnetic data for Mril^tHCCgHsJPO^h complexes. L=H2Q L=HCONH2 L=HCONH(CH3) Temp. XM Meff Temp. XM Meff Temp. XM Meff (K) (K) (K) 4.22 327 3.32 2.21 159 1.68 2.20 359 2.51 6.44 308 3.98 2.50 200 2.00 2.50 362 2.69 7.50 291 4.18 3.37 202 2.33 2.79 364 2.85 8.57 276 4.35 4.12 209 2.62 3.20 366 3.06 9.50 263 4.47 4.38 211 2.72 3.72 365 3.29 10.4 251 4.57 4.93 212 2.89 4.28 363 3.53 11.3 239 4.65 5.61 214 3.10 5.00 354 3.76 12.0 228 4.68 5.84 214 3.16 5.17 351 3.81 13.5 214 4.81 7.55. 210 3.56 6.06 338 4.05 15.5 196 4.93 7.67 209 3.58 7.95 308 4.43 17.8 179 5.05 8.00 207 3.64 10.9 263 4.78 21.5 155 5.16 9.56 199 3.90 16.0 205 5.13 29.0 123 5.34 10.6 193 4.04 21.1 170 5.35 36.2 102 5.43 11.2 188 4.11 25.9 146 5.49 45.7 83.0 5.51 13.6 174 4.35 30.7 127 5.59 53.7 72.2 5.57 14.7 167 4.42 40.4 100 5.69 57.6 68.5 5.62 16.1 159 4.52 47.6 86.9 5.75 61.1 64.7 5.62 17.5 152 4.62 54.6 77.4 5.81 70.2 57.3 5.67 21.3 135 4.80 60.3 70.2 5.82 82.0 49.4 5.69 24.0 125 4.90 65.5 65.7 5.87 26.0 118 4.95 69.1 62.5 5.88 28.5 111 5.03 74.1 58.4 5.89 30.5 106 5.08 81.8 53.5 5.92 35.9 93.3 5.17 40.1 84.9 5.22 46.4 75.8 5.30 53.1 67.5 5.36 60.4 60.9 5.42 70.1 53.7 5.49 81.7 46.8 5.53 268 11-3. Magnetic data for M n L ^ I H C C ^ J P O ^ k complexes. L = C H 3 C O N H 2 L = H ( C 6 H 5 ) P 0 2 H L = p y Temp. XM Meff Temp. XM Meff Temp XM Meff (K) (K) (K) 2.30 340 2.50 5.26 553 4.82 2.22 1279 4.76 2.40 341 2.56 5.73 516 4.87 2.31 1255 4.81 2.60 343 2.67 7.98 413 5.13 2.39 1231 4.85 2.79 345 2.78 10.8 329 5.33 2.50 1183 4.86 3.08 348 2.93 16.1 233 5.49 2.70 1129 4.94 3.38 349 3.07 21.1 185 5.58 3.09 1051 5.10 3.80 349 3.26 26.1 153 5.64 3.38 985 5.16 4.18 347 3.41 30.6 132 5.69 3.88 907 5.30 4.21 347 3.42 31.5 128 5.69 4.21 838 5.31 4.65 343 3.57 38.6 106 5.73 4.31 823 5.33 5.24 337 3.76 46.5 89.4 5.76 4.93 751 5.44 5.70 331 3.89 53.2 78.5 5.78 5.42 697 5.50 5.98 329 3.96 60.4 70.7 5.85 5.99 644 5.55 8.11 293 4.36 65.7 65.3 5.85 7.61 505 5.54 11.3 249 4.75 74.4 57.8 5.86 10.9 367 5.65 16.7 193 5.07 81.9 52.6 5.87 16.1 253 5.70 21.7 160 5.26 21.2 196 5.76 26.8 135 5.39 26.3 161 5.81 31.5 119 5.47 31.0 138 5.84 36.5 105 5.53 36.0 119 5.84 40.8 95.2 5.57 40.5 107 5.87 48.2 82.1 5.62 47.8 91.0 5.89 55.2 73.6 5.70 54.4 80.7 5.92 60.8 67.2 5.72 60.1 73.5 5.94 65.9 62.6 5.74 65.4 68.0 5.96 70.2 58.8 5.75 69.9 63.8 5.97 74.7 55.8 5.76 74.2 60.3 5.97 78.3 53.3 5.78 78.0 57.3 5.98 81.9 51.2 5.79 81.8 54.8 5.98 269 JJ-4 (1). Magnetic data for C o f H t C s H ^ P O ^ (Form I) at different magnetic fields. H = 1 0 0 G Temp. XM Meff (K) 2.30 3338 7.84 2.70 2670 7.59 2.79 2426 7.36 2.98 2193 7.23 3.20 1869 6.92 3.38 1630 6.64 3.64 1439 6.47 4.07 1172 6.18 4.24 1064 6.01 4.42 982 5.89 4.93 839 5.75 5.34 724 5.56 5.48 719 5.61 5.97 629 5.48 7.92 407 5.08 11.2 268 4.89 16.6 172 4.77 21.5 133 4.78 26.4 107 4.76 31.2 90.8 4.76 36.0 78.9 4.76 40.2 70.7 4.77 48.0 59.3 4.77 54.5 54.5 4.87 60.6 48.3 4.84 65.6 45.0 4.86 69.9 42.6 4.84 74.1 40.7 4.91 78.0 38.8 4.92 81.7 37.8 4.97 H=2549 G Temp. XM Meff (K) 2.30 1639 5.49 2.70 1409 5.51 2.89 1366 5.61 2.98 1290 5.54 3.20 1210 5.56 3.45 