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A synthetic, spectroscopic and magnetic susceptibility study of selected main group and transition metal.. Cader, Mohamed Shah Roshan 1992-12-31

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A SYNTHETIC, SPECTROSCOPIC AND MAGNETIC SUSCEPTIBILITY STUDY OF SELECTED MAIN GROUP AND TRANSITION METAL FLUORO COMPOUNDS  By M. SHAH ROSHAN CADER M.Sc., The University of British Columbia, 1986  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF  DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES  (Department of Chemistry)  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA April, 1992 ©  M.S.R. CADER, 1992  In  presenting  degree at the  this thesis  in  partial  fulfilment of  the  requirements for an  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 department  or  advanced  by  his  her  or  representatives.  It  is  by the head of my  understood  that  copying  or  publication of this thesis for financial gain shall not be allowed without my written permission.  Department of  CItE WI/c  The University of British Columbia Vancouver, Canada  Date ft TC)(36rQj  DE-6 (2/88)  ,  1di9J  ABSTRACT  This study was initiated in order to synthesize, and where appropriate, to investigate the magnetic properties of selected main group and transition metal cationic complexes, all F and 3 stabilized by weakly basic fluoro anions derived either from the Brönsted superacids HSO . 5 5 and AsF CF or the Lewis acids SbF 3 HSO ,  5 Of the preparative reactions, the solvolysis of metal(ll) fluorosulfates in excess SbF according to:  ) 2 F 3 M(SO  +  5 6SbF  25-60°C >  ) 6 M(SbF  +  ) SO 3 ( 9 F 2 2Sb F  with M=Ni, Pd, Cu, Ag or Sn, is found to be a useful synthetic route to the corresponding 2 divalent hexafluoro antimonates. The products, as their precursors, are characterized as CdC1 type layered polymeric compounds.  Relevant vibrational (Raman and IR), electronic and  er spectra as well as magnetic susceptibility measurements and X-ray powder 119 Sn-Mössbau data are reported.  Several compounds prepared by this method display unusual features:  2 ion in a 3 A2g ground 2 is, like its fluorosulfate precursor, paramagnetic with the Pd ) 6 Pd(SbF F unlike its paramagnetic blue valence isomer, is diamagnetic and nearly white 6 Ag(Sb , 2 state. ) . )(SbF 6 Ag(I)[Ag(III ] 4 in color, and is formulated as the mixed valency complex )  The  2 ions, small quantities of Cu(I) and 2 compound also contains, in addition to Cu ) 6 Cu(SbF Cu(Ill) ions.  2 exhibit temperature dependent low magnetic ) 6 Both Ni(SbF 2 and Pd(SbF ) 6  2 also displays very weak ferro ) 6 moments, indicative of antiferromagnetic exchange. Pd(SbF magnetism below —lOK.  11  ) react with 2 F 3 Sn(SO 2 product from the above synthesis, and its precursor , ) 6 The Sn(SbF mes Sn(SbF 2 2 ) excess 1,3,5-trimethylbenzene(mesitylene or mes) to give the it-arene adducts 6 ) in high yield. The adducts are characterized by elemental analysis and es 2 F 3 Sn(SO and m Sn Mössbauer spectroscopy. It is infrared spectra. The adduct formation is followed by 119 found that only tin(ll) compounds with large, weakly nucleophilic anions are capable of forming , and stannocene do not give any indication of adduct 2 , SnF 2 mesitylene complexes, while SnC1 formation under similar reaction conditions.  ) precursors to the ) and , 2 F 3 Ag(SO 2 F 3 ) Pd(SO 2 F 3 Ni(SO The divalent fluorosulfates , )(SO as well as their ) , 6 Pd(II)[Pd(IV F 3 2 compounds, and the mixed valency ] ) 6 M(SbF corresponding  trifluoromethylsulfate  derivatives  CF 3 Ni(SO , 2 )  CF 3 Pd(SO 2 )  and  CF investigated for their magnetic behavior by susceptibility studies down to -•4 K, 3 Ag(SO , 2 ) CF the onset of magnetic 3 Ag(SO , 2 show significant magnetic exchange, and except in ) exchange becomes observable at low temperatures.  The fluorosulfates are found to exhibit  strong ferromagnetism below —11 K, whereas the trifluoromethylsulfates behave as anti ferromagnets with the spin interactions noted over a wider temperature range. The maximum ) indicate saturation 2 F 3 ) and Ag(SO 2 F 3 ) Pd(SO 2 F 3 Ni(SO magnetic susceptibilities of , magnetization, and hence for these compounds field dependent maximum magnetic moments are obtained in the temperature range —5 to 10.5 K. Maxima in the susceptibility vs. tempera CF at —4 and —13 K Ag(SO 2 ) CF and 3 3 Pd(SO 2 ture plots are noted for the antiferromagnets ) respectively. Unlike in the corresponding divalent antiferromagnetic fluorides, no spin canting is detected in the trifluoromethylsulfates at lower temperatures.  Magnetic susceptibility measurements to —4 K are also carried out for the main group [Sb i]• The data are interpreted 2 I 1 6 and F Sb ] [ 2 Br 1 F , 3 AsF 6 [ 2 O molecular cations within ] utilizing previous results from photoelectron spectroscopy, known crystal structures, magnetic ], previous ESR 6 studies on the superoxide ion and the ozonide ion, and in the case of Oj[AsF studies. 111  6 obeys CurieSb ] [ 2 Br 1 F The magnetic properties of the three materials are quite different. 3 Weiss law between 80 and 4 K. The magnetic moment decreases slightly from 2.04 B at room temperature to 1.93 B at 4 K.  1 exhibits relatively strong antiferromagnetic Sb ] [ I 1 F 2  coupling with a maximum in XM observed at -54 K. The magnetic moment (corrected for TIP) decreases from 1.92 B at 124 K to 0.41 B at 4 K.  Experimental susceptibilities for this  compound over the temperature range 300-4 K have been compared to values calculated using three different theoretical models for extended chains of antiferromagnetically coupled [AsF exhibits Curie-Weiss behavior over the temperature range 6 + 2 0 paramagnetic species. ] 60-2 K. The magnetic moment, uncorrected for TIP, varies from 1.63 B at 80 K to 1.17 I.LB at 2 K, and the presence of weak antiferromagnetic coupling in this material is suggested.  iv  TABLE OF CONTENTS  Page ABSTRACT  ii  LIST OF TABLES  ix  LIST OF FIGURES  xi  LIST OF SYMBOLS  xiii  ACKNOWLEDGEMENTS  xiv  CHAPTER 1  INTRODUCTION  1  1.1  General Introduction  1  1.2  The Lewis Acid SbF 5  3  1.2.1  Physical and Chemical Properties  3  1.2.2  Cationic Derivatives  4  The Transition Metal Fluorosulfates and Trifluoromethyl sulfates  9  1.4  Post-Transition Metal Arene fl-Compounds  13  1.5  Magnetic Measurements  16  1.6  Objectives of this Study  20  References  22  GENERAL EXPERIMENTAL  27  2.1  Introduction  27  2.2  Chemicals  27  2.2.1  Purification Methods  29  2.2.2  Synthetic Methods  29  1.3  CHAPTER 2  V  Page 2.3 2.3.1  Apparatus  31  Reaction Vessels  33  5 Storage-bridge Vessel 2.3.2. SbF  2.4  33  2.3.3  F Addition Trap 6 0 2 S  33  2.3.4  Pyrex Vacuum Line  37  2.3.5  Metal Vacuum Line  37  2.3.6  Dry Atmosphere Box  37  Instrumentation and Methods  38  2.4.1  Infrared Spectroscopy  38  2.4.2  Raman Spectroscopy  38  2.4.3  Nuclear Magnetic Resonance Spectroscopy  38  2.4.4  Electronic Spectroscopy  39  2.4.5  Mössbauer Spectroscopy  39  2.4.6  X-ray Photoelectron Spectroscopy  39  2.4.7  Magnetic Susceptibility Measurements  40  2.4.8  X-ray Powder Diffractometry  41  2.4.9  Differential Scanning Calorimetry (DSC)  41  -  2.4.10 Elemental Analyses  42  References  42  , 2 ) 6 METAL(II) HEXAFLUORO ANTIMONATES M(SbF Ag(ll) AND Cu(ll) Pd(ll), M(ll) = Sn(II), Ni(II),  43  3.1  Introduction  43  3.2  Experimental  46  3.2.1  2 ) 6 General Synthetic Scheme to M(SbF  46  3.2.2  Physical Properties and Analyses  47  CHAPTER 3  48  F 6 Cu(Sb 2 3.2.2a )  vi  Page 2 ) 6 3.2.2b Pd(SbF  48  2 ) 6 3.2.2c f3-Ag(SbF  48  2 ) 6 Alternate Synthetic Route to 3-Ag(SbF  48  Results and Discussion  49  3.3.1  Synthesis  49  3.3.2  Vibrational Spectra  55  3.3.3  Electronic Spectra  62  3.3.4  Magnetic Susceptibility Measurements  66  3.3.5  X-ray Photoelectron Spectra  82  3.3.6  2 ) 6 Attempted Synthesis of Au(SbF  83  Conclusion  85  References  87  3.2.3 3.3  3.4  MESITYLENE ADDUCTS OF TIN(II) FLUORO COMPOUNDS, 90 2 2C 2 ) 6 Sn(SbF 1 H ) and 9 2 F 3 (SO 1 H 9 C Sn 2  CHAPTER 4 4.1  Introduction  90  4.2  Experimental  93  Synthesis  93  4.2.1  ,3,5-(CH H 6 C ) F) 1 3 3 Sn(SO 4.2.1 a Synthesis of 2  93  ] H 6 C ) 3 2[ 1 ,3,5(CH 2 ) 6 4.2.1 b Synthesis of Sn(SbF  94  Results and Discussion  95  4.3.1  Synthesis  95  4.3.2  Sn Mössbauer Spectra 119  99  4.3.3  Infrared spectra  101  Conclusion  108  References  108  4.3  4.4  vii  Page A LOW TEMPERATURE MAGNETIC STUDY OF 2 AND I2 THE MOLECULAR CATIONS O2, Br  111  5.1  Introduction  111  5.2  Experimental  112  5.3  Results and Discussion  113  5.3.1  Synthesis  114  5.3.2  Magnetic Measurements  118  5.3.3  6 Sb ] [ 2 Br 1 F 3  118  5.3.4  ] 6 O[AsF  126  5•3•5  1 Sb f [ I 1 F 2  130  Conclusion  136  References  137  MAGNETIC EXCHANGE IN M(II) SULFONATES, M(ll) = Ni(II), Pd(I1) AND Ag(II)  141  6.1  Introduction  141  6.2  Experimental  144  6.3  Results and Discussion  144  6.3.1  F) 3 Ni(SO , Ferromagnetism of M(II) fluorosulfates 2 ) )(SO F 3 Ag(SO 2 and ) Pd(II)[Pd(IV F 3 ] 6 F) 3 Pd(SO , 2  145  6.3.2  Antiferromagnetism of M(ll) thfluoromethylsulfates CF Ag(SO 2 ) CF and 3 Pd(SO 2 ) CF 3 Ni(SO , 2 ) 3  163  Conclusion  176  References  178  SUMMARY AND GENERAL CONCLUSIONS  181  CHAPTER 5  5.4  CHAPTER 6  6.4  CHAPTER 7 APPENDIX A  185  APPENDIX B  194  yin  LIST OF TABLES Page Table 1.1:  5 Solid Polyhalogen Cationic Derivatives of SbF  5  Table 1.2:  5 Solid Binary Transition Metal Derivatives of SbF  6  Table 2.1:  Chemicals Used Without Purification  28  Table 3.1:  F 6 Cu(Sb 2 2 and ) ) 6 , Pd(SbF 2 ) 6 Vibrational Spectra of Ni(SbF  56  Table 3.2:  Ag(SbF 2 ) Vibrational Spectra of the Two Valence Isomers of 6  57  Table 3.3:  Electronic Transitions and Ligand Field Parameters for 2 and Related Compounds ) 6 , Pd(SbF 2 ) 6 Ni(SbF  64  Table 3.4:  2 ) 6 Low Temperature Magnetic Data of Ni(SbF  67  Table 3.5:  Low Temperature Magnetic Data of Pd(SbF& 2  68  Table 3.6:  Cu(SbF 2 ) Low Temperature Magnetic Data of 6  69  Table 3.7:  2 for the Temperature Range ) 6 Magnetic Moment Data of Ni(SbF —80 to 295 K  75  Table 4.1:  Sn Mössbauer Parameters of Relevant Tin(H) Compounds at 80 K 119  100  Table 4.2:  Infrared Bands of Liquid Mesitylene and Bands Attributed to bF mes Sn(S 2 2 ) O and 6 ) es Sn(S F 3 m Mesitylene in the Adducts 2  104  Table 4.3:  2 and Bands ) 6 F) and Sn(SnF 3 Sn(SO Infrared Frequencies for 2 O ) es Sn(S F 3 m Attributed to the Anions in the Mesitylene Adducts 2 bF mes Sn(S 2 2 ) and 6  106  Table 5.1:  6 [Sb 2 Br 1 F 3 Magnetic Data of j  119  Table 5.2:  [AsF 2 O ] [Sb j and 6 I 1 F Magnetic Data of 2  120  Table 5.3:  [SbF 2 I ], , 11 [AsF 2 O i Structural and Spectroscopic Information on 6 2 and I2 6 and the corresponding Ions O2, Br Sb ] [ 2 Br 1 F 3  121  Table 6.1:  F) 3 Ni(SO Low Temperature Magnetic Data of 2  146  Table 6.2:  F) 3 Pd(SO Low Temperature Magnetic Data of 2  147  Table 6.3:  (SO ) Pd(II)[Pd(IV) F 3 ] Low Temperature Magnetic Data of 6  148  Table 6.4:  F) 3 Ag(SO Low Temperature Magnetic Data of 2  149  Table 6.5:  F) for the Temperature Range 3 Ni(SO Magnetic Data of 2 291 to 79K  150  x  Page Table 6.6:  F) 3 Pd(SO , F) 2 3 Ni(SO , Magnetic Parameters of 2 ) F 3 Ag(SO 2 and (SO ) Pd(IV) Pd(II)[ F 3 ] 6  151  Table 6.7:  Experimental and Calculated Saturation Magnetic Susceptibilities F) 3 Ag(SO Pd(IV)(SO and 2 Pd(ll)[)fJ F F) 3 3 Pd(SO , F) 2 3 Ni(SO , of 2  157  Table 6.8:  CF for the Temperature Range 304 to 4 K Ag(SO 2 ) Magnetic Data of 3  164  Table 6.9:  CF Pd(SO 2 ) Low Temperature Magnetic Data of 3  165  Table 6.10:  CF Ni(SO 2 ) Low Temperature Magnetic Data of 3  166  Table 6.11:  CF for the Temperature Range 292 to 80 K Ni(SO 2 ) Magnetic Data of 3  167  x  LIST OF FIGURES Page Figure 2.1:  F 6 0 2 Apparatus for Preparing S  30  Figure 2.2:  Typical Pyrex Reaction Vessels  32  Figure 2.3:  Vacuum Filtration Apparatus  34  Figure 2.4:  Kel-F Tubular Reactor  35  Figure 2.5:  5 Storage-bridge Vessel SbF  36  Figure 3.1:  2 ) 6 Raman Spectrum of -Ag(SbF  58  Figure 3.2:  2 ) 6 Crystal Structure of cz-Ag(SbF  60  Figure 3.3:  A Ground Term Spin Allowed Electronic Transitions from 3 2 (d ) in Octahedral Ligand 1e1d 8 2 and Ni for Pd  63  Figure 3.4:  Magnetic Moment vs. Temperature of M(SbF& ,M 2  Figure 3.5:  2 ) 6 Magnetic Moment vs. Temperature of Ni(SbF  74  Figure 3.6:  2 ) 6 Magnetic Moment vs. Temperature of HF-Treated Cu(SbF  80  Figure 3.7:  2 ) 6 -Treated Cu(SbF 5 Magnetic Moment vs. Temperature of SbF  81  Figure 4.1:  2 mes at 77 K ) 6 Sn Mössbauer Spectrum of Sn(SbF 119  102  Figure 5.1:  6 [Sb 2 Br 1 F 3 Magnetic Moment vs. Temperature of ], [AsF 2 O J 1 and 6 [51 1 1 2 J  122  Figure 5.2:  6 SbF J [ 2 Br 1 F [AsF and 3 2 O j Inverse Susceptibility vs. Temperature of 6  123  Figure 5.3:  6 Sb ] [ 2 Br 1 F Crystal Structure of 3  125  Figure 5.4:  Energy Level Diagram of the Dioxygenyl Ion with the a and it-Bonding 2p Orbitals  127  Figure 5.5:  1 [Sb I 1 F 2 Crystal Structure of J  131  Figure 5.6:  [Sb ] I 1 F Magnetic Susceptibility vs. Temperature of 2  132  Figure 6.1:  F) 3 Pd(SO Proposed Structure of 2  143  Figure 6.2:  F) 3 Ni(SO Inverse Susceptibility vs. Temperature of 2  152  Figure 6.3:  F) 3 Pd(SO , Inverse Susceptibility vs. Temperature of 2 F) 3 Ag(SO )(SO and 2 ) Pd(II)[Pd(IV F 3 } 6  154  Figure 6.4:  F) at 7501 and 9625 G 3 Pd(SO Magnetic Susceptibility vs. Temperature of 2  155  xi  =  Ni, Pd and Cu  70  Page Figure 6.5:  (SO ) Pd(H)[Pd(IV) F 3 ] Magnetic Susceptibility vs. Temperature of 6 at750land9625G  156  Figure 6.6:  F) 3 Ag(SO F) and 2 3 Pd(SO Magnetic Moment vs. Temperature of 2  159  Figure 6.7:  CF Pd(SO 2 ) Magnetic Moment vs. Temperature of 3  170  Figure 6.8:  CF Pd(SO 2 ) Magnetic Susceptibility vs. Temperature of 3  171  Figure 6.9:  ) 2 F 3 CF and Ni(SO Ni(SO 2 ) Magnetic Moment vs. Temperature of 3  173  xii  LIST OF SYMBOLS  N  =  AvogaLiro’s number  k  =  Boltzmann’s constant  T  =  Absolute temperature  g  =  Lande splitting factor  3  =  Exchange coupling constant  D  =  Zero-field splitting parameter  =  Spin-orbit coupling constant  Dq  =  Ligand field splitting parameter  B  =  Racah parameter (interelectronic repulsion parameter) Bohr magneton  or  Spin only magnetic moment eff  =  Effective magnetic moment  XM  =  Molar magnetic susceptibility  XMCOff  =  Molar magnetic susceptibility corrected for diamagnetism  Cm  =  Curie constant  e  =  Weiss constant  G  =  Magnetic field in Gauss  =  Quadrupole splitting  =  Isomer shift  xlii  ACKNOWLEDGEMENTS  It has been  rewarding experience to work under the supervision of Professor F. Aubke.  His guidance and encouragement were invaluable during the course of this work, and for this I extend my sincere gratitude and thanks to him. I also wish to thank Professor R.C. Thompson for his constructive and valuable collaboration in this study over the past few years.  Many thanks are also due to my co-workers Dingliang Zhang, Germaine Hwang, Fred Mistry and Walter Cicha for their pleasant friendship and enlightening discussions. Tom Otieno  and Martin Ehiert are thanked for their kind assistance in obtaining the magnetic measurements. Thanks are also due to the members of the mechanical, glassblowing, and electronic shops for their technical expertise. I am also indebted to Mr. P. Borda for his microanalytical services. Special thanks are extended to Germaine Hwang for proof-reading this thesis and Rani Theeparajah for the excellent work done in typing the manuscript.  Finally I would like to express my sincere thanks to my family for their kind understand ing and words of encouragement throughout my years of graduate study.  xiv  DEDICATED  TO MY MOTHER  J.BA. CADER  xv  CHAPTER 1  INTRODUCTION  1.1  GeneraJ Introduction  The synthesis and physical study of solid compounds where unusual metal and non metal cations are stabilized by wealdy coordinating fluoro anions is an area of research which has grown steadily over the last two decades, and is the primary focus of this dissertation. In recent years, there has been an increasing interest shown both by chemists and physicists in the synthetic and solid state properties of these rare cationic complexes, often obtainable only as derivatives of strong Brönsted (protonic) fluoroacids or Lewis acids (1, 2). The use of a wide array of physical methods including various magneto-chemical techniques to characterize these compounds has permitted structure-property relationships to be understood in detail and has also provided rational approaches to the synthesis of new and unusual materials.  The types of compounds which have been studied in this thesis are varied, and range from main group non-metallic molecular cationic complexes to inorganic and organometallic coordination polymers, where the organometallic polymers are t-arene adducts of the posttransitional metal Sn(ll) fluoro derivatives.  The molecular cations and the transition metal  coordination polymers have been investigated for their magnetic properties to obtain informa tion on the ground state electronic structure as well as to detect any magnetic exchange inter actions between the paramagnetic centers (particularly at low temperature) in the respective compounds. Furthermore, spectroscopic and structural data (where available) have been utilized in the interpretation of the magnetic behavior observed for the compounds.  1  The inorganic and organometallic polymers synthesized in this study contain , which are usually generated in superacidic media. S0 F 6 and 3 fluoroanions such as SbF Strong protonic fluoroacids and superacids have been used extensively as reaction media, solvents and synthetic reagents in both inorganic and organic syntheses (1). The role of these acids and their anions in the synthesis and stabilization of unusual cations is of significance to this work, since all the fluoro compounds studied here have anions which are derived from . Conse 5 5 and AsF CF or the Lewis acids SbF HSO F and 3 3 either the protonic fluoroacids HSO 6 and 1 3 Sb 1 F , 1 F 2 , Sb 6 , , CF SbF 3 S0 S0 F quently, the corresponding anions of interest 3 6 are all poorly coordinating, weakly nucleophilic anions, well capable of stabilizing a AsF variety of electrophiic cationic centers either in solid compounds or in solutions.  These fluoro anions are in general non-oxidizable and are reasonably resistant toward reduction and, when coordinating to transition metals, act as monodentate as well as bidentate or tridentate ligands, usually with bridging, rather than chelating configurations. The coordinating CF groups has been 3 , and the trifluoromethylsulfate SO SO F ability of the fluorosulfate 3 discussed relatively recently by Lawrence (3), and the generation and stabilization of various halogen and interhalogen cations in protonic fluoroacids and superacids has been reviewed in the past by Gillespie and Morton (4), and many years later by Shamir (5).  It is generally agreed that the anions mentioned above are all very weakly basic and have high group electronegativities. SnX (X 2 ) 3 (CH  =  For a number of dimethyltin(IV) compounds of the type  a fluoro or fluoroxy anion) with linear or near linear C-Sn-C groupings and  9 Mössbauer parameters suggest the following order of anion Sn 1 bidentate bridging anions, the ‘ basicity: F-  >  CH 3 S0  >  3 SOCF  Z  SOF  >  6 AsF  >  f (6). 1 F 2 SbF Z Sb  These general concepts mentioned briefly above will now be discussed in some detail in the following sections to provide the necessary background information for the extended study.  2  1.2  5 The Lewis Acid SbF  1.2.1  Physical and Chemical Properties  , is generally regarded as the strongest molecular Lewis acid 5 Antimony(V) fluoride, SbF (7). It is a very viscous (460 cP at 20°C) (8), colorless liquid, with a specific gravity of 3.145 3 at 15°C. It has a relatively high melting point (8.3°C) and a high boiling point (142°C) g/cm 5 (mp (la), compared to the Lewis acid AsF  =  -80°C, bp  =  -53°C). This suggests a considerable  degree of association for the molecule, and vapor density measurements indicate aggregates (SbF at 250°C (9). The polymeric structure of the 2 ) 3 at 150°C and 5 ) 5 corresponding to (SbF F-NMR spectroscopy (10), and is found to have a cis 5 has been established by 19 liquid SbF fluorine bridged framework in which each antimony atom is surrounded by six fluorine atoms in 5 is tetrameric with octahedral coordination an octahedral arrangement. In the solid state, SbF achieved again by cis-bridging fluorine atoms (11).  Antimony pentafluoride is a good oxidizing and a moderately strong fluorinating agent. As shown by conductomethc, cryoscopic, and related acidity measurements, it appears that 5 is by far the strongest Lewis acid known, and hence is preferentially used in preparing SbF stable metallic as well as non-metallic cationic derivatives. For the purpose of comparison, the 5 following order of acidity can be assigned for a series of Lewis acids (la): SbF >  3 BF  >  5 NbF  >  >  5 AsF  >  5 TaF  . For their anions, the basicity is expected to increase in nearly the same 5 PF  5 also shows a remarkable ability to coordinate to . Moreover, SbF 6 6 to PF order from SbF CF resulting in vastly enhanced acidity for 3 HSO F and , 3 protonic fluoroacids such as HF, HSO the conjugate superacid systems, where many types of unusual cations have been observed as stable species.  3  1.2.2  Cationic Derivatives  5 or in its conjugate superacid solutions is not resthcted to Cation formation in SbF metallic species only, but occurs with equal frequency among non-metals such as halogen and 5 has proven to be an excellent fluoride-ion polyhalogen derivatives (4,5). In most instances SbF , n . 5 6 (SbF ) 6 or polyanions of the type SbF acceptor, and the hexafluoro anion SbF  =  1 or 2,  Some selected solid polyhalogen and binary transition metal cationic  are readily formed.  species stabilized by such anions are listed in Tables 1.1 and 1.2. Extensive research has been carried out in our laboratory to study the possible extension of this fluoride-ion acceptor ability SbF to include a similar “fluorosulfate-ion transfer” via the solvolysis of fluorosulfate of 5 5 (12-15). compounds in SbF  The solvolysis process was initially used in our group to synthesize non-metallic cations Sn (16): 2 ) 3 (12,13,15), and later for the preparation of the dimethyltin(IV) cation (CH  SO 2 C1O F 3  SO 2 IX F 3 (X  =  +  5 4SbF  5 4SbF  —  —  1 ] [ C1O 1 F 2 Sb  1 J [ IX 1 F 2 Sb  +  +  ) 3 ( 9 F 2 Sb F SO  ) 3 ( 9 F 2 Sb F SO  [1.1]  [1.2]  Cl or Br)  F) 3 Br(SO  2 2Br  212  +  +  +  +  5 7SbF  F 6 0 2 5  F 6 0 2 S  ) 2 S CH F 3 n(SO  +  +  +  —  [SbF 2 BrF ] 6  5 1OSbF  5 8SbF  5 8SbF  —  .—>  —>  +  ) 3 ( 9 F 2 3Sb F SO  6 ] [ 2 2Br 1 F 3 Sb  1 ] [ 2I 1 F 2 Sb  +  +  ) 3 ( 9 F 2 2Sb F SO  1 ] S ) 3 (CH 1 F 2 n[Sb  4  ) 3 ( 9 F 2 2Sb F SO  +  ) 3 ( 9 F 2 2Sb F SO  [1.3]  [1.4]  [1.5]  [1.6]  Table 1.1:  Solid Polyhalogen Cationic Derivatives of SbF 5  Compound  Synthesis  [SbF 3 C1 ] 6  2 Cl  J [ 2 Br 1 F 3 Sb 6  -t-BrF 2 Br + 5 SbF  17  2+S Br F 6 0 2  15  12[2111]  +  Reference  CIF + SbF 5 in HF  +  5 SbF  5 in SO SbF 2  +  4  18  5 + 1 + F 6 0 2 SbF S  15  [SbF 2 C1F j 6  3 CW  +  5 SbF  19  [SbF 2 BrF ] 6  3 BrF  +  5 SbF  20  F) 3 Br(SO  +  5 SbF  [SbF 2 IF ] 6  3 IF  ] [ ICl 1 F 2 Sb 1  SO 2 IC1 F 3  +  5 SbF  13  ] 1 F 2 IBrj[Sb 1  SO 2 IBr F 3  +  5 SbF  13  [SbF 4 ClF j 6  5 C1F  +  5 in HF SbF  22  [Sb ] 4 BrF 1 F 2  5 BrF  +  5 SbF  22  [SbF 4 IF 1 6  5 IF  5 SbF  [Sb i] 6 BrF 1 F 2  5 BrF  1 [ 6 IF 1 F 2 Sb 1  5 IF+SbF  +  +  5 SbF  15  +  21  SbF 3 F 2 Kr 6  8 23 24  5  Table 1.2:  5 Solid Binary Transition Metal Derivatives of SbF  Reference  Compound  Synthesis  2 ) 6 Cr(SbF  2 CrF  2 ) 6 Mn(SbF  Mn  2 ) 6 Fe(SbF  2 FeF  +  Fe  5 in SO SbF 2  2 ) 6 Co(SbF  2 ) 6 Ni(SbF  +  +  5 in HF SbF  25  2 5 in SO SbF  26  5 in HF SbF  25  +  2 5 in HF or SO SbF  2 CoF  +  Co  5 in SO SbF 2  +  2 NiF  +  5 in HF SbF  26 25 26 25  2 n SO Ni+SbF i 5  26  F 2 + 5 Ni+SbF  27  2 ) 6 Ag(SbF  2 AgF  +  5 in HF SbF  25  2 ) 6 Zn(SbF  2 ZnF  +  5 in HF SbF  25  2 ) 6 Cd(SbF  ‘2  +  5 in HF SbF  25  1 Sb ) ( 3 Hg 1 F 2  Hg  2 5 in SO SbF  +  6  28  Two of the above halogen cations synthesized by the solvolysis route, i.e. 3 i& [Sb 2 Br F [Sb J, are investigated in this work for their magnetic properties by low temperature 2 I 1 and F magnetic susceptibility measurements.  This improved preparative method (15) provides a  simple and straightforward route to sufficiently large quantities of very pure paramagnetic Brj and 12+ compounds, and hence is of value in magnetic studies where highly pure materials are 1 are the only Sb } [ I 1 F 6 and 2 Sb ] [ 2 Br 1 F desired. It is interesting to note that in Table 1.1, 3 two solid polyhalogen cation derivatives that are paramagnetic.  ) and more SO 3 ( 4 (SbF The volatile components formed in these solvolysis reactions F 5 is in an excess) can be removed easily in a dynamic ) where SbF SO 3 ( 9 F 2 Sb frequently F vacuum (14), facilitating the isolation of pure solid products in very high yield. In this study, the solvolysis method is extended to divalent transition metal fluorosulfates as well.  5 listed in Table 1.1 are generally accepted to be of The polyhalogen derivatives of SbF ionic structure, although there is evidence that in most of them some secondary cation-anion Single crystal X-ray studies performed on two  interaction of various degrees does exist.  6 and F [Sb J, support an ionic for 2 I 1 Sb ] [ 2 Br 1 F compounds of interest to this study, i.e. 3 mulation since the cation-anion contacts are rather long, although shorter than the sum of the van der Waals radii, indicating a very small cation-anion interaction (17,18).  [Sb i] is almost the largest 2 I 1 Interestingly, the shortest FF contact distance in F derivatives with the following cations of  1 F 2 cation-anion contact observed in a series of Sb 4 decreasing contacts: SbCl  >  12+  >  3 XeF  >  + 2 Br  >  . This decreasing distance indicates 4 BrF  i& an increase in the acidity for the cations (18). The Sb-F (terminal) distances in 3 [Sb 2 Br F 1 (1.83 Sb J [ I 1 F and 2  A  and 1.85  A)  6 derivatives like are similar to those observed in SbF  , namely 1.84 SbF 6 [ 2 BrF SbF and j 6 [ 2 CW ]  A and 1.835 A respectively (19,20).  7  The transition metal hexafluoroantimonates listed in Table 1.2 are, in most reported , and are of the type 5 instances, formulated as metal difluoride adducts of the parent acid SbF (25). This formulation is derived from a common synthetic route where the metal 2 to yield the , usually in the presence of anhydrous l{F or SO 5 difluoride is reacted with SbF 2 and ) ) 6 11 are also F MF(Sb 2 desired product. However, alternative structural forms like M(SbF possible for these products. When other preparative methods such as the oxidation of metals by 5 (27) are used, the result 2 in the presence of SbF 5 in SO SbF 2 (26) or metal fluorination with F ing products are conveniently formulated as M(SbF ): 6  2 so M where M  +  =  5 4SbF  >  2 ) 6 M(SbF  +  [1.7]  bF 5 S 3 SbF  Mn, Fe or Ni 270°C  Ni  +  5 2SbF  +  2 F  >  [1.8]  Ni(SbF  250 atm  2 (26), whereas ) 6 In the case of cobalt, reaction [1.7] reportedly leads to the ternary CoF(SbF 1 (28). (Sb 3 Hg 1 F 2 mercury is converted to )  It is significant to note here that all the above routes to transition metal hexafluoro antimonates have various limitations and complications.  2 at elevated Metal oxidation by F  5 may not temperature may lead to higher oxidation state compounds, whereas oxidation by SbF be a suitable method for metals with higher oxidation potentials than provided for by the bF 5 S 3 Sb(V)/Sb(llI) couple. In addition, the quantitative separation of the solid byproduct SbF from the main product may prove to be the difficult (29), and consequently, impure materials are isolated as reaction products. Even the more versatile synthetic method of fluoride abstraction 1 F 2 5 (25) could lead to compounds of the type MF(Sb 2 by SbF from MF 2 lattice. , due to an incomplete breakup of the MF 2 ) 6 the binary M(SbF  8  a structural isomer of  5 (Table 1.2) has Some structural information on the transition metal derivatives of SbF 5 in SO 2 (26), magnetic been reported. For the Mn, Fe and Ni compounds obtained from SbF moment values at room temperature appear to indicate octahedral coordination for the metal , which is synthesized from the 2 ) 6 centers. Based on vibrational and X-ray powder data, Ni(SbF 6 struc 5 (27), is shown to be related to the LiSbF high temperature fluorination of nickel in SbF , leading to a layer type 2 ture by the occupation of only every second octahedral Li site with Ni structure. Furthermore, a crystal structure has been reported for the paramagnetic (vide infra) 2 ion is located in a tetragonally elongated octahedral environ 2 (25), where the Ag ) 6 Ag(SbF 6 moiety for the ment, which in turn implies a layer structure with iridentate bridging SbF compound.  Except for the observed distortion due to the Jahn-Teller effect, the reported  2 ) 6 structure appears to be consistent with the proposed structure of the above mentioned Ni(SbF compound (27).  1.3  Transition Metal Fluorosulfates and Trifluoromethylsulfates -  The transition metal sulfonates studied in this work can be considered as derivatives of ) and trifluoromethylsulfuric acid (HSO F the strong protonic fluoroacids fluorosulfuric acid 3 . CF 3 (HSO )  The two acids rank among the strongest known protonic acids (1,3,7).  F and 3 3 CF behave as weakly coordinating SO Consequently, the corresponding anions S0 ligands, and are well suited to stabilize many unusual transition metal (as well as main group) cations.  j or tetra 4 Compared to other poorly coordinating anions like perchiorate (C10  CF ions are arguably the most stable and non-oxidizing 3 F and S0 3 , the SO (BF j fluoroborate 4 Interestingly, almost all the transition metal  species available for synthetic purposes (3).  trifluoromethylsulfate compounds are made by the solvolysis of suitable metal salts in an excess of , CF and include many metal fluorosulfates as precursors (30,3 1). 3 HSO  Therefore, it is  appropriate to examine first the syntheses and properties of transition metal fluorosulfates (particularly the derivatives of electron rich metals) in some detail.  9  Fluorosulfate chemistry displays many parallels to halogen chemistry, and the fluoro sulfate group may be viewed as a pseudohalide. Hence, the synthetic methods used in the preparation of the flouorosulfates have striking parallels to those used in the synthesis of halides, with the necessary modifications.  Two synthetic methods in general have been used to prepare a large number of transition metal fluorosulfate derivatives:  , 2 (a) solvolysis of a corresponding metal salt such as MCi  , and (b) the oxidation of a metal with the strongly HSO F 2 in excess 3 4 or M(RCOO) MSO F (32,33) in the 6 0 2 oxidizing and fluorosulfonating reagent bis(fluorosulfuryl)peroxide, S F. 3 presence or absence of HSO  Solvolysis is almost exclusively the route of choice for the synthesis of 3d-block F yields a variety of electron 6 0 2 metal(ll) fluorosulfates (34,35), whereas metal oxidation by S ) (37), 2 F 3 ) (36), Ag(SO 6 F 3 Pd(U)[Pd(IV)(SO rich 4d- and 5d-metal fluorosulfates, in particular ] F) (39) according to: Au(SO ) (38) and 3 4 F 3 Pt(SO  F 3 HSO M where x  +  F 6 0 2 x12 S  >  M(SOF),  [1.9]  2, 3 or 4  HSO reagent combination in metal oxida 3 J 6 O 2 S A major advantage to the use of the F tion is that precursors, in the form of fine metal powders, are available in high purity for all the transition metals, and consequently, very pure products can be isolated after the removal of the excess reagents in a dynamic vacuum. Furthermore, some noble metal fluorosulfates such as F) (40) are also prepared by the oxidation of the 3 ) (40) and Au(SO 4 F 3 ) (36), Pt(SO 2 F 3 Pd(SO F 3 F (41). However, the use of BrSO 3 respective metals by bromine monofluorosulfate, BrSO  10  instead of F HSO in the synthesis of binary metal fluorosulfates offers no real 3 / 6 0 2 S F. 3 F is initially required to synthesize BrSO 6 0 2 advantage, primarily as S  For these transition metal fluorosulfates, only a single molecular structure, that of gold(llI) fluorosulfate, which was obtained by single crystal X-ray diffraction, has been reported so far (42).  The compound is a dimer and contains both monodentate and symmetrically  bridging bidentate fluorosulfate groups. Unfortunately, the polymeric nature of most transition F or other 3 metal fluorosulfates and their resulting lack of volatility and solubility in HSO suitable solvents have prevented the formation of single crystals, and hence structural evidence rests largely on vibrational spectra and magnetic properties.  ) appear to belong to a single structural type, derived 2 F 3 Fluorosulfates of the type M(SO 2 layer structure, with one exception from the CdC1  -  ) 4 F 3 Au(I)[Au(Ill)(SO the mixed valency ]  ) results in M0 2 F 3 -coordination 6 (43). The 0-tridentate bridging fluorosulfate group in M(SO polyhedra within the layer structure. Regular octahedra are found for M  =  Fe, Co, Ni, Pd, Zn,  F group appears to be reduced for M 3 Cd and Hg (35,36,44), while the symmetry of the SO  =  . This structure 2 2 and Ag Mn, Cu and Ag (35,37), with Jahn-Teller distortions expected for Cu CF (45), 3 Fe(SO 2 type is also postulated for the divalent metal trifluoromethylsulfates ) CF (46), and also extends to divalent 3 Cu(SO 2 CF (30) and ) 3 Pd(SO 2 CF (46), ) 3 Co(SO 2 ) CH derivatives as well. The 3 CF and SO 3 , S0 S0 F pre-transition and post-transition metal 3 ) 2 F 3 only two molecular structures reported so far for this type of compounds are that of Sn(SO ) type compounds with R 2 R 3 CH (47b). For the transition metal M(SO 3 Ca(SO 2 (47a) and )  =  F,  , electronic spectra and magnetic data, where reported, confirm the structural 3 3 or CH CF conclusions reached.  A greater structural diversity is encountered for binary fluorosulfates of the general F) (42) and the mixed-valency 3 [Au(SO 2 F) The dimeric structure of ] 3 M(SO composition .  