1110 5.53 3.81 991 5.49 4.21 895 5.49 4.26 880 5.48 4.56 785 5.35 5.05 689 5.27 5.08 689 5.29 5.48 625 5.24 5.97 544 5.10 7.71 383 4.86 11.0 249 4.68 16.4 158 4.55 21.4 120 4.53 26.5 97.2 4.54 30.9 83.2 4.53 35.7 72.5 4.55 40.2 65.0 4.57 47.6 55.9 4.62 54.3 49.8 4.65 60.3 45.6 4.69 65.5 42.5 4.72 70.1 39.8 4.72 74.3 37.9 4.74 78.2 36.2 4.75 81.7 34.6 4.75 270 H-4 (2). Magnetic data for C o f H C C s r l ^ P O i k (Form I) at different magnetic field. H=7501 G H=9225 G Temp. XM Meff Temp, X M Meff (K) (K) 2.40 799 3.92 2.30 689 3.56 2.50 795 3.90 2.50 689 3.71 2.79 777 4.16 2.70 682 3.84 3.08 755 4.31 2.98 671 4.00 3.38 724 4.42 3.29 653 4.15 3.81 684 4.57 3.64 628 4.28 4.26 640 4.67 4.11 592 4.41 4.81 583 4.74 4.24 589 4.47 5.46 526 4.79 4.65 556 4.55 6.12 486 4.88 5.24 513 4.64 31.7 82.4 4.57 5.70 492 4.74 60.7 46.0 4.73 5.91 467 4.70 81.8 35.6 4.83 7.93 349 4.70 11.3 230 4.65 16.6 155 4.54 21.5 118 4.51 26.6 96.4 4.53 31.2 82.4 4.54 36.2 71.6 4.55 40.7 64.4 4.58 48.2 55.4 4.62 60.6 45.3 4.69 65.8 42.5 4.73 70.3 39.9 4.74 74.5 38.1 4.76 78.2 36.3 4.76 81.7 35.1 4.79 271 II-5 Magnetic data for Co[H(C 6H 5)P02]2.( Form H and Form m). Form II Form UI Temp, XM Meff Temp. XM Meff (K) (K) 2.11 384 2.54 2.30 141 1.61 2.50 376 2.74 2.70 142 1.75 2.60 372 2.78 2.79 142 1.78 2.70 368 2.82 2.98 143 1.84 2.98 360 2.93 3.11 143 1.89 3.20 352 3.00 3.38 144 1.97 3.46 342 3.07 3.72 144 2.07 3.81 327 3.16 4.11 144 2.18 4.21 325 3.31 4.21 144 2.20 4.34 309 3.28 4.57 144 2.29 4.82 291 3.35 4.78 143 2.34 5.34 279 3.45 5.05 143 2.40 5.38 272 3.42 5.53 141 2.50 6.04 251 3.48 6.04 139 2.59 7.86 215 3.68 7.50 133 2.82 11.3 164 3.85 10.9 117 3.19 16.2 121 3.95 16.4 94.1 3.51 21.4 95.4 4.04 21.2 81.1 3.71 26.4 80.7 4.12 26.2 70.5 3.84 31.0 70.6 4.19 30.8 63.4 3.95 35.8 62.7 4.24 35.7 57.2 4.04 40.2 56.7 4.27 40.2 52.4 4.10 47.7 49.3 4.34 47.6 45.9 4.18 54.4 44.2 4.39 54.3 41.5 4.25 60.3 40.7 4.43 59.8 38.2 4.28 65.5 37.8 4.45 65.6 35.6 4.32 70.0 35.6 4.47 70.1 33.6 4.34 74.2 33.9 4.49 74.4 31.9 4.36 78.1 32.4 4.50 78.1 30.6 4.37 81.6 31.1 4.51 81.7 29.4 4.38 272 II-6. Magnetic data for C o J ^ ^ C g H s J P O ^ complexes. Temp. XM Meff Temp. XM Meff Temp, X M Meff (K) (K) (K) 2.30 180 1.82 2.20 81.3 1.20 2.40 214 2.02 2.60 183 1.95 2.50 84.7 1.30 2.70 213 2.14 2.70 183 1.99 2.60 85.7 1.33 2.88 212 2.21 2.98 184 2.10 2.70 87.2 1.37 3.08 210 2.27 3.11 185 2.14 2.89 88.7 1.43 3.20 208 2.31 3.38 186 2.24 3.20 91.1 1.53 3.46 206 2.39 3.64 186 2.33 3.45 93.1 1.60 3.81 202 2.48 4.07 185 2.45 3.81 96.1 1.71 4.31 197 2.61 4.21 184 2.49 4.21 97.0 1.81 4.50 192 2.63 4.34 184 2.52 4.26 98.5 1.83 5.06 185 2.74 4.69 181 2.60 4.73 101 1.96 5.20 182 2.75 4.93 182 2.68 5.31 103 2.10 5.54 178 2.81 5.24 178 2.73 5.91 105 2.23 6.40 172 2.96 5.99 173 2.88 6.50 105 2.34 7.74 148 ' 3.03 7.57 156 3.07 7.64 105 2.53 11.4 117 3.27 10.9 129 3.35 8.56 103 2.66 16.5 89.5 3.44 16.4 99.3 3.60 9.69 102 2.81 21.3 74.8 3.57 21.3 83.8 3.78 16.1 84.4 3.30 26.6 64.6 3.70 26.2 71.9 3.88 20.9 74.1 3.51 31.2 57.5 3.79 30.9 64.6 4.00 26.0 65.2 3.68 36.1 51.5 3.86 35.7 58.4 4.08 30.8 58.8 