11  6 F 3 Pd(II)[Pd(IV)(SO ] ) (36) are clear exceptions. The mixed valency formulation follows the precedent of 3 PdF (48) and is supported by the magnetic behavior and the synthesis and struc tural characterization of bimetallic compounds of the types ] 6 F 3 Pd(II)[M(IV)(SO ) (M  =  Pt or  Sn) and j 6 F 3 Ba[Pd(IV)(SO ) (49). The fluorosulfate group appears to bond strongly to the M(IV) metal center and coordinates weakly to M(II), in an “anisobidentate” bonding mode. Therefore, it seems that where the SO F (and the SO 3 CF or ) 3 CH group functions as a polydentate 3 SO ligand, a bridging configuration is observed, resulting in stable solids, often viewed as coordina tion polymers. Moreover, the versatile coordinating ability of the fluorosulfate group, which may function as a mono-, hi-, or tn-dentate ligand leads to the stabilization of metal ions in high, intermediate, and low oxidation states.  In contrast to the large number of binary transition metal fluorosulfate compounds reported, only a small number of trifluoromethylsulfate derivatives are known. Almost all the CF species are made by the solvolysis of suitable metal salts in an excess of 3 M(SO ) CF In the solvolysis of 3 3 HSO . CF (30,31), the reaction initially proceeds HSO M(SO F ) in 3 according to: CF 3 HSO M(SO F 3 ) where x  =  x HSO CF 3  +  2 or 3, M  =  >  CF 3 M(SO )  +  F 3 x HSO  [1.10]  Mn, Pd, Ag or Au  However, the by-product HSO F and the reactant HSO 3 CF undergo a degradation 3 reaction and produce a series of products (50,51) which do not appear to interfere in the isolation of the trifluoromethylsulfates (30). As mentioned above, for the divalent iron, cobalt and copper derivatives a layered lattice structure involving hexacoordinated metal centers has been suggested on the basis of vibrational and electronic spectra, as well as magnetic and Mössbauer data (45,46).  In a manner similar to the SO F groups discussed previously, the 3  12  CF groups act as bridging tridentate ligands in these compounds. 3 SO  Although the solvolysis of transition metal fluorosulfates in excess trifluoromethyl sulfuric acid, which is a generally applicable method, should allow the synthesis of a compara CF compounds (30), only limited use has been made of this 3 tively large number of SO synthetic possibility. The principal reasons for this are threefold: (a) As discussed in Section F group. An extended 3 CF group has a basicity comparable to that of the SO 3 1.1, the SO synthetic approach is not fruitful where compounds with similar properties and molecular struc tures result, as is often the case. (b) With vibrational spectroscopy used as a principal method of CF S0 3 stretching modes in 3 3 and CF structural analysis, the coincidence of SO  causes a  greater complexity, making vibrational assignments and structural conclusions frequently CF and its derivatives is sensitive to HSO uncertain and ambiguous. (c) The S—C linkage in 3 oxidative cleavage (30), and hence the acid’s use in the synthesis of high-valent metal deriva tives with a good oxidizing potential, is not advisable. However, the S-C linkage, unlike the S-F bond, is hydrolytically stable and hence chemistry in aqueous medium is possible with CF 3 HSO .  There are nevertheless a number of interesting cases where metal trifluoromethylsulfates display fundamentally different magnetic properties from the coffesponding fluorosulfates, as will be discussed in Chapter 6 of the text.  1.4  Post-Transition Metai Arene it-Compounds  Both main group and transition metal organometallic n-complexes have been studied extensively, and a very large number of compounds have appeared in the chemical literature in this field over the past few years alone. In this discussion, however, the emphasis is placed on the relatively rare post-transition metal arene n-complexes.  13  In terms of bonding, these  compounds differ significantly from most of the transition metal it-compounds for three principal reasons (52):  (a)  Metals of the post-transition series contain no partially filled or empty valence d subshells of comparable energy to those of the the  it  it  orbitals of arene ligands. As a result,  electron density of the ligand can be transferred only to a very small extent to the s  or p type orbitals of the metal.  (b)  The filled d subshells of the metals are usually of much lower energy than the antibond ing  it’  orbitals of the arene ligand. Consequently, unlike the transition metal counter  parts, back-donation from the d electrons to effect synergic bonding is not observed in post transition it-complexes.  (c)  The effective atomic number rule, which is so useful in transition metal carbonyls and arene and Cp derivatives, is rendered ineffective and inapplicable in the case of post transition metal derivatives.  The consequence of factors (a) and (b) is a weak metal ligand interaction, leading to compounds which are not as varied as the transition metal n-complexes. The study of neutral arene-metal complexes with the post transition metals in recent times has included the elements Ga, In, Tl, Sn, Pb, and Bi (53). However, these studies indicate that the it-interactions with the elements above the fourth period are very weak, resulting in reduced hapticity from a desired 6 3 or 2 (53) to i  Studies by Schmidbaur et al. (54) have concentrated on neutral arene complexes of univalent gallium, indium and thallium, which directly follow the d block elements. Both mono and bis(arene) complexes have been synthesized and characterized, and among these is the  14  1 whose crystal structure was [GaBr T 6 [(Mes) ] , ] mixed mono and bis(arene) thallium complex, 4 (GaBr with one T1 , ) also solved. This complex is actually a skeletal framework of tetrameric 4 or two mesitylene molecules alternately coordinated to the Tl+ cations. In the MesTl+ unit, the Tl is located directly above the face of the ring, implying 6 coordination. A similar structure a] indicating that, although GaC1 G [Mes) [ , ] was also found for the gallium analogue (55) 4 weak, it-interactions do exist with univalent Group 13 metals.  It is significant to note that in the above studies it was found that the complex salts 4 all dissolved in hot benzene to give colorless crystals upon cool 4 and T1GaC1 , TIA1Br 4 T1A1C1 , the benzene content of the crystals steadily 2 ing. However, when dried under a stream of dry N decreased, implying very weak  it  coordination of the benzene ligand to the Ti center.  Apparently, only the mesitylene ligand afforded a dry, isolable product. Strauss et al. (56) have )(Mes) but found that this compound 5 [Tl(OTeF , 2 also synthesized TI-Mes complexes such as } 2 atmosphere or in vacuo. There also loses all traces of the weakly bound arene ligands under N fore, it appears that the high lability of these arene ligands makes synthesis and purification a very delicate task, even though the synthesis itself is relatively simple (i.e., arene addition to a suitable substrate).  2 plays a (n+1)s 10 It is apparent from the above studies that the electronic configuration nd particularly important role in the metal’s affinity for arene ligands. In view of this, the next logical step is to explore the divalent Group 14 elements (which have the same electronic configuration) to investigate their affinities for arene ligands. In fact, the synthesis and structure , M=Pb(1I) or Sn(II), have been reported (C ) H )M(AlCl 6 H 6 (C 2 ) of the arene M(II) complexes 4 by Amma and co-workers (57,58). The X-ray crystallographic study of the compounds reveals a polymeric chain structure, with a benzene ring wealdy bound in a  manner to the M(II) center.  In this thesis, the synthesis and characterization of arene adducts of divalent tin fluoro deriva SbF and SO F ligands will be considered. 3 tives which contain the weakly coordinating 6  15  1.5  Magnetic Measurements  Magnetic susceptibility measurements, when recorded as a function of temperature, provide primarily information regarding the nature of the ground state of the paramagnetic ions. The extent of the information that can be obtained is related to the accuracy of the measure ments, the range of temperature over which the measurements are carried out, as well as to the purity of the samples used.  The magnitude and temperature dependence of the magnetic  moment data of magnetically dilute systems are determined by several factors such as ground state occupancy and degeneracy, crystal field symmetry, spin-orbit coupling and electron delocalization effects.  The theory of magnetic susceptibilities of paramagnetic molecular  species and transition metal complexes is well covered in several texts (59). In magnetically concentrated systems, the factors mentioned above are also present, and any magnetic inter action is superimposed upon these single-ion phenomena. Furthermore, it is now recognized that magnetic exchange interactions are not at all uncommon in inorganic compounds, even where magnetic dilution (usually at room temperature) appears at first sight to be dominant. It is for this reason that magnetic susceptibility measurements should be performed, where possible, over as wide a temperature range as possible.  Qualitatively, magnetic exchange interactions may be thought of as arising from unpaired spin densities on neighbouring paramagnetic centers, being aligned either parallel or anti-parallel to each other, resulting in ferromagnetism or antiferromagnetism respectively. Magneto-structural  relationships  emphasize  the  importance  of  such  factors  as  the  stereochemistry around the paramagnetic center, the efficiency of orbital overlap which may be direct or via a superexchange pathway, the geometry of the bridging anions, the types of substituents on the bridging group and the nature of any nonbridging groups. The theoretical aspects of magnetic exchange phenomena and the models used to interpret the empirical data have been the subject of extensive investigations (60).  16  The main group molecular complexes and several of the transition metal derivatives studied in this work for their magnetic properties contain unusual paramagnetic cations in the solid state, which are stabilized by weakly basic fluoroanions. Nearly all the previous magnetic measurements on the molecular cations and the divalent sulfonates have been carried out at higher temperatures only, where in most instances, magnetic exchange interactions are not detected.  H3g ground states with the first 2 are shown to have 2 The halogen cations I2 and Br  t above the ground state, respectively, excited states 2 1I2g at approximately 5100 and 2800 cm both in the gas phase (61) and in solution (15). The magnetic moment in both cases is expected to be independent of temperature due to the absence of thermally accessible excited states, and ’eff of the NO predicted to have a value of 2.0 B at higher temperatures, in analogy to the 1 molecule, discussed by van Vieck several years ago (62):  Peff where x  =  2[(1  —  [1.11]  2 / 1 e + xe”)/(x + xe)]  =  VkT.  =  Spin-orbit coupling constant  k  =  Boltzmann’s constant  T  =  Absolute temperature  In an earlier report, Gillespie and Mime (63) showed the magnetic moment of F to be 2.0 ± 0.1 3 solution of HSO  in a  Kemmitt et al. (64) reported a magnetic susceptibility  , a material thought to contain the ‘2 cation, and found magnetic moments (SbF 1 2 ) study on 5 that ranged from 2.25 B at room temperature to 2.05 B at 100 K. Considering the uncertainty in the chemical composition of the material, not much significance could be attached to these 6 compounds [Sb J ] 2 [Br 1 F [Sb i] and 3 2 I 1 values. A later work from our group, where the F  17  were synthesized by an improved method (15), indicated the possible existence of antiferro magnetic interaction between the ‘2 cations, with  jj  values of 2.15 and 1.68 B at 295 and  2 species was found to be magnetically dilute in the 81 K respectively. Furthermore, the Br temperature range 297 to 80 K, and a magnetic moment close to 2.0 B was obtained for the value of  compound (15). This is in contrast to a previous study, where a room tempreature 2 derivative (17). 1.6 11 B had been reported for the Br  In contrast to the 1f2g 2  2 cations, the dioxygenyl cation 02 (with ground state and Br  t above ground state) investigated in this work and first excited state 2 113ag at —1480 cm  has been the subject of several previous magnetic studies (65-68).  The 02+ cation can be  prepared by a variety of methods, and is stabilized in the solid state by various fluoroanions, [SbF 2 O ] [BF (70), 6 2 O ] [AsF (71), and 6 2 O ] [PtF (69), 4 2 0 ] leading to complexes like 6 [PtF over the temperature range 77-298 K has been postu 2 O } (71). The magnetic behavior of 6 lated to be similar to that of NO, and the magnetic moment was reported as 1.57  1.LB  at room  - compound 6 [ 2 O SbF temperature (65). A magnetic moment of 1.66 B has been found for the ] [AsF down to 2 O ] [BF (68a). Two previous studies on 6 2 O J (68b), and a value of 1.70 B for 4 4 K give contradictory results. The study by Grill et al. (67) indicates no magnetic ordering of the 02+ cations down to 4 K, whereas weak O2O2+ interaction is suggested in the work of DiSalvo et al. (66).  Even though in all the above studies the eff values reported for the O2 salts fall well below the spin only value of 1.73 B’ no satisfactory reason has been given so far to explain this curious phenomenon. It appears, however, that sample purity and identity play an important role in the interpretation of magnetic data of the O2 salts.  Several transition metal sulfonate derivatives studied here for their magnetic properties contain paramagnetic cations in unusual coordination environments.  18  As in PdF 2 (48), in  ) with 3 8 CF (30) compounds, the Pd(ll) ions (d 3 Pd(SO 2 ) (36) and ) 2 F 3 Pd(SO A2g ground states are located in octahedral environments, a situation found only in some of their cationic and anionic derivatives.  CF 3 Ag(SO 2 ) (37) and ) 2 F 3 Similarly, the two silver derivatives Ag(SO  2 compound (72), the only (31) investigated in this work have remained, in addition to the AgF 9 configuration. simple binary compounds of Ag(I1) with a d  ) 2 F 3 Pd(SO Previous magnetic susceptibility measurements down to —80 K on , ) indicated that these fluorosulfate derivatives were relatively 2 F 3 F) and Ag(SO 3 “Pd(SO ” magnetically unconcentrated in that temperature range with Peff values of 3.34, 3.45 and 1.92 B respectively (36,37).  Furthermore, their susceptibilities followed the Curie-Weiss law with  CF was found to be 3 Ag(SO 2 positive Weiss constants. The trifluoromethylsulfate derivative ) an antiferromagnetic compound, with Xmax at —138 K (31).  ) 4 F 3 Only two other binary fluorosulfate and trifluoromethylsulfate derivatives, Ir(SO CF (45), are known up to now to be magnetically concentrated. However, Fe(SO 3 (73) and ) F) are only slightly below 3 Ir(SO CF the magnetic moments obtained for 4 3 Ag(SO , 2 unlike in ) the calculated values, suggesting weak antiferromagnetic coupling down to —80 K (73). The CF compound is magnetically more concentrated than the iridium species, exhibiting Fe(SO 3 ) magnetic moments which are significantly less than the expected values, and which also decrease with decreasing temperature, although no maximum is detected in the susceptibility curve down to —80 K (45). As in the cases of palladium and silver derivatives mentioned above, no low temperature magnetic data are available for these complexes.  The antiferromagnetic coupling observed in all the above mentioned sulfonates is not unusual for magnetically concentrated transition metal fluoro compounds, since antiferro magnetism, rather than ferromagnetism, appears to be the more common type of magnetic ex change interactjon among the majority of these compounds (59). Moreover, in most instances  19  these antiferromagnetic transition metal fluoro derivatives contain small monoatomic ligands (59b,c), whereas the sulfonate coordination polymers studied in this work are composed of the CFç ligands. 3 F and SO 3 much larger polyatomic S0  1.6  Objectives of this Study  The research work presented in this thesis can be categorized into two general, but inter related sections: (A) Synthesis and characterization of divalent metal coordination polymers, and (B) Magnetic susceptibility studies on unusual main group and transition metal cations. The specific types of research relevant to these two sections are summarized below.  (A)  Synthesis and Characterization  (i)  5 was The solvolysis of main group fluorosulfate derivatives in the Lewis acid SbF extended in the present study to include the transition metal fluorosulfates according to:  25-60°C ) 2 F 3 M(SO  +  5 6SbF  >  M(SbF  +  ) SO 3 ( 9 F 2 2Sb F  [1.12]  5 SbF Where M  =  Ni, Pd, Cu, Ag or (Sn)  , 5 ) precursors, the low oxidation potential of SbF 2 F 3 The ready availability of the M(SO ), as well as mild reaction SO 3 ( 9 F 2 Sb and the easy removal of the volatile byproduct F conditions and the possibility of using glass vessels as reactors were all positive factors in choosing the above solvolysis preparation. The divalent metal hexauluoro anlimonates obtained were characterized, where appropriate, by elemental analysis, vibrational, Sn Mössbauer spectra, and magnetic susceptibility measurements. electronic and 119  20  (ii)  The favorable properties of 1 ,3,5-trimethylbenzene (mesitylene) as a ii-adduct ligand and the possible participation of the lone pair electrons of the Mössbauer nuclide Sn in the +2 state in bonding by being donated to the antibonding  it’  ligand orbitals are contributing  factors in the syntheses of the post-transition metal Sn(ll) arene adducts according to:  25°C ) 2 F 3 Sn(SO  +  mes  ) es 2 F 3 Sn(SO m  >  [1.131  mesitylene 25°C 2 ) 6 Sn(SbF  +  2 mes  >  mes Sn(SbF 2 2 ) 6  [1.14]  mesitylene (mes  =  mesitylene)  SnThe adducts isolated were characterized by elemental analysis, infrared and tt9 Mössbauer spectra.  (B)  Magnetic Susceptibility Studies  (i)  Low temperature magnetic susceptibility measurements down to —4 K were performed [Sb i]’ in order to compare the magnetic 2 I 1 , 2 AsF on j 6 [ 2 0 i& and F [Sb Br F behavior of the three cations. These paramagnetic homonuclear derivatives seem to be the only three stable and isolable cations formed by non-metals that are suitable for solid Br were investigated for + state magnetic studies. The two dihalogen cations 12+ and 2 possible exchange interactions, and the dioxygenyl cation 02+ was studied here to explain its observed low magnetic moment values. Furthermore, the application of van Vleck’s theory of molecular paramagnetism to solid state cations was also examined.  (ii)  Several Group 10 and Group 11 divalent transition metal sulfonate compounds were considered in this study as likely materials to exhibit magnetic exchange interations.  21  F) 3 3 Pd(SO , The metal fluorosulfates 2 F) and 2 “Pd(SO ” F) previously described 3 Ag(SO , as relatively magnetically dilute down to —80 K, were re-investigated down to —4 K for their low temperature magnetic properties. The nickel(ll) fluorosulfate, 2 F) was, 3 Ni(SO however, measured in the temperature range —291 to 2 K.  The corresponding  trifluoromethylsulfate derivatives 3 CF 3 Ni(SO , 2 ) CF and 3 Pd(SO 2 ) CF were Ag(SO 2 ) similarly studied for their variable temperature magnetic susceptibilities. The last two compounds were measured at low temperatures, whereas the 3 CF complex was Ni(SO 2 ) studied in the extended temperature range —292 to 2 K.  References  1.a)  G.A. Olah, G.K.S. Prakash, and J. Sommer, “Superacids”, John Wiley and Sons, New York, 1985.  b) 2.  T.A. O’Donnell, Chem. Soc. Rev., i. 1 (1987). P. Hagenmuller (Ed.), “Inorganic Solid State Fluorides”, Academic Press, New York, 1985.  3.  G.A. Lawrence, Chem. Rev.,  4.  R.J. Gillespie and M.J. Morton, Ouart. Rev. Chem. Soc., 25, 553 (1971); and M.T.P.  ,  17 (1986).  International Review of Science, Inorg. Chem., Ser. 1, Vol. 3, Butterworths, London, 1972. 5.  J. Shamir in “Structure and Bonding”, Eds. J.D. Dunitz, J.B. Goodenough, P. Hem merich, J.A. Ibers, C.K. Jorgensen, J.B. Neilands, D. Reinen, and R.J.P. Williams, vol. 37, Springer-Verlag, Berlin, pp 141-210, 1979.  6.  S.P. Mallela, S. Yap, J.R. Sams, and F. Aubke, Inor. Chem., 25, 4327 (1986).  7.  P.-L. Fabre, J. Devynek, and B. Tremillon, Chem. Rev.,  8.  A.A. Woolf and N.N. Greenwood, J. Chem. Soc., 2200 (1950).  22  ,  591 (1982).  9.  E.E. Ainsley, R.D. Peacock, andP.L. Robinson, Chem. md., 1117 (1951).  10.a)  E.L. Muetterties and W.D. Phillips, Adv. Inorg. Chem. Radiochem., 4, 234 (1962).  b)  G.J. Hoffman, B.F. Holder, and W.L. Jolly, 3. Phys. Chem., 62, 364 (1958).  11.  A.J. Edwards and P. Taylor, Chem. Comm., 1376 (1971).  12.  P.A. Yeats and F. Aubke, J. Fluorine Chem.,  13.  W.W. Wilson, J.R. Dalziel, and F. Aubke, J. Inorg. Nucl. Chem., 2. 665 (1975).  14.  W.W. Wilson and F. Aubke, J. Fluorine Chem., fl, 431 (1979).  15.  W.W. Wilson, R.C. Thompson, and F. Aubke, Inor. Chem., j, 1489 (1980).  16.  S.P. Mallela, S. Yap, J.R. Sams, and F. Aubke, Rev. Chim. Minerale, 2, 572 (1986).  17.a)  A.J. Edwards, G.R. Jones, and R.J.C. Sills, Chem. Comm., 1527 (1968).  b)  4, 243 (1974).  A.J. Edwards and G.R. Jones, J. Chem. Soc., A2318 (1971). C.G. Davies, R.J. Gillespie, S.R. Ireland, and J.M. Sowa,  18.  Can. 3. Chem.,  2048  (1974). 19.a) b) 20.a)  F. Seel and 0. Detmer, Z. Anorg. Aug. Chem.,  ,  113 (1959).  A.J. Edwards and R.J.C. Sills, J. Chem. Soc., A2697 (1970). A.J. Edwards and G.R. Jones, Chem. Comm., 1304 (1967).  b)  A.J. Edwards and G.R. Jones, 3. Chem. Soc., A 1467 (1969).  c)  K.0. Christe and C.J. Schack, Inorg. Chem.,  21.a) b)  2 2296 (1970).  M. Schmeisser and W. Ludovici, Z. Naturforsch.,  602 (1965).  M. Schmeisser, W. Ludovici, D. Naumann, P. Sartori, and E. Scharf, Chem. Ber., 101, 4214 (1968).  22.  K.O. Christe and W. Sawodny, Inorg. Chem., j.2. 2879 (1973).  23.a)  R.J. Gillespie and G.J. Schrobilgen, Inorg. Chem., j3, 1230 (1974).  b)  K.O. Christe and R.D. Wilson, Inorg. Chem., .1.4, 694 (1975).  24.  F.A. Hohorst, L. Stein, and E. Gebert, Inorg. Chem., 14, 2233 (1975).  25.  D. Gantar, I. Leban, B. Friec, and J.H. Holloway, J. Chem. Soc. Dalton Trans., 2379 (1987).  23  499 (1975).  26.  P.A.W. Dean, J. Fluorine Chem.,  27.  K.O. Christe, W.W. Wilson, R.A. Bougon, and P. Charpin, J. Fluorine Chem.,  ,  34, 287  (1987). 28.  B.D. Cutforth, C.G. Davies, P.A.W. Dean, R.J. Gillespie, P.R. Ireland, and P.K. Ummat, Inorg. Chem., 12, 1343 (1973). 1 (1965).  29.  L. Kolditz, Adv. Inorg. Chem. Radiochem,  30.  S.P. Mallela, J.R. Sams, and F. Aubke, Can. J. Chem., 3, 3305 (1985).  31.  P.C. Leung, K.C. Lee, and F. Aubke, Can. J. Chem., 2. 326 (1979).  32.  F.B. Dudley and G.H. Cady, J. Am. Chem. Soc.,  33.  R.A. DeMarco and J.M. Shreeve, Adv. Inorg. Chem. Radiochem., j., 109 (1974).  34.  A.A. Woolf, J. Chem. Soc., A355, (1967).  35.  C.S. Alleyne, K.O. Mailer, and R.C. Thompson, Can. J. Chem.,  36.  K.C. Lee and F. Aubke, Can. 3. Chem.,  37.  P.C. Leung and F. Aubke, Inorg. Chem., 1.2, 1765 (1978).  38.  K.C. Lee and F. Aubke, Inorg. Chem.,  39.  K.C. Lee and F. Aubke, Inorg. Chem., 31. 389 (1979).  40.  W.M. Johnson, R. Dev, and 0. Cady, Inorg. Chem., 11, 2260 (1972).  41.  F. Aubke and R.J. Gillespie, Inorg., Chem., 7, 599 (1968).  42.  H. Wiliner, S.J. Rettig, J. Trotter, and F. Aubke, Can. J. Chem., 69, 391 (1991).  43.  H. Wiliner, F. Mistry, 0. Hwang, F.G. Herring, M.S.R. Cader, and F. Aubke, 3. Fluorine  ,  ,  2. 513 (1957).  ,  336(1974).  2473 (1977).  3, 2124 (1984).  Chem., 5, 13 (1991). 382 (1984).  44.  S.P. Mallela and F. Aubke, Can. J. Chem.,  45.  J.S. Haynes, J.R. Sams, and R.C. Thompson, Can. J. Chem., 59, 669 (1981).  46.  A.L. Arduini, M. Garnett, R.C. Thompson, and T.C.T. Wong, Can. J. Chem., 53, 3812  ,  (1975). 47.a)  D.C. Adams, T. Birchall, R. Faggiani, R.J. Gillespie, and J.E. Vekris, Can. J. Chem., 2122 (1991).  24  ,  b)  F. Charbonnier, R. Faure, and H. Loiseleur, Acta Crvst,  1478 (1977).  48.  N. Bartlett and P.R. Rao, Proc. Chem. Soc., 393 (1964).  49.  K.C. Lee and F. Aubke, Can. J. Chem.,  50.  G.A. Olah and T. Ohyama, Synthesis,  51.  R.E. Noftie, Inorg. Nuci. Chem. Lett., j, 195 (1980).  52.  H. Schmidbaur, Angew. Chem.  53.  H. Schmidbaur, W. Bublak, B. Huber, and G. Muller, Angew. Chem.  ,  2058 (1979).  5, 319 (1976).  mt. Ed. Engi., 24, 893 (1985). mt. Ed. Engi.,  .,  26 (1987). H. Schmidbaur, W. Bublak, I. Riede, and G. Muller, Angew. Chem.  54.  mt. Ed. Engi., 5,  24, (1985). 1642 (1984).  55.  H. Schmidbaur, U. Thewalt, and T. Zafiropoulos, Z. Naturforsch,  56.  S.H. Strauss, M.D. Nairot, and O.P. Andersen, Inorg. Chem.,  57.  E.L. Amma, P.F. Rodesiler, and M.S. Weininger, Inorg. Chem., jj, 751 (1979).  58.  P.F. Rodesiler, Th. Auel, and E.L. Amma, J. Am. Chem. Soc., 97,7405 (1975).  59.a)  R.J. Myers,  25, 3850 (1986).  “Molecular Magnetism and Magnetic Resonance Spectroscopy”, Prentice  Hall Inc., Englewood Cliffs, New Jersey, 1973. b)  E.A. Boudreaux and L.N. Mulay (Ed.), “Theory and Applications of Molecular Paramagnetism”, John Wiley and Sons, New York, 1976.  c) 60.a)  R.L. Carlin, “Magnetochemistry”, Springer-Verlag, Berlin, 1986. W.E. Hatfield, W.E. Estes, W.E. Marsh, M.W. Pickens, L.W. ter Haar, and R.R. Weller in “Extended Linear Chain Compounds”, Ed. J.S. Miller, Vol. 3, Plenum Press, New York, pp. 43-50, 1983.  61.  b)  A.P. Ginsberg, Inorg. Chim. Acta. Rev., 5, 45 (1971).  c)  C.J. O’Connor, Prog. Inorg. Chem.,  22. 203 (1982).  A.B. Cornford, D.C. Frost, C.A. McDowell, J.L. Ragle, and l.A. Stenhouse, J. Chem. Phys., M 2651 (1971).  25  J.H. van Vieck,  62.  “Electric and Magnetic Susceptibilities”, Oxford University Press,  London, 1932. 1577 (1966).  63.  R.J. Gillespie and J.B. Mime, Inorg. Chem.,  64.  R.D.W. Kemmitt M. Murray, V.M. McRae, R.D. Peacock, M.C.R. Symons, and T.A.  ,  O’Donnell, I. Chem. Soc., A862 (1968). 65.  N. Bartlett and S.P. Beaton, Chem. Comm., 167 (1966).  66.  F.J. DiSalvo, W.E. Falconer, R.S. Hutton, A. Rodriguez, and J.V. Waszczack, J. Cheni Phys.,  2575 (1975). 747 (1970).  67.  A. Grill, M. Schieber, and 3. Shamir, Phys. Rev. Lett.,  68.a)  V.1. Belova, V. Ya. K. Syrkin, D.V. Bantov, and V.F. Sukhoverkhov, Russ. J. Inorg. Chem., (Engi. Trans.), j.., 772 (1971).  b)  V.1. Belova, V. Ya. Rosolovskii, and E.K. Nikitina,  Russ. 3. Inorg. Chem., (Engi.  Trans.), .j, 772 (1971). 69.  N. Bartlett and D.H. Lohmann, J. Chem. Soc., 5253 (1962).  70.  J.N. Keith, 1.3. Solomon, I. Sheft, and H.H. Hyman, Inorg. Chem., 7, 230 (1968).  71.  D.E. McKee and N. Bartlett, Inorg. Chem.,  72.  P. Fischer, G. Roult, and D. Schwarzenbach, 3. Phys. Chem. solids,  73.  K.C. Lee and F. Aubke, J. Fluorine Chem.,  26  U 2738 (1973). i, 501 (1982).  32, 1641 (1971).  CHAPTER 2  GENERAL EXPERIMENTAL  2.1  Introduction  This chapter will deal with general experimental techniques, chemical sources, purifica tion procedures and the syntheses of starting materials used in this study. Specific synthetic procedures will be described in the appropriate chapters.  Since most of the compounds involved in this work are extremely hygroscopic, they had to be handled in an environment free of moisture. Hence, standard vacuum line techniques were employed for the transfer of volatile liquids, and less volatile liquids and solids were manipulated inside an inert atmosphere dry box.  All reactions were performed inside well  ventilated fumehoods.  Reactions were monitored by weight where possible, and the removal of volatile materials in vacuo was usually done at room temperature. However, where liquids with low 5 or HSO F were involved, elevated temperatures had to be used even 3 vapor pressures like SbF under vacuum conditions.  Fluorolube grease type 25-1OM (Halocarbon Corporation) was used to lubricate ground glass connections to maintain vacuum tight conditions.  2.2  Chemicals  Some chemicals were used without purification as received, and these are listed in Table  27  The other chemicals used were purified or  2.1, along with their sources and purities.  synthesized according to the methods described below.  Table 2.1: Chemicals Used Without Purification  Chemical  Source  Purity (%)  Ag, -100 mesh  Alfa  99.95  Au, -20 mesh  Alfa  99.99  Pd, -60 mesh  Alfa  99.95  Pt, -60 mesh  Alfa  99.90  Sn, -100 mesh  Alfa  99.99  ‘2  Fisher  99.9  2 CuF  Alfa  99.5  2 AgF  Aldrich  98.0  2 SnF  Matheson  98.0  6 AgSbF  Aldrich  98.0  5 AsF  Ozark Mahoning  reagent grade  HF  Matheson  reagent grade  2 SnC1  BDH  reagent grade  KJ  Fisher  99.95  2 CaH  BDH  reagent grade  H 5 NaC  Aldrich  2.0 M solution in THF  28  2.2.1  Purification Methods  (a)  , obtained from Ozark Mahoning, was purified (1) first by purging the crude liquid 5 SbF 2 through in a 500 mL two-necked Pyrex flask fitted with a of most HF by bubbling dry N gas inlet tube and Drierite guard tube. Subsequent purification was done by repeated 2 and later in vacuo. distillation, first at atmospheric pressure in a stream of dry N  (b)  , from Orange County Chemicals, was purified by double distillation in a Pyrex HSO F 3 2 at atmospheric pressure (2). The constant apparatus under a counter flow of dry N boiling fraction at 162-163°C was collected into Pyrex storage vessels.  (c)  CF from Aldrich, was purified by repeated vacuum distillation and stored in 3 HSO , Pyrex vessels for synthetic use.  (d)  5 to exclude moisture and 0 2 , from Aldrich, was stored in a Pyrex vessel containing P 2 Br . 2 KBr to remove Cl  (e)  2 for Mesitylene (1 ,3,5-Trimethylbenzene), obtained from Aldrich, was dried over CaH one week and distilled in vacuo prior to use.  2.2.2  Synthetic Methods  (a)  , was prepared in one to two kilogram quantities by F 6 0 2 Bis(fluorosulfuryl) peroxide, S 2 as carrier gas (3). 2 as catalyst and N , using AgF 2 the reaction of SO 3 and F  The  synthesis was carried out at —180°C in a flow reactor made of Monel metal (Figure 2.1). The crude liquid product was condensed into Pyrex vessels, cooled to -78°C with dry ice.  29  C  Hok. 413 Volv.  -f3-  Autoclav. Engln..rlng Valv.s  Whlt.y  Reactor  6  Copper  To Flowm.t.r  Figure 2.1:  B —7C —7WC  F 6 0 2 Apparatus for Preparing S  COLLECTION VESSELS  A 25C  F 2 Outlet  Oil Tube  Trap  To F 2 cylinder  Crosby Pressure Guoge  F was removed by intemittently 3 Most of the potentially explosive byproduct FSO warming the product to room temperature and cooling down to -7 8°C. Further purifica tion was achieved by pumping on the product overnight at -7 8°C to remove any residual F with concentrated 6 0 2 3 was removed by extracting the crude S . Unreacted SO FSO F 3 0 in a separatory funnel. A product obtained by this route may contain a small 4 S 2 H , which has no effect on the synthetic reactions, F 5 0 2 amount of disulfuryl difluoride, S F is required. 6 0 2 except where a stoichiometric amount of S  The purified colorless  liquid was vacuum distilled into large (500-1000 mL) one-part Pyrex storage vessels equipped with Kontes Teflon stem stopcocks. The purity of the reagent was checked by F-NMR spectroscopy. both JR and 19  (b)  F (4) in a long 6 0 2 2 with a slight excess of S F was synthesized by reacting Br 3 BrSO F was required to remove any unreacted 6 0 2 stem one-part Pyrex reactor. The excess S 2 from the liquid product. Br  F obtained by this method can be vacuum 3 The BrSO  distilled directly from the Pyrex vessel when required.  2.3  Apparatus  2.3.1  Reaction Vessels  One part glass Pyrex reactors of 25-100 mL capacity were used when solid products could be isolated by removing the volatiles in vacuo. These round bottom reactors were fitted with Kontes Teflon stem stopcocks and had side arms extending to B 10 ground glass cones (Figure 2.2(a)). If high pressures were anticipated during reactions, 3 mm thick-wall rather than 2 mm normal wall vessels were employed.  To facilitate the isolation of products by filtration, two-part reactors made from 50-100  31  tJ  (a)  Figure 2.2:  (b) Typical Pyrex Reaction Vessels (a) One Part Reactor (b) Two Part Reactor  50—lOOmL BO1IOM FLASKS  B—1O GROUND GLASS CONE  KONTES TEFLON STEM  B—19 GROUND GLASS JOINT  B—1O GROUND GLASS CONE  mL round bottom flasks were utilized (Figure 2.2(b)). A typical reactor consisted of a round bottom flask with a B 19 ground glass cone fitted with a “drip lip” to trap possible greasecontaminated liquids.  The corresponding adaptor top had a Kontes Teflon stem stopcock  between the B 19 socket and a B 10 cone. substituted by an appropriate equipment  -  During reaction work-up, the adaptor could be  such as a vacuum filtration apparatus, seen in Figure  2.3. The design of the filter was adopted from the one described by Shriver (5).  A Kel-F tubular reactor (Figure 2.4) was employed for syntheses involving liquid HF. The Kel-F tube (2 cm o.d. and 1.2 cm i.d.; obtained from Argonne National Laboratory, USA) was held by a Monel top adaptor equipped with a Whitey valve (type 1KS4-316) which could be fitted to a metal vacuum line.  2.3.2. SbF 5 Storage-bridge Vessel -  5 was stored in a dual purpose one-part Pyrex container as shown The purified liquid SbF in Figure 2.5. The two Kontes Teflon stem stopcocks and BlO ground glass joints made it feasible for the vessel to be attached to a glass vacuum line and a Pyrex reactor simultaneously. 5 could then be distilled directly from the storage vessel into the reactor via the side arm SbF extension.  2.3.3  F Addition Trap 6 0 2 S -  F had to be used, a 1.00 or 4.00 mL graduated pipet 6 0 2 Where exact amounts of S equipped with an overflow bulb and fitted on top with a Kontes Teflon stem stopcock was employed.  The side arm of the trap ended in a BlO ground glass cone, which could be  . Determination of the precise F 6 0 2 connected to a Pyrex T-shaped bridge for the transfer of S F used was obtained by weight difference. 6 0 2 amount of S  33  Figure 2.3:  Vacuum Filtration Apparatus  50—lOOmI ROUND BOflOM F1.ASK KONTES TEFLON STEM STOPCOCK  GLASS FRIT (MEDIUM POROSITY) B—1O GROUND GLASS CONE  B—19 GROUND GLASS JOiNT  34  Figure 2.4:  Kel-F Tubular Reactor  Whitey Valve C’2  Monel Alloy Top  m  Kel—F Tube  SC.)  2cm Copper Ferrule  Scp  Brass Nut  35  Figure 2.5:  -Storage-bridge Vessel 5 SbF  B—iC GROUND GLASS CONE  KONTES TEFLON STEM STOPCOCK  8cm  E  1) Lfl  B—iC GROUND GLASS SOCKET  36  2.3.4  Pyrex Vacuum Line  A general purpose glass vacuum line, consisting of five Kontes Teflon stem stopcocks with B 10 ground glass sockets, was used. The manifold was approximately 60 cm long, and a , was placed between the manifold and the vacuum 2 detachable safety trap, cooled with liquid N pump to protect the pump from volatile corrosive materials. Typical vacuum generated on this line was about 10.2 torr.  2.3.5  Metal Vacuum Line  For the reactions involving liquid HF, a metal vacuum line was used. It was operated in a manner similar to that of the Pyrex line. The metal manifold was constructed using 6 cm o.d. 2 Monel tubing equipped with Whitey valves (type 1KS4-316), and connected to a liquid N cooled safety trap via a Teflon adaptor.  