3.81 40.4 47.8 3.93 40.2 53.8 4.16 35.4 53.9 3.90 48.1 42.2 4.03 47.6 47.7 4.26 39.9 49.9 3.99 55.0 38.5 4.12 54.3 43.6 4.35 47.4 44.9 4.13 60.6 35.9 4.17 60.3 40.6 4.42 54.0 41.3 4.22 65.8 33.9 4.22 65.5 38.3 4.48 60.2 38.6 4.31 70.2 32.3 4.26 70.1 36.5 4.52 65.3 36.6 4.37 74.4 30.8 4.28 74.2 34.9 4.55 70.0 34.9 4.42 82.0 28.6 4.33 78.1 33.5 4.52 74.0 33.5 4.45 81.7 32.2 4.59 77.8 32.3 4.48 81.6 31.2 4.51 273 II-7. Magnetic data for N i t H C C g r ^ P O ^ at different magnetic fields. H=2549 G Temp. X M Meff (K) 2.09 1803 5.49 2.10 1780 5.47 2.20 1692 5.46 2.40 1581 5.51 2.60 1474 5.54 3.08 1287 5.63 3.46 1131 5.59 4.07 936 5.52 4.12 1000 5.73 4.65 788 5.41 5.24 654 5.23 5.48 640 5.30 5.91 554 5.12 7.80 359 4.74 11.5 208 4.36 16.5 125 4.05 21.4 87.5 3.87 26.5 67.9 3.80 31.1 55.7 3.72 36.0 46.8 3.67 40.4 40.9 3.63 47.9 33.9 3.60 54.3 29.7 3.59 61.0 26.8 3.61 65.6 24.7 3.60 70.1 23.0 3.59 74.4 21.6 3.58 78.2 20.4 3.58 81.7 19.6 3.57 H=7501 G Temp, X M Meff (K) 2.20 941 4.07 2.30 935 4.15 2.50 928 4.31 2.60 915 4.36 2.88 895 4.54 3.11 862 4.63 3.38 836 4.75 3.64 783 4.77 4.10 734 4.91 4.12 756 4.99 4.74 649 4.96 5.19 587 4.93 5.32 577 4.96 5.97 506 4.92 7.80 344 4.63 11.4 208 4.36 16.5 125 4.06 21.8 87.2 3.90 26.5 68.0 3.80 31.1 55.3 3.71 36.0 46.2 3.65 40.4 40.2 3.61 47.9 33.1 3.56 54.3 28.6 3.52 60.4 25.6 3.52 65.6 24.5 3.51 70.1 21.8 3.49 74.4 20.5 3.49 78.3 19.4 3.48 81.7 18.5 3.47 H=9225 G Temp, X M Meff (K) 2.20 814 3.78 2.60 798 4.07 2.79 792 4.21 2.88 782 4.24 3.08 771 4.36 3.28 749 4.43 3.54 723 4.52 3.98 696 4.71 4.32 679 4.84 4.34 653 4.76 4.81 604 4.82 5.32 556 4.86 5.34 583 4.99 5.97 493 4.85 8.24 341 4.74 11.4 212 4.38 17.1 132 4.24 21.6 88.2 3.90 26.5 67.7 3.79 31.2 55.8 3.73 36.3 46.2 3.66 40.1 40.3 3.59 48.2 33.1 3.57 55.1 28.7 3.55 60.7 25.7 3.53 65.8 23.5 3.52 70.4 21.8 3.50 74.6 20.5 3.50 78.3 19.4 3.48 82.0 18.4 3.48 274 II- 8. Magnetic data for M n [ ( C g r l ^ P O J 2 complexes. fj-form Temp. XM Meff (K) 2.20 289 2.25 2.40 289 2.35 2.50 289 2.40 2.70 289 2.50 2.89 289 2.58 3.11 287 2.67 3.54 288 2.85 3.98 285 3.01 4.24 283 3.10 4.47 280 3.18 4.74 282 3.26 5.48 275 3.47 5.84 272 3.57 6.12 269 3.63 8.24 246 4.03 11.5 214 4.44 16.9 172 4.83 21.7 145 5.02 26.5 126 5.17 31.2 112 5.28 36.3 98.4 5.35 40.6 89.8 5.40 48.0 78.1 5.48 55.0 70.2 5.56 60.6 64.7 5.60 65.8 60.2 5.63 70.2 56.8 5.65 74.2 54.2 5.67 78.0 51.7 5.68 81.8 49.6 5.70 y-form Temp, XM Meff (K) 2.20 620 3.30 2.40 608 3.42 2.50 604 3.48 2.70 598 3.59 2.88 590 3.69 3.20 577 3.84 3.56 565 4.01 3.81 547 4.08 4.24 536 4.26 4.40 526 4.30 4.74 504 4.37 5.55 473 4.58 5.91 454 4.63 6.40 451 4.81 7.97 373 4.87 11.7 289 5.19 16.9 212 5.35 22.0 170 5.48 27.0 143 5.55 31.7 124 5.60 36.2 109 5.62 40.6 98.5 5.65 48.1 84.4 5.70 55.0 75.1 5.75 60.7 68.3 5.76 65.7 63.4 5.77 70.2 59.7 5.79 74.3 56.6 5.80 78.2 54.0 5.81 81.8 51.8 5.82 275 II-9. Magnetic data for C o K C g H s ^ P O j h complexes. p*-form Temp. XM Meff (K) 2.20 501 3.04 2.40 495 3.08 2.60 487 3.18 2.89 470 3.30 3.08 447 3.32 3.29 426 3.35 3.54 402 3.37 3.90 378 3.43 4.21 368 3.52 4.42 350 3.47 4.77 339 3.59 4.97 328 3.60 5.32 305 3.60 6.04 286 3.72 7.44 244 3.81 10.8 186 4.01 16.4 132 4.17 21.2 106 4.24 26.2 88.0 4.30 30.9 75.3 4.32 35.7 65.8 4.33 40.2 59.1 4.36 48.0 50.0 4.38 54.3 44.4 4.39 60.5 40.4 4.42 65.6 37.5 4.44 70.1 35.0 4.43 74.2 33.1 4.43 78.0 31.6 4.44 81.7 30.2 4.44 y-form Temp. XM Meff (K) 2.30 219 2.01 2.70 227 2.21 2.79 228 2.26 2.98 230 2.34 3.11 231 2.40 3.38 233 2.51 3.64 233 2.61 4.07 233 2.75 4.24 229 2.79 4.49 231 2.88 5.05 227 3.03 5.20 225 3.06 5.53 223 3.14 5.97 218 3.23 7.74 195 3.48 11.3 160 3.80 16.4 120 3.97 21.3 97.4 4.08 26.4 81.9 4.15 30.9 71.2 4.20 35.9 62.4 4.23 40.5 55.9 4.26 48.0 47.8 4.28 54.5 42.4 4.30 60.4 38.7 4.33 65.6 35.9 4.34 70.2 33.7 4.35 74.4 31.9 4.36 78.1 30.5 4.36 82.0 29.2 4.37 276 II-10. Magnetic data for Mnj.xCaxfHCCgHsJPOJi complexes. x=0.01 Temp. X M Meff (K) 3.46 41.3 1.07 3.72 41.0 1.10 4.07 40.6 1.15 4.24 40.3 1.17 4.42 40.1 1.19 4.89 39.7 1.25 5.42 38.1 1.29 5.46 39.2 1.31 5.97 38.9 1.36 7.77 38.0 1.54 11.3 37.7 1.85 14.2 37.9 2.07 16.7 38.1 2.25 19.4 38.3 2.44 21.4 38.6 2.57 24.5 38.8 2.76 26.4 38.8 2.86 31.0 38.8 3.10 34.2 38.6 3.25 36.0 38.5 3.33 40.2 38.0 3.50 47.8 37.0 3.76 54.8 35.9 3.97 60.4 35.0 4.11 65.5 34.1 4.23 70.1 33.3 4.32 74.1 32.5 4.39 78.1 31.7 4.45 81.7 31.1 4.51 x=0.26 Temp. X M Meff (K) 2.20 202 1.88 2.40 201 1.96 2.60 196 2.02 2.79 192 2.07 2.98 185 2.10 3.54 168 2.18 3.98 160 2.25 4.24 160 2.33 4.34 151 2.29 4.93 143 2.37 5.27 140 2.43 5.48 135 2.43 6.04 127 2.48 x=0.19 Temp. X M Meff (K) 2.60 160 1.82 2.70 158 1.85 2.79 156 1.86 2.98 151 1.90 3.11 145 1.90 3.64 136 1.99 3.98 130 2.03 4.24 126 2.06 4.42 123 2.09 4.93 118 2.15 5.00 115 2.15 5.32 111 2.18 5.97 106 2.25 7.63 91.6 2.36 11.0 77.1 2.60 16.5 66.0 2.95 21.4 60.7 3.22 26.4 57.1 3.47 31.0 54.5 3.67 35.9 52.0 3.86 40.2 50.1 4.01 47.8 47.3 4.25 54.3 44.9 4.42 60.5 43.2 4.57 65.6 41.5 4.67 70.1 40.2 4.75 74.1 39.1 4.82 78.0 38.1 4.88 81.8 37.1 4.93 x=0.41 Temp. X M Meff (K) 2.30 317 2.42 2.60 295 2.47 2.70 287 2.49 2.89 276 2.53 3.08 267 2.56 3.29 254 2.58 3.64 242 2.65 4.07 228 2.72 4.21 226 2.76 4.50 212 2.76 4.97 198 2.81 5.08 200 2.85 5.46 186 2.85 277 7.77 111 2.62 6.04 174 2.90 11.4 91.0 2.88 7.77 146 3.01 16.4 75.4 3.15 11.2 113 3.18 21.4 68.6 3.42 16.6 90.5 3.46 26.4 63.6 3.66 21.3 80.0 3.69 31.0 60.1 3.86 26.4 72.5 3.91 35.9 57.0 4.04 30.9 67.5 4.08 40.2 54.7 4.19 35.9 63.0 4.25 47.8 50.9 4.41 40.3 59.7 4.39 54.2 48.2 4.57 47.8 55.0 4.59 60.3 46.0 4.71 54.3 51.5 4.73 65.5 44.1 4.81 60.4 48.9 4.86 70.1 42.7 4.89 65.4 46.8 4.95 74.1 41.3 4.95 70.1 45.0 5.02 78.0 40.2 5.01 74.3 43.5 5.08 81.6 39.2 5.06 78.0 42.2 5.13 81.6 40.9 5.16 II-11. Magnetic data for Mn 1. xCd x(HCONH2 ) 2[H(C 6H5)P02]2 complexes. x=0.01 x=0.04 x=0.05 Temp, X M Meff Temp, X M Meff Temp, X M Meff (K) (K) (K) 2.30 211 1.97 2.50 236 2.17 2.60 244 2.25 2.60 213 2.10 2.60 237 2.22 2.70 244 2.29 2.79 215 2.19 2.70 237 2.26 2.89 243 2.37 2.89 216 2.24 2.89 237 2.34 3.08 243 2.45 3.20 218 2.36 3.11 237 2.43 3.20 243 2.49 3.54 220 2.50 3.38 238 2.54 3.46 243 2.59 4.07 223 2.69 3.64 238 2.63 3.72 243 2.69 4.21 222 2.73 