2.3.6  Dry Atmosphere Box  Hygroscopic solids and low volatility liquids were manipulated inside a Vacuum Atmos 2 gas. The phere Corporation ?DriLabH Model DL-001 SG dry box, filled with K-grade N removal of moisture inside the dry box was accomplished by circulating the nitrogen over molecular sieves located in the “Dri-Train” Model HE-493. The molecular sieves were periodi 5 was also kept 0 2 . Fresh P 2 2 mixed with N cally regenerated by heating in a stream of 10% H inside the dry box to exclude any residual moisture.  37  2.4  Instrumentation and Methods  2.4.1  Infrared Spectroscopy  Room temperature IR spectra were recorded using three types of spectrometers: (a) Nicolet 5DX Fr-IR, (b) Perkin Elmer 1710 FT-IR, and (c) Perkin Elmer 598.  Samples were run on thin solid films pressed between AgCl or AgBr windows, with t respectively. transmission ranges down to —400 and —250 cm  The high reactivity of the  compounds studied precluded the use of mulling agents or other window materials. Samples were prepared inside the dry box and the spectra were recorded immediately after removing the samples from the box. Spectra of gaseous samples were recorded using a glass cell of 10 cm path length, fitted with AgBr windows and a Kontes Teflon stem stopcock. All spectra were calibrated with a polystyrene reference.  2.4.2  Raman Spectroscopy  Raman spectra were obtained with a Spex Ramalog 5 Spectrophotometer equipped with a Spectra Physics 164 argon ion laser, using the 514.4 nm green line as the excitation wavelength.  Solid samples were packed in the dry box into melting point capillaries,  temporarily sealed with Fluorolube grease and then immediately flame-sealed.  2.4.3  Nuclear Magnetic Resonance Spectroscopy  The FT-NMR spectra were obtained on a Varian XL-300 multinuclear spectrometer, H with the following operating frequencies and external references: (a) 1 =  =  300 MHz, TMS; (b)  282.23 1 MHz, CFC1 . The solutions were either loaded into 5 mm NMR tubes inside the 3  38  dry box or, in the case of volatile liquids, transferred via a static vacuum into NMR tubes fitted with B 10 ground glass cones and then flame sealed. Low temperature spectra were recorded by 2 and controlling the temperature with a high precision thermo cooling the probe with liquid N couple.  2.4.4  Electronic Spectroscopy  Solid state electronic spectra in the near infrared and visible regions (4,000 to 30,000 ) were recorded on a Cary 14 spectrophotometer. Samples were prepared in the dry box, 1 cm5 or Fluorolube oil as mulling agent in a Teflon cell fitted with and run as mulls in either SbF quartz windows of 2.5 cm diameter. The absorbance level was adjusted with neutral density filters.  ) were run on a 4 Nujol mull spectra in the UV-visible range (12,000 to 50,000 cm  Hewlett Packard 8452-A diode array spectrophotometer using the same Teflon Cell described above.  2.4.5  Mössbauer Spectroscopy  5n Mössbauer spectra were recorded on a constant acceleration spectrometer (6). The 119 Data counts were accumulated on a Tracer-Northern TN-1706 multichannel analyzer, linked to the mainframe computer via an IBM-PC.  nO and the 3 S 9 Ba The y-ray source used was ,  Co source. The chemi Doppler Velocity Scale was calibrated with an iron foil absorber and a 57 . 2 cal shifts were measured relative to Sn0  2.4.6  X-ray Photoelectron Spectroscopy  X-ray photoelectron spectra were recorded with a Varian IEE-15 spectrometer using Al Ka X-rays of 1486.6 eV energy. The detachable XPS sample probe was taken inside the dry  39  box where powdered samples were thinly dusted onto 2 cm length 3M Scotch tapes, which were 1 binding energy peak at 284.0 eV was used wrapped around the sample slugs. The carbon 1S as a calibrant in all the measurements. The chemical shift is taken as the difference between the measured binding energy of a peak and that of the chosen standard atomic peak for a given energy level. The accuracy of the measurements is estimated to be ±0.1 eV.  2.4.7  Magnetic Susceptibility Measurements  Variable temperature magnetic susceptibility measurements from —2.0-124 K were made using a Princeton Applied Research Model 155 Vibrating Sample Magnetometer, internally calibrated with ultrapure nickel (7).  Temperature equilibration was obtained using a Janis  Research Company Model 153 Cryostat and a Princeton Applied Research Model 152 Cryogenic temperature controller. Accurately weighed samples of --200-300 mg were loaded into Kel-F capsules inside the dry box and sealed with epoxy resin.  Temperature measurements were taken with a chromel vs. Au-0.02% Fe thermocouple, located in the sample holder immediately above the sample. The thermocouple was calibrated using the known susceptibility vs. temperature behavior of tetramethylethylenecliammonium tetrachiorocuprate (II) and checked with mercury tetrathiocyanatocobaltate (II).  From the  scatter in data points of four different calibrations, the temperatures are estimated to be accurate to ±1% over the range studied.  Thermocouple potentials were measured using a Fluke 8200A  digital voltmeter. Magnetic fields of 7501, 9225, and 9625 G were employed, and set to an accuracy of 0.5%, and measured with a F.W. Bell Inc. Model 620 Gaussmeter. The accuracy of the susceptibility values is estimated to be ±1%.  A Gouy balance, equipped with a Mettler AE 163 balance was used in the temperature range —80-300 K to measure the susceptibility of some compounds. Samples were packed in a  40  Pyrex tube containing an air-tight Teflon cap.  Measurements were made in a nitrogen  4 was again used as a calibrant. The atmosphere at a field strength of 8000G and HgCo (NCS) accuracy of the susceptibility values obtained by this method is estimated as ±5%. Corrections were made for the diamagnetic contribution of the holders and the molar susceptibilities were SO 40; F : 3 31 mol) corrected for diamagnetism using the following values (8) (units of 10-6 cm 2 61; 1 149; AsF Sb 1 F 6 72; O 6 218; 2 1 F 3 6 80; Sb CF 46; SbF 3 S0 2 7; Br  2 11; 89; Ni  2 24. 4 18; Cu 2 25; Pd Pd 2 11; Ag  2.4.8  X-ray Powder Diffractometry  X-ray powder diffraction patterns were obtained using a RU 200B series Rigaku Rotating Anode Diffractometer operating at 12 KW maximum power output. The Diffracto meter detected Cu Ka target radiation through a 200 urn nickel filter with a horizontal-type Nal Scintillator probe. A horizontal goniometer was used for the rotating anode. The diffractometer was interfaced with a DMaxIB computer system driven by an IBM PS/2. The peak-finding program was provided by Rigaku.  Finely powdered samples were put on two sided 3M Scotch tapes attached to glass slides and protected from moisture by sealing the samples with plastic film. All preparations were carried out inside the dry box and samples were analyzed as soon as they were removed from the dry box.  2.4.9  Differential Scanning Calorimetry (DSC)  DSC studies were performed using a Mettler DSC-20 cell interfaced with a Mettler TC1O TA processor and a Swiss Matrix printer. Finely powdered samples of approximately 2 flow 2-4 g were sealed into aluminum pans and mounted on the measuring cell, under a dry N  41  rate of 50 mI/mm. The samples were scanned through a temperature range of 35 to 450°C with 4°C per minute increments.  2.4.10 Elemental knalyses  Carbon, hydrogen and some of the sulfur analyses were performed by Mr. Peter Borda of this Department. All other elemental analyses were carried out by the Analytische Laboratorien, Gummersbach, Germany.  References  1.a) b)  W.W. Wilson and F. Aubke, J. Fluorine Chem., 13, 431 (1979). W.W. Wilson, R.C. Thompson, and F. Aubke, Inorg. Chem., j, 1489 (1980).  2.  J. Barr, R.J. Gillespie, and R.C. Thompson, Inor. Chem., , 1149 (1964).  3.a)  J.M. Shreeve and G.H. Cady, Inorg. Synth., 2, 124 (1963).  b)  G.H. Cady, Inorg. Synth., 11, 155 (1967).  4.  F. Aubke and R.J. Gillespie, Inorg. Chem., 2, 599 (1968).  5.  D.F. Shriver, “The Manipulation of Air Sensitive Compounds”, McGraw Hill Book Co., New York, 1969.  6.  J.R. Sams and T.B. Tsin, Inorg. Chem., .14, 1573 (1975).  7.  J.S. Haynes, K.W. Oliver, S.J. Rettig, R.C. Thompson, and J. Trotter, Can. J. Chem., 62, 891 (1984).  8.  Landolt-Börnstein, Numerical data and functional relations in Science and Technology, Vol. 2, Magnetic properties of coordination and organometallic compounds, SpringerVerlag, Berlin, 1966.  42  CHAPTER 3  , 2 ) 6 METAL(1I) HEXAFLUORO ANTIMONATES M(SbF M(ll)  3.1  =  Sn(J1), Ni(I1), Pd(II), Cu(ll) AND Ag(H)  Introduction  , is commonly regarded as the strongest molecular Lewis 5 Antimony(V) fluoride, SbF 1 are extremely weak nucleophiles 1 F 2 6 and the related Sb acid (1). Conversely the anions SbF (2), capable of stabilizing a wide range of electrophilic cations, both in solid compounds and in 5 superacid solution (3). HF-SbF  6 salts formed The objective of this study was the synthesis and characterization of SbF by divalent metal cations. The synthetic route chosen was the solvolysis of metal fluorosulfates 5 according to the general route: in liquid SbF  ) 2 F 3 M(SO with M  =  +  5 6SbF  25-60°C >  M(SbF  +  ) SO 3 ( 9 F 2 2Sb F  [3.1]  Sn, Ni, Pd, Cu, or Ag.  Early work by Gillespie and Rothenbury (4), and a subsequent investigation by our group (5) into the antimony-fluoride-fluorosulfate system, form the basis for this synthetic reaction. O which is the most volatile component in this system, facilitates the 3 S 9 2 Sb The byproduct F F- group from the reaction mixture. 3 ready removal of the SO  5 have As mentioned previously in Chapter 1, initial uses of the solvolysis reaction in SbF + (6), a series of triatomic inter2 involved the stabilization of non-metallic cations, such as C10  43  2 and I2 (8) (see Chapter 4) in solid halogen cations (7), or the dihalogen cations Br SbF (9) and 8 C compounds. Use of this method in the synthesis of the first stage graphite salt 6 Sn(Sb 1)2 (10) illustrate its versatility. 2 ) 3 (CH 1 stabilization of the dimethykin(IV) cation as F  There has been a variety of alternative methods used for the synthesis of hexafluoro antimonates of divalent metals, and  two  2 (11,12) ) 6 of the compounds discussed here (Ni(SbF  2 (13)) had been prepared when this study was started. All methods have the use ) 6 and Sn(SbF of SbF 5 in common, even though the routes  vary.  Metal oxidation either by elemental fluorine  2 ) 6 2 solution has allowed the synthesis of Ni(SbF& 5 in SO or by SbF 2 (11,12) as well as Fe(SbF 2 (12). However, there ) 6 and Mn(SbF oxidation states  are  are  obvious limitations to this approach. Where higher  accessible, direct fluorination may result in oxidation beyond the +2 state,  unless the reaction conditions  are  5 well understood and carefully controlled. Oxidation by SbF  fails for metal with higher oxidation potentials than provided for by the Sb(V)/Sb(III) couple bF may prove to 5 S 3 SbF (Appendix A-i). Quantitative separation of the reduced product, solid , ) (12) may form instead. 6 be difficult, and mixed fluoride-hexafluoroantimonates like CoF(SbF  2 by SbF 5 in SO 2 or anhydrous HF may be a more versatile Fluoride abstraction from MF 2 lattice could be synthetic method (13,14), but here another problem surfaces: the MF incompletely broken up under the reaction conditions.  This can lead to the formation of  , and consequently chemical analysis becomes 2 ) 6 1 i)’ a structural isomer of M(SbF F 2 MF(Sb 6 in these compounds, vibra 6 to coordinated SbF inconclusive. When moving from ionic SbF tional spectra become more complex and are less readily interpreted.  As a consequence,  SbF is employed in a recent publication for materials obtained in this 5 2 2 formulation as MF manner (14).  There is a fair amount of evidence for the existence of cations of the type [MFI+, 6 is used as a counter anion (15,16), and a crystal structure , and [MF1 when AsF [M j 3 F 2  44  6 as counter anion. In sF (17) shows a chain-type cation [AgF] with AsF 5 A 2 obtained on AgF 2 appears to be present and the crystal structure supports its SbF however, a true Ag 5 2 2 AgF 2 (14). ) 6 formulation as Ag(SbF  5 solvolysis method as a viable ) excess SbF 2 F 3 M(SO The advantages of using the synthetic route to metal(II) hexafluoro antimonates are summarized below:  (i)  , 2 2 or NiC1 ) precursors are readily available either from the solvolysis of SnC1 2 F 3 M(SO F (18), or 3 or the corresponding Ni(ll) or Cu(II) benzoates or other carboxylates in HSO F) (20). 3 Ag(SO F) (19) and 2 3 Pd(SO F in the case of 2 6 0 2 by the use of S  (ii)  5 appears unlikely, since higher oxidation states In all instances further oxidation by SbF for the metals cannot be achieved with the potential provided for only by the Sb(V)/Sb(ffl) couple.  (iii)  SO F Vibrational spectra allow monitoring of the reaction by probing the absence of 3 , whereas 1 6 appear below —750 cm vibrations. All the vibrational bands due to SbF F stretching vibrations are present well above this value (see Appendix A-2). 3 SO  (iv)  Reactions can be carried out under mild conditions in glass vessels and followed by weight. This also facilitates detection of any color changes that may occur during the reaction process.  2 compounds for this ) 6 The reasons for the preparation and selection of these five M(SbF study, with M  (i)  =  Sn, Ni, Pd, Cu, or Ag are two-fold:  To avoid structural ambiguities of the type observed above, it became necessary to  45  2 prepared by a different ) 6 Sn Mössbauer spectrum on a sample of Sn(SbF obtain a 119 route and to compare it to the spectrum reported previously (13). Furthermore, it was 6 and Sb 11 anions allow a close approach to the true F 2 found previously that the SbF Sn cation (10) on account of their low nucleophilicity. The same anions, it is 2 ) 3 (CH Sn2 cation. In both instances, 119 felt, also permit the closest approach to a true Sn Mdssbauer spectroscopy can be effectively employed.  (ii)  Significant ferromagnetism was observed at low temperature in the fluorosulfates of 2 and Ag Pd 2 (Chapter 6, also ref. 21) with a weaker manifestation of this interesting ) compound. 2 F 3 coupling phenomenon seen also in the analogous Ni(SO  However,  ) compound is magnetically dilute to low temperatures (see 2 F 3 surprisingly the Cu(SO Chapter 6). Therefore it is of interest to study the magnetic properties of the four cor 6 derivatives at temperatures below 80 K. responding transition-metal SbF  2 had been obtained previously by all three methods (11,12,14) discussed ) 6 Since Ni(SbF 5 is viewed as a test case. A final point of inter above, its formation by solvolysis in liquid SbF est concerns the nickel(II) and palladium(ll) compounds.  2 ions in the 2 and Ni The Pd  , Pd + fluorosulfate are located in an octahedral coordination environment which is unusual for 2 ) 2 F 3 and as a result paramagnetic Pd(ll) and Ni(11) with 3 A2g ground state is found in both Ni(SO ) It is expected that similar paramagnetic ions are present in the corresponding and . 2 F 3 Pd(SO 2 compounds as well. ) 6 2 and Pd(SbF ) 6 Ni(SbF  3.2  Experimental  3.2.1  2 ) 6 General Synthetic Scheme to M(SbF  ) (19), ) (18), Pd(SO 2 F 3 2 F 3 ) (18), Sn(SO 2 F 3 ) (18), Cu(SO The fluorosulfates Ni(50 2 F 3  46  and Ag(SO 2 F 3 ) (20) were all synthesized according to published methods.  A general synthetic method was applied to the solvolysis reactions in liquid SbF . 5 Approximately 500 mg of the M(SO 2 F 3 ) compound was transferred inside the inert-atmosphere box into a preweighed reaction vessel, and -P10 mL of freshly purified SbF 5 was added subsequently by vacuum distillation.  The reaction vessel was warmed up, initially to room  temperature, and subsequently to 50-60°C in an oil bath. Detailed temperatures and reaction times are given below.  Only the reactions of Pd(SO 2 F 3 ) (purple —  yellow-green  —>  —>  light-grey) and Ag(SO 2 F 3 ) (black-brown  off-white) involved perceptible color changes of the solid reactant and the  mixture remained heterogeneous throughout. The initially very viscous antimony(V) fluoride became less viscous after about 24 h and the mixture could be stirred effectively with a magnetic stirrer. Volatiles were removed in a dynamic vacuum. A sample of Ni(SbF , made 2 ) 6 from Ni and SbF 5 by fluorinating with F 2 (11), was obtained from Dr. Karl 0. Christe of Rocketdyne, U.S.A.  3.2.2  Physical Properties and Analyses  Both Ni(SbF 2 (11,12,14) and 6 ) 6 Sn(SbF (13) are known compounds. Their identities 2 ) were ascertained by weight and by infrared spectroscopy. Formation of both Ni(SbF 2 and ) 6 2 required reaction times of 14 and 2 days at 60 and 50°C, respectively. ) 6 Sn(SbF  The JR  frequencies observed for Ni(SbF 2 are listed in Table 3.1. For Sn(SbF ) 6 2 the following JR ) 6 bands were found (estimated intensities are in parentheses): 700 (s, sh), 678 (s), 648 (s), 620 (m), 595 (ms), 571 (ms), 520 (m, sh), 477 (m), 432 (w).  47  3.2.2a Cu(SbF 2 ) 6  Reaction time 10 days, reaction temperature 50°C, white hygroscopic solid that is thermally stable up to 210°C. 2 Cu, 11.88; Sb, 45.51; F, 42.61%. : 1 F 2 Anal. Calcd. for CuSb Found: Cu, 11.65; Sb, 45.75; F, 42.47. Total: 99.87%.  3.2.2b Pd(SbF 2 ) 6  Reaction time 14 days, reaction temperature 50°C, light-grey solid, very hygroscopic and thermally stable up to 250°C. 12 Pd, 18.62; Sb, 42.14; F, 39.45%. F 2 PdSb Anal. Calcd. for : Found: Pd, 18.35; Sb, 41.90; F, 39.18. Total: 99.43%.  2 ) 6 3.2.2c f-Ag(SbF  Reaction time 10 days, reaction temperature 25°C, creamy white, hygroscopic solid, melts at 180-182°C to clear liquid. 11 Ag, 19.25; Sb, 43.45; F, 37.25%. F 2 AgSb Anal. Calcd. for : 12 Ag, 18.62; Sb, 42.03; F, 39.35%. F 2 AgSb Calcd. for : Found: Ag, 18.65; Sb, 42.30; F, 39.06. Total: 100.01%.  3.2.3  2 ) 6 Alternate Synthetic Route to 3-Ag(SbF  6 and 2 using the silver compounds AgSbF ) 6 Two other preparative methods for 3-Ag(SbF 2 as precursors are shown below: AgF  48  a)  F at room temperature. 6 0 2 6 was allowed to react with an excess of S 0.323 g of AgSbF 6 changed immediately from white to black-brown. The color of AgSbF  The excess  . The 5 F was removed in vacuo and subsequently replaced by an excess of SbF 6 0 2 S mixture was kept at room temperature for 2 days, then heated at 60°C for 2 h. A white 5 in vacuo 2 was isolated by removing the excess SbF ) 6 solid of the composition Ag(SbF and identified by its JR spectrum.  b)  2 was loaded inside the dry box into a Kel-F reactor together 0.436 g (2.99 mmol) of AgF . About 6.5 mL anhydrous HF was distilled into this 5 with 4.50 g (20.8 mmol) of SbF mixture in vacuo. After warming to room temperature under magnetic stirring, a lightyellow solid formed immediately.  The solution’s initial color was light blue, which  faded quickly. Removal of all volatiles yielded again a compound corresponding to the 2 as a cream-colored solid. ) 6 composition Ag(SbF  3.3  Results and Discussion  3.3.1  Synthesis  As noted previously (6-10), solvolysis reactions of fluorosulfates in a large excess of 5 proceed smoothly and frequently without any color change of the solid reactant. Hence, SbF rather long reaction times are chosen to ensure complete conversion. Two indications that a 5 after about one day, and a reaction takes place are a noticeable decrease in the viscosity of SbF slight increase in the vapor pressure above the reaction mixture. Both observations may be ) (7). (SO 9 F 2 Sb F attributed to the formation of 3  To reduce the viscosity even further in order to stir the heterogeneous mixture more effectively, slightly elevated reaction temperatures are chosen.  49  Removal of all volatiles  proceeds easily in a dynamic vacuum, with the reaction flask at room temperature.  2 is ) 6 It is noteworthy that after pumping overnight, the correct weight for M(SbF obtained. Previous use of this synthetic method (6-8,10) had in all instances led to products 16 For the F 3 Sb , and in one case (8) even by . Sb f 1 F where molecular cations are stabilized by 2 + cations, SbF 2 6 appears to be the more suitable counter anion spherical, less electrophilic M allowing formation of layered materials, as discussed below.  In any event, neither product  weights on isolation, nor chemical analyses, nor vibrational spectra give any indication of 1 F 2 Sb  containing intermediates or by-products.  2 (13) are identified by their ) 6 2 (11) and Sn(SbF ) 6 Of the resulting compounds, Ni(SbF 2 ) 6 Sn Mössbauer spectrum of Sn(SbF weights and their previously reported IR spectra. The 119 shows a single broad line  (r’  =  1.35 mm s ) caused by unresolved quadrupole splitting. The 1  , in excellent agreement with the previously 2 1 relative to Sn0 isomer shift is found at 4.39 mm s reported value (13).  ) is expected to lead to the recently reported blue form of 2 F 3 The solvolysis of Ag(SO 2 in HF are deep blue in color. The X-ray diffraction study 2 since solutions of Ag ) 6 Ag(SbF 2 ion in a distorted octahedral environment (14). However, in this study had revealed a true Ag the course of the solvolysis and the final product obtained are unanticipated. The initial black F) quickly disappears and a greenish-blue solid slowly changes to yel 3 Ag(SO brown color of 2 low in color. Ultimately a cream-colored, diamagnetic solid is isolated, which melts at -480°C without decomposition to a clear, colorless liquid.  The magnetic behavior, the color, and the observed lack of solubility in anhydrous HF (22) suggest the possible presence of univalent silver in the resulting yellow compound. An 11 is, however, not supported by the F 2 alternative formulation of the reaction product as AgSb  50  weight change during reaction, a complete chemical analysis (see experimental section), the vibrational spectrum, or the chemical behavior of the material. Furthermore, with paramagnetic , can 5 ) (20), the other reactant, the Lewis acid SbF 2 F 3 divalent silver well established in Ag(SO hardly be regarded as a reducing agent. A possible reductive decomposition of the reaction ) is the only volatile product (SO 9 F 2 Sb F , 3 5 product appears unlikely, since besides excess SbF formed during the reaction process.  2 is not consistent with the presence of Ag ) 6 The chemical behavior of the white Ag(SbF Unlike other silver(I) salts, the material will not undergo further  in the reaction product.  . HSO F F in the presence or the absence of 3 6 0 2 oxidation by S  6 is In contrast, AgSbF  F alone, to give a black-brown solid, with an increase in weight 6 0 2 immediately oxidized by S ). (SO 3 ) 6 Ag(SbF consistent with the composition F  Subsequent solvolysis of this material in  F) suggesting a viable alter 3 Ag(SO , 5 proceeds in an identical manner to the solvolysis of 2 SbF . 2 ) 6 native synthetic route to the white diamagnetic Ag(SbF  Strong evidence for the presence of silver in an oxidation state higher than +1 comes 2 in aqueous KI solution. ) 6 from the hydrolysis of Ag(SbF  The reaction proceeds very  vigorously and ‘2 and 02 (where the latter evolves with rapid bubbling) are produced. Forma tion of 2 may in part be due to oxidation by Sb(V) in an acidic environment (23), but evolution of 02 can only be caused by Ag(II) or Ag(llI) ((24), also Appendix A-i):  2 2Ag  +  0 2 H  —÷  2Ag  +  2W  +  1/202  [3.2]  and 2 Ag  +  2K1  —  AgI  +  1/212  +  [3.3]  2K  In summary, all evidence suggests that the material obtained in the solvolysis of  51  2 ) 6 J3-Ag(SbF a valence isomer of the previously reported a-Ag(SbF , 2 ) 5 is 6 ) in SbF 2 F 3 Ag(SO (14).  Attempts were made to synthesize the a-form using the published method (14), where 5 in anhydrous HF according to: 2 was reacted with SbF AgF HF 2 AgF  +  5 2SbF  >  [3.41  Ag(SbF  AgF 2 : 5 5 (ratio SbF These syntheses are only partialiy successful if a slight excess of SbF  =  2.32)  2 forms in ) 6 over the stoichiometric amount is used. Even here a fair amount of solid -Ag(SbF 2 is obtained by slow evaporation ) 6 addition to a blue solution, from which crystalline a-Ag(SbF AgF 2 : 5 5 is used (SbF of the volatiles. When a larger excess of SbF  =  2 is the ) 6 6.01), -Ag(SbF  only product. The blue color of the HF solution quickly fades within an hour. Removal of the . 2 ) 6 5 yields pure 3-Ag(SbF HF and the excess SbF  2 in HF represents an acid-base titration with both ) 6 It seems that formation of a-Ag(SbF the cation  0 l) 5 ( 2 Ag  2 stable in, and isolable from, anhydrous and the final product a-Ag(SbF  HF. Similar behavior is reported for all other transition-metal hexafluoro antimonates of the 2 is insoluble in anhydrous ) 6 SbF type (14). On the other hand, p-Ag(SbF 5 2 2 2 or MF ) 6 M(SbF HF,  suggesting  structural differences.  The observed diamagnetism of the compound is best explained by assuming a mixed. To account for the diamag 4 ) 6 oxidation-state compound of the composition Ag(I)Ag(Ill)(SbF 3 should be in a square netism, Ag  planar,  or at least in a tetragonally elongated, octahedral  environment while Ag+ would be located in a tetragonally compressed, nearly linear coordina tion environment. Argentic oxide, AgO, represents a precedent, according to neutron diffraction studies on this compound (25). The black-brown color, also found for the recently reported  52  4 (24), is seemingly common to binary oxides and oxysalts of di0 3 3 (26) and Ag 0 2 oxides Ag ) (20) or ) 2 F 3 CF (27), and may possibly 3 Ag(SO 2 or trivalent silver, e.g. the sulfonates Ag(SO  ] 4 be due to a charge transfer transition (28). In contrast, alkali metal salts containing the [AgF AgF and many Ag(ffl) fluoro derivatives are blue ion are reported to be yellow (25,29), while 2 2 (14). ) 6 (30), just like a-Ag(SbF  It appears, then, that all the observations mentioned above support formulation of the F is not 6 0 2 ; however, the inability to oxidize Ag further with S 4 ) 6 [3-form as Ag(I)Ag(Ill)(SbF consistent with an ionic formulation as silver(I) tetrakis(hexafluoroantimonato)argentate(Ill), . Ag[Ag(SbF ] 4 ) 6  No report has been published so far of any other valence isomeric pair of the Ag(II) vs. 2 (25), but a true Ag(I)Ag(ITI) type. The above mentioned AgO is reported to be Ag(I)Ag(llI)0 4 (24) shows both 0 3 Ag(ll)O appears to be still missing. However, the crystal structure of Ag Ag(ll) and Ag(III) in square planar coordination sites, and mixed oxidation-state compounds of F (19), are known for palladium, the neighbor 3 , with X F (31) or SO 6 the type Pd(II)Pd(IV)X 3 so far unknown. Little is known, at least with regard ing element in the 4d series, with Pd(llI)X 3 (32). The mixed valency for to structure, about the paramagnetic red-brown compound AgF 6 has been proposed but the product may still contain some impurities (33). mula Ag(II)Ag(IV)F  2 may be ) 6 Observations made during the course of this study suggest that a-Ag(SbF irreversibly converted to the [3-valence isomer. This conversion occurs at room temperature, if 5 is present in an excess, either in the presence or absence of HF. It is therefore not surpris SbF 5 in anhydrous 2 and SbF 2 from AgF ) 6 ing that all the attempts made to synthesize pure a-Ag(SbF 2 as well, as an insoluble precipitate in addition to the blue solution. ) 6 HF (14) produce [3-Ag(SbF Removal of the solvent at -7 8°C in a dynamic vacuum affords a mixture of the two valence isomers.  53  Heating the isomeric mixture allows transformation to the pure [3-form. Following this conversion by differential scanning calorimetry indicates two endothermic events, a sharp peak at 100°C, and a broad peak at 139-140°C. The latter peak coincides with the melting point, where a colorless liquid forms. The [3-form melts at —180°C, consistent with differential scan ning calorimetry. Absence of the peak at 100°C suggests interpretation of this thermal event as a phase transition from a-Ag(SbF 2 to [3-Ag(SbF ) 6 . 2 ) 6  It seems likely that electron transfer between two Ag 2 ions to give Ag and Ag 3 is mediated by an antimony(V) fluoro species (SbF 5 or SbF ). Considering the observations made 6 regarding the relative stability of the two valence isomers, it is surprising that [3-Ag(SbF 2 has ) 6 not been reported while the a-form has.  The solvolysis of 2 F) in SbF 3 Pd(SO , on the other hand, does not appear to change the 5 electronic structure of the Pd 2 ion (31,34). The electronic spectra and magnetic susceptibility data clearly show that in Pd(SbF , the palladium ion, like in its parent compound, remains as a 2 ) 6 paramagnetic Pd 2 species.  However, in Cu(SbF , the solvolysis product of , 2 ) 6 2 F 3 Cu(SO )  identification of all the copper ions as purely divalent may not be possible. Magnetic measure ments taken on Cu(SbF 2 also indicate, as in the case of [3-Ag(SbF ) 6 , mixed valency although 2 ) 6 to a more limited extent. This is discussed in more detail in Section 3.3.4, which deals with magnetic studies.  It is of interest to note here that this solvolysis behavior leading to unexpected mixed valent products is exhibited by the two transition metal precursor compounds Cu(SO 2 F 3 ) and 2 F 3 Ag(SO ) with HJahnTeller ions”, i.e. Cu 2 and Ag 29 (d ) .  54  3.3.2  Vibrational Spectra  The infrared spectra obtained for Ni(SbF , Pd(SbF 2 ) 6 , Cu(SbF 2 ) 6 , and -Ag(SbF 2 ) 6 , 2 ) 6 together with the Raman spectra for the last two compounds, are summarized in Tables 3.1 and 3.2.  Also included are the previously reported Raman spectra for Ni(SbF 2 (11) and ) 6  2 (14) as well as an approximate band description, also proposed previously (11). ) 6 a-Ag(SbF However, this description pertains only to the Ni , Pd 2 , and Cu 2 2 compounds in Table 3.1. The Raman spectrum of [3-Ag(SbF 2 is illustrated in Figure 3.1. Attempts to obtain a Raman ) 6 spectrum of Pd(SbF 2 result in partial sample decomposition. Apparently the excitation line of ) 6 the Ar laser falls within  2 ii  of the electronic spectrum of Pd(SbF . 2 ) 6  Agreement with the JR and Raman spectra previously reported for Ni(SbF 2 (11) is very ) 6 good with only a minor exception: an JR band at 585 cm 1 attributed to  out of phase for  bridging SbF 3 group is not observed in this study. This band does not have a counterpart in the Raman spectrum, and may be spurious. The band description in Table 3.1 has been amended slightly. There is only a partial comparison possible with the vibrational spectra reported for 5 2 2 NiF SbF (14).  The limited  number of bands listed,  six Raman and four JR bands  with five non-coincidences, suggests an incomplete listing. Nevertheless, the Raman bands reported for 5 •2SbF (14) are all observed with similar relative intensities in the Raman 2 NiF spectrum of Ni(SbF 2 (11). Since the reported X-ray powder data have the principle lines in ) 6 common (11,14; see also Appendix A-3), it is reasonable to conclude that the two compounds are identical.  This is possibly not the case for Cu(SbF 2 reported here, and CuF ) 6 5 2 2 SbF (14). Very intense Raman and IR bands at 725 cm 1 (see Table 3.1) are apparently not observed for 5 2 2 CuF SbF (14). However, the case for polymorphism as evidenced by magnetic measure ments (see Section 3.3.4) is by no means as strong as in the case of the two forms of Ag(SbF . 2 ) 6  55  =  335m,sh —300w 285 w  330w 310w 295 w  (5)  (24)  (25)  (3)  322  308  299  272  Ref. 14  b)  symmetric, t = terminal, b = bridging  1 1 and shoulders at 172, 146, and 130cm Additional bands at 246, 220 and 198 cm  =  very, sh, = shoulder,  465 m  a)  b = broad, as = asymmethc, sym  =  295 (26)  345 m  350 w, sh  (0+)  348  weak, v  305 (19)  522 ms  521 mw  (2)  511  medium, w  335 (11)  550 w,sh  560 w,sh  =  395 (7)  556 ms  570 m  573 s  (2)  568  strong, m  592 (8)  617m  615ms  621 m,sh  (5)  618  =  620 (4)  633 m  630 m  631 m  Abbreviations:  671 (100)  665 m  667 ms  672 m  (100)  674  496 m  t in phase 3 1SbF  709 (18)  672 s  698 s  710 vs  (44)  710  270 (29)  450 (8)  Sb-F deformation modes  M”F-Sb stretching  ’ in phase 1 3 l)SbF  SSbF in phase l.) b 3  ’outofphase 3 l)SbF  b out of phase 3 asSt  t out of phase 3 lJSbF  721 (70)  707 vs, b  716 vs  721 s, sh  (12)  717  657 (22)  t in phase 3 lJasSbF  725 (65)  729 s  730 s, sh  738 vs  l)asSb1 out of phase ’ 3  =  Ni, Pd or Cu  for M(SbF ;M 2 ) 6  mt.  Al) [cm] 1  Approximate Band Description  2 Ra ) 6 Cu(SbF  (1)  s  1) [cm] Tnt. 1  1) [cm 1 Tnt.  mt.  ] 1 1) [cm  2 IR ) 6 Pd(SbF  2 IR ) 6 Ni(SbF  2 IR ) 6 Cu(SbF  2 ) 6 , Pd(SbF 2 ) 6 , and Cu(SbF 2 ) 6 Vibrational Spectra of Ni(SbF  742  ] Tnt. 1 Al.) [cm  ) Ra.b) Ni(SbF a 2 ) 6  Table 3.1:  719 s,sh 692vs 673 s 654 s  (12) (33) (100) (93) (30)  (16)  720sh 700sh 682 659 651 sh  600  526  365  a)  (18)  Ref. 14.  290•  283s 278 s  301 sh 290  (37)  368mw  (1)  312sh (13) 303 (32)  (20)  552  515vw 490ms  (4)  357w,sh  (37) (31)  600 580  mt.  602m  j 1 M)[cm  (100) (75)  mt.  1 f  2 Raa) ) 6 (X-Ag(SbF  668 658  ] 1 t\D[cm  ] 1 )[cm  2 JR ) 6 -Ag(SbF  554w 496w  583w  668 ms 640 m  692 vs  1 1)[cm  mt.  2 IRa) ) 6 C-Ag(SbF  2 ) 6 Vibrational Spectra of the Two Valence Isomers of Ag(SbF  mt.  2 Ra ) 6 -Ag(SbF  Table 3.2:  SbF deformation  MFSb stretching  SbFb stretching  SbF’ stretching  Approximate Band Description  Figure 3.1:  2 ) 6 Raman Spectrum of -Ag(SbF  682 659  65! 303  700  750  700  650  600  290  312  600  550  500  450  1 v, cm  58  400  350  300  250  2 compounds facilitates a discussion of ) 6 The available structural information on M(SbF type layer structure is proposed for CdC1 the vibrational data shown in Table 3.1. A common 2 2 from the ) 6 , based on X-ray powder diffraction data (11), and evident for a-Ag(SbF 2 ) 6 Ni(SbF 2 is deduced, ) 6 X-ray single crystal diffraction study (14) (Figure 3.2). The structure for Ni(SbF 2 into every second, nearly 6 structure (35) by placing Ni starting from the well known LiSbF 2 is situated in a tetragonally elongated octahedral , Ag 2 ) 6 octahedral Li site (11). In a-Ag(SbF site (Figure 3.2(c)), resulting in almost square planar coordination, similar to the coordination in 2 (36). SbF AgF 6 acts as a thdentate bridging group (Figure 3.2(b)), with the bridging fluorines, Fb, and the terminal fluorines, Ft, in fac-octahedral positions.  