3.98 239 2.76 4.11 243 2.83 4.34 224 2.79 4.21 238 2.83 4.21 243 2.86 4.93 225 2.98 4.42 239 2.90 4.50 243 2.96 5.40 225 3.11 4.89 239 3.05 4.89 243 3.08 5.48 225 3.14 5.46 237 3.22 5.32 242 3.21 5.97 225 3.27 5.48 237 3.22 5.40 242 3.23 6.58 223 3.43 5.99 236 3.36 5.97 239 3.38 7.74 217 3.67 8.17 222 3.81 7.92 227 3.79 11.4 196 4.22 11.3 200 4.25 11.2 202 4.25 16.6 162 4.63 16.7 164 4.68 16.7 164 4.68 21.6 139 4.90 21.5 140 4.91 21.5 141 4.93 26.4 121 5.04 26.6 121 5.08 26.4 122 5.08 30.9 107 5.15 31.0 108 5.17 31.0 108 5.19 35.9 95.7 5.24 36.0 95.9 5.26 35.9 96.4 5.26 40.2 87.4 5.30 40.2 87.8 5.31 40.4 88.3 5.34 47.6 76.0 5.38 47.8 76.6 5.41 48.0 76.9 5.43 54.3 68.8 5.46 54.5 69.1 5.49 54.3 68.8 5.47 60.3 63.1 5.51 60.4 63.5 5.54 60.4 63.6 5.54 65.4 58.9 5.55 65.5 59.3 5.57 65.5 59.0 5.56 69.8 55.3 5.56 69.9 55.9 5.59 70.0 56.0 5.60 74.1 52.7 5.59 74.2 53.1 5.62 74.3 53.2 5.62 78.1 50.4 5.61 78.1 50.8 5.63 78.0 50.9 5.63 81.7 48.4 5.63 81.7 48.8 5.65 81.7 48.9 5.65 278 x=0.14 x=0.32 x=0.54 Temp. X M Meff Temp, X M Meff Temp, X M Meff (K) (K) (K) 2.10 301 2.25 2.30 463 2.92 2.50 683 3.69 2.30 299 2.34 2.40 461 2.98 2.70 650 3.75 2.40 295 2.38 2.50 453 3.01 2.89 633 3.83 2.79 292 2.55 2.70 444 3.09 3.08 615 3.89 3.08 289 2.67 2.98 431 3.21 3.20 592 3.89 3.46 284 2.80 3.11 417 3.22 3.54 564 4.00 3.88 286 2.98 3.46 403 3.34 3.72 543 4.02 3.98 280 2.99 3.81 389 3.44 4.07 515 4.10 4.56 275 3.17 4.21 353 3.45 4.21 504 4.12 5.08 270 3.31 4.47 371 3.64 4.50 487 4.19 5.62 269 3.48 4.74 357 3.68 4.96 461 4.28 5.97 262 3.54 5.48 341 3.87 5.48 440 4.39 7.94 244 3.94 5.62 339 3.90 5.62 428 4.38 11.3 213 4.39 5.97 329 3.96 5.97 412 4.44 16.7 172 4.79 8.11 286 4.31 7.94 343 4.67 21.7 146 5.04 11.4 237 4.65 11.3 271 4.96 26.7 126 5.19 16.4 188 4.97 16.8 202 5.20 31.2 112 5.28 21.9 154 5.19 21.9 165 5.37 35.7 99.7 5.33 26.7 131 5.29 26.7 140 5.47 39.9 91.7 5.40 31.4 116 5.40 31.0 130 5.52 47.4 79.4 5.48 36.0 103 5.44 36.0 107 5.56 53.9 71.1 5.53 40.2 93.5 5.48 40.4 97.0 5.59 59.9 65.2 5.59 47.6 80.6 5.54 48.0 83.4 5.66 65.1 60.7 5.62 54.3 72.0 5.59 54.3 74.4 5.68 69.5 57.1 5.63 60.4 65.9 5.64 60.4 68.0 5.73 73.9. 54.3 5.66 65.5 60.5 5.63 65.5 62.7 5.73 77.7 51.8 5.67 70.1 57.6 5.68 70.1 58.8 5.74 81.3 49.5 5.68 74.5 54.4 5.59 74.4 55.7 5.75 78.1 52.0 5.70 78.2 52.9 5.75 81.7 49.9 5.71 81.9 50.7 5.76 11-12. Magnetic data for Mni.xCdx[n-(C6Hi3)2P02]2 complexes. x=0.0 x=0.08 Temp, X M Meff Temp, X M Meff (K) (K) 4.39 340 3.45 2.30 434 2.82 5.56 329 3.83 2.50 429 2.93 7.94 289 4.28 2.79 428 3.09 11.4 240 4.68 2.95 425 3.17 16.7 185 4.97 3.11 422 3.24 21.9 152 5.15 3.46 418 3.40 24.8 137 5.21 3.72 412 3.50 26.5 131 5.27 4.11 405 3.65 29.3 120 5.31 4.31 401 3.72 30.9 115 5.33 4.49 396 3.77 36.1 100 5.38 4.89 383 3.87 39.5 90.9 5.36 5.32 375 3.99 279 48.1 78.4 5.49 54.5 70.1 5.53 60.5 64.3 5.58 65.8 59.8 5.61 70.2 56.4 5.62 74.5 53.4 5.64 78.3 51.0 5.65 81.8 49.2 5.67 x=0.33 Temp. X M Meff (K) 2.30 635 3.42 2.60 622 3.60 2.79 612 3.70 2.95 601 3.76 3.11 585 3.81 3.38 566 3.91 3.64 548 4.00 4.07 527 4.14 4.21 525 4.20 4.42 506 4.23 4.89 479 4.33 