Unlike the SbF ’ unit, the 1 3  t trigonal pyramid is remarkably regular with two dsb..Ft --1.836 3 corresponding SbF  A and one  slightly longer at 1.846 A.  2 by Christe et al. (11), adopted here in this ) 6 The vibrational assignment for Ni(SbF SbF stretching modes found above —660 cm t 1 and study, suggests a useful subdivision into 3 ) below —635 cm SbF t 3 . Each set is further divided into symmethc and asymmetric in-phase 1 , is that the SbF t SbF and 3 b and out-of-phase modes. The basic difference between both sets, 3 -layer 2 ) 6 former belong to a filled, and the latter to an unoccupied octahedral hole in the M(SbF structure.  2 with M ) 6 The data summarized in Table 3.1 for M(SbF  =  Ni, Pd, and Cu, show indeed a  2 not ) 6 common group of four strong vibrations, some small band splittings for Cu(SbF withstanding, which are assigned as SbFt vibrations. Most prominent among them is a Raman , which is clearly the strongest band in the respective spectra. Interestingly, 1 band at —670 cm 2 compounds with M ) 6 this band is found as well for a number of additional M(SbF  =  Mg, Zn,  Fe, Co, and Cu (14), in the same position, and always of the highest intensity. This is not unexpected, since the reported X-ray powder diffraction data had indicated the existence of two structurally related triads, consisting of the hexafluoro antimonates of Mg, Zn, and Ni, and those  59  Figure 3.2:  2 (Ref. 14) ) 6 Crystal Structure of cz-Ag(SbF  ] anion 6 (b) ORTEP view of [SbF  (a) The Unit Cell  F(3)  (c)  2 environment ORTEP view of Ag  60  of Fe, Co, and Cu (14). However, the structural differences between the two triads appear to be USbF bands. In the Raman data, t so small that they do not seriously affect the positions of the 3 t stretching mode, which suggests 3 1 band is attributed to a symmetric in-phase SbF the 670 cm L grouping in both triads as well as in Cu(SbF 3 2 reported in this work. A ) 6 a common SbF corresponding IR band of medium intensity is observed in all instances as well. This band is . 1 2 at 667 cm ) 6 found for Pd(SbF  In addition, there is a close correspondence between  2 in both JR band positions and intensities to suggest isostructural ) 6 2 and Pd(SbF ) 6 Ni(SbF compounds.  2 compounds reported by Gantar et al. (14) with M ) 6 The remaining M(SbF  =  Cr, Pb, and  Cd, differ slightly in both vibrational spectra and X-ray powder diffraction data. The highest . Even for these compounds, as for all the 1 intensity Raman band is now found at about 650 cm 2 is suggested. None of the vibrational data reported here or ) 6 others (14), formulation as M(SbF 1 by comparison to , 1 F 2 published previously (11,14) suggest the presence of the anion Sb published precedents (13,37,38).  2 in Table 3.2 show interesting ) 6 The vibrational data for both forms of Ag(SbF t region, at 3 differences. Both have two very intense Raman bands, rather than one, in the uSbF 1 for the f3 form (see Figure 3.1). In 2 and at 682 and 659 cm ) 6 668 and 658 cm’ for a-Ag(SbF each case the band with the largest Raman shift also has the highest intensity, and yet in spite of , there appears to be some structural similarity 2 ) 6 the incomplete band listing for a-Ag(SbF between the two forms. Only a rather general band description is suggested, because there may , while the listing for the a-form appears, as stated above, 2 ) 6 be some band overlap for 3-Ag(SbF to be incomplete.  2 with all tetragonally elongated ) 6 The distorted layer structure formed for a-Ag(SbF , and concommitant tetragonally compressed, vacant sites 2 octahedral holes occupied by Ag  61  (14) provide a suitable model for the valence isomer as well. Regular occupation of half of the 3 would allow retention of the compressed holes by Ag and half of the elongated holes by Ag Ag square planar coordination. Conversely, + layer structure, where Ag achieves linear and 3 two types of vacant sites are formed with two sets of SbFt vibrations and different band positions for the SbFb stretching modes as well, consistent with observations.  3.3.3  Electronic Spectra  Electronic mull spectra were recorded for the nickel and palladium hexafluoro ) and 2 F 3 antimonates, and it appears based on these spectra that the solvolysis of Ni(SO 2 and Pd 2 ions. 5 does not lead to a change in the electronic structures of Ni ) in SbF 2 F 3 Pd(SO , like their precursors, are paramagnetic 2 ) 6 2 and Pd(SbF ) 6 The resulting compounds Ni(SbF (Section 3.3.4). It is therefore not surprising that the magnetic results and the vibrational spectra . 2 ) 6 2 and Pd(SbF ) 6 point to octahedrally coordinated Ni(ll) and Pd(II) in Ni(SbF  These two compounds show similar three-band electronic spectra, which can be attributed to d-d transitions. Although no extinction coefficients were obtained to support the assignment due to the insolubility of the compounds in a suitable solvent, it seems that the ligand field parameters Dq and B derived from such an assignment are very reasonable, particularly in comparison to the reported Dq and B values of the two parent compounds F) (19). 3 Pd(SO ) (39) and 2 2 F 3 Ni(SO  8 ion in an octahedral ligand field is 3 The electronic ground term for a d A2g and three spin allowed d-d transitions to the excited triplet-terms are expected. The energy level diagram for a d 8 ion in an octahedral field is given in Fig. 3.3. The band positions of the observed , Pd(SbF 2 ) 6 , 2 ) 6 electronic spectra and the calculated ligand field parameters of Ni(SbF ) (19) are listed in Table 3.3. It seems that the agreement in band 2 F 3 ) (39) and Pd(SO 2 F 3 Ni(SO  62  Figure 3.3:  2 and 5 Ground Term for Pd 3 2 Spin Allowed Electronic Transitions from A ) in Octahedral Ligand Field 8 2 (d Ni  P 3  ig  / /  ig  /  /  / / / / /  \ \ \  2g  \ \ \ \  3 V;  \ \  2 V  11  \ \  \ ‘  free—ion terms  2g weak flgand field terms  63  Table 3.3:  , 2 ) 6 Electronic Transitions and Ligand Field Parameters for Ni(SbF 2 and Related Compounds ) 6 Pd(SbF  Compound  Electronic Transition Energy ) 1 (cm-  ) 2 F 3 Ni(SO  6740  -  B  B/B° d  Reference  c 3  a 1  2 ) 6 Ni(SbF  lODq (cm-’)  11300  22400  6740  899  0.832  This work  12400  23300  7340  912  0.844  39  2 ) 6 Pd(SbF  11900  18200  26700  11900  613  0.739  This work  ) 2 F 3 Pd(SO  11800  17400  27000  11800  606  0.730  19  a  i:  A2g 3  __>  T2g 3  b 2: 3 A2g  Tig (F) 3  C  1)3:  Tig(P) 3  d  B/B°  A2g 3 =  f3, where B° is the free ion value obtained from Ref. 34(a).  64  ) pairs suggests similar coordina Pd(SbF 6 F 3 Pd(SO I 2 ) and ) Ni(SbF 6 F 3 Ni(SO / 2 positions for ) + in the fluorosuifate and hexafluoroantimonate 2 + and Pd 2 tion environments for the Ni derivatives.  In addition, the Dq and B values reported here also point to a close structural similarity between the two types of compounds.  For 2 F) (19), like for most fluorosulfates of 3 Pd(SO  2 prototype is postulated. As discussed divalent metals (18), a layer structure based on the CdC1 2 (14) and implicitly also for ) 6 in Section 3.2, the same structural type is reported for a-Ag(SbF 2 (1 1). ) 6 Ni(SbF  Pd complexes with fluorometallate anions have precedents. Complexes + Paramagnetic 2 , with M Pd[MF ] of the general type 6  =  Pd, Pt, Ge, or Sn, have been known for over 25 years  now (31), and their magnetic susceptibility measurements have been reported down to 80 K. 2 anion would suggest a different structural type, but the coordination 6 The presence of MF 2 should again be octahedral. environment of Pd  The ligand field parameters, the octahedral splitting Dq and the interelectronic repulsion  term B are obtained by using the appropriate equations (see Appendix A-4) as suggested by Lever (34(b)). The increase in Dq and the decrease in j (defined as B/B°, where B° is the free ) are not unexpected in view of the 8 ) to Pd(II), (4d 8 ion value) when moving from Ni(ll), (3d higher nuclear charge and more spacially diffuse 4d orbitals for palladium (40).  Although no splitting of any of the bands is observable, the broad nature of the bands makes it difficult to confinn or deny the possible existence of distortion in the octahedral coordination sphere of the respective metal centers.  65  3.3.4  Magnetic Susceptibility Measurements  Magnetic susceptibilities over the temperature range of —2 to 80 K are recorded for , Pd(Sb1 2 ) 6 Ni(SbF , and Cu(SbF& 2 ) 3 2 on a P.A.R. vibrating sample magnetometer. Relevant data are summarized in Tables 3.4, 3.5 and 3.6 respectively, and the plot of the magnetic moments vs. temperature for all three compounds is given in Figure 3.4.  2 in ) 6 As discussed in the experimental section, attempts to obtain pure a-Ag(SbF quantities large enough for a bulk magnetic measurement were not successful. The results of measurements made, on what is obviously a mixture of the two valence isomeric forms, allow only limited conclusions, since the small amount of paramagnetic material in the sample did not permit the extension of the measurements to temperature higher than 65 K.  Generally, for  paramagnetic materials with one or two unpaired electrons, the vibrating sample magnetometer used in this work is useful to —90 K. In the temperature range of 65-3 K the magnetic moment 2 appears to be independent of temperature with a shallow maximum ) 6 calculated for cx-Ag(SbF at --6 K before falling off. It is unclear whether the observed dilute magnetic behavior is due to 2 acting as a diluent. ) 6 , or caused by 3-Ag(SbF 2 ) 6 a-Ag(SbF  2 is confirmed by measurements made at room ) 6 The diamagnetism of -Ag(SbF 1 is 3 mo1 temperature, using the Gouy technique. The measured susceptibility of -68 x 10 cm ; however, the Gouy balance used 1 3 mol less than the sum of Pascal constants of -128 x 10-6 cm is insufficiently sensitive for a more accurate determination of diamagnetic susceptibilities. In 2 could be responsible for the slight discrepancy, as well ) 6 addition, trace amounts of a-Ag(SbF as temperature independent paramagnetism (TIP).  As seen in Figure 3.4, the magnetic moment decreases gradually with decreasing , before a steep decline becomes apparent at —10 K, 2 ) 6 2 and Pd(SbF ) 6 temperature for Ni(SbF  66  Table 3.4:  2 ) 6 Low Temperature Magnetic Data of Ni(SbF  Temperature [K]  XMCOff  ol 5] 1 m 3 [cm x i0  Peff B 1  81.67  750  2.21  77.78  780  2.20  74.08  820  2.20  69.72  870  2.20  65.31  920  60.15 54.20  1000 1100  2.19 2.19  47.60  1240  2.18 2.17  40.05  1450  2.15  30.80  1850  2.14  26.28  2150  2.13  21.17  2610  2.10  16.20 11.00  3280  2.06  4560  2.00  7.72  6060  1.93  5.34 4.78  8020  1.85  8660  1.82  4.32  8990  1.76  3.70 2.99  9770  1.70  10340  1.57  2.50  10730  1.47  2.00  11160  1.34  67  Table 3.5:  2 ) 6 Low Temperature Magnetic Data of Pd(SbF  Temperature [KJ  XMCOIT  oP 1 m 3 [cm 5] x10  J4ff [PB]  81.50  1460  3.09  77.55  1530  3.08  73.91  3.07  69.77  1600 1680  65.19  1770  3.06 3.04  60.03 54.00  1900  3.02  2060  2.99  47.15  2300  2.95  39.80  2630  2,89  31.10  3210 3260  2.83 2.82  3620 4200  2.77  30.45 26.55  4310  2.69 2.68  16.50  5220  2.62  10.80  8410  2.70  9.94  9170  2.70  7.12  11270  2.53  5.84  11720  2.34  5.26  11830  2.23  4.76  11910  2.13  4.36  11910  2.04  4.00  11950  1.96  3.64  11950  3.37  11990  1.87 1.80  2.99  11990  2.29 2.10  11990  1.69 1.45  12020  1.42  21.60 20.80  68  Table 3.6:  2 ) 6 Low Temperature Magnetic Data of Cu(SbF  Temperature [K]  XMCOff  ol 1 m 3 [cm ]  x  eff [ILBI  81.83  370  1.56  78.06  1.56  70.11  390 410 440  1.57 1.57  65.65  470  1.57  60.44  510  1.57  54.45  1.56  51.40  560 590  47.95  640  1.56  40.55 30.70  750  1.56  980  1.55  26.00  1150  1.55  21.22  1.55  16.25  1410 1820  11.00  2690  1.54 1.54  7.46  3970  1.54  5.56  5420  1.55  4.24  7290  1.57  4.04  7250  1.49  3.02 2.40  8890  1.47  10750  1.44  12480 13230  1.40  74.24  1.97 1.86  69  1.56  1.40  , M=Ni, Pd and Cu 2 ) 6 Magnetic Moment vs. Temperature of M(SbF  Figure 3.4:  f2K<T<82K1 ‘  2 ) 6 Pd(SbF  2.:• .-o-.-o.-.o.-.o  ..  0  2 ) 6 Ni(SbF  2-  •...+....•.--4...•..•-.•..•  4  1.5—i  • Cu(SbF 2 ) 6  10  20  40  60  TEMPERATURE,K  70  80  100  indicative of possible antiferromagnetic ordering. An additional contributing factor to the sharp drop in the magnetic moment values at very low temperatures could come from zero-field splitting of the triplet spin states in the nickel and palladium compounds. It was shown in 2 were discussed that ) 6 2 and Pd(SbF ) 6 Section 3.3.3 wher’ the electronic spectra of both Ni(SbF 2 ions in these two compounds is 3 2 and Pd the ground term of Ni A2g.  ion in an octahedral ligand field with 3 d For a 8 A2g ground term, the magnetic moment can be expressed as follows (41):  jie  (8)112 (1—  =  4?. lODq  )  =  S.O.  (1—  4 lODq  [35]  )  . 8 where ? = spin-orbit coupling constant = J2 for d lODq =  =  ligand field splitting parameter  spin-only magnetic moment  =  112 [4S(S+l)]  Since the ground term discussed here is 3 A2g a first-order orbital contribution to the magnetic moment is not expected. However, through spin-orbit coupling, which is expected to be quite large for second and third row transition metals, the observed magnetic moment is enhanced beyond the spin-only value. In the absence of any magnetic exchange between the paramagnetic centers, the moment calculated is independent of temperature and should depend only on lODq. The sign of  .  and  is negative for transition metals where the d-shell is more than half full,  2 and Pd 2 ions Peff greater than and therefore according to equation [3.5], for Ni  is  expected.  For Pd(SbF , using equation [3.5] with lODq 2 ) 6 2 estimated value of ?. for Pd  =  =  11,900 cm (Table 3.3) and the  4 (42), a temperature independent-moment of 3.59 B 1600/2 cm  is obtained. The observed magnetic moment of 3.09 B at —82 K is reasonable when compared  71  2 has been lowered by anti) 6 to the predicted value, since the magnetic moment in Pd(SbF ferromagnetic exchange, as evident from the plot in Figure 3.4.  2 plot (also to a ) 6 A slight increase in the magnetic moment is observed in the Pd(SbF , just before dropping off at very low temperatures. Cu(SbF ) 2 ) very small extent in 6  The  observed weak effect is reproducible and two possible interpretations are suggested: (a) a phase transition occurs at --10 K and (b) very weak ferromagnetism is responsible for the small effect.  The latter explanation is favored here because there are a number of precedents for simultaneous  ferromagnetic  and  antiferromagnetic  ordering  in  fluoro  derivatives of  PdF (43), which has a rutile structure palladium(ll). Very weak ferromagnetism is observed in 2 6 (45). According to a recent 6 and Pd(U)Pt(IV)F (44), and in the ternary fluorides Pd(ll)Pd(IV)F crystal structure reported for the latter compound (46), there may even be a close structural relationship:  6 structure. 6 has a LiSbF Pd(ll)Pt(IV)F  For Pd(ll)(SbF 2 a layer structure is ) 6  6 prototype, with half of the suggested, which, as discussed above, is also derived from the LiSbF 6 (46). 2 compared to all holes filled for Pd(ll)Pt(IV)F octahedral holes occupied by Pd  Some similarity in magnetic behavior is also evident from the I’ eff values, which are 80 for the ternary palladium(ll) fluorides in the range of 2.7 to —3.0 B for the series , with M 6 Pd(II)M(IV)F  =  , where Pd 2 ) 6 2 is slightly Pd, Pt, Ge or Sn (31a), while for Pd(SbF  more dilute, a value of 3.09 B is found.  Substantially higher magnetic moments (3.30-3.60 B) are found for the corresponding fluorosulfato complexes of palladium(II) (19b), where the bulkier fluorosulfate groups appear to prevent antiferromagnetic exchange. It is interesting to note that at low temperatures (—20 K) ) and 2 F 3 significant ferromagnetism has been observed for two members of this group Pd(SO , has a layer structure, derived 2 ) 6 ) (see Chapter 6). The former, like Pd(SbF 6 F 3 Pd(ll)Pd(IV)(SO  72  2 ion in very similar electronic environ from the CdC1 2 type, and both appear to have the Pd ments at room temperature, as reflected in their respective electronic mull spectra (Table 3.3) discussed in Section 3.3.3.  2 are rather low (g ) 6 The magnetic moments observed for Ni(SbF  =  2.21 B at —82 K),  even though the moments are reduced by possible antiferromagnetic exchange (see Figure 3.4 and Table 3.7).  Ni centers, + If there is no magnetic exchange between the paramagnetic 2  equation 3.5 can again be utilized to calculate the temperature independent moment. The lODq 2 is 644/2 1 (Table 3.3), and the estimated value of . for Ni value of the compound is 6740 cm 1 (42) which when substituted in equation 3.5 yields a 1 cm l e ff value of 3.37 B•  2 ) 6 , two other Ni(SbF 2 ) 6 In order to understand the unusual magnetic results of Ni(SbF samples, made by different methods were also investigated for their magnetic properties. A sample was obtained for this study from Dr. Karl 0. Christe of Rocketdyne, U.S.A., which was 2 under high temperature and pressure (11). The second sample 5 and F prepared from Ni, SbF 2 and SbF 5 in anhydrous HF according to the published was synthesized for this study from NiF method (14). The low temperature magnetic moment vs. temperature plot of these two samples is given in Figure 3.5 (see Appendices A-5 and A-6 for data).  In addition, magnetic measurements were also taken using a Gouy balance on the solvolysis sample as well as on the above mentioned high temperature fluorination product (11). Results of this high temperature study are given in Table 3.7.  2 display the common behavior of tempera ) 6 Although all the three samples of Ni(SbF ture dependent low magnetic moments, it is rather puzzling to note that their moments differ so substantially. The plots of ieff vs. T display very similar slopes which suggests the possible presence of a common magnetic substance at different concentrations in these samples. The  73  2 ) 6 Figure 3.5: Magnetic Moment vs. Temperature of Ni(SbF  3.4  -  o o  ,  0  °  .  .  [A]  0 0 0 0 0 0  0  C’  -  C  g  2.6-  •  .  .  .  .  [B]  •  • •  .  2.4-  . o . . C C  L.L  I  0  20  40  60  TEMPERATURE,K  +  2 [B] Sample from NiF  5 in HF, Ref. 14 SbF  +  74  2 F  , Ref. 11 5 SbF  [A] Gift sample, from Ni  +  80  100  Table 3.7:  2 for the Temperature Range 8O to 295 K ) 6 Magnetic Moment Data of Ni(SbF  Ni(SbF a 2 ) 6 ] 5 F) + SbF 3 [Ni(SO 2 Temperature (K)  Ni(SbF b 2 ) 6 J 5 [Ni + F 2 + SbF Temperature (K)  ILeff (PB)C  p. (JtB)’  290.5  2.64  293.5  4.25  268.5  2.61  268.8  4.16  251.0  2.61  251.0  4.11  234.5  2.61  234.5  4.07  218.0  2.60  218.0  4.02  200.3  2.58  201.0  3.97  176.0  2.58  177.0  3.90  151.0  2.56  151.5  3.81  126.3  2.45  127.5  3.73  101.8  2.42  103.0  3.61  86.5  2.31  86.5  3.53  78.0  2.26  78.0  3.46  a This work b  Gift sample, made according to Ref. 11  C  eff = 2.828 [(Xmoi  = -  2  ; 2 / 1 TIP)T]  75  1 3 mo1 320 x 10-6 cm  solvolysis product from this study appears to have the lowest magnetic moments, whereas the gift fluorination  sample exhibits moments which are unexpectedly high for an octahedrally  coordinated Ni(I1) species (Table 3.7).  The sample made using HF as solvent medium has  moments (measured up to —80 K only, Figure 3.5) which fall between the above two sets of values.  2 5 in SO 2 sample made from the oxidation of Ni by SbF ) 6 Furthermore, a Ni(SbF  solution is reported as having a magnetic moment of 3.16 1 B at 294 K (12).  8 ion It is also important to note here that if the symmeuy of the ligand field acting on a d like Ni(II) is allowed to be lower than cubic and this low symmetty component is large enough, then a spin free-spin paired (triplet-singlet) equilibria may occur in the paramagnetic ions of the compound (47,48).  This could reduce the magnetic susceptibility of the system, yielding  magnetic moments lower than expected. Although this situation is observed mostly in Ni(II) complexes, it is reported to occur almost exclusively in solutions and is dependent on the solvent, concentration and temperature (47). Therefore, this unusual behavior may not be a . However, the existence of 2 ) 6 significant factor in this solid state magnetic study of Ni(SbF such systems in the solid state cannot be ruled out completely.  The temperature dependent low moments obtained for the solvolysis sample may be due primarily to the following factors: (a) possible antiferromagnetic interaction between the Ni(II) centers, which will lead to lower than expected moments; (b) small amounts of nickel ions in oxidation states other than +2 acting as cliluents to predominantly octahedral Ni(ll) ions in the lattice; and  (c) a combination of factors (a) and (b) which will result in lower magnetic  moments for the compound.  The contribution of antiferromagnetism toward lower moments can be seen clearly in both Figure 3.5 and Table 3.7, where in the latter tabulation the small contribution (320 x 10-6 ) from the temperature independent paramagnetism (TIP) to the susceptibility has 1 3 mo1 cm  76  been removed, since this contribution is relatively significant at higher temperatures.  However, as no Xmax is observed in the susceptibility data, antiferromagnetism alone cannot account for such low moments in the solvolysis product. Therefore, the existence of small quantities of other nickel ion species than octahedral Ni(II) in the lattice may have to be considered as a possibility.  Interestingly, two octahedrally coordinated spin paired Ni(ffl) fluoro compounds, NiF and 6 3 K 6 NiF have been reported in the literature (49), where the elongation of the 3 Na 3 octahedron is ascribed to the Jahn-Teller effect to be expected for the t2g ] 6 [NiF eg’ 6 NiF is given as 2.51 and 2.12 B at 295 and 90 K 3 K configuration. The magnetic moment of 6 respectively (50), although the large temperature dependence of the moments is surprising for an Eg ground term, unless thermal equilibrium between low and high spin configurations (49) 2 and/or antiferromagnetism is taken into consideration.  It is however still rather difficult to  rationalize the generation and hence the presence in the solvolysis product of nickel ions in F) is well characterized as a 3 Ni(SO oxidation states other than +2, since the parent compound 2 Ni(ll) octahedral complex, both by electronic spectra (39) and magnetic studies (Chapter 6).  The magnetic moments calculated at higher temperature for the fluorination product 8 Ni(II) complex. It (Table 3.7) in contrast, are significantly above the values expected for a d was shown earlier that equation [3.5] predicts a temperature independent moment of 3.39 1 B’ whereas the moment obtained at room temperature of this compound exceeds this value by nearly one Bohr magneton. As discussed in Section 3.1, the obvious limitation in the high 2 is that direct fluorination may lead to oxidation of the metal ) 6 temperature synthesis of Ni(SbF beyond the +2 state. This is possible in nickel where higher oxidation states are accessible and the metal can be oxidized under severe conditions up to the +4 state (40). However, as pointed out above, the known octahedral Ni(ffl) fluoro compounds are of the spin-paired type (49) and  77  NiF (5 1,40) are diamagnetic with the low-spin 2 K ) and 6 iF 6 O (CIF N Ni(IV) derivatives like 2 6 t2g  configuration.  Therefore, the origin of the high magnetic moments calculated for this  compound is not clear, especially as the compound has been sufficiently characterized using microanalysis, vibrational spectroscopy and X-ray powder diffraction (11). However, a very likely cause of the high magnetic moments for this sample can be Ni metal impurities. Since Ni metal is ferromagnetic, trace amounts of it would cause significantly larger ).teff values for the sample. Furthermore, the metal saturates at relatively low magnetic fields, and as ‘eff is propor tional to (XMT)” , this will result in decreasing moments with decreasing temperatures for the 2 compound. Field dependent magnetic susceptibility studies are required to verify this possible ferromagnetic contamination of the samples.  2 are given in Table 3.6, and appear to be ) 6 The magnetic moments obtained for Cu(SbF independent of temperature down to —4 K. It is also of interest to note here that of the four ) is magnetically 2 F 3 transition metal fluorosulfate precursors used for this study, only Cu(SO 2 are lower than expected for ) 6 dilute to low temperatures (Chapter 6). The moments of Cu(SbF Eg has no orbital ) ion in an octahedral ligand field (52). Since the ground term 2 9 a Cu(II) (d angular momentum associated with it the moments should be close to the spin only value of 1.73 B  E ground in the first approximation. However, spin-orbit coupling can occur between the 2  term and the higher lying 2 T2g term, leading to slightly higher moments predicted by the follow ing expression (41):  Peff  (3)  (1  2?. lODq  =  (1  2A lODq  [3.6]  where the terms used are as in equation [3.5].  2 made via ) 6 It was noted earlier in Section 3.3.2 that the vibrational spectrum of Cu(SbF SbF (14). This was 5 2 2 the solvolysis method is slightly different when compared to that of CuF  78  , 2 ) 6 taken as a clue to the possible existence of polymorphism in the two forms of Cu(SbF . 2 ) 6 although to a very limited extent than in the case of Ag(SbF  2 also indicate this ) 6 Magnetic measurements obtained on several samples of Cu(SbF possibility (Figures 3.6 and 3.7), with Cu(I), Cu(II), and Cu(III) present in an equilibrium of the type:  2 Cu(II)  1 k 2 k  2 Cu(I) Cu(Ill), k  >>  [3.7]  1 k  with the ratio 1 /k differing very slightly relative to the experimental conditions of the 2 k formation reaction and the subsequent treatment of the reaction product.  Solvolysis of  5 appears to generate small quantities of Cu(I) and Cu(III) ions, in addition to ) in SbF 2 F 3 Cu(SO 2 the relatively larger number of Cu(ll) ions (k  >>  . The diamagnetic Cu(I) and Cu(llI) ions k ) 1  seem to act as diluents to the paramagnetic Cu(ll) centers, thereby lowering the observed magnetic moments of the compound below the expected values. This could also account for the temperature independent magnetic moment behavior of the compound, where the Cu(II) centers are now more dilute than in the corresponding Pd(II) or Ni(ll) derivatives.  When the product is treated with anhydrous HF for 3 days, equilibrium [3.7] is shifted 2 further to the left (k  >>>  , resulting in an increase in the Cu(II) ions present in the k ) 1  compound. Consequently, the magnetic susceptibility of the sample is enhanced to a small but significant extent leading to correspondingly higher magnetic moments (Figure 3.6).  The  5 for a prolonged 2 is re-reacted with an excess of SbF ) 6 opposite effect is found when Cu(SbF period of time, —6 to 8 weeks (Figure 3.7). In all instances, no weight changes were observed in the vacuum dried products.  79  Figure 3.6  2 ) 6 Magnetic Moment vs. Temperature of HF Treated Cu(SbF  1.8aD —  1.6-  0  +  0  excess HF  I  I  Z  —  0  2 ) 6 Cu(sbF  2 ) 6 Cu(SbF  1.4-  C-) LI  z  o  1.2-  1—  0.80  20  40  60  TEMPERATURE,K  80  80  100  Figure 3.7:  2 ) 6 5 Treated Cu(SbF Magnetic Moment vs. Temperature of SbF  1.8-  1.6-  ‘ I  z I  0  °  o  • • .  .  • • .  .  —  I  o  o  o  o  0  0  0  0  °  °  °  —  C-)  2 ) 6 Cu(SbF Cu(SbF 2 ) 6 + excess SbF 5  LJ  z  ç  1.2-  1—  0.8-  I  I  0  20  60  40  TEMPERATURE,K  81  80  100  2 is not totally ) 6 The presence of Cu(I) and Cu(IH) ions, in addition to Cu(H) in Cu(SbF ), 9 ) which contain “Jahn-Teller ions” (d 2 F 3 Cu(H)(SO ) and , 2 F 3 unexpected, since both Ag(II)(SO , generating Ag(I), Ag(llI) and to a lesser degree 5 could behave in a similar manner toward SbF , the 2 ) 6 Cu(I), Cu(llI) ions in their respective reaction products. As in the case of 3-Ag(SbF , with 2 ) 6 Cu(I) and Cu(llI) centers could be accommodated in the layer structure of Cu(SbF Cu(I) in a linear and Cu(ffl) in a square planar environment respectively.  3.3.5  X-ray Photoelectron Spectra  2 compounds using ) 6 2 and Cu(SbF ) 6 Attempts were made to characterize the f3-Ag(SbF X-ray photoelectron measurements. It was hoped that the difference in Binding Energy (BE) between the cations in oxidation states +1, +2, and ÷3 could be utilized to identify these ions present in the silver compound as Ag(I), Ag(III) and in the copper compound as Cu(I), Cu(II), and Cu(Ill) respectively. The reported BE values corresponding to these oxidation states (for a given energy level) were reconfirmed by a series of measurements carried out with relevant silver  and  copper fluoro complexes.  For  found at BE  the XPS  =  512 energy level is chosen, which is 2 compound, the 3d ) 6 study of -Ag(SbF  366.8 eV in Ag(0). The Ag(I) and Ag(llI) BE peaks for the same energy level are  expected at —367.7 and —371.0 eV respectively (53,54). The sample was scanned in the BE 52 level, only a broad band spanning a BE range of 357 to 377 eV. Unfortunately, for the 3d range of —367.5 to 370 eV is obtainable, with no resolution of the relevant peaks expected for the Ag(I) and Ag(Ifl) species. It is however possible that the two peaks corresponding to the two silver ions are hidden under the broad band centered at —369 eV. A similar situation is 32 is chosen for the measurements. observed when the alternate energy level 3d  82  2 show a more complicated spectral pattern. The ) 6 The XPS spectra obtained for Cu(SbF 3 located at BE energy level 2P  =  932.2 eV for Cu(O) is chosen, and BE peaks of Cu(I), Cu(II)  and Cu(Ill) corresponding to this energy level are expected at 932.6, 936.1 and 938.0 eV respectively (53,54,55). However, in this compound, only small amounts of Cu(I) and Cu(ffl) ions are expected to be present (see Section 3.3.4), in contrast to the silver compound, where Ag(1) and Ag(ffl) ions are present in equimolar quantities.  2 is from 921 to 941 eV, and as in the silver ) 6 The BE range scanned for Cu(SbF compound, no distinct peaks corresponding to the three oxidation states are observed. The broad band obtained covers an energy range of —932.5 to 938 eV, and is split by several intense satellite lines. This phenomenon is commonly seen in the XPS spectra of cupric compounds, and the number and the splitting of the peaks are found to be sensitive to the chemical environ ment of the ions (55). This situation is further complicated by the reduction of Cu(ll) ions when subjected to X-rays, and consequently, additional satellite peaks may appear in the spectra (55).  312 are seen in the spectra, it is again Although no individual peaks at energy level 2P possible to have the less intense Cu(I) and Cu(ffl) peaks hidden under the broad band, since the energy range of the band covers the three BE values of the copper ions Cu(I), Cu(II), and Cu(III) . 2 ) 6 expected in Cu(SbF  3.3.6  Attempted Synthesis of Au(SbF& 2  Gold(lI) fluorosulfate, which was synthesized recently in our group by the reduction of F) with either gold powder or CO (56), was selected as the precursor to react with 3 Au(SO 5 in the attempted preparation of the corresponding gold(ll) hexafluoro antimonate, excess SbF . 2 ) 6 Au(SbF  The gold compound has been formulated as a mixed valency, diamagnetic  ) complex, based on magnetic measurements and vibrational spectra (56). 4 F 3 Au(I)[Au(III)(SO 1  83  Therefore, it was expected that the resulting binary compound may also have the composition 2 compound. ) 6 ], analogous to the diamagnetic -Ag(SbF 4 ) 6 Au(I) [Au(III)(SbF  However, in contrast to the other four transition metal fluorosulfate precursors, the , carried out in a manner similar to the other prepara 5 ) with excess SbF 2 F 3 reaction of Au(SO tions discussed in this chapter (equation 3.1), does not yield the anticipated binary product . InsteaLt, the synthesis follows the reaction scheme shown below, yielding a ternary 2 ) 6 Au(SbF compound:  ) 2 F 3 Au(SO  +  60°C  5 excess SbF  The values of x and y (typically x  21 days  =  >  )(SbF 6 F 3 Au(SO )  1 to 1.5, and y  =  [3.81  2-x), calculated from microanalytical data,  seem to vary slightly and appear to depend on the reaction conditions.  The bright yellow  ) gradually turns color to give a dark brown-green powder. When the reaction is 2 F 3 Au(SO performed at elevated temperatures, a dark brown, very viscous liquid which may form due to the melting or decomposition of the lower temperature product, is isolated. Infrared spectra run 6 groups, and magnetic F and SbF 3 on several samples clearly show the presence of both SO measurements indicate a diamagnetic compound, as anticipated.  F) which is synthesized 3 Au(SO Interestingly, when diamagnetic gold(III) fluorosulfate , 5 under F (57), is reacted with excess SbF 3 F in HSO 6 0 2 by the oxidation of gold powder with S the same experimental conditions (equation [3.8]), a dark blue-green powder is isolated, again with composition 6 F)(SbF where the values of x and y (typically x =2 to 2.3 and 3 Au(SO ) y =3-x), are dependent on the reaction conditions. However, this ternary compound, in contrast, is weakly paramagnetic. The low temperature magnetic data, tabulated in Appendix A-7, yield moments that range from 0.52 to 0.72 B at 82 and 2.7 K respectively.  84  These values are  tentative, since the composition of the compound (and hence the molar mass) cannot be deter mined accurately. It is important to note here that like in the fluorides, where both AuF and 2 are unknown (33), examples for lower valent fluoro derivatives of gold are so far lacking. AuF  F) which is dimeric in the solid state (58) when reacted 3 Au(SO It is conceivable that , , may undergo a reduction process to a veiy slight extent. This reduction of the gold 5 with SbF 6 anions to suitably stabilize the higher compound may be due to the inability of substituent SbF oxidation state and hence strongly oxidizing Au(Ill) species, and consequently, may lead to the formation of small quantities of paramagnetic Au(II) ions in the solid lattice. This observation ) in SbF 4 F 3 . When about 5 appears to be valid also for the solvolysis reaction of Sn(IV)(SO ) made according to a published method (59) is reacted with an excess of 4 F 3 Sn(SO 0.679 g of , 2 is ) 6 5 for two weeks at 60°C, a white solid that corresponds to the composition Sn(SbF SbF isolated. The reduction of the Sn(IV) species to Sn(II) could occur according to:  ) 4 F 3 Sn(SO  +  5 6SbF  60°C >  Sn(SbF  +  ) SO 3 ( 9 F 2 2Sb F  3 2S0  +  02  +  [3.91  F 6 0 2 S  and  F 6 0 2 2S  +  5 SbF  —*  F 2 2S0  +  [3.10]  5 (5) leads to byproducts which are all F in the presence of SbF 6 0 2 The decomposition of S 2 is obtained in high yield. ) 6 removable in a dynamic vacuum and consequently solid Sn(SbF  3.4  Conclusion  Solvolysis of M(ll) fluorosulfates with M  =  Sn, Ni, Pd, Cu or Ag, in antimony(V)  fluoride is found to be a useful synthetic route to the corresponding metal(ll) hexafluoro  85  antimonate compounds.  