5.27 467 4.44 5.46 453 4.45 5.97 432 4.54 7.86 367 4.80 11.4 282 5.08 16.7 209 5.29 22.0 167 5.42 26.9 140 5.49 31.5 122 5.54 36.1 107 5.55 40.6 95.7 5.57 48.1 82.1 5.62 54.9 72.9 5.66 60.6 66.4 5.68 65.8 61.5 5.69 70.2 57.9 5.70 74.5 54.6 5.70 78.2 52.3 5.72 81.7 50.3 5.73 5.42 376 4.04 6.04 361 4.17 8.11 313 4.51 11.4 256 4.84 16.7 195 5.10 22.1 158 5.28 26.9 132 5.33 31.3 118 5.42 36.3 103 5.48 40.6 93.0 5.50 48.2 80.3 5.56 55.2 71.4 5.61 60.6 65.3 5.63 65.8 60.6 5.65 70.2 56.8 5.65 74.5 53.9 5.67 78.2 51.4 5.67 81.8 49.4 5.68 x=0.54 Temp. XM Meff (K) 2.30 847 3.95 2.50 834 4.08 2.60 819 4.13 2.79 798 4.22 2.95 768 4.26 3.38 734 4.45 3.63 696 4.49 3.93 657 4.54 4.21 645 4.66 4.42 613 4.66 4.93 575 4.76 5.27 553 4.83 5.32 539 4.79 5.97 503 4.90 7.96 410 5.11 10.9 316 5.25 16.5 223 5.42 21.6 176 5.51 26.4 147 5.56 31.3 127 5.63 36.2 110 5.64 40.4 98.5 5.64 47.9 84.1 5.68 54.5 74.6 5.70 60.4 68.2 5.74 65.5 63.0 5.75 70.1 58.9 5.74 74.2 55.8 5.75 78.1 53.4 5.77 81.6 51.5 5.80 280 11-13. Magnetic data for Cu[H(C6H5)P02]2 and Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2 Cu[H(C6H 5)P02]2 Ni(DMF) 2[(C6H5)2P02H]2[(C 6H5)2P02]2 Temp. XM Meff Temp, XM Meff (K) (K) 2.30 7.36 0.37 5.16 228 3.07 2.40 7.29 0.37 5.99 199 3.09 2.50 7.16 0.38 8.37 144 3.11 2.70 6.94 0.39 9.64 128 3.14 2.89 6.63 0.39 11.4 108 3.12 3.11 6.39 0.40 14.9 83.5 3.16 3.46 6.11 0.41 16.9 73.8 3.16 3.81 5.91 0.42 19.7 63.5 3.17 4.21 5.84 0.44 21.9 58.0 3.19 4.26 5.66 0.44 25.1 50.8 3.19 4.74 5.56 0.46 26.9 47.7 3.20 5.32 5.56 0.49 29.7 43.2 3.20 5.62 5.53 0.50 30.7 41.8 3.21 6.04 5.66 0.52 40.6 32.2 3.23 7.94 6,42 0.64 48.2 27.7 3.27 11.3 9.00 0.90 55.2 24.8 3.31 16.7 10.1 1.16 60.8 22.8 3.33 17.9 10.3 1.22 65.8 21.1 3.34 19.6 10.3 1.27 70.3 19.9 3.35 21.7 9.92 1.31 74.5 19.0 3.36 26.7 9.88 1.45 78.3 18.2 3.38 31.2 9.26 1.52 82.1 17.5 3.39 36.0 8.64 1.58 40.4 8.08 1.62 47.6 7.19 1.65 54.5 6.60 1.69 60.4 6.18 1.73 65.5 5.73 1.73 70.1 5.42 1.74 74.2 5.18 1.75 78.1 4.90 1.75 81.7 4.52 1.72 281 Appendix III Unassigned infrared absorptions. Compound Frequencies (cm - 1) Mn(HCONH 2) 2[H(C 6H5)P02]2 1437 m., 1340 m., 1071 w., 1028 m., 1011 s., 992 w., 984 s., 751 m., 712 m., 695 m., 657 w., 635 w., 576 w., 488 m, 446 w., 392 w., 382 w.. Mn(H20)2[H(C 6H 5)P0 2]2 1591 w., 1436 s M 1161 s.sh., 1031 m.sh., 1023 s., 1002 vw., 932 vw., 762 w.sh., 752 m.sh., 741 s., 708 m., 691 s., 559 s., 488 m., 428 w., 419 vw.. M n ( H C O N H C H 3 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 1608 w., 1547 m., 1436 s., 1406 m., 1326 s., 1256 m., 1133 s., 1071 w., 1030 m., 1007 s., 986 s., 982 s., 964 w., 920 w., 874 w., 800 w., 773 vw., 753 s., 709 m „ 697 m., 575 s., 487 m., 446 w., 396 m., 365 w., 320 w.. Mn(CH3CONH2)2[H(C 6H 5)P02]2 1611 m.sh., 1441 s., 1402 m., 1313 vw., 1072 w., 1032 s., 1003 s., 991 s., 984 s.sh., 925 w., 889 vw., 875 vw., 757 s., 712 m., 701 m., 654 m., 575 s., 495 s., 483 m.sh., 449 w., 385 w., 324 w.. M n [ H ( C 6 H 5 ) P 0 2 H ] 2 [ H ( C 6 H 5 ) P 0 2 ] 2 1591 w., 1438 s., 1221 m., 1185 s.sh., 1172 s., 1154 s.sh., 1131 s.sh., 1110 m.sh., 1071 w., 