Even though alternate synthetic routes to compounds of the type  2 ) 6 2 and the f3-Ag(SbF ) 6 2 are known, only the solvolysis method leads to the Pd(SbF ) 6 M(SbF compounds. The latter complex, unlike a recently reported paramagnetic, blue valence isomer is diamagnetic and based on its chemical and magnetic behavior, formulated as a mixed valency ] species. Additionally, the copper compound synthesized by this route 4 ) 6 Ag(I)[Ag(III)(SbF also appears to be unique, with Cu(ll) and, to a lesser extent Cu(I) and Cu(llI) ions, all present , as confirmed by low temperature magnetic 2 ) 6 simultaneously in the lattice of Cu(SbF susceptibility measurements.  2 compound prepared via solvolysis appears to be structurally similar to the ) 6 The Ni(SbF compound obtained by the high temperature fluorination method. However, in the solvolysis sample the nickel centers are predominantly found as Ni(II) ions, whereas in the fluorination product trace Ni metal impurities seem to be present, which is evident from their respective magnetic studies.  2 indicate that, ) 6 2 and Pd(SbF ) 6 Ligand field analyses of the electronic spectra of Ni(SbF like in their fluorosulfate precursors, the Ni(ll) and Pd(ll) ions are located in approximate octahedral ligand fields with 3 A2g ground terms.  Both compounds exhibit temperature  dependent low magnetic moments, most likely due to antiferromagnetic exchange. Addition 2 shows very weak ferromagnetism below -40 K. ) 6 ally, Pd(SbF  2 It appears, based on X-ray powder data and vibrational spectra that a common CdC1 2 compounds synthesized in this study, although ) 6 type layer structure is present in all the M(SbF ultimate structural proof will have to come from single crystal X-ray diffraction studies. The lack of solubiity of the compounds in suitable solvents like anhydrous HF and their high reactivity toward many of the organic solvents present substantial obstacles to the crystal growth process.  86  References  P.L. Fabre, J. Devynck, and B. Tremillon, Chem. Rev.,  1.  ,  591 (1982), and references  therein. 4327 (1986).  2.  S.P. Mallela, S. Yap, J.R. Sams, and F. Aubke, Inor. Chem.,  3.  G.A. Olah, G.K.S. Prakash, and J. Sommer, “Superacids”, John Wiley and Sons, New  ,  York, 1985, and references therein. 4.  R.J. Gillespie and R.A. Rothenbury, Can. J. Chem., 42,416 (1964).  5.  W.W. Wilson and F. Aubke, J. Fluorine Chem., j.j 431 (1979).  6.  P.A. Yeats and F. Aubke, J. Fluorine Chem., 4, 243 (1974).  7.  W.W. Wilson, J.R. Dalziel, and F. Aubke, J. Inor. Nuci. Chem., 37, 665 (1975).  8.  W.W. Wilson, R.C. Thompson, and F. Aubke, Inorg. Chem., i, 1489 (1980).  9.  S. Karunanithy and F. Aubke, J. Fluorine Chem., fl 541 (1983).  10.  S.P. Mallela, S. Yap, J.R. Sams, and F. Aubke, Rev. Chim. Minerale, j 572 (1986).  11.  K.O. Christe, W.W. Wilson, R. Bougon, and P. Charpin, J. Fluorine Chem.,  3.4, 287  (1987). 12.  P.A.W. Dean, J. Fluorine Chem., 5, 499 (1975).  13.  T. Birchall, P.A.W. Dean, and R.J. Gillespie, J. Chem. Soc. A, 1777 (1971).  14.  D. Gantar, I. Leban, B. Friec, and J.H. Holloway, J. Chem. Soc. Dalton Trans., 2379 (1987).  15.  B. Friec, D. Gantar, and J.H. Holloway, J. Fluorine Chem., 20, 385 (1982).  16.  B. Frlec, D. Gantar, and J.H. Holloway, J. Fluorine Chem., 1.2. 485 (1982).  17.  D. Gantar, B. Frlec, D.R. Russell, and J.H. Holloway, Acta Crvst.. C, 4j 618 (1987).  18.  C.A. Alleyne, K. O’Sullivan-Mailer, and R.C. Thompson, (1974). 2473 (1977).  19.a)  K.C. Lee and F. Aubke, Can. J. Chem.,  ,  b)  K.C. Lee and F. Aubke, Can. J. Chem.,  2. 2085 (1979). 87  Can. J. Chem., 52, 336  ii, 1765 (1978).  20.  P.C. Leung and F. Aubke, Inorg. Chem.,  21.  M.S.R. Cader, R.C. Thompson, and F. Aubke, Chem. Phys. Lett., j.4, 438 (1989).  22.  A.F. Clifford, H.C. Beachell, and W.M. Jack, S. Inorg. Nuci. Chem.,  23.  A.I. Vogel, “Quantitative Inorganic Analysis”, 3rd Edition, John Wiley and Sons, New  ,  57 (1957).  York, 1961.  mt. Ed.,  77 (1986).  24.  B. Standke and M. Jansen, Angew. Chem.  25.  J.A. McMillan, Chem. Rev.,  26.  B. Standke and M. Jansen, Angew. Chem.  27.  P.C. Leung, K.C. Lee, and F. Aubke, Can. J. Chem., 7, 326 (1979).  28.  L. Helmholtz and R. Levine, J. Am. Chem. Soc., 4, 354 (1942).  29.  W. Klemm, Angew. Chem.,  30.  B.G. Muller, Z. Anorg. Aug. Chem.,  31.a)  N. Bartlett and R.P. Rao, Proc. Chem. Soc., 393 (1964).  b)  ,  2. 65 (1962) and references therein.  ,  mt. Ed., 24, 118 (1985).  468 (1954).  3, 196 (1987) and references therein.  R.P. Rao, Ph.D. Thesis, University of British Columbia, 1965.  32.  R. Bougon, T.B. Huy, M. Lance, and H. Abazli, Inorg. Chem., 23, 3667 (1984).  33.  B.G. Muller, Angew. Chem. Tnt. Ed. Engi.,  34.a)  B.N. Figgis, “Introduction to Ligand Fields”, John Wiley and Sons, New York, 1966.  b)  ,  1081 (1987).  A.B.P. Lever, I. Chem Educ., 4, 711 (1968).  35.  J.H. Burns, Acta Crvst., .15, 1098 (1962).  36.  P. Fischer, 0. Roult, and D. Schwarzenbach, J. Phys. Chem. Solids,  37.  B. Friec and J.H. Holloway, J. Chem. Soc. Dalton Trans., 535 (1975).  38.  J. Fawcett, J.H. Holloway, D. Laycock, and D.R. Russell, J. Chem. Soc. Dalton Trans.,  32, 1641(1971).  1355 (1982). 39.  D.A. Edwards, M.J. Stiff, and A.A. Woolf, Inorg. Nuci. Chem. Letters., 3, 427 (1967).  40.  F.A. Cotton and G. Wilkinson,  “Advanced Inorganic Chemistry”, 5th Edition, John  Wiley and Sons, New York, 1989.  88  F.E. Mabbs and D.J. Machin, “Magnetism and Transition Metal Complexes”, Chapman  41.  and Hall, London, 1973. 42.  R.L. Carlin, “Magnetochemistry”, Springer-Verlag, Berlin, 1986.  43.  R.P. Rao, R.C. Sherwood, and N. Bartlett, J. Chem. Phys., 42. 3728 (1968).  44.  N. Bartlett and R. Maitland, Acta. Cryst., .IQ, 63 (1957).  45.  J.-M. Dance and A. Tressaud in “Inorganic Solid Fluorides”, Ed. P. Hagenmuller, Academic Press, New York, 1985, and references therein.  46.  B.G. Muller, Z. Anor. Aug. Chem., 55, 79 (1988).  47.  B.N. Figgis and 3. Lewis, Prog. Inorg. Chem.,  48.  G. Maid, I. Chem. Phys., 2. 651 (1958).  49.  G.C. Allen and K.D. Warren, Inorg. Chem., 8, 1895 (1969).  50.  W. Klemm, W. Brandt, and R. Hoppe, Z. Anorg. Aug. Chem., 3, 179 (1961).  51.a)  W.W. Wilson and K.O. Christe, Inorg. Chem.,  b)  ,  37 (1964).  ,  3261 (1984).  R. Hoppe in “Inorganic Solid Fluorides”, Ed. P. Hagenmuller, Academic Press, New York, 1985.  52.  Landolt-Börnstein,  Numerical Data and Functional Relationships in Science and  Technology, Vol. 2, Magnetic Properties of Coordination and Organometallic Transition Metal Compounds, Springer-Verlag, Berlin, 1966. 53.  T.A. Carlson, “Photoelectron and Auger Spectroscopy”, Plenum Press, New York, 1975.  54.  C.D. Wagner in “Practical Surface Analysis by Auger and X-ray Photoelectron Spectroscopy”, Ed. D. Briggs and M.P. Seth, John Wiley and Sons, Newe York, 1983.  55.  D.C. Frost, A. Ishitani, and C.A. McDowell, Mol. Phys., 24, 861 (1972).  56.  H. Willner, F. Mistry, G. Hwang, F.G. Herring, M.S.R. Cader, and F. Aubke, J. Fluorine Chem.,  ,  13 (1991).  57.  K.C. Lee and F. Aubke, Inorg. Chem.,  58.  H. Wiliner, S.J. Rettig, J. Trotter, and F. Aubke, Can. J. Chem., 69, 391 (1991).  59.  S.P. Mallela, K.C. Lee, and F. Aubke, Inorg. Chem., 2, 653 (1984).  .,  89  389 (1979).  CHAFFER 4  MESITYLENE ADDUCTS OF TIN(II) FLUORO COMPOUNDS, 2 C 9 2 2 ) 6 Sn(SbF 1 ) and H 2 2 F 3 Sn(SO 1 H 9 C  4.1  Introduction  Arene ic-complexes, where low valent post-transition metal centers act as acceptors, and benzene or various alkyl benzenes, function as ic-donors, form a small but interesting group of weakly bound complexes. Structural and bonding aspects of these compounds have become more widely known through the work of Amma et al. (1), and Schmidbaur et al. (2). A review on the more general topic of ic-complexes of main group elements has also appeared recently (3).  Arene complexes of the post-transition metals are best regarded as donor-acceptor adducts, with the arene ic-system being the donor component. For Group 13 metal derivatives, an increased arene donor strength through electron releasing substituents leads to enhanced stability of the complexes. However, as observed in X-ray crystal structure studies, the metal ligand interactions are not strong enough in these complexes to induce significant distortions of the arene rings (2). Consequently, complexes with low thermal stability are usually isolated (1,2).  Within this group of it-complexes, interest has focussed mainly on arene complexes with univalent metal centers such as Ag(I), Cu(I), Hg(I), Ga(I), In(I) and Tl(I) and comparatively little is known about similar compounds with the Group 14 centers like Sn(II) (4-7) and Pb(II) (1,8). There are commonly two reasons given for the paucity of arene H-complexes in group 14:  90  a) as exemplified by the structural chemistry of divalent tin (9), the 52 pair is stereochemically far more active than in compounds of isoelectronic In(I) and consequently the Sn(II) derivatives are apparently less inclined to form it-complexes with arenes (2); b) lattice energies for Sn(II) and Pb(II)-salts tend to be considerably higher than those of Ga(I), In(I), or Tl(I) salts. The non-polar, it-donating arenes are normally incapable of breaking up such lattices effectively. To reduce the lattice energy and to facilitate complex formation, salts with large, univalent anions are chosen and the majority of arene it-complexes reported so far feature tetrahalometallate (III) 4 with M=B, Al, Ga, In or Ti, and X=Cl or Br (1-8) as counter anions; anions of the type MX 5 appear to be suitable as well (10). however weakly basic anions like OTeF  The tin(II)-ic-arene complexes reported so far are limited largely to mono-arene C1 (5) or (Sn ) 2 (4) or the chloride bridged moieties such as 2 complexes with either Sn Ci (7) as acceptors, but recently the first bis(arene) complex has been reported as well, (Sn 4 ) 6 J (6). Benzene functions primarily as donor, bonded to tin in the rj C nC1(AlC1 [(‘ S 2 ) H 6 ) 4  4 is the counter anion, with Cl atoms bridging to tin. Frequently, however, mode, and A1C1 arenes are also found in the lattice, without being coordinated to tin (4,6,7). Detailed crystal structures (see Appendix A-8) are reported for all compounds (4-7) and have been used in the development of bonding concepts based on the Molecular Orbital theory ((1, 4, 5), Appendix A-9).  The interest in the chemistry of tin for this work stems from the following two specific Sn Mössbauer spectroscopy as a structural tool (this spectro related objectives: a) the use of 119 scopic technique has not been applied so far to this small group of tin complexes) and, b) the stabilization of “bare”, non  -  Sn (12). 2 2 (11) or R or very weakly coordinated cations like Sn  ) and 2 F 3 Sn(SO As discussed in Chapter 3, two compounds of interest, tin(II)bis(fluorosulfate), , 2 (13), both originally reported by Gillespie and ) 6 tin(II)bis(hexafluoroantimonate), Sn(SbF coworkers (14), appear to be capable of functioning as potential acceptors in arene it-complexes.  91  Sn Mössbauer spectra with large Both compounds give rise to broad single line 119 ) a small resolvable 2 F 3 Sn(SO , and, in the case of , 2 positive isomer shifts relative to Sn0 2 quadrupole splitting (11, 14) suggests non-directional, nearly spherical distribution of the 5s Sn Mössbauer parameters, electron pair. In addition, it had been shown previously, based on 119 f are extremely wealdy basic and the least nucleophilic anions 1 F 2 - and Sb 6 that the anions SbF Sn with a linear C-Sn-C group (12). Therefore, it was 2 ) 3 when stabilizing the cation (CH 2 ion equally well. The 6 anion to be ideally suited to stabilize the “bare” Sn expected the SbF 2 1 relative to Sn0 Sn Mössbauer spectrum with an isomer shift of 4.39 mm s single line 119 2 (see Chapter 3), which is a shift of about 0.45 mm s’ lower than ) 6 obtained for Sn(SbF 2 (15), indicate that steric factors rather than low suggested by calculations for Sn nucleophilicity of the counter anion may be important. The list of stannous compounds with Sn Mössbauer spectra and isomer shifts higher than the ones observed for single-line 119 2 provides a clue. ) 6 Sn(SbF  (15-crown5) 4.53 (16); ) 4 Sn(ClO , ) 4.48 (11); 2 , 6 F 3 Sn[Sn(SO ]  2 (18) all 1 relative to Sn0 CF 4.69 mm s Sn[Sn(SO 1 6 ) AsF 4.66 (17); and 3 3 2 2 ) 6 Sn(SbF , 2 and all involve sterically more hindered ) 6 2 more closely than Sn(SbF approach a true Sn 3 is AsF (17), where the Lewis base AsF 3 2 2 ) 6 . A crystal structure for Sn(SbF 6 ligands than SbF coordinated to tin as well, indicates 9-coordinate tin. The use of crown ether ligands (16) also 2 ion. supports the view that steric factors play an important role in stabilizing the “bare” Sn  , as seen earlier in 6 F and SbF 3 Furthermore, the two anions of the compounds, SO Chapter 3, function frequently as weakly coordinating, tridentate ligands towards divalent metal -prototype. 2 ions giving rise to layer structures, based on the CdCl  This structural type is  commonly found for most sulfonates of divalent metals, and the recently reported structure of F groups 3 ) confirms this structural type, where a three-dimensional framework of SO 2 F 3 Sn(SO linked by O-Sn-O bridges with the two crystallographically independent fluorosulfates acting as 2 ) 6 tridentate bridging ligands between the tin atoms is indicated (19). The structure of Ag(SbF (20) (Chapter 3, Figure 3.2) may serve as an example for the layer structure formed by  92  6 are very weakly basic, and covalent contributions to the F and SbF 3 . Both SO 2 ) 6 M(SbF lattice energies of their tin(J1) salts should be small. Alternatively, both anions may stabilize arene complexes of tin with the help of oxygen or fluorine bridges.  As donor, 1,3,5-  trimethylbenzene (mesitylene) is chosen, because it is expected and found (2) to be a better Sn Mössbauer spectroscopy is proven to be a useful technique for this donor than benzene. 119 investigation. Its application to the study of tin(II) compounds has been reviewed previously (21).  4.2  Experimental  4.2.1  Synthesis  2 ) 6 F (22) as described (23), and Sn(SbF 3 2 and HSO ) was obtained from SnCI 2 F 3 Sn(SO 5 as pointed out in Chapter 3, F) in an excess of SbF 3 Sn(SO was prepared from the solvolysis of 2 . The crude H 5 2 and NaC n, was synthesized from SnCI -C ( S 2 ) 5 Section 3.2. Stannocene, H product was purified by sublimation and its purity checked by microanalysis.  H O ) ,3,5-(C Sn(S F 1 2 H 6 C ) 4.2.la Synthesis of 3  ) (1.06 g, 3.35 mmol) was added, and after 2 F 3 To a one part reactor a sample of Sn(SO evacuation of the reactor, dry mesitylene (—7 mL, —50 mmol) was transferred into the reaction vessel via a distillation bridge. The white suspension was stirred in vacuo at room temperature for three days. Excess mesitylene was removed in vacuo at -20 to -15°C (ice/NaCl bath) over a ) with es, 2 F 3 Sn(SO period of three days yielding 1.39 g of a white powder, of the composition m a decomposition point of 97.2-98°C.  93  n: 2 C, 24.74; H, 2.77; F, 8.70; S, 14.67; and Sn, 27.16%. 1 H 9 C S S 6 O 2 Anal calcd. for F Found: C, 25.77; H, 2.87; F, 8.53; S, 14.84; and Sn, 27.10%.  An alternate preparation with mesitylene removed in vacuo at 50C gave the following analysis: Anal. calcd.: C, 24.74; H, 2.77; and S, 14.67%. Found: C, 24.97; H, 2.80; and S, 14.55%.  : [cm ] JR bands and estimated intensities 1  2910w,b, 2860vw, 1760vw, 1604m,  1575w,sh, 1446w, 1337w, ll9lvs, 1127w,sh, 1054vs, 888s, 786w, 667w, 589ms, 544m, 507vw, and 405m.  2[1,3,5(CH 2 Sn(SbF ] H 6 C ) 4.2.lb Synthesis of 3  2 (3.11 g, 5.27 ) 6 To the bottom portion of a two part reactor, freshly prepared Sn(SbF mmol) was added. The flask was then fitted to the lower end of a filtration apparatus (24). On the top end of the filtration apparatus a seond 100 mL flask was fitted and the entire apparatus was then evacuated. Through a Teflon valve in the bottom chamber of the apparatus mesitylene (15 mL, 108 mmol) was transferred via a distillation bridge. Upon exposure to the mesitylene vapor, the white powder immediately turned yellow and then during the filtration, pale, off white. When the mesitylene distillation was complete, the suspension was stirred in vacuo for 1.5 hours. The apparatus was inverted, and the mixture filtered. The filtrate flask was cooled to -10°C (ice/NaC1 bath) and the mixture was left to filter for 17 hours.  When gravity filtration was complete, the filtrate chamber of the apparatus was evacuated to further dry the solid. The apparatus was refilled with dry nitrogen inside the dry box, and the filtrate chamber was evacuated again. At the end of this drying procedure, a pale,  94  off-white solid (4.18 g, 5.04 mmol, 95.5% yield) was obtained together with a yellow-green filtrate, which was discarded. The product was transferred to a two part reactor and was further dried in vacuo for 24 hours at room temperature. No further weight change was observed. The solid decomposed at 69.5-71.5°C to a greenish yellow liquid.  8 C, 26.03; H, 2.91; F, 27.45; Sb, 29.32; Sn, 14.29%. n: 1 C S 2 Sb 12 Anal. calcd. for HF Found: C, 26.87; H, 3.00; F, 27.31; Sb, 29.05; Sn, 14.20; Total 100.43%.  : [cm] JR bands and estimated intensities 1  2920mw, 2860w, 1601m, 1580m, 469w,  1384m, 1168vw, lO8Ovw, lO4Ovw, 1007w, 960vw,b, 860w, 687s, 671vs, 635s, sh, 580m,b, 544m, 5 12w, 440w, and 395w.  4.3  Results and Discussion  4.3.1  Synthesis  The previously reported synthesis of Sn(II) containing benzene it-complexes (4-7) 3 at different mole ratios and temperatures (4,5), 2 and A1C1 involves either the reaction of SnC1 l ’ C 4 (Sn , ) 2 Cl or ) (Sn 2 2 (6, 7) with the arene to give either Sn ) 4 or of molten Sn(A1C1 containing complexes as colorless crystals. Crystalline material suitable for single crystal X-ray diffraction studies are obtained (4-7) in all instances. The course of the reaction appears to be influenced in part by the mole ratios of the reactants used and in part by the reaction tempera ture.  2 or (SnCl)’, n The different products obtained, with Sn  =  2 or 4, are not totally  -A1C1 phase studies (9) have revealed the existence 2 SnC1 , surprising since in the binary system 3 AlCl It appears that the same two phases 3 2 2 SnC1 A1C1 and . 2 SnC1 of two distinct phases: 3 4 as a coordinated counter ion and in crystallize now in the form of ,t-arene complexes with A1C1 several instances with the lattice arene present (4, 6, 7).  95  The synthetic reactions reported here differ in a number of ways. Binary rather than tertiary reaction mixtures are used, the reaction temperature is room temperature and the tin(U) substrates are synthesized and characterized prior to their reaction with mesitylene.  Addition of mesitylene occurs smoothly according to:  ) 2 F 3 Sn(SO  +  mes  2 ) 6 Sn(SbF  +  2 mes  25 C 0 mesitylene  ) es 2 F 3 Sn(SO m  >  [4.1]  or  mes  =  25°C mesitylene  >  mes Sn(SbF 2 2 ) 6  [4.2]  l,3,5-trimethylbenzene (mesitylene), and the two complexes are formed in nearly  ) as 2 F 3 quantitative yield. Solid material remains throughout the reaction and in case of Sn(SO acceptor, there is no visible sign of a reaction, except for an increase in the bulk of the solid residue. Complete removal of excess mesitylene in vacuo is difficult to judge and the conditions quoted in the experimental section were arrived at by trial and error. It does appear that samples submitted for microanalysis (C, H, and S content) immediately after isolation had small amounts of residual mesitylene trapped while samples sent to Germany for further analysis (S, Sn, Sb, and F content) seemed to have lost the excess reactant.  2 differs even further. A 2:1 complex forms ) 6 The reaction of mesitylene with Sn(SbF and a color change to bright yellow is noted as soon as the tin salt is exposed to mesitylene vapor. However the color of the solid quickly fades during product isolation and an off-white solid is obtained in very high yield together with a yellow-green filtrate. The origin of the initially observed color is unclear.  A UV-visible spectrum taken as Nujol mull on a solid  sample at this stage shows an intense UV-absorption at —240 nm tailing off in the visible region  96  with weak shoulders at 486, 580 and 656 nm respectively.  Observations made during product isolation suggested that the intense color seen was due to a by-produc., which was soluble in excess mesitylene. A complex formed by mesitylene 5 becomes a distinct possibility. Furthermore, the addition of and small, residual amounts of SbF 5 resulted in an intensely colored dark brown solid, which was not mesitylene to pure SbF investigated further. There is little doubt that the final product, like other arene complexes of Group 13 and 14 metals (1-8), is a white solid.  The use of gravity filtration as a means of product isolation is important in the case of mes synthesis. Attempts to isolate this compound by slow, careful removal of Sn(SbF 2 2 ) the 6 2 at room temperature and at -5°C lead to excess mesitylene in vacuo or in a stream of dry N 2 1 .5mes. In addition, the product ) 6 partial decomposition and materials that analyze as Sn(SbF has a slight yellow tint.  The thermal stability of both mesitylene complexes described here is limited. 2mes has a decomposi 2 ) 6 ) melts with decomposition at 97-98°C while Sn(SbF es 2 F 3 Sn(SO m tion range of 69.5-71.5°C, where a greenish yellow liquid forms.  Attempts to extend the mesitylene addition reaction to three other tin(ll) compounds + in 2 2 were recovered unchanged. Both salts have Sn 2 and SnF were unsuccessful. Both SnC1 2 2 (25) and orthorhombic SnF distorted octahedral environments (7) and the structures of SnC1 (14,26), one of the two polymorphic forms, may be regarded as layer structures. It can be concluded that the lattice energies of both compounds are too high and adduct formation does not occur in these two compounds.  97  n, has a molecular structure with a tilted arrangement of the -C ( S 2 ) 5 Stannocene, H Sn Mössbauer -rings (27) and presumably a stereochemically active electron pair. Its 119 H 5 C spectrum shows a quadrupole splitting of 0.86 mms (28).  The compound dissolves in  mesitylene, but stnocene is again recovered unchanged after removal of the arene in vacuo. The 1 H NMR spectrum of stannocene in mesitylene is studied down to -40°C, but only rather subtle changes are noted. The principle resonance due to stannocene (29) shifts from 5.96 ppm H 1 in CDC1 3 to 5.91 ppm relative to TMS in the presence of mesitylene while J  -  17 Sn 1 / 119  changes from 15.76 Hz to 15.16 Hz. Beginning at -20°C and becoming more pronounced at -40°C, a second, smaller and rather broad resonance at 5.88 ppm emerges with a similar separa tion of the satellite peaks. Mesitylene resonances appear almost in the same position as in pure ) and 6.78 (C-H) ppm and do not shift with decreasing 3 mesitylene as single lines at 2.28 (CH temperature. While there may be a weak interaction between stannocene and mesitylene at reduced temperature, all attempts to isolate a reaction product by low temperature filtration have failed.  Therefore, it appears that tin(ll) is sufficiently acidic only when bulky and very weakly 6 are present, and when lattice energies are F and SbF 3 , S0 4 nucleophilic anions like A1C1 reduced in the resulting layer structures.  From a correlation of 119 Sn Mössbauer data of  6 is the weaker nucleophile of the two fluoroanions, dimethyltin(IV) salts (12) it seems that SbF ) forms a 1:1 2 F 3 and formation of a 2:1 complex with mesitylene is not unexpected, while Sn(SO complex only. Complex formation by addition of mesitylene to a solid tin(ll) salt as described here does not lead to the formation of single crystals suitable for structural studies. Hence Sn evidence for the presence of n-arene complexes has to come from two other sources, i.e. 119 Mdssbauer and vibrational spectra, to be discussed subsequently.  98  4.3.2  Sn Mössbauer Spectra 119  Isomer shifts, relative to Sn0 2 for tin(1I) compounds, fall within the range of —2.1 mm s , viewed as the borderline between Sn(II) and Sn(IV), and values of about 5.1-7.7 mm s 1 1 for a t “bare’ 2 Sn have been calculated where a spherically distributed 5S 2 electron pair (9,15) is considered. Experimental values obtained have not reached the ionic limit. The highest values reported so far are 4.69 mm s 1 for the tin(II) moiety in ) C 3 Sn(II)[Sn(IV)(SO & F (18) and 4.66 mm s 3 2 2 ) 6 AsF (17), where an X-ray diffraction study reveals a distorted nine1 for Sn(SbF +. 2 coordinated environment for Sn  + ion no quadrupole splitting is observed(17,18); however, 2 In these close approaches to a Sn with decreasing isomer shift, first line broadening already evident for Sn(SbF , is noted and 2 ) 6 eventually small but well resolved quadrupole splittings are found (30).  Hence 119 Sn  Mössbauer spectroscopy provides two criteria which determine the ionic character of Sn(II) compounds: (a) the isomer shift which should be high, close to or in excess of 4.69 mm s’ relative to Sn0 , and (b) the quadrupole splitting which should be zero. 2  Sn Mössbauer data of Sn(II) compounds which are of interest to this study are Some 119 listed in Table 4.1. Of the five tin(II) compounds studied here Sn(SO 2 F 3 ) (4.18 mm s ) and 1 2 (4.44 mm c ) 6 Sn(SbF ) have the highest isomer shifts of those listed and only the former has a 1 small, resolvable quadrupole splitting.  Not unexpectedly, the more acidic Sn(SbF 2 is the ) 6  better acceptor, seemingly capable of coordinating two mesitylene donors, while Sn(SO 2 F 3 ) forms a 1:1 complex only.  Upon arene uptake the isomer shift is reduced by 0.17 mm s 2 F 3 1 for Sn(SO ) and by 0.40 mm s for Sn(SbF . This reduction suggests that mesitylene is interacting with Sn(ll) and, 2 ) 6 judging by the magnitude of the shift, that in the case of 6 Sn(SbF 2 2 ) mes both mesitylene  99  Table 4.1:  Sn Mössbauer Parameters of Relevant Tin(I1) Compounds at 80K 119  Quadrupole Splitting  Isomer Shift Compound  2 ] rel. to Sn0 1 8 [mm s  LLEQ [mm s ] 1  Reference  2 (orthorhombic) SnF  3.30  2.15  14  2 (tnonoclinic) SnF  3.49  1.61  14  n -C (r S 2 ) 5 H  3.74  0.86  28a  Sn(A1C1 4 ) (n-C H 6 C 2 )  3.93  0  4c  2 SnC1  4.08  0.66  15c  ) 2 F 3 Sn(SO  4.18  0.68  14  ) es 2 F 3 Sn(SO m  4.01  1.04  This work  2 ) 6 Sn(SbF  4.44  0  14  mes Sn(SbF 2 2 ) 6  4.04  1.13  This work  Accuracy limits for 6 and AEQ are ± 0.03 mm 54  100  molecules are probably coordinated to tin. A similar isomer shift of 3.93 mm s 1 is reported for H (4c) but no Mössbauer data appear to have been reported for the two 6 C 2 ) 4 (-CH)Sn(AlCl -A1C1 phases (9), which would allow an estimation of the decrease in the isomer shift 2 SnC1 3 upon arene addition.  The reduction in the isomer shift upon binding to mesitylene is  t for 2 ) whereas F 3 Sn(SO m es accompanied by an increase in quadrupole splitting to 1.04 mms for Sn(SbF 2mes a slightly asymmetrical doublet (see Figure 4.1) with a £S.EQ value of 1.13 2 ) 6 mm s 1 is obtained. These findings are consistent with trends on 6 and  summarized above.  The occurrence of quadrupole splitting suggests an increase in asymmetry in the coordination environment of tin(1I) when coordination to only oxygen or fluorine changes to 5n Mössbauer include coordination to the arene as well. For both mesitylene adducts the 119 parameters obtained remain well within the range reported for typical tin(II) compounds (21). , as suggested by the 119 2 The addition of mesitylene to Sn Sn Mössbauer data, is expected to F and SbF 3 6 coordinate to tin. This cause a change in the manner in which the anions SO change in anion denticity is probed by infrared spectroscopy and discussed in the subsequent section.  4.3.3  Infrared Spectra  Attempts to obtain Raman spectra of both mesitylene adducts are unsuccessful and quick darkening of areas exposed to laser light indicates thermal degradation is occurring even at very low laser power.  Hence evidence rests on infrared spectra obtained on solid films between  silver halide windows.  ) (14, 23) and Sn(SbF 2 F 3 Both infrared and Raman spectra for Sn(SO 2 (14) have been ) 6 -groups present in M(SbF 6 2 compounds a useful ) 6 reported previously, and for tridentate SbF vibrational assignment has been presented (13, 31). As discussed previously in Chapter 3,  101  Figure 4.1:  ) at 77K mes Sn(SbF 2 Sn Mössbauer Spectrum of 2 119  0  I0&  C 0  c  98  0 Cl)  Cl)  E  (I) 96 C 0  H  -75  -6.0 -4.5 -3.0 -1.5  0  s 1 (mm Velocity )  102  1.5  3.0  4.5  Section 3.3.2, to account for the observed spectral complexity in the SbF-stretching region, a subdivision into metal coordinated, through fluorine bridges SbFb, and non-coordinated or 1 and the terminal SbFt stretches is suggested with the former usually between 550 and 650 cm 2 (14) allow such a division ) 6 latter above 650 cm 1 (31). Vibrational bands reported for Sn(SbF as well, even though a distorted environment around tin introduces additional complexity. F with the symmetry of 3 ) have suggested the presence of ionic SO 2 F 3 Assignments for Sn(SO the anion reduced from C ,, for the free ion to Cs due to coordination to tin (14, 23), but there 3 are still unresolved problems, best reflected in the occurrence of two equally intense bands at . It seems more (A 3 3S0 ) ) and a splitting found for 1 1 1 possibly due to iSF(A --770 and 830 cm F-groups with 3 appropriate here to view the spectrum as being due to two non-equivalent SO approximately C ,, symmetry with some band overlap in the areas of deformation modes. This 3 implies either ionic groups or more likely 0-tridentate groups. As mentioned previously, these ) 2 F 3 conclusions are further confirmed by the recently published crystal structure study of Sn(SO by Adams et al. (19).  Addition of mesitylene to both Sn(II) compounds has two general effects: a) the infrared F and SbF 3 6 groups, respec spectrum is dominated in both instances by bands due to the SO tively, with all mesitylene bands of very low intensity, and b) the vibrational spectra of the 6 bands reflect a change in anion coordination. anions appear to change, and at least the SbF Low intensity of vibrational bands due to organic groups is commonly found for organotin(IV) salts (32), and this feature appears to extend to the mesitylene adducts of tin(U) salts as well.  The observed infrared frequencies for the two mesitylene adducts are listed in the experimental section together with estimated relative intensities. The discussion in this section will center around two aspects, (a) the mesitylene bands in neat mesitylene and in the ) and 2 F 3 complexes, and (b) the “anion” bands before and after mesitylene addition to Sn(SO , respectively. Vibrational bands attributed to mesitylene are listed in Table 4.2 for 2 ) 6 Sn(SbF  103  Table 4.2:  Infrared Bands of Liquid Mesitylene and Bands Attributed to Mesitylene in mes Sn(SbF 2 2 ) ) and 6 es 2 F 3 Sn(SO the Adducts m  Mesitylene  ) es 2 F 3 Sn(SO m  mes Sn(SbF 2 2 ) 6  ] Tnt. 1 [cm  ] Tnt. 1 [cm  ] 1 [cm-  2921 vs  2910w,b  2920mw  2860 s 2730m 1760 m-w  2860 vw  2860 vw  mt.  3018 s  1760 vw  1715 m-w 1608vs  1604m,1575w,sh  1601m,1580m  1446w  1469w  1512w 1473s 1442 m, sh 1375m-s  1384m  ll7Ovw  1168vw 1080 vw, 1040 vw, 1007 w  1037 s 932vw  960vw,b  882vw  860w  835 vs 687 vs  786w 687 ms  667 w  544m  561w,b 515w  512w  507vw  440w  443m 421 m  395w  411m  See Table 4.3 for abbreviations  104  both adducts and compared to bands observed for liquid mesitylene. The listing of bands for the adducts is incomplete because of the very low intensity mentioned above which causes medium ) partial overlap of mesitylene es, 2 F 3 Sn(SO and weak bands to be unobservable and in case of m bands with more intense anion bands, in particular in the region of 800-1300 cm’.  In regions where no anion bands are expected, small band shifts are observed, mostly to lower frequencies.  1 in free mesitylene is a good The aromatic C=C stretch at 1608 cm  ) and Sn(SbF es 2 F 3 Sn(SO 2mes 2 ) 6 1 for m example. This peak is shifted to 1604 and 1601 cm respectively. The lower frequency indicates a very slight withdrawal of it electron density of the aromatic ring towards tin.  Interestingly, some bands assigned to bonded mesitylene appear to be split compared to 1 region of both spectra, and those of free mesitylene. This is noticeable in the 1570-1610 cm 2mes. The splitting can be attributed to a 2 ) 6 especially in the 1000-1200 cm’ region for Sn(SbF reduction in symmetry of the bonded mesitylene, and/or the presence of two non-equivalent ) However some solid state splitting is possible as es. 2 F 3 Sn(SO mesitylenes, in particular in m well.  All features affecting bands due to mesitylene are subtle, and the observed features are in general consistent with a very weak interaction between the arene and the two Sn(11) salts.  The infrared bands attributed to the anion are summarized in Table 4.3 and are compared 2 (14). For ) 6 ) (14, 23) and Sn(SbF 2 F 3 to the reported values for the parent compounds Sn(SO 1 ) the JR spectrum is dominated by an intense broad band centered at 1054 cm es 2 F 3 Sn(SO m 3 stretching modes, . These are assigned collectively as SO 1 and two bands at 1191 and 1127 cm probably masking some of the less intense motions of the mesitylene component in the adduct.  105  C  629s -.613sh —575sh 477w 313sh 292m 271m  ) 1 3 (A uSO  3 (E) SO  1054vs  1062s  589ms  544m  405m  606m 592m  573s  554s 403m 395sh  a Ref. 23 b Ref. 14 C Refs. 13 and 31  888s 786w  833s 772s  m = medium, sh shoulder, t = terminal,  6 SbF deformations  Sb.Fb inandout of phase  SbFt in and out of phase  Assignment C  Abbreviations: s = strong, v = very, as = asymmetric,  (E) öSO F 3  A 1 ( 3 öSO )  oSF (A ) 1  741m, sh 713s 676ms 650s  3 (E) uSO  1337w ll9lvs 1127w, sh  1290s, sh 1240vs 1180s, sh  [cm]  [cm] Tnt.  Sn(SbF b 2 ) 6  Band Description for C ,, 3  Approximate  1 hit. [cm  ) es 2 F 3 Sn(SO m  mes Sn(SbF 2 2 ) ) and 6 Adducts 2 es F 3 Sn(SO m  mt.  6 (E2g) USbF  6 uSbF as. (Ei)  Assignment C  w = weak b = broad b = bridging  580m, b  671vs 635s, sh  [cm]  mes Sn(SbF 2 2 ) 6  ) and Sn(SbF 2 F 3 2 and Bands Attributed to the Anions in the Mesitylene ) 6 Infrared Frequencies for Sn(SO  mt.  )a 2 F 3 Sn(SO  Table 4.3:  The most noticeable change appears to have occurred in the S-F stretching region. The F) (Table 4.3) are now replaced by a 3 Sn(SO 1 in 2 1 and 833 cm two intense bands at 772 cm 1 (possibly due to mesitylene). , with a weak band at 786 cm 1 single strong band at 888 cm  From this overall band distribution and the increased wave number of the US-F band, it appears that a change in denticity of the anion has taken place due to mesitylene adduct formation.  The findings are consistent with a bidentate, possibly bridging configuration  tentatively formulated as 2 ) rather than an ionic (perturbed) or tridentate -mes)Sn(SO 6 [(ri F 3 ] grouping (33).  2 in the region of ) 6 Compared to the rather complicated pattern observed for Sn(SbF mes Sn(SbF 2 2 ) 1 (Table 4.3), the band pattern displayed by the anion in the adduct 6 520-750 cm , and a weak 1 , a sharp, medium band at 635 cm 1 is very simple: a very strong band at 671 cm 6 anion, a peak at —660 cm’ is attributed to the 1 are found. For a free SbF band at 580 cm . The 1 asymmetric stretch with Raman active bands observed at —660 again and at 575 cm 6 2mes suggests the presence of a wealdy coordinated SbF 2 ) 6 pattern observed for Sn(SbF , with 1 6 stretching region produces bands at 671 and 635 crn anion. Peak splitting in the SbF 1 the loss of a symmetry center allowing detection of a Raman active fundamental at 580 cm (34).  It appears then that addition of mesitylene has a different effect on the anion bands in F group seems 3 mes, respectively. In the former adduct the SO ) and 6 Sn(SbF 2 2 ) es 2 F 3 Sn(SO m to be still coordinated to tin, but more likely in a bidentate, possibly bridging manner.  In  6 group is evident and any departure from an mes only weak coordination of the SbF Sn(SbF 2 2 ) 6 ionic SbF 6 with °h symmetry is rather slight.  It is unfortunate that in particular for this  compound support from Raman spectroscopy is lacking due to sample decomposition in the laser light, as mentioned earlier.  107  mes are consistent with the view that both mesitylene Sn(SbF 2 2 ) The findings for 6 Sn M6ssbauer spectra. groups are coordinated to tin, which in turn is supported also by the 119  4.4  Conclusion  Direct addition of an arene, in this case mesitylene, to suitable Sn(II) salts like ) and Sn(SbF& 2 F 3 Sn(SO 2 at room temperature, and product isolation well below room temperature, allow the high yield synthesis of veiy wealdy bound mesitylene complexes. However, only microcrystalline materials result which precludes structural studies by single crystal X-ray diffraction.  The adducts are characterized by chemical analysis and infrared  Sn Mössbauer spectroscopy. This spectroscopic spectra and their formation is followed by 119 method allows not only product characterization, but also, using the isomer shift and the absence of quadrupole splitting as criteria, the identification of other suitable substrates for complex for mation. It is observed that only tin(II) compounds with large, weakly nucleophilic anions are 2 and stannocene do not give any , SnF 2 capable of forming mesitylene adducts, while SnC1 indication of adduct formation under similar conditions.  References  1.  A.G. Gash, P.F. Rodsiler, and E.L. Amma, Inorg. Chem., j., 2429 (1974).  2.a)  H. Schmidbaur, Angew. Chem.  b)  mt. Ed. (English), 4, 893 (1985).  H. Schmidbaur, W. Bublak, B. Haber, and G. Muller, Angew. Chem. mt. Ed. (English), ,  234 (1987). 217 (1986).  3.  P. Jutzi, Adv. Organomet. Chem.  4.a)  Th. Auel and E.L. Amma, J. Am. Chem. Soc., 90, 5941 (1968).  b)  ,  H. Luth and E.L. Amma, J. Am. Chem. Soc., 91,7515 (1969).  108  c) 5.a)  P.F. Rodsiler, Th. Auel, and E.L. Amma, J. Am. Chem. Soc., 97, 7405 (1975). M.S. Weininger, P.F. Rodsiler, A.G. Gash, and E.L. Amma, J. Am. Chem. Soc.,  4,  2135 (1972). b) 6.  M.S. Weininger, P.F. Rodsiler, and E.L. Amma, Inorg. Chem.,  Ia. 751 (1979).  H. Schmidbaur, T. Probst, B. Huber, 0. Steigelmann, and G. Muller, Organomet.  ,  1567 (1989). H. Schmidbaur, T. Probst, B. Huber, G. Muller, and C. Kruger, 3. Organomet. Chem.,  7.  ,  53 (1989).  8.  Th. Auel and E.L. Amma, 3. Am. Chem. Soc., 9Q, 5941 (1968).  9.  J.D. Donaldson, Prog. Inorg. Chem.,  10.  S.H. Strauss, M.D. Noirot, and 0.P. Anderson, Inorg. Chem., 2, 3851 (1986).  11.  S.P. Mallela, S.T. Tomic, K. Lee, J.R. Sams, and F. Aubke, Inorg. Chem.,  ,  287 (1967) and references herein.  ,  2939  (1986). 12.  S.P. Mallela, S. Yap, J.R. Sams, and F. Aubke, Inorg. Chem., 5, 4327 (1986).  13.  M.S.R. Cader and F. Aubke, Can. J. Chem., 2, 1700 (1989).  14.  T. Birchall, P.A.W. Dean, and R. 3. Gillespie, J. Chem. Soc. A, 1777 (1971).  15.a)  J.K. Lees and P.A. Flinn, Phys. Lett., j, 186 (1965); and J. Chem. Phys.,  4, 882  (1968). b)  P.A. Flinn, G.K. Shennoy, F.E. Wagner, Eds., HMössbauer Isomer Shifts”, NorthHolland Publishing Co., Amsterdam, 1978, p. 593 ff.  c)  J.D. Donaldson and B.J. Senior, 3. Chem. Soc. (M, 1821 (1967).  16.  R.H. Herber and G. Carrasquilo, Inorg. Chem.,  17.  A.J. Edwards and K.I. Khallow, Chem. Comm., 50 (1984).  18.  R.J. Batchelor, J.N.R. Ruddick, J.R. Sams, and F. Aubke,  ,  3693 (1981).  Inorg. Chem., .j, 1414  (1977). 19.  D.C. Adams, T. Birchall, R. Faggiani, R.J. Gillespie, and J.E. Vekris, Can. J. Chem., 2122 (1991).  109  9,  D. Gantar, I. Leban, B. Friec, and J.H. Holloway, 3. Chem. Soc. Dalton Trans., 2379  20.  (1987). R.V. Parish in “Mössbauer Spectroscopy Applied to Inorganic Chemistry”, Vol. I, Ed.  21.  G.J. Long. Dienum Press, New York, 1984.  a, 1149 (1964).  22.  J. Barr, R.J. Gillespie, and R.C. Thompson, Inorg. Chem.,  23.  C.S. Alleyne, K. O’Sullivan Mailer, and R.C. Thompson, Can. 3. Chem.,  24.  D.F. Shriver, “The Manipulation of Air-Sensitive Compounds”, McGraw-Hill, New  ,  336 (1974).  York, 1969. 25.  R.E. Rundle and D.H. Olson, Inorg. Chem., 3, 596 (1964).  26.  J.D. Donaldson, R. Oteng, and B.J. Senior, Chem. Comm., 618 (1965).  27.  A. Almenningen, A. Haaland, and T. Motzfeld, 3. Organomet. Chem., 7., 97 (1967).  28.a)  P.G. Harrison and J.J. Zuckerman, 3. Am. Chem. Soc., 9, 2577 (1970).  b)  T.S. Dory and J.J. Zuckerman, J. Organomet. Chem., 264, 295 (1984).  29.  L.D. Dave, D.F. Evans, and G. Wilkinson, 3. Chem. Soc., 3684 (1959).  30.a)  J.G. Stevens and V.E. Stevens in “Mössbauer Effect Data Index”, Plenum Press, New York, 1958.  b)  J.J. Zuckerman in “Chemical Mössbauer Spectroscopy”, Ed. R.H. Herber, Plenum Press, New York, 1984.  31.  K.O. Christe, W.W. Wilson, R. Bougon, and P. Charpin, J. Fluorine Chem., (1982).  ii, 2634 (1972).  32.  P.A. Yeats, J.R. Sams, and F. Aubke, Inorg. Chem.,  33.  W.W. Wilson and F. Aubke, Inorg. Chem.,  34.  A.M. Qureshi, A.H. Hardin, and F. Aubke, Can. 3. Chem.,  110  fl, 326 (1974). 4, 816 (1971).  ,  385  CHAPTER 5  A LOW TEMPERATURE MAGNETIC STUDY OF 2 AND I2 THE MOLECULAR CATIONS O2, Br  5.1  Introduction  Only a limited number of compounds with paramagnetic homonuclear ions of non metallic main group elements are known. Of these, compounds with diatomic cations stabilized by very weakly basic fluoroanions are the subject of this study. The cations in this group consist [PtF by Bartlett and Lohmann (1), and 2 O ] of the dioxygenyl cation Oj’, first discovered in 6 , first identified in solutions of strong acids and super2 the two dihalogen cations I2 and Br acids by Gillespie et al. (2,3).  6 (4) ] [ 2 Br 1 F Sb Single crystal X-ray diffraction studies were subsequently reported for 3 and 2 [Sb J (5), while powder diffraction studies have afforded a more limited structural I 1 F insight into a number of dioxygenyl salts (6). For the dihalogen cations, electronic spectra of the solvated species (2,3), resonance Raman spectra (7), and magnetic measurements at room temperature (2,4(a)) have allowed some information on the electronic structure, suggesting a fl3jg 2  ground state (10). In addition, the study by Herring and McLean (8) has pointed out the  close similarity between the solvated cations I2+(1v) and  (SOlV) 2 Br  and their gaseous counter  parts as studied by photoelectron spectroscopy (9) or molecular spectroscopy (10). This strong resemblance should permit at least an approximation of the energy separation to the nearest excited states, not only for the dihalogen cations, but also for 02+, where a 2 1,’2g ground state is indicated (10).  111  The objectives of the present study which involves low-temperature magnetic suscep tibility measurements on suitable compounds containing the three homonuclear diatomic cations can be summarized as follows:  (i)  To investigate the magnetic behavior of what appear to be the only three suitable paramagnetic molecular cations formed by non-metals.  Structural and spectroscopic  information mentioned previously should help in the interpretation.  (ii)  To explore whether, and to what extent, van Vleck’s theory of molecular paramagnetism (11), developed 60 years ago, can be applied to solid-state cations. So far, nitric oxide, NO, has served as the best example; however, useful experimental data for this molecule do not extend into the condensed phase due to intermolecular association.  (iii)  To examine the reasons why the magnetic moments reported so far for O2 salts fall well below the spin-only value of 1.73 B• Measurements down to very low temperatures should allow the detection of magnetic behavior consistent with antiferromagnetic exchange, which is a possible cause for reduced magnetic susceptibilities.  (iv)  6 below [Sb 2 Br 1 F 3 1 and J Sb J [ I 1 F To compare the magnetic susceptibilities of 2 —80K, since earlier measurements above that temperature (12) had suggested anti6 [Sb 2 Br 1 F 3 1 but not for j. [Sb I 1 F 2 ferromagnetic coupling for ],  5.2  Experimental  [Sb i] were synthesized according to the method reported 2 I 1 Both 3 i& and F [Sb 2 Br F by Wilson et al. (12).  2 and This method involved the oxidation of previously purified Br  , at a precise 2:1 mole ratio, and the F 6 0 2 resublimed 12 by bis(fluorosulfuryl) peroxide, S  112  subsequent solvolysis of the product mixture in an excess of freshly distilled antimony(V) fluoride. The reactions were followed by weight and the purity checked by melting points.  2 6 (4.777 g, 5.762 mmol) was obtained from 0.924 g (5.782 mmol) of Br Sb ] [ 2 Br 1 F 3 5 at room temperature and F after solvolysis in —10 g of SbF 6 0 2 and 0.5724 g (2.89 1 mmol) of S removal of all volatiles in vacuo. The bright red solid melted at 84 ± 1°C (lit. 85.5°C) (12). [Sb J- (2.775 g or 3.928 mmol) was synthesized from 0.9986 g (3.934 mmol) ‘2 and 2 I 1 F 5 at 50°C. The F and subsequent solvolysis in —12 g of SbF 6 0 2 0.3895 g (1.967 mmol) of S black-blue solid isolated after the removal of all volatiles melted at 129 ± 1°C (lit. mp. 127°C) (12).  [AsF was obtained from Dr. Karl 0. Christe of Rocketdyne. The 2 0 j A sample of 6 5 in quartz. Magnetic field , and AsF 2 compound was synthesized by UV photolysis of 02, F strengths of 7501, 9225, and 9625 G and a temperature range of —2-124K were used in this study.  Molar magnetic susceptibilities, XM, were corrected for diamagnetism and for  [Sb ], slightly larger X values were used than reported previously 2 I 1 6 and F Sb ][ 2 Br 1 F 3 2 and (12). The magnetic moments of the Br independent paramagnetism (TIP  =  compounds were corrected for temperature-  3 mol 1 respectively, calculated as 120 and 68 x 10 cm  described in the text). The Curie-Weiss law in the form XM = CmITO is used throughout.  5.3  Results and Discussion  The discussion of the magnetic behavior of the three cationic species will center around three aspects:  (i)  The selection of suitable compounds for this study in the light of previous magnetic susceptibility studies.  113  (ii)  6 Sb J. [ 2 Br 1 F ,2 [AsF 2 O ] [Sb ], and 3 I 1 F The magnetic measurements on 6  (iii)  An attempted interpretation of these results.  5.3.1  Synthesis  Magnetic measurements on a single compound in the current study require —300-500 mg of high-purity sample for duplicate measurements when the vibrating sample magnetometer is used, while the Gouy measurements require between 1 and 2 g.  All cations are extremely  F-SbF solution (2,12), not undergoing 3 HSO reactive and only ‘2 is sufficiently stable in 5 disproportionation or further oxidation.  This rules out purification by recrystallization as a  general procedure for all the three salts. The limited thermal stability reported for all materials has so far precluded purification by sublimation. Hence, synthesis on the desired scale from pure starting materials, with little or no chance for side-reactions and facile product isolation, becomes the only route to the compounds of this study.  2 containing compounds, since There appears to be no real choice among the Br 2 salt, are not readily AsF (14), the only other Br 6 [ 2 Br structural and spectroscopic details on ] , did produce a 5 , and SbF 2 , Br 5 6 (4), from BrF [Sb 2 Br 1 F 3 available. The original synthesis of } sample suitable for a single-crystal X-ray diffraction study, but judging by the reported physical data, in particular the melting point and a magnetic moment of Peff  —  1.6 B’ the product  obtained from this method appears to be unsuited for this study.  A similar problem arises in the case of the ‘2 species as well. The method used for the 5 in SO , is not 2 1 (5), the oxidation of 12 by SbF Sb ] [ I 1 F preparation of single crystals of 2 suited for the preparation on a larger scale, as is evident from the reported analytical data (5). bF 5 S 3 SbF 3 or . The problem appears to be the quantitative separation of the by-products SbF  114  14 becomes a possibility and, in addition, a diamagnetic F 3 Formation of anions of the type Sb 4 has recently been obtained by this (Sb )] [ 4 I ) 6 1 F 3 (SbF compound of the composition 2 synthetic route (15) with reaction conditions only slightly different.  [Sb ] of a higher purity, I 1 F 3 as solvent appears to lead to 2 2 by AsF Substitution of SO 6 may form as a by-product as well (16). Any uncertainty in the molar mass of ] [ 2 I 1 F Sb but 3 the product will limit the usefulness of a magnetic study. Other materials considered unsuitable 1 (17) and 2 ) 5 for this study, as mentioned in Chapter 1, include the substances formulated as (SbF [’aF (17). 2 1 J the insufficiently characterized 6  6 the oxidation of 12 [Sb i] and ], I 1 F [Sb 2 Br 1 F 3 An alternate synthetic route to both 2 or Br 2 by stoichiometric amounts of bis(fluorosulfuryl) peroxide and subsequent solvolysis in an 5 according to: excess of SbF  212  2 2Br  +  +  F 6 0 2 S  F 6 0 2 S  +  +  5 8SbF  5 1OSbF  50°C >  1 ] [ 2I 1 F 2 Sb  >  6 ] 1 2 2Br 1 F 3 Sb  25°C  +  , 3 S 9 F 2 2Sb F O  +  , 3 S 9 F 2 2Sb F O  [5.1]  [5.2]  has produced sufficiently large quantities of both compounds for a magnetic study between 298 and 80 K using the Gouy technique (12). With all starting materials readily purified and the SO (18) easily separated from the product, this method, employed in 9 2 Sb F volatile byproduct 3 [Sb i] I 1 F the present study, was chosen as the most appropriate route to the synthesis of both 2 6 ]. [ 2 Br 1 F Sb and 3  With well over a dozen different O2 salts reported so far, this group of compounds appears to offer a wider choice, but here additional problems surface, which seem to have [PtF (1), 2 O ] adversely affected earlier magnetic studies. Some of the reported compounds, 6  115  RhF (20) have two different paramagnetic centers 6 [ 2 O RuF (20), or ] 6 [ 2 0 PdF& (19), j O [ 2 in the same molecular unit.  The initial approach by Bartlett and Beaton (21) involving the  [PtF has 2 0 ] subtraction of the molar susceptibilities of N0[PtF&- from those obtained for 6 clearly allowed th identification of 02+ as a paramagnetic ion; however, magnetic exchange ) is a plausible contributing factor for the observed decreasing trend 5 between 02 and Pt(V) (d of the magnetic moments attributed to 02+ with decreasing temperature. Magnetic ordering due to 02  Pt(V) exchange has subsequently been reported for this compound (23).  /F mixtures and 0 In addition, the high-pressure synthesis of dioxygenyl salts from 2 either metal fluorides or the metal itself (20,22,24) in metallic reactors has often resulted in materials with ferromagnetic contaminants (19,23). Although monel impurities can be recog nized by the characteristic Curie temperature of 335 K and corrections have been attempted (23), such materials remain suspect in magnetic susceptibility studies.  This is due to the  possible existence of weak antiferromagnetic ordering in such materials contaminated with monel.  UV photolysis in quartz vessels (25) represents a more suitable synthetic method, but a [GeF (27) prepared in this manner show 2 0 ] BF (26) and 5 4 [ 2 0 number of 02 salts such as ] [BF between 293 and 2 0 J rather limited thermal stability. Nevertheless, a magnetic study of 4 85 K has been reported (28a), but only limited conclusions were reached.  5 by either UV 2 with SbF For the products obtained from the reaction of 02 and F photolysis or high-pressure synthesis, some structural ambiguity has been noticed. This problem arises since in these reactions, a variety of [SbF +iJ type anions may be formed to stabilize 5 the 02 species.  [Sb i1 2 0 1 SbF and F 6 [ 2 0 Both j  6 has been postulated as well (29). Sb ] [ 2 O 1 F 3  116  are well characterized (6,24), and  The problems caused by this structural  ” reported in the SbF 6 [ 2 “O ambiguity are apparent from magnetic susceptibility studies on j Soviet literature (28).  AsF obtained by UV photolysis (25) was chosen for 6 [ 2 O To avoid similar problems ] this study. An additional reason for this choice is the availability of structural information on this compound. A phase transition at 255 ± 3 K (30) results in a rhombohedral distortion of the cubic structure found at room temperature (6) This distortion is also evident from ESR studies down to 4 K (23,3 1). Conclusions reached regarding the ground state of 02 in these ESR studies are useful in the interpretation of our low temperature susceptibility results.  [AsF down to 2 0 ] There have been two previous magnetic susceptibility studies of 6 4 K, with rather contradictory results. In a study by Grill et al. (32), no magnetic ordering of the 02+ cations is observed down to 4 K, while weak 0202+ exchange is suggested in another study (23) based on the small Weiss constant obtained.  However, these conclusions are  rendered somewhat tenuous because of ferromagnetic monel impurities in the sample, requiring correction of the susceptibility data (23).  In all previous magnetic susceptibility studies of 02k, the magnetic moments obtained over the whole temperature range are well below the spin-only value of 1.73 B’ and explana tions have varied from suggesting “van-Vleck behavior” (22) in analogy to the behavior of NO (11), to invoking the presence of 17% of an unidentified, magnetically inert impurity in AsF (32). Likewise in some studies down to 80 K (28), 6 [ 2 0 ]  values for O [SbF& 2  , appear to decrease with decreasing temperature, while for the structurally related 6 ’IAsF 2 0 ] eff is said to be invariant with temperature to 4 K (32). It is unclear why there are so many 1 I discrepancies and contradictions in previous studies. It is felt, however, that sample identity and purity play a major role here.  117  5.3.2  Magnetic Measurements  The results of our magnetic susceptibility studies on 3 id below 80 K, together [Sb 2 Br F with results obtained in an earlier study (12) at higher temperatures, are summarized in Table 5.1. Both sets of XM and eff data have been calculated using the same diamagnetic correction , respectively). The agreement between the data 1 3 mo1 and TIP values (279 and 120 x 10-6 cm sets in the overlap region is excellent for this compound.  1 and } AsF are given in Table 5.2. Because [Sb I 1 F 2 6 [ 2 O The data obtained here for ] of poor agreement in the 100 K region with the earlier Gouy data (12), the current study was extended with the vibrating sample magnetometer up to 124 K for the I2 compound. Addition ally, the measurements for the 02+ compound was also extended down to 2 K in the hope (not realized, unfortunately) of observing a maximum in the susceptibility data of this compound at very low temperatures. Pertinent structural and spectroscopic features of the three compounds , and 12+, either as solvated or gaseous species, are Br + studied and of the three cations, 02+, 2 summarized in Table 5.3.  The contrast in the magnetic properties of the three paramagnetic cationic species studied in this work is clearly evident from the plots of magnetic moment versus temperature 6 exhibit Curie Sb ], [ 2 Br 1 F [AsF and 3 2 0 ] shown in Figure 5.1. Two of the compounds, 6 Weiss behavior over a wide temperature range, as is seen by the plots of  /XM 1  vs. T given in  Figure 5.2.  5.3.3  6 Sb ] [ 2 Br 1 F 3  6 appears to be rather straightforward and will be Sb } [ 2 Br 1 F The magnetic behavior of 3 discussed in detail first. The 1 /XM versus T plot of this compound indicates Curie-Weiss  118  Table 5.1:  [Sb 2 Br 1 F 3 6 Magnetic Data of ]  Temperaturea (K)  XM X 106  L’eff (JIB)b  3 mol (cm ) 1  297  1870  2.04  275  2010  2.04  255  2160  2.04  235  2330  2.03  213  2530  2.03  193 172  2780  2.03  151  3070 3430  2.02 2.00  131  3900  1.99  116  4500  2.02  104  4910  2.00  6130  1.96  73.5  6070 6720  1.96 1.97  65.7  7440  1.96  55.0  8870  1.96  43.7  10900  1.94  31.4  15000  1.93  21.4  21900  1.93  10.2  1.93  9.88  45700 45900  4.20  111300  1.93  80.0 81.1  1.90  a First twelve data points from Ref. 12. b  1t with TIP Corrected for TIP using 11 eff = 2.828 ((XM TIP)T) -  119  =  120 x 10-6 cm 3 mo1 . 1  Table 5.2:  [Sb ] and 6 I 1 F Magnetic Data of 2 [AsF 2 O i  [AsF 2 O ] 6  [Sb J2 I 1 F Temperature XM  X  106  ffa  Temperature XM x 106  (RB)  (K)  ffb (iB)  3 mo1 (cm ) 1  (K)  3 mo1 (cm ) 1  124.1  3770  1.92  80.1  4170  117.5  3860 4290  76.3 72.7  4410  106.5  1.89 1.90  1.63 1.64  4650  1.64  98.6  4510  1.87  68.5  4950  1.65  90.9 84.3  4730  1.84  64.3  5480  1.65  4900  1.81  59.2  5600  1.63  81.2  5030  1.80  53.2  6170  1.62  76.8  5120  1.76  46.5  6990  1.61  71.8  5300  1.73  42.9  7520  66.6  5380  1.68  39.1  8200  1.61 1.60  63.5  5470  1.66  30.3  10530  1.60  58.4  5560  1.59  5560  25.3 20.5  12430  51.9  1.60 1.51  15100  1.57  44.9  5090  1.34  15.3  19700  1.55  36.9  4910  1.20  10.1  28800  1.52  31.6  4700  1.08  27.4  4490  27.1  37500  1.46  0.98  7.12 5.92  44500  1.45  4520  0.98  5.28  48300  1.43  21.8  4300  0.86  52200  1.41  11.6  4270  0.62  4.78 4.62  52700  1.40  8.64  4290  0.54  4.40  54800  1.39  6.30 4.54  4490  0.47  4.04  59400  1.39  4790  0.41  2.70 2.40  70400  1.23  75500  1.20  2.10  81300  1.17  a Corrected as in Table 3.1 with TIP = 68 x 106 cm 1 3 mo1 b Not corrected for TIP  120  [Sb i]’ 2 I 1 , F IAsF 2 O ] Structural and Spectroscopic Information on 6  Table 5.3:  , and I2 2 6 and the Corresponding Ions O2, Br ]’, 1 F 3 Brj’1Sb  Data, X Denotes 0, Br, or I  Shortest XX non-bonding interaction  [A]  van der Waals Radii for X  AsF 6 [ 2 O J  6 Sb J [ 2 Br 1 F 3  1 Sb ] [ I 1 F 2  or °2g)  or Br +(g) 2  or 1 2g)  05 • 4 4 to a  6.445  4.29  (ref. 28b,30)  (ref. 12, 4b)  (ref. 12, 6)  1.85  1.98  1.52  [A] (ref. 34)  Ground state of X2(g)  hhl/2g 2  Spin orbit coupling  185 (ref. 52)  const.  ] for X2(g) 1 [cm  /2g 2 3  f2g 2 3  195 (ref. 10)  2820 ± 40  5125 ± 40  (ref. 53)  (ref. 53)  3141 ± 160  5081 ± 60  (ref.  55)  (ref.  55)  l 1/2g tS.E( f 2 h13/2g) 2  ] 1 As above for X (l) [cm 2  ---  Diamagnetic Correction (ref. 56)  79  2890 (ref. 12)  279  [10-6 cm ] 1 3 mo1  a Estimated from powder diffraction data  121  5190 (ref. 2)  238  6 ], 1 and [Sb 2 Br 1 F 3 1Sb I 1 F 2 Magnetic Moment vs. Temperature of ],  Figure 5.1:  ] 6 O[AsF  2-  -  -  8  0-  0—  -  --CD  —  -  .-.  .  ..._..-  —.—  _ —  1.5-  z  F  ,  / /  1  Lii  /  0  / /  1  4  4  /  Z  o  °  /  6 Sb j [ 2 Br 1 F 3  1 [sb I 1 F 2 . ]—  /  AsF 6 [ 2 O • ] 0.5-  w /  00  20  40  60  80  TEMPERATURE,K  122  100  120  140  Figure 5.2:  -J 0  6 Sb ] [ 2 Br 1 F [AsFj and 3 2 Inverse Susceptibility vs. Temperature of O  250 0 0 0 0  200 0  () ,0  ‘Pt -J  /  150  0’  /  A’  0’ /  0’ /  0  w  0 U) D U)  /  /  100 /  /  /  0’  C-)  z  /  .—  AsF 6 [ 2 O J r 6 Sb B [ 2 1 F 3 . J  0  /  50  .-.  C,  0 0  20  60  40  TEMPERATURE,K  123  80  100  behavior over the temperature range from 80-4 K (Cm 0.01 K).  =  1 K, 9 0.49 ± 0.01 cm 3 mo1  =  -0.74 ±  The magnetic moments (even when corrected for TIP) decrease slightly with  temperature. A TIP correction had been arbitrarily assigned in the earlier work (12) in order to bring the magnetic moments in the high-temperature region into agreement with the value of H3g ground state and no thermally acces 2.0 B predicted by theory (11) for a species with a 2  sible excited state (see Table 5.3).  /3zE (33), where sE is the 2 The correction for TiP in the present study was taken as 4N3 state with which it is  l3g and the next excited 2 energy separation between the ground f mixing.  2 is the spin-orbit coupling constant, The AE value for Br  ,  and for this species,  1 for the solvated ion (Table 5.3), and using this value a TIP of 120 x 10-6 estimated at 2890 cm mo1 is calculated. Magnetic moments calculated using this TIP correction are within ±2% 31 cm of the theoretical value of 2.0 B over the wide temperature range of 297-55 K (Table 5.1).  The cause of the very small drop in the moment, particularly at very low temperatures (corresponding to the effect of a Curie-Weiss rather than Curie law behavior) is not certain. Although the shortest non-bonding BrBr contact at 6.445 A (4b) is too long  to invoke  significant direct magnetic interaction (Figure 5.3), F”Br contacts ranging from 2.86-3.34 comparable to or shorter than the sum of the van der Waals radii of 3.32  A  A,  (34), suggest the  possibility of very weak exchange via bridging anions. However, the effect is very minor and it 2 cation is in a thermally isolated 6 the Br Sb ] [ 2 Br 1 F is reasonable to conclude that in 3 ground state and there is no conclusive evidence for any magnetic exchange between para 6 is somewhat unique, since for all Sb ] [ 2 Br 1 F magnetic centers down to 4.2 K. In this regard 3 , 3 other paramagnetic main group species, including 02 (35), the recently studied ozonides, K0 , and Cs0 3 Rb0 3 (36), and solid 02 (37), as well as ‘2 and O2 (discussed below), at least weak antiferromagnetic coupling has been suggested.  124  Figure 5.3:  Crystal Structure of ] ISb 2 Br 1 F 3 6 (redrawn using data from ref. 4b)  [Br]  [Br]  r  0  2 Br—Br  =  6.445A  I 1 F 3 B4Sb Menoclinic 13.58 i 0.02 A 7.71 * 0.01 A 14.33 ±0.02 A 93.7 a 0.2 3 1497 A 3 3.68 g cm 4 2.15 A 2.86 A 1.83 A 2.10; 1.97 A 1,11  a b C  V z X—X, bond length X F, closest contact Sb..F (terminal) t Sb...F(btidIng) t ...  R  tbrid,Irter  125  5.3.4  O[MF(]  2 compound in that [AsF are similar to those of the Br 2 0 ] The magnetic properties of 6 Curie-Weiss behavior is followed (Figure 5.2), although over a more limited temperature range of 60-2 K. Here the Curie constant Cm, is significantly smaller and the absolute value of the Weiss constant, 101, greater (C  =  3 moi 0.34 ± 0.01 cm 1 K, 0  =  -1.90 ± 0.01 K). Consequently,  +[A5F and show a stronger 2 0 J the effective magnetic moments are significantly smaller for 6 temperature dependence, particularly in the low temperature region (Figure 5.1).  A slight  departure from linear behavior in the Curie-Weiss plot is noted (Figure 5.2) above 60 K. This may be significant, as it coincides with the observed broadening of the ESR line (23), possibly caused by tumbling motions of 02 in the crystal lattice.  These findings are at variance with a previous report by Grill et al. (32), who observed Curie-Weiss behavior for 02+ with a positive 0 value (according to our formulation of the law) of 0.7 K. The results of our study are in reasonable agreement with those of DiSalvo et al. (23), who obtained Cm  =  1 K and 9 0.309 cm 3 mol-  =  -0.8 K (sign changed from (23) to conform to  our formulation of the law), although it must be taken into consideration that a temperatureindependent paramagnetism contribution  as well as corrections for ferromagnetic impurities  were made in the earlier work.  In this work the susceptibilities of 02 were not corrected for TIP.  A crystal-field  - suggests the separation between the ground and first AsF 6 [ 2 0 analysis of ESR data for ] 1 (Figure 5.4), caused by both spin-orbit coupling and electronic excited state to be 1480 cm crystal-field splitting due to 02 being in a site of orthorhombic or lower symmetry (31). In this 113flg states and it is not clear what the TIP case one is clearly not dealing with pure 2 1i2g and 2 correction should be. In any event, the large separation between the states means such a correc tion will be small, and hence ignoring it should not significantly affect the conclusions.  126  Figure 5.4:  Energy Level Diagram of the Dioxygenyl Ion with the a and it-Bonding 2p Orbitals (Ref. 31)  2pJ*  T  (2÷2)j-  2pit  ii  2p  H  2p  (a)  (b)  (c)  free ion  spin—orbit coupling. ?  spin—orbit coupling + orthorhombic field,  127  When considering the magnitude of the magnetic moment, it is observed that for O [AsFj the measured magnetic moments in the range of 1.6 B at the higher temperature 2 region agree well with values predicted using the average g values, gay of 1.89 (23) and 1.905 (31) obtained by ESR. Using the equation for the magnetic moment of a single electron B  =  , values of 1.64 and 1.65 B are obtained respectively for the above two gay data. 2 / 1 g[S(S+1)1  As described by Goldberg et al. (31), both crystal-field splitting and spin-orbit coupling -. In a pure 2 6 [ 2 O AsF contribute to the ground state in ] fllag ground state the spin and orbital contributions cancel, and there is no first-order paramagnetism associated with this state (33). If this were the case for O2 with negligible thermal popuation of excited states, only temperature-independent paramagnetism would be present. This is clearly not the case here. The crystal-field interactions have the effect of quenching the orbital contribution, although not completely, resulting in a ieff value slightly below the spin-only value. Quite the opposite effect 2 with M is observed for the alkali metal superoxides, MO ground state is  =  Na, K, Rb, Cs (35). Here the  and in all instances the .teff values are well above the spin-only value of  1 and Y [Sb I 1 F 2 6 (12). 1.73 B’ as was found for ] [Sb 2 Br 1 F 3  , particularly 6 [ 2 O AsF The decrease in neff values with decreasing temperature for ] 1 separat significant below —20 K, requires further consideration. With a splitting of 1480 cm ing the ground state from the nearest excited state, the variation in the effective magnetic moment with temperature observed here cannot be accounted for by the sort of van Vieck behavior observed for gaseous NO (33). The existence of antifeffomagnetic exchange between paramagnetic centers must be considered as a possibility.  [AsF (25,31,38) derived from 2 O } The limited structural information available on 6 powder diffraction data does not permit an accurate determination of the shortest OO non bonding contact distance. Estimates of 4.00 (30b) and 4.05  128  A  (32) respectively, which were  used to argue against 0”{) interaction, are simply half the unit cell length ad2 for the roomtemperature phase (25,31,38).  The distance ad2 describes the separation between the mass  centers of the 02+ cations, which are assumed to be in the most probable sites.  The low-  temperature phase, which is directly relevant to this study, has a powder diffraction pattern that has not been successfully indexed (30); hence the conclusion (32) that there can be no antiferro magnetic exchange in 6 - because the 02 ions are too far apart is most likely invalid. [AsF 2 0 1  For 2 , where a single crystal X-ray diffraction study at room temperature and [Mn 0 ] 9 F at -150°C is reported (39), non-bonding 00 contacts of 3.86 values of 3.98  A observed at room temperature.  A are detected at -150°C with  However, the anion is described as a double  6 octahedra with 02 cations between the anion layers, and the chain of cis-bridged MnF . Moreover, susceptibility studies 6 [ 2 0 AsF resulting structure is not comparable with that of ] on this material would not be suitable for the purposes of this work as the magnetism would be +, a second paramagnetic center. 4 complicated by the presence of Mn  With the sum of the van der Waals radius 3.02 reasonably expect distances of 3.2-3.3  A  A  for two oxygen atoms, one would  as the limit for significant direct antiferromagnetic  exchange. This estimation is corroborated by recent reports on the structures of the alkali metal 3 (43), all of which exhibit significant anti 3 (40,4 1) and Cs0 ozonides K0 3 (40,41,42), Rb0 , and where 00 non-bonding contacts range between 6 [ 2 0 AsF ferromagnetism (34) than ] 3.01-3.15  A  for K0 3 and 3.01-3.30  A  for Rb0 , respectively. For Cs0 3 , where antiferro 3  magnetic exchange is rather weak (36), only powder data are reported (43) and indexed, suggest . The unit-cell dimensions indicate slightly longer 00 3 ing Cs0 3 to be iso-structural with Rb0 contacts for this compound (42).  Contact distances of the order of those observed in the  ozonides could be present in 6 [AsF and this could account for its observed magnetic 2 0 1 properties.  129  5.3.5  ] 11 I[SbF  1 it was shown that a TIP correction in [Sb ] + 1 1 F In a previous report from our group on 2 + compound was required to bring the experimental room2 excess of that assumed for the Br temperature moment into agreement with the value of 2.0 B predicted by theory (12).  