1021 s., 1003 s., 998 s., 981 s., 963 s., 948 s., 929 m., 752 s., 748 s., 710 s., 694 s., 578 s., 542 m., 496 s., 458 m., 429 w., 400 w., 369 m.. Co[H(C6H5)P02] 2 (Form I) 1593 vw., 1437 m., 1311 vw., 1184 m., 1071 w., 1049 w.sh., 1032 w., 1011 m., 1004 m.sh., 993 s., 928 w., 758 w., 749 m., 712 m., 695 m., 567 m., 503 w., 472 vw., 426 vw., 382 vw., 372 vw., 367 vw.. C o [ H ( C 6 H 5 ) P 0 2 ] 2 (Form II) 1594 w., 1435 s.sh., 1308 vw., 1215 vw., 1182 s., 1069 w.sh., 1039 m., 1010 s., 1004 m.sh., 992 s., 977 m., 929 w., 585 m., 571 s., 506 vw., 491 w., 472 w., 421 w.. C o r H ( C 6 H 5 ) P 0 2 ] 2 (Form IU) 1591 w., 1436 s., 1309 vw., 1186 s., 1071 m.sh., 1041 s.sh., 1024 m., 1011 m., 993 m., 975 m.sh., 929 vw., 921 vw., 746 s., 712 s., 694 s., 581 s., 571 s., 518 w., 492 w., 470 w., 419 w.. C o ( H C O N H 2 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 1591 vw., 1573 vw., 1436 s.sh., 1342 s., 1071 m., 1029 m., 1009 s., 1000 w.sh., 992 w.sh., 983 s., 932 vw., 923 vw., 753 s., 713 s., 695 s., 655 m., 639 m., 584 s., 492 m., 452 w., 399 w., 336 w.. 282 Compound Frequencies (cnr 1) C o ( H 2 0 ) 2 [ H ( C 6 H 5 ) P 0 2 ] 2 Co(H20 ) 4 r H(C 6H 5)P0 2]2 N i [ H ( C 6 H 5 ) P 0 2 ] 2 Ni(HCONH2)2[H(C 6H 5)P0 2]2 Ni(H 20)2[H(C 6H5)P0 2]2 N i ( H 2 0 ) 4 [ H ( C 6 H 5 ) P 0 2 ] 2 Y-Co[(C 6H 5)2P0 2]2 B-Co[(C6H 5) 2P02] 2 Y-Mn[(C 6H 5)2P0 2]2 p - M n K Q J ^ P C ^ Y - C d [ ( C 6 H 5 ) 2 P 0 2 ] 2 1593 w., 1435 m.sh., 1159 s.sh., 1024 w., 982 m., 931 vw., 755 m., 746 m., 712 m., 698 m., 568 s., 492 w., 421 w „ 1591 w., 1434 s.sh., 1310 vw., 1290 vw., 1070 w., 1027 m., 1006 s., 988 s., 986 vs., 930 vw., 750 s., 708 s., 698 s., 563 vs., 476 m., 419 m., 339 m., 332 m.. 1592 vw., 1438 m.sh., 1069 w., 1030 m., 990 s., 745 m., 710 m., 692 w., 568 m., 500 w.. 1591 vw., 1570 w., 1439 s., 1347 s., 1071 m., 1029 s., 1009 s., 983 s., 931 vw., 924 vw., 879 vw., 751 s., 71- s., 702 s., 666 s., 641 s., 585 vs., 487 s., 450 m., 394 m., 341 m.. 1591 vw., 1434 s., 1154 s., 1037 w., 1028 m., 981 m., 754 w., 745 m., 708 m., 695 m., 567 s., 497 w., 430 vw., 367 vw.. 1591 w., 1437 s.sh., 1070 w., 1026 m., 1006 s., 998 m., 987 s., 751 m., 709 m., 698 s., 566 s., 476 m., 419 w., 346 w.. 1593 w., 1439 m., 1212 m., 1180 w.sh., 1069 w.sh., 1026 s., 1001 m., 760 w.sh., 755 w., 723 s., 700 s., 696 w.sh., 576 s., 546 s., 440 w., 420 w., 335 w.sh., 324 w., 308 w.. 1593 w., 1438 m., 1210 w., 1070 w.sh., 1025 s., 1001 m., 757 m., 731 s., 696 s., 575 s., 545 s., 470 w., 439 w., 408 w., 400 w.. 1595 w., 1443 m., 1211 m., 1183 w., 1072 w., 1026 s., 1002 m., (757, 761) w., 727 s., 701 s., 698 w.sh., 578 w.sh., 572 s., 549 s., 438 w., 415 w., 318 w., 310 w.. 1593 w., 1440 m., 1310 w., 1210 w., 1185 w.sh., 1028 s., 1002 m., 758 m., 733 s., 696 s., 570 s., 544 s., 466 w., 426 w., 403 w., 390 w.. 1595 w., 1440 s., 1310 w., 1203 s., 1183 w., 1070 w., 1024 s., 1001 m., 929 vw., 755 m., 725 vs., (702, 596) s., 570 vs., 549 s., 465 w., 439 w., 394 w.. 283 Compound Frequencies (cm-1) Mn[(n-C6Hi3)2P02]2 1400 m., 1323 w., 1198 w., 1260 m., 1238 w., 1208 m., 1198 m.sh., 