In  addition, it was suggested in the earlier work that the observed decrease in the magnetic moment on decreasing the temperature to 80 K may arise from antiferromagnetic exchange between contiguous  cations in the crystal lattice, where the shortest Fl non-bonding contact distance  (5) is found to be 4.29  A (Figure 5.5).  [Sb ] down to 4.2 K 2 I 1 Magnetic measurements on F  reported here confirm the presence of antiferromagnetic coupling. The susceptibility rises to a maximum at —54 K, then decreases on further cooling (Figure 5.6). The rise again in suscep tibility on cooling below l0 K is probably due to trace amounts of paramagnetic structural impurity, as is often observed in antiferromagnetically coupled systems (13).  In view of the clear evidence that this system is exchange-coupled, there is no justifica tion for arbitrarily reducing the room-temperature moment to 2.00 B with an appropriate TIP correction, as was done previously (12). Indeed, in view of the fact that the 2 1t2g 3/2j 2 separation is significantly greater in the  2 (see Table 5.3), any compound compared to Br  TIP would be expected to be smaller in the former. TIP for  (calculated as described above  3 mo1 1 and magnetic moments calculated employing this value are j is 68 x 10.6 cm 2 for Br given in Table 5.2. The decrease in  with decreasing temperature is consistent with anti  ferromagnetic coupling; interestingly though, the absolute values in the high-temperature region are in excess of the theoretically predicted value of 2.0 B (11).  An attempt is made here to analyze the magnetic susceptibility data of I2 (including the data from 295-130 K from ref. (12)) according to three theoretical models for antiferromagnetic exchange in one-dimensional systems. For a magnetically concentrated system with spins Si  130  11 (redrawn using data from ref. 5) F 2 Ij[Sb Figure 5.5: Crystal Structure of ]  2]  + 1 r £2  T+4.29A 2  Fj 2 ISb  Monoclinic I  b C  P V Dcsi 2  X—X, bond enth X F, closest contact ...  rSbF(termin.I) tSb_E(brIdgng)  R  brd./’ter  131  13.283(5)A L314(3)A 5.57J(2)A 103.75(2) 597.5 A 3 3 3.92gcm 2 2.557(4) A 2.89 A 1.85 A 2.00 A 1.08  Figure 5.6:  [Sb I 1 F 2 1 Magnetic Susceptibility vs. Temperature of ]. (Circles are experimental data; Solid line is the best fit to the Ising S’  =  112 model)  >F— -j o0 c1  F— ULU 0 C U) rO D U) C-)  5  0  r  0  C-) F— 0 LU  z  0  100  200  TEMPERATURE (K)  132  300  and S, the nearest neighbor exchange coupling is given by the Hamiltonian Hex ()  H  =  N -23 Z aSjzSz  SJX 1 I3S  +  +  ySYSY  [5.3]  z are the components of the spin vector S 1 Y and S 1 S 1 of the ith atom, N the number of  where  magnetic atoms and 3, the exchange coupling constant, which can either have a positive or negative value, i.e. ferromagnetic or antiferromagnetic interaction. The values of a, f3 nd y in equation (4.3) define the nature of the exchange coupling. When a  =  =  Heisenberg exchange Hamiltonian results. In the extreme situation where a  1, the isotropic  =  =  1 and f  =  y  =  0,  the Ising model is described (anisotropic coupling).  The isotropic Heisenberg Hamiltonian has been extensively examined but no exact solutions are presently known. However, results of many approximate methods exist (45). For the Ising model Hamiltonian, closed-form solutions are available for both the parallel and perpendicular magnetic susceptibilities of the S  =  1/2 system (46).  Considering the 2 113/2g ground state of I2 as having an effective spin S’  =  3/2 (47), our  data were fitted to an isotropic Heisenberg model developed by Weng (48), employing the following polynomial expression and appropriate coefficients given by Hiller et al. (49) for the molar susceptibility:  3 2 Ng XM where x  =  =  kT  [A  +  kT/IJI.  133  [1 Bx ] 2  +  Cx  +  ’ Dx 1 3  [5.4]  In the above equation (and equations [5.6] and [5.7], see below) g is the Lande splitting factor,  the Bohr Magneton, N the number of spins in the lattice, k Boltzmann constant, T the  temperature and 3 the exchange coupling constant. The values of the coefficients for S=1/2 and S=3/2 are as follov s:  S  A  1/2  0.2500  3/2  1.2500  B  C  D  0.18297  1.5467  3.4443  17.041  6.7360  238.47  Allowance was made for paramagnetic impurity by modelling it as a Curie paramagnet with a g value equal to that of the bulk sample, i.e.  =  3 Expressing XM from equa f 2 Ng S (S+1)/3kT.  tion [5.4] as hain’ the susceptibility expression including paramagnetic impurity is X  [lP1x.jn  +  Xpara The experimental data were fitted to this expression using g, J, and P as 1  fitting parameters. The best fit was considered to be that set of fitting parameters which gave the minimum value of the function F (50):  F  =  n [‘/ E 1 ” 1 ] 2 (X c alcd X’obs / X’b)  [5.5]  -  where n is the number of data points, and X’cacd and X’ 5 are the calculated and observed b 0 susceptibilities, respectively. For S’ the effective g  =  1.23, P  =  =  3/2, the best fit of the data for I2 was with 3  0.0035, and F  =  =  -7.2 cm , 1  0.0560. In view of the molecular anisotropy of the  magnetic species, the anisotropic Ising model should be examined as well. Unfortunately, while an exact solution exists for the parallel susceptibility of the Ising S  =  3/2 case (51), there is no  solution for the perpendicular case and hence one cannot analyze the powder data according to  134  this model.  An alternative approach to the data analysis is to consider the possibility that the four fold degeneracy of the ground  fl3flg 2  state has been lifted by second- or higher-order  interactions with excited states, leaving a thermally isolated Kramer’s doublet as the only significantly thermally populated ground level. In this case one needs to consider an effective spin, S’  =  1/2, and here both Heisenberg and Ising models are available. Employing again the  Weng model and equation [5.4], a best fit between theory and experiment was obtained with 3 , effective g 1 -28 cm  =  2.72, P = 0.0061, and F  =  =  0.0487.  As mentioned earlier, exact solutions for both the parallel and perpendicular suscep tibilities for the anisotropic Ising S’  =  1/2 case are available, and the data were analyzed using  the equations of Fisher (46):  (Ng22  I  Xii  =  Assuming Xwder 2.61, P S’  =  =  =  XII 3 / 1  0.0054, and F  =  +  \lexp.i/2IJ1  \  4kT/  / I  Ng232\  \81J1  ‘\  J  [5.6]  \kT/  /  IJI 1[tanh j J \kT/ —  /  131 +  kT  /  (IJI) 2j Sech \kT  2/3, the best fit was generated with 3  =  JI  [5.7]  /  -38 cm , effective g 1  =  0.0368. The agreement between experiment and theory for this Isihg  1/2 case is illustrated in Figure 5.6 where the solid line is calculated from theory. The  agreement between experiment and theory for the other two models is visually very similar to that shown in Figure 5.6, although in both cases the agreement is slightly poorer, as is indicated  by the higher F values.  In all three cases, as the temperature is lowered the experimental  susceptibilities rise more steeply to a higher maximum value and then decrease more steeply  135  when compared to the calculated susceptibilities.  The analysis of the magnetic susceptibility data clearly indicates that in the lattice of 1 contiguous Sb ] [ 1 1 F 2  ions are relatively strongly antiferromagnetically coupled, although  it does not provide a clear answer to the question of whether or not the thermally occupied ground state at low temperatures is a pure 2 3Rg state. Measurements of magnetic suscep tibilities at low temperatures on suitably oriented single crystals to obtain  values (47) would  be informative, but would require the synthesis of relatively large crystals of the material.  1 Sb J [ I 1 F It is important to note that the antiferromagnetic coupling observed here for 2 F (2), just as 3 is distinctly different from the dimerization process suggested for ‘2(1v) in HSO 1 Sb ] [ I 1 F the solid-state structure of 2  [AsF and 4 I 2 ] differs from the structures of 6  4 (15) where square planar, diamagnetic 142+ cations are found. (SbF (Sb )J [ 4 I ) 6 1 F 3 2  5.4  Conclusion  , AsF 6 [ 2 O Magnetic susceptibility measurements to 4.2 K are reported for j 1 Sb j. [ I 1 F 6 and 2 Sb ], [ 2 Br 1 F 3  The data are interpreted utilizing previous results from  photoelectron spectroscopy of the gaseous cations, known crystal structures, magnetic studies on , previous ESR studies. +[AsF 2 0 ] the superoxide ion and the ozonide ion, and in the case of 6  6 obeys [Sb 2 Br 1 F 3 The magnetic properties of the three materials are quite different. ] Curie-Weiss law between 80 and 4 K: Cm (with TIP  =  =  0.49 ± 0.01 cm 3 mo1 1 K and  e  =  -0.74 ± 0.01 K  120 x 10-6 cm 3 mol ). The magnetic moment decreases slightly from 2.04 B at 1  1 exhibits relatively strong antiferromagnetic Sb ] [ I 1 F room temperature to 1.93 B at 4 K. 2 coupling with a maximum in X observed at 54 K. the magnetic moment (corrected for a TIP ) decreases from 1.92 B at 124 K to 0.41 B at 4 K. 1 3 mo1 contribution of 68 x 10 cm  136  Experimental susceptibilities for this compound over the range 300-4 K have been compared to values calculated using three different theoretical models for extended chains of antiferro magnetically coupled paramagnetic compounds.  Br and 12+ is due to structural + The major difference in magnetic behavior between 2 [Sb 2 Br 1 F 3 6 and F difference between ] [Sb J. Magnetic exchange through contiguous ‘2 2 I 1 ions is suggested by the crystal structure of J. [Sb I 1 F 2 1 The shortest FI non-bonding contact is 4.29  A,  comparable to the sum of the van der Waals radii of 3.96  shortest Br”Br contact is 6.445  A,  about 2.8  A  A.  In 3 ] [ 2 Br 1 F Sb 6 the  longer than the van der Waals distance, and  direct magnetic exchange becomes improbable as discussed above.  [AsF exhibits Curie-Weiss behavior over the range 60-2 K (Cm 2 O ] 6 1 K, 8 mo1  =  =  0.34 ± 0.01 cm 3  -1.90 ± 0.01 K). The magnetic moment, uncorrected for TIP, varies from 1.63 B  at80Kto B 17 at2K. • 1  Finally, in the ] 6 [ 2 O AsF , there appears to be weak antiferromagnetic coupling that may involve either super-exchange through intervening AsF 6 anions (the smallest anion of the three encountered in this study) or even direct weak O 0 interaction.  References  1.a) b)  N. Bartlett and D.H. Lohmann, Proc. Chem. Soc., 115 (1962). N. Bartlett and D.H. Lohmann, 3. Chem. Soc., 5253 (1962).  2.  R.J. Gillespie and J.B. Milne, Inorg. Chem.,  3.a)  R.J. Gillespie and M.J. Morton, Chem. Comm., 1565 (1968).  b)  ,  R.J. Gillespie and M.J. Morton, Inor. Chem.,  137  1577 (1966).  II, 586 (1972).  4.a) b) 5.  A.J. Edwards, G.R. Jones, and R.J. Sills, Chem. Comm., 1527 (1968). A.J. Edwards and G.R. Jones, J. Chem. Soc. A, 2318 (1971). C.G. Davies, R.J. Gillespie, P.R. Ireland, and J.M. Sowa,  Can. J. Chem., 52, 2048  (1974). 6.  R.J. Gillespie and 3. Passmore, Adv. Inorg. Radiochem.,  fl, 49 (1975) and references  therein. 7.  R.J. Gillespie and M.J. Morton, J. Mol. Spectrosc., 30, 178 (1969).  8.  F.G. Herring and R.A.N. McLean, Inorg. Chem., 11, 1667 (1972).  9.  D.W. Turner, C. Baker, A.D. Baker, and C.R. Brundle,  “Molecular Photoelectron  Spectroscopy”, Wiley, New York, 1970. 10.  G. Herzberg, “Spectra of Diatomic Molecules”, van Nostrand, New York, 1950.  11.  J.H. Van Vieck,  “The Theory of Electric and Magnetic Susceptibilities, Oxford  University Press, Oxford, 1932. 12.  W.W. Wilson, R.C. Thompson, and F. Aubke, Inorg. Chem., j, 1489 (1980).  13.  J.S. Haynes, K.W. Oliver, S.J. Rettig, R.C. Thompson, and J. Trotter, Can. J. Chem., 891 (1984).  14.  A. Smaic, Inst. Josef Stefan, I.J.S. Report R. 612, 1 (1972); Chem. Abstr.  13032t  (1973). 15.  R.J. Gillespie, R. Kapoor, R. Faggiani, C.J.L. Lock, M.J. Murchie, and J. Passmore, Chem. Comm., 8 (1983).  16.  J. Passmore, E.K. Richardson, and P. Taylor, J. Chem. Soc. Dalton Trans., 1006 (1976).  17.  R.D.W. Kemmitt, M. Murray, V.M. McRay, R.D. Peacock, M.C.R. Symons, and T.A. O’Donnell, J. Chem. Soc. A, 862 (1968).  j3, 431 (1979).  18.  W.W. Wilson and F. Aubke, J. Fluorine Chem.,  19.  W.E. Falconer, F.J. DiSalvo, A.J. Edwards, J.E. Griffiths, W.A. Sunder, and M.J. Vasile, J. Inorg. Nuci. Chem. Suppl., 59 (1976).  138  A.J. Edwards, W.E. Falconer, J.E. Griffiths, W.A. Sunder, and M.J. Vasile, J. Chem.  20.  Soc. Dalton Trans., 1129 (1974). 21.  N. Bartlett and S.P. Beaton, Chem. Comm., 167 (1966).  22.  J.B. Baal, Jr., C. Pupp, and W.E. White, Inorg. Chem.,  23.  F.J. DiSalvo, W.E. Falconer, R.S. Hutton, A. Rodriguez, and J.V. Waszczack, J. Chem.  ,  828 (1969).  Phys., 62, 2575 (1975). I.V. Nikitin and V. Ya. Rosolovskii, Russ. Chem. Rev. (Engi. Trans.)  24.  4, 889 (1971);  Usp. Khim. 4, 1913 (1971) and references therein. J. Shamir and J. Binenboym, Inorg. Chim. Acta,  25.  ,  37 (1968); Inorg. Svnth.,  .14. 39  (1973). 26.  J.N. Keith, I.J. Solomon, I. Sheft, and H.H. Hyman, Inorg. Chem., 2 230 (1968).  27.  K.O. Christe, R.D. Wilson, and I.B. Goldberg, Inor. Chem., j, 1271 (1976).  28.a)  V.1. Belova, Ya.K. Syrkin, D.V. Bantov, and V.F. Sukhoverkhov, Russ. J. Inorg. Chem. (Engi. Trans.)  b)  .j3, 765 (1968).  V.1. Belova, V.Ya. Rosolovskii, and E.K. Nikitina, Russ. J. Inorg. Chem (Engi. Trans.)., 772 (1971).  29.  D.R. Slim, Ph.D. Thesis, University of Birmingham, 1974.  30.a)  P. Rigny and W.E. Falconer, 3. Chem. Phys.,  b)  C. Naulin and R. Bougon, 3. Chem. Phys.,  ,  2581 (1975).  4, 4155 (1976). 14, 152 (1975).  31.  I.B. Goldberg, K.O. Christe, and R.D. Wilson, Inorg. Chem.,  32.  A. Grill, M. Schieber, and J. Shamir, Phys. Rev. Lett.,  33.  R.J. Myers, “Molecular Magnetism and Magnetic Resonance Spectroscopy”, Prentice-  25, 747 (1970).  Hall Inc., Englewood Cliffs, New Jersey, 1973. 34.  A. Bondi, 3. Phys. Chem., 68, 441 (1964).  35.  A. Zumsteg, M. Ziegler, W. Kanzig, and M. Bosch, Phys. Cond. Matter, jJ, 267 (1974).  36.  K. Lueken, M. Deussen, M. jansen, W. Hesse, and W. Schnick, Z. Anorg. Alig. Chem.,  3, 179 (1987). 139  37.  D.E. Cox, E.J. Samuelson, and K.H. Beckurts, Phys. Rev.  38.  A.R. Young, II, T. Hirata, and S.I. Morrow, J. Am. Chem. Soc., 86, 20 (1964).  39.  B.G. Mueller, J. Fluorine Chem., 12,409 (1981).  40.  W. Schnick and M. Jansen, Angew. Chem. mt. Ed. (English’). 92. 54 (1985).  41.  W. Schnick and M. Jansen, Z. Anorg. Aug. Chem.,  42.  W. Schnick and M. Jansen, Rev. Chem. Miner., 24, 446 (1987).  43.  M. Jansen, and W. Hesse, Z. Anorg. Aug. Chem., Q, 47 (1988).  44.  J.S. Miller, Ed. “Extended Linear Chain Compounds”, Vol. 3, Plenum Press, New York,  3102 (1973).  32, 37 (1986).  1983. 1991 (1981).  45.  J.D. Johnson, J. Appl. Phys.,  46.  M.E. Fisher, J. Math. Phys.,  47.  R.L. Carlin, “Magnetochemistry”, Springer-Verlag, Berlin, 1986.  48.  C.H. Weng, Ph.D. Dissertation, Carnegie-Mellon University, Pittsburgh, PA, (1968).  49.  W. Hiller, J. Strahle, A. Datz, M. Hanack, W.E. Hatfield, L.W. ter Haar, and P. Gutlich,  ,  4, 124 (1963).  J. Am. Chem. Soc., 106, 329 (1984). 50.  W.V. Cicha, J.S. Haynes, K.W. Oliver, S.J. Rettig, R.C. Thompson, and J. Trotter, J. Chem., 63, 1055 (1985). 124 (1976).  51.  M. Suzuke, B. Tsujiyama, and S. Katsura, J. Math Phys.,  52.  0. Edquist, E. Lindholm, L.E. Selin, and L. Asbrink, Phys. Scripta, 1, 25 (1970).  53.  A.B. Comford, D.C. Frost, C.A. McDowell, J.L. Ragle, and l.A. Stenhouse, J. Chem.  ,  Phys., 4, 2651 (1971). 54.  P. Venkateswarlu, Can. J. Phys., 47, 2525 (1969).  55.  P. Venkateswarlu, Can. J. Phys., 4, 2525 (1969).  56.  Landolt-Börnstein, Numerical data and functional relations in science and technology, Vol. 2, Magnetic properties of coordination and organometaflic transition metal com pounds, Springer-Verlag, Berlin, 1966.  140  CHAPTER 6  MAGNETIC EXCHANGE IN M(II) SULFONATES, M(ll)  6.1  =  Ni(I1), Pd(ll) AND Ag(ll)  Introduction  ) 2 F 3 Ni(SO The sulfonates described in this Chapter include the metal(II) fluorosulfates , , more appropriately formulated as the mixed valency F) “Pd(SO ” ) and 3 2 F 3 ) Ag(SO 2 F 3 Pd(SO , CF 3 Ni(SO , 2 ) and the metal(ll) thfluoromethylsulfates ) , 6 F 3 Pd(II)[Pd(IV)(SO compound ] CF These compounds can also be considered as transition metal 3 Ag(SO . 2 CF and ) 3 Pd(SO , 2 ) F 3 CF respectively. The anions SO 3 F and HSO 3 derivatives of the strong sulfonic acids I-{SO CF have the potential to coordinate to the metal ions as bidentate or tridentate 3 and S0 bridging ligands (1-5), and consequently polymeric, layered materials with paramagnetic metal centers are formed. As pointed out in Chapter 3, only a limited number of paramagnetic binary fluoro compounds of divalent nickel, palladium and silver has been synthesized so far, and therefore it is of interest to study the magnetic properties of the above sulfonates which are rare binary fluoro derivatives of the respective divalent metals.  Several transition metal fluorosulfate and trifluoromethylsulfate compounds have been studied previously for their magnetic properties in the higher temperature range, usually down to ) 4 F 3 —80 K only (1-4,6-15). Interestingly, it appears that among the fluorosulfates, only Jr(SO ) (11) are magnetically concentrated, and in the trifluoromethyl Ir(SO 6 [ 2 Cs F 3 and its derivative ] CF (4). The 3 Ag(SO 2 CF (14) and ) Fe(SO 3 sulfates magnetic exchange is detected only in ) exchange coupling observed in all four of these derivatives is reported as antiferromagnetic. This is significant and not totally unexpected, since the majority of the magnetically concentrated transition metal fluoro compounds exhibit antiferromagnetism rather than ferro- or  141  ferrimagnetism (16).  Ferromagnetic ordering is hence a rare phenomenon in ionic solids, and is largely confined to small groups of transition (d-block) and lanthanide metal -oxides, -chalcogenides and -halides with distinct structural features that permit one, two or three dimensional exchange via monoatomic anions (17, 18).  However, in contrast the four metal(II) fluorosulfate  F anion and show significant ferromagnetic 3 compounds studied here contain the polyatomic SO exchange at low temperatures. Previous magnetic measurements down to —80 K on the binary F) (2), showed that the compounds 3 “Pd(SO ) (3) and ” 2 F 3 ) (2), Ag(SO 2 F 3 fluorosulfates Pd(SO were relatively magnetically unconcentrated in that temperature range, and their susceptibilities followed the Curie-Weiss law closely with small positive Weiss constants.  CF and 3 Pd(SO 2 CF ) 3 Ni(SO , 2 The three metal(lI) trifluoromethylsulfate compounds ) CF investigated here for their magnetic behavior have all been synthesized 3 Ag(SO 2 ) previously (4, 5, 19) although no variable temperature susceptibility studies have been reported CF compounds until now. A previous high temperature 3 Pd(S0 2 CF and ) 3 Ni(SO 2 for the ) CF compound indicated that the Ag(ll) ions in the sample were coupled 3 Ag(SO 2 study on the ) antiferromagnetically (4). Therefore, the two analogous nickel and palladium derivatives were investigated in this work to determine whether these compounds are also magnetically concentrated with antiparallel spins.  In addition, magnetic measurements were run on the  CF compound at lower temperatures to verify the previously reported higher tempera 3 Ag(SO 2 ) ture susceptibility data.  It is significant to note here that the metal(ll) fluorosulfates and the irifluoromethyl type structure, CdC1 sulfate analogs described in this Chapter are assumed to have the common 2 which is also seen in the metal(II) hexafluoroantimonates discussed in Chapter 3. Layered struc CH (20b) have been previously 3 Ca(SO 2 ) (20a) and ) 2 F 3 tures of the type seen in Sn(SO  142  proposed for a number of divalent metal sulfonates (6, 10, 13, 15), on the basis of magnetic properties and vibrational spectra. It was proposed that these compounds adopt a polymeric two-dimensional structure, where each metal site is surrounded by an octahedral arrangement ) 2 F 3 (tetragonally distorted in the silver derivatives) of oxygen ligands, as illustrated for Pd(SO in Figure 6.1.  Figure 6.1:  F) 3 Pd(SO Proposed Structure of 2  0  0  S  0  Metal  143  F  6.2  Experimental  F) (13), 3 Ni(SO The synthetic procedures for the preparation of metal(ll) fluorosulfates 2 ) (3), 3 2 F 3 F) (2), and the metal(ll) trifluoromethylsulfates “Pd(SO ’ t F) (2), Ag(SO 3 Pd(SO CF (4) have been described in detail previ 3 Ag(SO 2 CF (5) and ) 3 Pd(SO 2 CF (19), ) 3 Ni(SO 2 ) ously. These methods were followed in the present study as well. Attempts were made to ) F, 3 “Pd(SO ’ , the corresponding trifluoromethylsulfate derivative of t CF “Pd(SO ” 3 synthesize ) CF (5) led to the binary 3 F) in excess HSO 3 “Pd(SO but in all instances the solvolysis of ” CF compound only. 3 Pd(SO 2 )  All the reactions were monitored by weight, and the purity of the products was determined by elemental analysis and IR spectroscopy.  Magnetic data were corrected for  Temperature Independent Paramagnetism (TIP) using the following reported lODq values CF 3 Ni(SO 2 ) 16600 (3) and ) 2 F 3 ) 11770 (1); Ag(SO 2 F 3 : 2 [cm ] 1 F) 7340 (1); Pd(SO 3 Ni(SO , 7350 (19).  6.3  Results and Discussion  The magnetic data obtained on the M(II) sulfonates with M=Ni, Pd and Ag, clearly indicate two distinct types of magnetic exchange present in the two groups of compounds. All the M(II) fluorosulfates studied here exhibit strong ferromagnetic exchange at lower tempera tures, whereas the M(II) trifluoromethylsulfates show antiferromagnetism with varying degrees of magnetic concentration over a wider temperature range. Therefore, the discussion of the magnetic results can be conveniently divided into two parts, ferromagnetism and antiferromag netism of the respective sulfonate derivatives. Ferromagnetism will be discussed first and in greater detail, since this phenomenon is rare and unusual in transition metal fluoro compounds.  144  6.3.1  ) 2 F 3 Pd(SO ) , 2 F 3 Ni(SO Ferromagnetism of M(ll) fluorosulfates ,  ) 2 F 3 ) and Ag(SO 6 F 3 Pd(II)[Pd(IV)(SO ]  Previous magnetic susceptibility measurements on the three palladium and silver fluorosulfates investigated here indicate that the compounds are relatively magnetically dilute F) Therefore, 3 Ni(SO . down to —80 K (2,3). No detailed magnetic study exists in the case of 2 F) are extended down to —4 K (—2 K “Pd(SO ” ) and 3 2 F 3 ) Ag(SO 2 F 3 Pd(SO measurements on , ) is studied in the temperature range of —291 to 2 K. The pertinent 2 F 3 for 2 F) and Ni(SO 3 Pd(SO ) magnetic data obtained with the vibrating sample magnetometer in the lower temperature range F) from —291 to 3 Ni(SO are presented in Tables 6.1, 6.2, 6.3 6.4, and the Gouy measurements of 2 79 K are given in Table 6.5. A summary of the relevant magnetic parameters on all four fluoro sulfates is listed in Table 6.6 (see Appendices B-i to B-3 for additional magnetic data).  ) previous higher temperature measure 2 F 3 Ag(SO F) and , 3 “Pd(SO ) ” 2 F 3 Pd(SO For , ments were presented as plots of 1 /XM vs. T, which were linear, and had positive Weiss constants (Table 6.6), indicative of Curie-Weiss behavior. The magnetic moments calculated for the three compounds (1-3) were in good agreement with expected values for approximately ) species. A similar situation is observed in 9 ) and Ag(II)(d 8 octahedrally coordinated Pd(II)(d ) where the inverse susceptibility vs. temperature graph in the higher 2 F 3 Ni(SO the case of , temperature region also gives a straight line plot (Figure 6.2). However, the Weiss constant ) appears to be magnetically dilute 2 F 3 obtained here 0.41 K is relatively small and hence Ni(SO down to —80 K. The 1 eff value of about 3.27 B (Table 6.5) in this temperature range is not F) with the Ni(II) ions located in octahedral ligand sites (13,21; see also 3 Ni(SO , unexpected for 2 Chapter 3).  145  Table 6.1:  F) 3 Ni(SO Low Temperature Magnetic Data of 2  Temperature (K)  XMCOff  x 106  Peff (P.B)a  3 mol (cm ) 1  a  81.72  15520  3.16  77.72  16370  3.16  74.02  17250  3.17  69.72  18370  3.18  65.19  19740  3.18  59.86  21590  3.19  54.40  23880  3.20  47.60  27390  3.21  40.40  32800  3.24  31.25  43800  3.30  26.23  54310  3.37  20.65  71640  3.43  15.98  100200  3.57  11.17  170500  3.90  7.60  4.47  6.30  329600 502700  5.08  670900  5.22  4.24  766000  5.10  4.12  775700  5.05  3.37 2.60  839100  4.75  880500  4.28  2.30  900000  4.07  ; TIP 112 2.828 [(xMcoff TIP)T] Magnetic field = 9225 G. =  -  =  /10Dq 2 8N  146  5.03  =  3 mo1 1 285 x 10 cm  Table 6.2:  F) 3 Pd(SO Low Temperature Magnetic Data of 2  Temperature (K)  .,  COlT  X  106  Peff (IB)a  ) 1 3 mol (cm 82.06 79.89 78.33 76.60 74.47 72.55 70.28 67.95 65.77 63.40 60.73 58.00 55.00 51.40 47.90 44.50 40.60 31.23 21.35 16.50 11.25 8.11 5.99 4.32 3.88 3.30 2.70 1.74  a  ; TIP 2 / 1 2.828 .[(xMCOIT TIP)T1 Magnetic field = 7501 G. =  -  3.52 3.52 3.53 3.54 3.54 3.55 3.55 3.56 3.59 3.60 3.61 3.63 3.66 3.67 3.71 3.76 3.82 4.08 4.66 5.29 7.19 8.11 7.46 6.48 6.19 5.74 5.21 4.20  19010 19560 20060 20610 21250 21950 22640 23520 24640 25740 27060 28620 30600 33020 36130 39870 45170 66750 127300 211800 574900 1015000 1162000 1215000 1236000 1248000 1258000 1271000  =  /lODq 2 8Nj3  147  =  177 x 10 cm 3 mo1 1  Table 6.3:  F) 3 Pd(H)[Pd(W)(SO ] Low Temperature Magnetic Data of 6  Temperature (K)  XMCO X  106  eff (IIB)a  3 moP (cm ) 1 82.28 78.73 74.64 70.34 65.88 60.60 55.00 48.00 44.20 40.60 31.65 27.23 21.75 16.34 11.17 7.94 5.98 5.08  a  21220 22130  23460 24860 26750 29130 32420 37180 40610 44880 60000 73720 98300 155000 355300 581500 663400 681600  2 / 1 Peff = 2.828 [XMCOIT X TI Magnetic field = 7501 G.  148  3.74 3.73 3.74 3.74 3.75 3.76 3.78 3.78 3.79 3.82 3.90 4.01 4.14 4.50 5.63 6.08 5.63 5.26  Table 6.4:  F) 3 Ag(SO Low Temperature Magnetic Data of 2  Temperature (K)  XM X  106  eff (JB)a  3 mol (cm ) 1  82.06  7950  2.27  78.28  8450  74.53 70.34  9070 9840  2.29 2.32  65.82  10840  2.38  60.50  12300  2.43  55.00  14270  2.50  47.95  17560  2.59  44.35  20080  2.66  40.55  23560 40400  2.76 3.15  58350  3.52  21.23  110400  4.33  16.34  277000  6.02  10.53  605800  7.14  7.40  688000  6.38  5.08 4.54  730300  5.45  735300  5.17  30.85 26.58  a  ; TIP 112 Peff = 2.828 [(XMCOnI. TIP)T1 Magnetic field = 7501 G. -  =  2.35  1 /lODq =63 x 10 cm 2 4N13 3 mo1  149  Table 6.5:  F) for the Temperature Range 291 to 79 K 3 Ni(SO Magnetic Data of 2  Temperature (K)  XMCOff X  106  eff (B)a  ) 1 3 mo1 (cm  a  291.3  4840  3.26  271.0  5240  3.28  253.1  5580  3.27  235.7  5970  3.27  219.0  6420  3.28  201.7  6940  3.28  177.6  7860  3.28  152.0  9120  127.5 103.0  10920  3.28 3.29  13250  3.27  87.0 79.0  15690  3.27  17100  3.26  ; TIP 112 ’1 eff = 2.828 [(XM’°’ TIP)T] Magnetic field = 8000 G. -  =  3 mo1 1 /lODq = 285 x 10 cm 2 8Nj3  150  Table 6.6:  F) , 3 Ni(SO , ) ) ] 2 F 3 Pd(SO 6 F 3 Pd(ll)[Pd(IV)(SO Magnetic Parameters of 2 ) 2 F 3 and Ag(SO  Compound  ) 2 F 3 Ni(SO  Temperature Weiss Const. Range (K) 0 (K)  ie  291—79  3.27  0.41±2  (B)  299—103  13±4  ) 2 F 3 Ag(SO  301—80  Values for 290 K.  b  Values for magnetic field  7.94  7501 G.  151  This work (3)  1.92 7.14  =  This work (1)  6.08 20±2  8.11  3.45  82.1—4.5  a  (1) 8.11  10±2  4.78  3.34  82.1—1.7 F) 334—107 3 “Pd(SO ” 82.3—5.1  This work 5.27  81.7—2.3 ) 2 F 3 Pd(SO  (max)b Tm (ff max) ’ Reference 1 (K) (RB)  j.Lff  10.53  This work  O Ni(S) F 3 Inverse Susceptibility vs. Temperature of 2  Figure 6.2:  -J  0 250-  r€)  from Curie—Weiss Low (29V79K) t K 3 moE Cm = 1 .34 cm  () “  e  200-  =0.41  K  >-  F— -J  150-  F a LU  (-) U)  100-  (1)  (-)  50-  .  F LU  z  0  0 0  50  I  I  100  150  TEMPERATURE,K  152  200  250  300  ) are 2 F 3 F) and Ag(SO 3 “Pd(SO ’ F) 1 3 Pd(SO , The low temperature plots of 1 /XM vs. T for 2 ) and 2 F 3 shown in Figure 6.3. Extrapolation of the higher temperature linear portion ((Pd(SO ) 14 K) of these plots produces intercepts on the temperature 2 F 3 Ag(SO ) 11 K, > > F 3 “Pd(SO ” axis in excellent agreement with the values reported earlier (Table 6.6).  In the lower  temperature region all four compounds show a temperature independent 1 /XM (and therefore XM) behavior as the temperature is lowered.  This change in the temperature dependence of the  ) and 1 F) in 3 ‘Pd(SO ’ 2 F 3 magnetic susceptibility at low temperature is illustrated for Pd(SO Figures 6.4 and 6.5, where the field dependence of the susceptibility in this region is also shown for the two compounds.  The approximate maximum susceptibilities expected for these compounds can be calculated with the following (spin only) expression given by Carlin (22):  Msat  where Msat N  [6.1]  NgpS  =  saturation magnetic moment (M/H  =  Avogadro’s number  =  Xt)  Lande splitting factor  g  S  =  =  Bohr magneton  =  Spin system, S=1 (Pd(II)) and S=1/2 (Ag(II))  The maximum or saturation magnetization situation corresponds to the alignment of all the magnetic spins parallel to the external field (H), where the magnetization becomes independ ent of field and temperature. The saturation susceptibility values calculated using equation [6.11 ) 2 F 3 Pd(SO ) , 2 F 3 Ni(SO are compared with the observed maximum susceptibilities for , F) in Table 6.7. 3 Ag(SO F) and 2 3 “Pd(SO ”  153  O ) 2 Pd(S F 3 Inverse Susceptibility vs. Temperature of ,  Figure 6.3:  O ) 2 Ag(S F (SO and 3 ) Pd(IV) 6 Pd(ll)[ F 3 ]  140I  120-  o 2 ) Pd(SO F 3  0,  SO ) I)[Pd(V)( 6 Pd(I F 3 • ] 100.  —  SO ) 2 Ag( F 3  >80-  60-  I  (/) D  LI)  (_)  I  •  c •  40-  .  0  LJ  z  .  2O-  t 0— 0  20  60  40  TEMPERATURE,K  154  80  100  F) at 7501 and 9625 G 3 Pd(SO Magnetic Susceptibility vs. Temperature for 2  Figure 6.4:  c%J 0 x  140120-  S  0  S  100 C-) >-  80  • AT 9625G  -J  cL  AT 7501G  0  60  C.) D  LI)  40-  C-)  z  C)  20 •  0  0 0  20  oc• ooo  I  I  I  40  I  60  80  100  TEMPERATURE,K  155  F) at 3 Pd(II)[Pd(IV)(SO ] Magnetic Susceptibility vs. Temperature for 6  Figure 6.5:  7501 and %25 G  799998C ><  0  0 >-  I-J  o AT 7501G  399999-  • AT 9625G cL i-J  C) V.) V.) 0 I  200000-  LJ  z C, •  0 0  I  I  I  20  40  60  TEMPERATURE,K  156  80  100  Table 6.7:  Experimental and Calculated Saturation Magnetic Susceptibilities of ) 2 F 3 )6 2 F 3 Pd(SO F) and Ag(SO 3 Pd(II)[Pd(W)(SO ] ), 2 F 3 Ni(SO ,  Compound  XM sat. calculateda ) 4 3 mo! (cm  XM’ max. observeda 3 mo!) (cm  Temp. (XM’ max) (K)  % saturation = XM max. x 100 XM sat.  ) 2 F 3 Ni(SO  1.488  1.041  2.69  70  ) 2 F 3 Pd(SO  1.488  1.271  1.74  85  F) 3 “Pd(SO ”  1.488  0.682  5.08  46  ) 2 F 3 Ag(SO  0.744  0.735  4.54  99  a  Susceptibility data for magnetic field  =  7501 0.  157  It appears from the data in Table 6.7 that the magnetic behavior observed at lower ) may be largely a result of saturation 2 F 3 ) and Ag(SO 2 F 3 ) Pd(SO 2 F 3 Ni(SO temperature in , magnetization. As a consequence, the magnetic moments of these compounds are temperature dependent and pacs through maxima at -5, —8, and —10.5 K respectively (Table 6.6). This is F) in Figure 3 Ag(SO F) and 2 3 Pd(SO illustrated in the magnetic moment vs. temperature plot for 2 6.6.  F) may be achieved at higher magnetic 3 “Pd(SO Spin saturation in the mixed valent ’  fields, since closer approach to saturation magnetization would be expected at stronger applied fields. Even at a field of 7501 G, the magnetic moments of this compound shows temperature dependent behavior and has a maximum at —8 K.  F) compounds, the paramagnetic Ni(ll) and 3 “Pd(SO ) and ” 2 F 3 ) Pd(SO In the , 2 F 3 Ni(SO Pd(II) ions have been shown to be in octahedral environments with 3 A2g ground states (1,2,21). Although there is no orbital contribution to the susceptibility associated with this state, to first order, zero-field splitting via second order spin orbit coupling could lift the triplet spin degeneracy which can significantly affect the magnetic properties of such systems, particularly at low temperatures.  The average susceptibility <X> of powder samples (X>=(X +2X±)/3) in the presence of 11 zero-field splitting for S=1 spin systems is obtained from the expression (22):  =  2Ngt  1  3kT  where x  =  DIkT, D  =  (2/x —2 exp(-x))/(x +  +  exp(-x))  2 exp(-x)  zero-field splitting parameter, k  as defined for equation [6.1].  158  =  [6.2]  Boltzmann’s constant, and N, g and  B  ) 2 F 3 F) and Ag(SO 3 Pd(SO Magnetic Moment vs. Temperature of 2  Figure 6.6:  9-  8-  o 2 F) 3 Pd(SO  7-  • 2 F) 3 Ag(S0  I.  z U  6-  a C)  5-  U  z  C  4.  2 0  20  I  I  1  40  60  80  TEMPERATURE,K  159  100  1 at room In general, the value of D is only a few wavenumbers, and with kT —205 cm temperature, D/kT <c 1. However, at lower temperatures D/kT becomes significant, thereby affecting the measured susceptibilities of these samples. The sign of D could be either positive or negative, and in the case of nickel, both signs have been observed (22).  Attempts were made to fit the magnetic susceptibility data to equation [6.2]. However, only very poor fits were obtained, which indicates clearly that this effect cannot explain the magnetic behavior exhibited by the nickel and palladium complexes. Moreover, the magnetic ) cannot be rationalized by this effect, since in Ag(II) ions with 2 2 F 3 behavior of Ag(SO Big ground states, the possibility of zero-field splitting does not exist.  The magnetic properties observed in these four fluorosulfate compounds bear a strong 2 and NiC1 , CoCl 2 2 by Starr et al. resemblance to those reported for the binary chlorides FeCI (23). Neutron-diffraction studies on the iron and cobalt compounds have revealed ferromagnetic coupling between the metal centers within each layer (intralayer exchange), and weak antiferro magnetic coupling between layers (interlayer exchange) (24). This magnetic behavior, termed metamagnetism, has been extensively reviewed for other compounds as well (25). Interestingly, type structure, with each layer of CdCl the binary chlorides mentioned above have the typical 2 the metal atoms separated by two layers of chlorine atoms from the next metal atom layer. Each metal atom layer forms a two-dimensional hexagonal network in which every metal atom has six near neighbours (26).  