1137 vs., 1127 s.sh., 1110 m., 1067 s., 1052 m., 1015 s., 976 w., 958 w., 892 w., 858 m., 818 s., 779 w., 723 w., 505 m., 493 m., 440 w., 426 w., 368 w., 350 w., 312 w.. Y-Cd[(n-C6H13)2P02]2 1406 m., 1315 w., 1299 w., 1263 w., 1239 w., 1208 m., 1199 m., 1129 vs., 1110 s.sh., 1060 s., (1049, 1040 ) s., 1013 s., 927 w., 959 w., 894 w., 858 m., 818 s., 781 w., 724 m., 509 m., 492 m., 440 w., 425 w., 368 w., 312 w.. Cd(HCONH2)2[H(C6H5)P02]2 1433 m.sh., 1336 m., 1125 vs., 1070 m., 1040 s., 1025 m., 1007 m., 980 s., 750 s., 710 m., 694 m., 671 w., 663 w., 636 w., 576 w., 513 vw., 489 m., 446 w., 383 w., 365 w., 322 w.. 1591 w., 1437 s., 1308 w., 1070 m.sh, 1031 s., 1015 s., 999 s., 988 s., 965 m., 929 w., 919 w., 863 w., 744 s., 709 s., 693 s., 618 w., 598 s., 557 s., 521 w., 495 m., 481 vw., 471 w., 414 w., 359 w., 298 w.. 1591 w., 1224 m., 1158 s., 1020 m., 1000 w., 976 m., 731 vw., 711 w., 698 w., 556 m., 470 w., 367 w.. Cu[H(C6H5)P02]2 Zn[H(C6H5)P02]2 Ni(DMF)2[(C6H5)2P02H]2[(C6H5)2P02]2 1593 w., 1433 s., 1298 s., 1256 s., 1027 w., 1010 w., 1000 w., 900 vs. br., 758 s., 721 s., 691 s., 458 vs., 487 s., 472 s., 462 s., 437 w., 417 s., 407 m., 327 m., 304 m.. {Ni(DMF)2(H20)4}(H20)2[(C6H5)2P02]2 1591 w., 1435 s., 1256 m., 1168 vs., 1126 vs., 1103 m.sh., 1070 m., 1043 vs., 1022 m., 1000 m., 930 w., 760 s., 722 s., 703 s., 685 m.sh., 663 w., 563 s., 481 w., 404 w.sh., 383 m., 363 w., 333.. Cd(H20)Cl[HC6H5)P02]2 1591 w., 1436 s., 1313 w., 1069 m., 1025 s., 1005 s., 1003 s.sh., 997 m., 987 s., 931 w., 780 w., 744 ., 710 m., 690 m., 573 m., 483 w., 428 w., 384 w., 323 w.. 284 Appendix IV Vibrational assignments for pyridine1 and its complexes2. Py. 3080 s. 3054 s. 3030 s. 3004 s. 1580 s. 1482 s.. 1437 s. 1217 s. 1146 s. 1067 s. 1029 s. 990 s. 938 w. 883 w. 746 s. 702 s. 601 s. 405 s. Assn. 20b 2 20a 8b+19b 8a 19a 19b 9a 15 18a 12 1 5 10a 10b 11 6a 16b Mn(py)2[H(C6H5)P02]2 3058 w. 1599 m. 1433 vs.1218 m.l 135 s. 1068 s. 1009 m. 932 w 752 w. 710 s. 624 m. 424 w. 997 w. Co(py)2[H(C6H5)PO]2 3050 w. 1599 m. 1471 w. 1443 m. 1208 m. 1009 m. 750 m. 710 s. 628 m. 433 w. Ni(py)2tH(C6H5)P02l2 3078 w. 3054 w. 1602 m. 1478 m.1445 vs. 1133 s. 1026 m. 1013 w. 934 w. 751s. 697 vs. 632 m. 441 w. 1432 s 1. T a k e n f r o m r e f e r e n c e [ 1 3 7 ] . 2 . A l l v a l u e s a r e i n c m " 1 . Appendix V Vibrational assignments for pyrazine1 and its complexes. P y f a z u i e 2"9~73~w7 T 4 " 8 3 ~ v s ! TrfifnT T 0 0 6 ~ w T 9 2 " 6 vw7 80Tvs. 70"0~vw7 4 T f m . 3 0 6 6 w . 1 4 9 0 s . 1 1 2 5 w. 1 0 2 2 m . 8 2 3 v w . 7 5 2 v w . 5 9 7 w . 1 1 4 8 v s . 1 0 3 2 v w . 7 0 0 v w . 1 1 7 8 m . 1 0 4 8 v w . 1 0 6 7 v s . C o ( p y z ) [ H ( C 6 H 5 ) P 0 2 ] 2 3 1 1 0 w . 1 4 7 7 m . s h . 1 1 3 7 s . 1 0 8 1 s . s h . 9 3 2 w . 8 1 7 m . 7 9 4 v w . 4 2 2 w . 3 0 5 8 w . 1 4 1 9 m . 1 0 2 3 m . N i C p y z j r H C C t f r t y P O ^ 3 1 1 2 w . 1 4 3 6 m . s h . 1 1 3 4 s . 9 3 4 w . 8 2 0 m . 7 4 6 m . 4 2 0 v w . 3 0 5 8 w . 1 4 2 2 w . 1 0 2 5 m . 1. T a k e n f r o m r e f e r e n c e [ 1 4 4 ] . 

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