Furthermore, in a number of layer type fluorides containing Jahn-Teller ions, the intralayer ferromagnetic couplings are found to be much stronger than the interlayer anti ferromagnetic couplings, and as a result ferromagnetism is observed in these compounds (17). F) studied in this 3 Ag(SO Similar interactions may be present in “the Jahn-Teller compound” 2 work as well.  160  Similar crystal and magnetic structures are possible for the M(II) fluorosulfates 2 prototype have also been examined in this work. Indeed, layer structures based on the CdC1 proposed for the compounds discussed here, as mentioned in the introductory section of this chapter (see also Figure 6.1). The apparent lack of solubility of these metal fluorosulfates in a , has so far precluded single crystal X-ray HSO F suitable solvent such as fluorosulfuric acid, 3 diffraction studies as well as magnetic measurements on oriented crystals leading to studies on paramagnetic anisotropy.  It is significant to note that octahedral Pd(II) ions with a 3 A2g ground state is found only ) 3 2 F 3 Pd(50 CF and in some of their cationic Pd(SO , 2 ) 2 (27), , 2 (Chapter 3), PdF ) 6 in Pd(SbF CF have remained the 3 Ag(50 2 ) and ) 2 F 3 2 (28), Ag(SO and anionic derivatives, just as AgF 2 9 configuration. However, the fluorides AgF only simple binary compounds of Ag(II) with a d 2 (30) are essentially antiferromagnetic compounds, and compare more 2 (27), and NiF (28), PdF , 2 appropriately with the trifluoromethylsulfate derivatives discussed in the next section. In PdF , weak ferromagnetism is observed due to a canting of the spins (27,28,30). 2 , and AgF 2 NiF  The ternary Pd(II)[Pd(IV)F 1 is reported to have a significant ferromagnetic component 6 at low temperatures, although the complex is weakly ferromagnetic over a wide temperature F) is found here as a 3 Pd(II)[Pd(IV)(SO ] range (17, 18, 29). In contrast, the structurally similar 6 strongly ferromagnetically coupled compound. The fluorosulfate ligand seems to bond strongly to the Pd(IV) center and weakly to Pd(ll), in an “anisobidentate” bonding mode (1,2). A large 6 type fluorides with both M and M’ transition metals such as Pd, Pt number of M(II) M’(IV)F and Ni, have been studied for their ferromagnetic contribution (17,18) as already noted above in 6 compound. Ferromagnetism in these compounds may be associated with F 2 the case of the Pd 6 from neutron diffraction measurements (29). F 2 cationic ordering, which is observed in Pd Magnetic ordering at low temperatures is explained in these ternary species by a mechanism where the spins of the eg 2 electrons of the divalent metals 2 eg are ferromagnetically 6 (t2g )  161  coupled via a superexchange interaction involving the 2p fluorine orbitals and the empty eg orbitals of the tetravalent cations (17,18).  Therefore, it has been shown that when cationic ordering in M(II) and empty eg orbitals on the transition metal M([V) are present, ferromagnetism can occur in these bimetallic F) complex as well, although the 3 Pd(II)[Pd(IV)(SO ] compounds. This may be applicable to the 6 - anion may significantly affect the extent of ferromagnetic interaction. SO F much larger 3 Interestingly, when the tetravalent cation is replaced by a non-transition metal ion such as Sn(IV) or Ge(IV), magnetic ordering is not observed even at 4.2 K (17). This observation appears to be valid for the ternary bimetallic fluorosulfates as well. A number of previously synthesized fluorosulfate derivatives with three different divalent metals where the tetravalent cation is Sn(IV) were studied for their low temperature magnetic properties in this work. ) (31) and 6 F 3 Cu(II)[Sn(IV)(SO ) (31), ] 6 F 3 Ni(ll)[Sn(IV)(SO The compounds chosen were ] ) (3). The magnetic measurements obtained for these three samples are 6 F 3 Ag(lJ)[Sn(IV)(SO 1 given in Appendices B-4, B-5, and B-6. It is clear from these data that the compounds are rela tively magnetically dilute to ‘—4 K.  Furthermore,  previous  high  temperature  magnetic  measurements  on  ) (3) indicated Curie-Weiss behavior for 6 F 3 Ag(II)[Sn(IV)(SO ) (2) and j 6 F 3 Pd(II)[Sn(IV)(SO J the compounds down to liquid nitrogen temperature. However, stronger magnetic exchange in ) 6 F 3 Ag(II)[Pt(1V)(SO teractions may be present at lower temperatures in j  (3) and  )& (2), where the tetravalent cation is a transition metal ion, i.e. Pt(IV), al Pd(II)[Pt(IV)(SO F 3 though no magnetic exchange is observed in the two samples down to —80 K (3,2).  Even though the above described superexchange mechanism may be valid for the F) com 3 Ag(SO ) and 2 2 F 3 Pd(SO ) , 2 F 3 Ni(SO ) complex, for the binary , 6 F 3 Pd(II)[Pd(IV)(SO ] pounds detailed magneto-structural relationships cannot be made, especially in the absence of  162  structural evidence from single crystal X-ray studies.  This is also true in the case of the  corresponding thfluoromethylsulfate derivatives discussed below.  ) 2 F 3 Ag(SO ) ’ F) and , 3 “Pd(SO 2 F 3 Pd(SO Crystal growth was, however, attempted for , F) the structure of which 3 Au(SO utilizing the method employed to obtain single crystals of , was reported recently by our group (32).  Unfortunately, the highly polymeric compounds  formed only microcrystalline materials, unsuitable species for single crystal measurements.  In the following section, antiferromagnetic behavior in the divalent nickel, palladium and silver thfluoromethylsulfates will be discussed in some detail.  6.3.2  CF 3 Pd(SO 2 CF ) 3 Ni(SO , 2 Antiferromagnetism of M(II) trifluoromethylsulfates ) CF 3 Ag(SO 2 and )  It was mentioned in the introduction that in previous magnetic susceptibility studies to —80 K, the only four sulfonates which had detectable magnetic exchange all showed antiferro magnetism, which is observed more frequently than ferromagnetism in magnetically concentrated transition metal compounds (16,33).  CF were extended down to —4 K 3 Ag(SO 2 In this study, the magnetic measurements on ) to complete the earlier Gouy work, and also to detect unusual magnetic properties, if any, at lower temperatures. The results of the low temperature study are given in Table 6.8, together with the previous Gouy data obtained for the compound.  CF and 3 Pd(SO 2 Similarly, the )  CF complexes are investigated here for their possible antiferromagnetic behavior, and 3 Ni(SO 2 ) pertinent low temperature data for the two compounds are shown in Tables 6.9 and 6.10 respec tively. The nickel compound is also measured in the higher temperature range of —292 to 80 K by the Gouy method, and the results of this work are presented in Table 6.11.  163  Table 6.8:  CF for the Temperature Range 304 to 4 K Ag(SO 2 ) Magnetic Data of 3  ‘Temperature (K)  XMCOff  x 106  (ii  3 mo1 (cm ) 1 304 278 254 226 204 179 154 128 108 82.06 78.28 70.34 65.82 60.38 47.80 40.40 31.85 26.35 21.40 16.55 11.20 8.04 5.34 4.39  1100 1150 1200 1270 1320 1380 1420 1430 1390 650 630 620 610 570 550 540 540 520 520 510 510 510 510 510  a First nine data points from Ref. 4. b Not corrected for TIP; eff 1 I  2.828  [xMCOt X 11h12  164  1.64 1.60 1.56 1.52 1.47 1.41 1.32 1.21 1.10 0.66 0.63 0.59 0.57 0.53 0.46 0.42 0.37 0.33 0.30 0.26 0.21 0.18 0.15 0.13  Table 6.9:  Low Temperature Magnetic Data of 3 CF Pd(SO 2 )  Temperature (K)  COlT  x 106  eff (B)a  3 mo[ (cm ) 1 123.2 118.0 112.8 108.2 103.0 97.97 93.46 88.31 84.81 81.95 78.33 74.47 70.23 68.46 65.59 60.40 54.45 51.40 47.92 44.20 40.32 31.60 20.88 16.00 10.75 7.52 5.78 5.62 4.32 3.70 2.99 2.40 2.10 a Not corrected for TIP; eff 11  6950 7220 7460 7730 8030 8330 8690 9020 9350 9670 9970 10180 10540 10630 10990 11530 12190 12550 13030 13510 14140 15700 17970 19020 20220 21060 21330 21630 21720 21330 21270 21270 21240  2.828  [(XMCOff X  2 ” 1 T]  165  V  2.62 2.61 2.59 2.59 2.57 2.55 2.55 2.52 2.52 2.52 2.50 2.46 2.43 2.41 2.40 2.36 2.30 2.27 2.24 2.19 2.14 1.99 1.73 1.56 1.32 1.13 0.99 0.99 0.87 0.79 0.71 0.64 0.60  Table 6.10:  CF Ni(SO 2 ) Low Temperature Magnetic Data of 3  Temperature (K)  XMCOff x  106  Ieff (B)a  3 mol (cm ) 1 81.78 77.72 74.19 69.72 65.19 60.15 54.00 47.60 40.10 30.80 25.93 20.70 15.90 10.42 7.16 5.92 4.85 4.78 3.96 3.29 3.11 2.79 2.60 2.50  a  eff = 2.828  [(xMcoff  -  ; TIP 2 / 1 TIP)T1  3.27 3.26 3.26 3.25 3.25 3.24 3.22 3.21 3.19 3.18 3.15 3.11 3.07 2.96 2.83 2.75 2.65 2.64 2.52 2.37 2.34 2.27 2.21 2.17  16620 17360 18200 19240 20570 22160 24290 27270 31970 41390 48220 58650 74230 105700 140000 159800 181500 182100 200300 213900 220000 230400 234600 236200  =  /10Dq 2 8N3  166  =  284 x 10 cm 3 mo1 1  Table 6.11:  CF for the Temperature Range 292 to 80 K Ni(SO 2 ) Magnetic Data of 3  Temperature (K)  XMCOff  x 106  neff (B)a  ) 1 3 mo1 (cm  a  291.8  5270  3.41  286.2  5390  3.42  269.3  5700  3.42  251.7  6050  3.41  234.5  6450  3.40  218.0  6890  3.39  200.3  7380  3.37  175.7  8310  3.36  150.0  9540  3.33  125.5  11320  3.33  103.0  13510  3.30  86.5  15740  3.27  79.6  16890  3.25  ; TIP 112 1 e ff = 2.828 [(xMcoff TIP)T] -  =  /10Dq 2 8N3  167  =  3 mo1 284 x 10 cm 1  CF where antiferromagnetic behavior was 3 Ag(SO 2 The previous magnetic report on ) seen with Xm at —138 K (4) is further confirmed by the present low temperature study. The magnetic moments decrease continuously with decreasing temperature, and the suscep tibility  also folio ‘s a similar trend, falling rapidly in value below the Nel temperature (Table  6.8). The very small magnetic moments observed down to —4 K indicate that the compound has no ferromagnetic component present in the low temperature region.  This behavior of  AgF in which ferromagnetism is , CF is in contrast to the magnetic behavior of 2 3 Ag(SO 2 ) detected below 163 K (28).  2 and 3 CF play significant Ag(SO 2 ) Therefore, it seems that structural differences in AgF roles in determining the extent of antiferromagnetic coupling, although the exact exchange CF compound. It has been shown that in 3 Ag(SO 2 mechanism remains still unclear in the ) 9 fluorides, the Jahn-Teller effect leads to two octahedrally coordinated transition metal d crystallographic distortions, termed ferro and antiferrodistortive ordering, with the former favor , the ferromagnetic units are 2 ing antiferromagnetism and the latter ferromagnetism (34). In AgF coupled antiparallel, which give a bulk 3D antiferromagnetism to the compound, although spin canting produces a small ferromagnetic component below 163K (28). However, in layer type fluoride structures with Jahn-Teller ions, the intralayer ferromagnetic couplings are much F) 3 Ag(SO stronger than the interlayer antiferromagnetic couplings, as postulated in the case of 2 discussed earlier, leading to ferromagnetism (17).  But in contrast, the magnetic behavior  observed in ) CF may arise from strong interlayer antiparallel coupling of the spins 3 Ag(SO 2 with weak intralayer exchange, resulting in a bulk 3D antiferromagnetism for the compound.  CF also clearly indicate antiferromagnetic 3 Pd(SO 2 The magnetic data obtained for ) behavior, where the magnetic moments calculated in the temperature range —123 to 2K show typical temperature dependent low values (Table 6.9). The moments decrease with decreasing temperature, and a sharp decline becomes apparent below —40K, as seen in the magnetic  168  moment vs. temperature plot for the compound illustrated in Figure 6.7. From a previously unpublished study in our group, the room temperature magnetic moment for ) CF was 3 Pd(SO 2 found as 2.90 B (35). This value seems to be reasonable when compared with the l.Leff of 2.62 B  obtained at 123 K in this study (Table 6.9), and it also confirms the continuous decreasing  trend of the magnetic moments with decreasing temperatures. The higher temperature eff value is not unexpected for an octahedrally coordinated Pd(II), where the moments are lowered by antiferromagnetic exchange.  The magnetic susceptibility vs. temperature plot of ) CF shown in Figure 6.8, 3 Pd(SO , 2 has a Xm at approximately 4K. This is conclusive evidence, as in 3 CF that the spins Ag(SO , 2 ) in the palladium compound are coupled antiferromagnetically. The appearance of Xm at a very low temperature, in contrast to the Xm observed at 138 K in 3 CF (4), indicates that in Ag(SO 2 ) the palladium compound the antiferromagnetic interaction is much weaker than in the corresponding silver species. It is not uncommon however, to observe stronger spin couplings in a d -Jahn-Teller system than in a d 9 -octahedral system. 8  Significant differences are also noted between the magnetic behavior of ) CF 3 Pd(SO 2 and its fluoride derivative PdF . 2  The difluoride, although antiferromagnetic with a Nel  temperature of --217K, shows a ferromagnetic magnetization component (“weak ferro magnetism”) below this temperature (27).  Consequently, the magnetic moment of 1.84 B  found at room temperature has a much larger value at lower temperatures.  This magnetic  behavior of PdF , as in the case of AgF 2 2 (28), is accounted for by Moriya’s theory of single-ion magnetocrystalline anisotropy (30), where the preferred direction of magnetization is different for the nonequivalent magnetic ions, leading to a canting of the spins.  This is in contrast to the magnetic properties of ) CF in which a continuous 3 Pd(SO , 2 decreasing trend of the magnetic moments with decreasing temperatures is observed (Figure  169  Figure 6.7:  CF Pd(SO 2 ) Magnetic Moment vs. Temperature of 3  3  2.5  I—  z  2  0  Q  w z  1.5  0  0.5 0  20  40  60  80  TEMPERATURE,K  170  120  140  CF Pd(SO 2 ) Magnetic Susceptibility vs. Temperature of 3  Figure 6.8:  25000 (0  x 0 :2  20000  N,  2 () I-J  a:i  15000  I— 0 1J  C)  (n  10000 C) I— U  z  C) :2 5000 0  20  40  60  80  TEMPERATURE,K  171  100  120  140  6.7), with the susceptibility also falling off below the Nel temperature of —4 K (Figure 6.8). It CF the dominant magnetic interaction is 3 Pd(SO 2 appears from these observations that in ) , weak ferromagnetism is not seen at lower temperatures in 2 antiferromagnetic and unlike PdF the thfluoromethylsulfate compound.  CF illustrated in Tables 6.10 and 6.11, show tempera Ni(SO , 2 ) The magnetic results of 3 ture dependent magnetic moments that decrease with the gradual lowering of the temperature, indicative of antiferromagnetic interaction among the Ni(ll) centers. Excellent agreement is noted between the Gouy and the vibrating sample magnetometer data for the overlap region. The Gouy data (Table 6.11) in the temperature range 292 to 80 K are plotted as the following Weiss and Curie constants are obtained respectively: 8  =  vs. T, and  -12.56 K and Cm  =  1.52  3 1 cm mo1 K. The negative Weiss constant is characteristic of antiferromagnetism, and this behavior in 3 CF is further confirmed by the low temperature magnetic data given in Ni(SO 2 ) Table 6.10.  The  of 3.41 B calculated at room temperature falls within the expected range for an  octahedrally coordinated Ni(II) species. However, curiously this value is slightly larger than the ) (Table 6.5), 2 F 3 moment of 3.26 B found at the same temperature for the corresponding Ni(SO although both compounds appear to have similar electronic environments for the respective Ni(fl) ions with near identical lODq values (1,21,19).  Furthermore, the antiferromagnetic  CF is expected to have a lower moment at room temperature than its ferromagnetic 3 Ni(SO 2 ) fluorosulfate derivative, analogous to the palladium and silver derivatives discussed previously.  Interestingly, when the low temperature magnetic moments are plotted against tempera F) become 3 Ni(SO CF and 2 Ni(SO 2 ) ture, the effects of magnetic coupling interactions for 3 observable nearly at the same temperature, but are of opposite nature, as illustrated in Figure 6.9.  172  Figure 6.9:  O ) F and 3 2 Ni(S F Ni(SO C 2 ) Magnetic Moment vs. Temperature of 3  6-  5-  ) SO 2 Ni( F •3 o 3 2 ) 3 Ni(SO F C  I  z 0  4-  () bJ  z 3-  2 20  60  40  TEMPERATURE,K  173  80  100  CF the nickel derivative does not have a 3 Ag(SO , 2 CF and ) 3 Pd(SO 2 In contrast to ) Xmax in its susceptibility data. Therefore, the decrease of the moment values with decreasing CF (Table 6.10). Ni(SO 2 ) temperature is less pronounced in the case of 3  These observations indicate that the antiferromagnetic interaction in the nickel species is relatively weak in comparison to that in the palladium and silver derivatives. The magnetic CF differs also from the reported antiferromagnetism of the Ni(SO 2 ) behavior observed in 3 , where a weak ferromagnetic moment is detected below the 2 corresponding binary fluoride NiF 2 and PdF 2 discussed previously, to Ne1 temperature of 73.2 K, which is attributed, as in AgF spin canting (30). The theoretical basis of this phenomenon has been developed extensively by 2 (30). Moriya in his study of the magnetic behavior of NiF  In concluding this discussion on the magnetic exchange interactions of the M(II) sulfonates, a few comments will be made here regarding the magnetic behavior of the CF 3 Cu(SO 2 ) and ) 2 F 3 corresponding copper derivatives. A previous magnetic study of Cu(SO (down to 100 and 127 K respectively) indicated that the salts are essentially magnetically dilute with moments normally observed for hexacoordinated copper(II) (15).  For this work, the  ) is extended down to —4 K, and a summary of the data 2 F 3 magnetic measurements on the Cu(SO is given in Appendix B-7. The compound was synthesized according to the method described by Alleyne et al. (13). The magnetic moments calculated are independent of temperature and remain close to the expected value of —2.0 B down to —4 K. Good agreement is also noted in the overlap region between the previous high temperature neff values and the low temperature F) is not 3 Cu(SO moments of this study. The reason for this magnetically dilute behavior of 2 ) shows strong magnetic exchange 2 F 3 clear, and it is rather surprising to note that while Ag(SO below —10 K, the corresponding Group 11 copper derivative is magnetically dilute down to very low temperatures. Interestingly, the copper(II) difluoride is antiferromagnetic with a Nel , spin canting produces a 2 2 and NiP , PdF 2 temperature of 69 K, and as seen previously in AgF  174  weak ferromagnetic moment below the Nel temperature in CuF 2 as well (37).  In summary, it may be envisioned that in the layer type metal(ll) sulfonates discussed in this Chapter, magnetic exchange may occur preferentially via one of two possible spin inter actions:  ferromagnetism in the fluorosulfate compounds could arise from strong intralayer  parallel  spin  coupling,  while  in  the corresponding trifluoromethylsulfate derivatives  predominant interlayer spin coupling could lead to an antiparallel arrangement of the spins in the lattice. Alternatively, the O-S-O bridging angle in the two types of sulfonates may favor ferromagnetism and antiferromagnetism for the fluorosulfates and trifluoromethylsulfates respectively. Although the exchange pathway cannot be stated clearly in these compounds due to a lack of X-ray crystal data, it is interesting to note that in the divalent sulfates 4 FeSO 4 , NiSO and CuSO 4 which also have oxygen bridging extended 3D lattice structures, antiferromagnetic ordering is postulated to occur through the O-S-O bridges (38,39). Furthermore, neutron diffrac tion data obtained on FeSO 4 and NiSO 4 indicate magnetically ordered sheet-type structures, and the structurally similar CrVSO 4 appears to have ferromagnetically ordered sheets which stack antiferromagnetically (38). In other examples involving sulfate derivatives, the compounds are found as linear chains, and their magnetic properties have been analyzed utilizing either the Ising or Heisenberg exchange coupling models (40).  In the case of the sulfonates discussed here, however, analyzing the magnetic data is made difficult by several factors. The choice of either the Ising or Heisenberg 2-D model is usually not appropriate for the metal(II) sulfonates. These models do not apply to a system where three-dimensional interactions are also present in the lattice structure.  The one  dimensional models of the type used in Chapter 5 cannot be utilized for the sulfonates for the same reason. The available 2-D Heisenberg model is not applicable in this instance, as this model only takes into account interactions between one paramagnetic center and only the four (but not six) nearest neighbors in a square array. In contrast, for the metal(II) sulfonates, the  175  proposed structure consists of each metal center being surrounded by six nearest neighbours (see Figure 6.1). It appears that the degree and sign of magnetic exchange in these compounds is a function of the O-S-O bridging angle, the M-O and S-O bond distances and the steric and 3 and F groups. Unfortunately, in the absence of any X-ray single electronic properties of the CF crystal data it is rather difficult to make detailed magneto-structural correlations for these sul fonates in order to explain the observed magnetic interactions.  6.4  Conclusion  , ) 6 F 3 Pd(ll)[Pd(IV)(SO )] 2 F 3 Pd(SO F) , 3 Ni(SO , The paramagnetic divalent fluorosulfates 2 CF 3 Ni(SO , 2 ) and their corresponding trifluoromethylsulfate derivatives ) and Ag(SO 2 F 3 CF investigated for their magnetic properties show significant 3 Ag(SO 2 CF and ) 3 Pd(SO 2 ) CF the effects of magnetic exchange become 3 Ag(SO , 2 magnetic exchange, and except in ) observable at low temperatures. Two types of magnetic interactions are seen in the respective groups of compounds. The fluorosulfates exhibit ferromagnetism at all temperatures, whereas the trifluoromethylsulfates couple antiferromagnetically with the spin interactions noted over a wider temperature range.  ) were initially described as 2 F 3 F) and Ag(SO 3 “Pd(SO ) ” 2 F 3 Pd(SO The fluorosulfates , ) compound studied 2 F 3 relatively magnetically dilute down to —80 K, and similarly, the Ni(SO here in the temperature range —291 to 2 K also follows the Curie-Weiss law between —291 and 79 K with Cm  1 K and 8 3 mo[ 1.34 ± 0.01 cm  =  0.41 ± 2 K. For the ferromagnetic M(II)  fluorosulfates, the following field dependent maximum magnetic moments are obtained in the ) 8.11 2 F 3 ) 5.22 B (5 K), PdSO 2 F 3 temperature range —5 to 10.5 K: Ni(SO  (8 K),  ) 7.14 B (10.5 K). Furthermore, the maximum 2 F 3 F) 6.08 PB (8 K), and Ag(SO 3 “Pd(SO ” ) appear to indicate, for 2 F 3 ) and Ag(SO 2 F 3 ) Pd(SO 2 F 3 Ni(SO magnetic susceptibility values of , the magnetic fields used, saturation magnetization where all the magnetic spins align parallel to  176  the external magnetic field.  F) shows “Pd(SO ” Although the mixed valency fluorosulfate 3  significant ferromagnetism at low temperatures, the structurally similar bimetallic fluorosulfates ) are found to be 6 F 3 Ag(II)[Sn(IV)(SO ) and ] 6 F 3 Cu(H)[Sn(IV)(SO ) ] , 6 F 3 Ni(ll)[Sn(IV)(SO j magnetically dilute down to —4 K with calculated temperature independent magnetic moments of —3.3, —2.0, and —1.8 B respectively.  In contrast to the fluorosulfates, the divalent trifluoromethylsulfate derivatives couple antiferromagnetically, and maxima in the susceptibility vs. temperature plots are noted for CF does 3 Ni(SO 2 CF at —4 and —138 K respectively. However, ) 3 Ag(SO 2 CF and ) 3 Pd(SO 2 ) not show a Xm in its susceptibility plot, indicative of a weaker magnetic concentration in the compound. The magnetic moments of the three compounds decrease continuously with decreas ing temperatures, and hence no ferromagnetic contribution to the magnetic moments is detected at lower temperatures.  CF 3 Ni(SO , 2 Therefore, the antiferromagnetic behavior observed in )  CF seems to differ from that seen in the corresponding antiferro 3 Ag(SO 2 CF and ) 3 Pd(SO , 2 ) , where a ferromagnetic magnetization component due 2 , and AgF 2 , PdF 2 magnetic fluorides NiF to spin canting is detected at lower temperatures.  Although the exchange pathways of the divalent sulfonates cannot be explained adequately due to a lack of X-ray single crystal data, the common layer type structure appears to indicate a possible intralayer vs. interlayer spin interaction, leading to predominantly parallel and antiparallel spin arrangements in the respective fluorosulfate and trifluoromethylsulfate lattices. However, the magnetic behavior observed in these sulfonates may be dependent on the O-S-O bridge angle, which may result in ferro- or antiferromagnetism for the respective groups of compounds investigated in this study.  177  References  1.  K.C. Lee and F. Aubke, Can. J. Chem., 5, 2473 (1977).  2.  K.C. Lee and F. Aubke, Can. J. Chem., 57, 2058 (1979).  3.  P.C. Leung and F. Aubke, Inorg. Chem., fl, 1765 (1978).  4.a)  P.C. Leung, K.C. Lee, and F. Aubke, Can. I. Chem., 57, 326 (1979).  b)  P.C. Leung, Ph.D. Thesis, University of British Columbia (1979).  5.  S.P. Mallela, J.R. Sams, and F. Aubke, Can. J. Chem., j 3305 (1985).  6.  J.R. Sams, R.C. Thompson, and T.B. Tsin, Can. 3. Chem., 55, 115 (1977).  7.  J. Goubeau and J.B. Mime, Can. J. Chem., 45, 2321 (1967).  8.  P.C. Leung and F. Aubke, Can. J. Chem.,  9.  P.C. Leung, G.B. Wong, and F. Aubke, I. Fluorine Chem., 35, 607 (1987).  10.  J.M. Taylor and R.C. Thompson, Can. J. Chem., 4, 511 (1971).  11.  K.C. Lee and F. Aubke, J. Fluorine Chem., 19, 501 (1982).  12.  K.C. Lee and F. Aubke, Can. J. Chem., 59, 2835 (1981).  13.  C.S. Alleyne, K.O. Mailer, and R.C. Thompson, Can. J. Chem., 5, 336 (1974).  14.  J.S. Haynes, J.R. Sams, and R.C. Thompson, Can. 3. Chem., 52, 669 (1981).  15.  A.L. Arduini, M. Garnett, R.C. Thompson, and T.C.T. Wong, Can. J. Chem., 5, 3812  2892 (1984).  (1975). 16.a) b)  0. Muller, Angew. Chem.  mt. Ed. Engi., 2. 1081  (1987).  L.N. Mulay in “Theory and Applications of Molecular Paramagnetism”, Eds. E.A. Boudreaux and L.N. Mulay, John Wiley and Sons, New York, 1976.  17.  J.-M. Dance and A. Tressaud in “Inorganic Solid Fluorides”, Ed. P. Hagenmuller, Academic Press, New York, 1985.  18.  A. Tressaud, J.-M. Dance, and P. Hagenmuller, Israel J. Chem., 17, 126 (1978).  19.  M.T. Jansky and J.T. Yoke, 3. Inorg. Nuci. Chem., 41, 1707 (1979).  178  em., , and J.E. Vekris, Can. 3. Ch ie, sp lle Gi J. R. i, ian gg , R. Fa D.C. Adams, T. Birchall  20.a)  2122 (1991).  1478 (1977). iseleur, Acta Crvst., , Lo H. d an , ure Fa R. F. Charbonnier, 427 (1967). Nuci. Chem. Letters, ., rg. Ino lf, oo W A. A. d , an D.A. Edwards, M.J. Stiff York, 1986. , Springer-Verlag, New y” str mi he toc ne ag ‘M R.L. Carlin, (1940). n, Phys. Rev., 5, 977 an ufm Ka R. A. d an r, tte C. Starr, F. Bi Rev., IU. 497 W.C. Koehier, Phys. d an , an oll W O. E. , Cable M.K. Wilkinson, J.W.  b) 21. 22. 23. 24.  (1959). 25. 26. 27.a) b) 28.a) b)  7 (1977). Adv. in Physics, , 48 o, an ord Gi G. d an i sk E. Stryjew 984 (1940). C. Starr, Phys. Rev., , (1964). o, Proc. Chem. Soc., 393 N. Bartlett and P.R. Ra 68). em. Phys., 49, 3728 (19 Ch 3. , ett rtl Ba N. d an d, P.R. Rao, R.C. Sherwoo (1937). , turwissenschaften, 59 25 Na m, em Kl . W d an E. Gruner Acad. Sci. Fr., and C.R. Nguyen-Nghi, s, lli t-E ue arq M H. x, ou P. Charpin, A.J. Dian C264, 1108 (1967).  7 (1970). r., c. Fr. Mineral Cristollog 9, So ll. Bu el, eri M P. d an en, c) P. Charpin, P. Pluri 1). . Solids, 3., 1641 (197 em Ch . ys Ph 3. , ch ba , and D. Schwarzen d) P. Fischer, 0. Roult ., uller, C.R. Acad. ScL.Fr nm ge Ha P. d an , ett rtl enberger, N. Ba A. Tressaud, M. Wint 29. C282, 1069 (1976). 635 (1960). T. Moriya, Phys. Rev., 112, (1954). t, Phys. Rev., 24, 1792 ou St . J.W d an se rre ata b) L.M. M n. J. ms, and F. Aubke, ca Sa . J.R , sen ten ris Ch . P.F. Gehrs, 3.1 S.P. Mallela, K. Lee, 31. Chem., 5, 2649 (1987). 391 (1991). bke, Can. 3. Chem., , Au F. d an er, ott Tr 3. H. Wiliner, S.J. Rettig, 32. Weller W. ter Haar, and R.R. L. s, en ck Pi . .W M h, tes, W.E. Mars W.E. Hatfield, W.E. Es York, 33. Plenum Press, New er, ill M . J.S . Ed ’ ds un Compo , Chain t in “Extended Linear  30.a)  V  1983. 179  34.  D. Reinen and C. Friebel in “Structure and Bonding”, Eds. J.D. Dunitz, P. Hemmerich, C.K. Jorgensen, and D. Reinen, Vol. 37, Springer-Verlag, Berlin, 1979.  35.  S.P. Mallela and F. Aubke, unpublished results.  36.  F.A. Cotton and G. Wilkinson, “Advanced Inorganic Chemiostry”, 5th Edition, John Wiley and Sons, New York, 1989.  37.  R.J. Joenk and R.M. Bozorth, J. Appl. Phys., 36, 1167 (1965).  38.  B.C. Frazer and P.J. Brown, Phys. Rev., j, 1283 (1962).  39.  I. Almodovar, B.C. Frazer, J.J. Hurst, D.E. Cox, and P.J. Brown, Phys. Rev., j., A153 (1965).  40.  H.T. Witteveen and J. Reedijk, J. Solid State Chem., .IQ, 151 (1974).  180  preparation. The solvolysis product show temperature dependent low  values, whereas the  fluorination sample has unexpectedly high magnetic moments, which also decrease with decreasing temperature.  As a preparative method, there appears to be a wide synthetic potential for this solvolysis route to the corresponding metal hexafluoro antimonates, since a large number of well charac terized transition metal fluorosulfates are available as precursors.  The transition metal precursors of the hexafluoro antimonates, the divalent fluorosulfates F) all exhibit ferromagnetic 3 “Pd(SO ’ ) and the ternary 1 2 F 3 Ag(SO ) , 2 F 3 Pd(SO ) , 2 F 3 Ni(SO , exchange at lower temperatures.  Additionally, the three binary fluorosulfate compounds  indicate saturation magnetization at very low temperatures.  In contrast, the corresponding  CF couple antiferro 3 Ag(SO 2 CF and ) 3 Pd(SO 2 CF ) 3 Ni(SO , 2 trifluoromethylsulfates ) magnetically, and for the last two compounds Xm are also found in their susceptibility vs. tem perature plots. The antiferromagnetism observed in these compounds differ from that seen in the corresponding binary fluorides, in that no ferromagnetic magnetization component due to spin canting is detected even at very low temperatures.  Interestingly, both the divalent  hexafluoro antimonates and the sulfonates studied in this work have a common layered structure 2 prototype. which is based on the CdCl  ) and 2 F 3 Furthermore, the two post-transition metal layered compounds Sn(SO , which are structurally similar to their transition metal derivatives mentioned above, 2 ) 6 Sn(SbF ) es 2 F 3 Sn(SO form it-arene adducts with mesitylene(mes) to give the weakly bound complexes m mes in high yield. The reduction of the lattice energies in the layer structures of Sn(SbF 2 2 ) and 6 F appear to 3 6 and SO the parent tin compounds by the wealdy nucleophilic anions SbF 6 been the more effective of the facilitate adduct formation, with the weaker nucleophile SbF two ions, leading to the 2:1 complex with the arene. Mössbauer data of the adducts indicate  182  partial back-donation of the 5s electrons of tin to the antibonding  it’’  orbitals of mesitylene to  further stabilize the tin-arene bond, giving rise to synergic bond characteristics.  The remaining group of non-transition metal fluoro complexes, the molecular species [Sb i]’ which were investigated for their low temperature 2 I 1 ,] 6 [ 2 O ] AsF 6 and F [Sb 2 Br 1 F 3 magnetic behavior, exhibit magnetic properties that are quite different for the three derivatives. This is reflected in the magnetic data of the respective complexes, measured down to -4K. Of 6 is magnetically dilute to low temperatures, whereas [Sb 2 Br 1 F 3 the halogen compounds, J [Sb ] show relatively strong antiferromagnetic coupling with a Xm at 54K. I 1 F 2  As in  [AsF compound also exhibits Curie-Weiss behavior down to low 2 O ] 6 the 6 J, [ 2 Br 1 F 3 Sb temperatures, but weak antiferromagnetic exchange seems to be present in the very low end of 6 the shortest non-bonding Br”Br distance is too large ], [ 2 Br 1 F Sb the temperature region. In 3 1 magnetic exchange can occur via contiguous ] + 1 1 F [Sb to invoke direct orbital overlap, but in 2 12+ ions, where the non-bonding II distance is comparable to the sum of the van der Waals radii. The low  , which are below the spin only magnetic 6 [ 2 O AsF values observed for ]  moment value, result from crystal field interactions in the solid lattice that partially quench the orbital contribution to the magnetic susceptibility.  183  APPENDICES  184  APPENDIX A  A-i:  Standard Reduction Potentials of Selected (M/M9 Couples*  Potential (V)  Electrode  2 Ni  +  2e  —>  Ni  -0.250  2 Pd  +  2e  —>  Pd  +0.987  Cu  +  2e  2 Cu  +  e  2 Ag Au  e  +  —  +0.337  Cu  -i-0.153 +0.7991  Ag  —  e  +  Cu  —  e  +  +0.521  Cu  —  2 Cu  Ag  +1.980  Ag  —  +1.691  Au  —>  3 Au  +  3e  —>  Au  +1.498  2 Sn  +  2e  —  Sn  -0.136  Sn  +  2e  —  2 Sn  +0.15  5 0 2 Sb  +  6H  +  4e —> 2SbO  5 0 2 Sb  +  2W  +  4 O 2 2e —> 2Sb  02  *  e  +  +  4W  +  0 2 3H  +0.58 1  0 2 H  +0.479  +  +  4e  0(1) 2 2H  +1.229  +  0(g) 2 4e — 2H  +1.185  —  From J.E. Huheey, “Inorganic Chemistry”, 2nd Ed., Harper and Row, New York, 1978.  185  00  >.  -.‘  =  (-)  -P  COVALENT BIDENTATE  COVALENT MONODENTATE  IONIC PERTURBED  PURELY IONIC  COVALENT TRIDENTATE  Bonding or E Coordination Mode  -  A-2:  1400  w(S—O)  ,,,(SO) ip 0 I -‘  Li  is(S—O)  ci  i  ) 2 ,,,,(SO  [f//A  ) 2 v..ym(S0  F  v,,,.(S—O)  1200  CE]  ) 7 (SO  rzz’  V/ZZZJ v,,,,(SO ) 2  U  v.,.,,(S—O)  I  i’(S—O)  Stretching Band  1000  .  ciii  800  v(S—F)  is(S—F)  (s—a)  ODD  Q(50)  (SOi)  0  I  400 600  2 F) 7 (so  ) r(SO F 2  ) 7(SO F 2  Ci  0  2 F) (SO  I  ) 2 (SO  D  6(S07) i,(S-F)  8.(SOi) ?.,(s-F)  rj  ci  9fi 7(5.J) DOr (502 F)  cri w’zzi  ) 7,,i.(SO F 7  ) 3 ,.,,(S0 6(SO 3 _ 1 6 )  ) 3 (so  Deformation Bond  —________  i.(S—F)  -1)  v(S—F)  v(S—F)  Frequency Range (cm  Frequency Range of Vibrational Fundamentals for Fluorosulfate Group  A-3:  2 ) 6 X-ray Powder Data for Ni(SbF  ) 2 F 3 [Ni(SO d-space  +  la 5 SbF  (A), Intensity  4.60 4.17  rn-s s  3.71 2.702 2.534 2.344 2.273 2.224 2.167 1.859 1.841 1.768 1.714 1.704 1.648  s rn m-w m-w rn-s rn rn rn m w rn-s rn rn  1.553 1.534 1.493 1.465 1.426 1.398 1.352  vw rn-w m rn w w w  ]b 5 F + SbF [Ni + 2 d-space  (A), Intensity rn-s s w s rn-s m-w m s rn-w rn-w rn rn w s m m w vw rn m m-w rn-w w m  4.61 4.24 4.03 3.75 2.744 2.576 2.363 2.252 2.207 2.125 1.881 1.819 1.746 1.728 1.681 1.646 1.625 1.550 1.521 1.491 1.447 1.420 1.377 1.332  a This work b Christe et at, J. Fluorine Chem., 4, 287 (1987) C Gantar et at, 3. Chem. Soc. Dalton Trans., 2379 (1987)  187  2 [NiF  +  d-space  ]C 5 SbF  (A), Intensity  4.56 4.26 4.17 3.68 3.58 2.70 2.51 2.33 2.22 2.10 1.86  rn m rn s rn rn w w m w rn  1.70  m  1.61  m  1.50 1.47 1.44  w w w  A-4:  ) Ligand Field 8 The Assignments and Energies of Octahedral Ni(IT) and Pd(II) (d Spectra, According to Lever,* are as Follows:  lODq  A2g 3  _>  T2g 3  A2g 3  _*  Tig(F) 3  =  7.5B  +  2 18ODqB)’a 2 + lOODq l5Dq 1/2(225B  Tig(P) 3  =  7.5B  +  l5Dq  A2g 3  1)1  =  -  -  +  112 2 18ODqB) 2 + lOODq 1/2(225B  u 3i 15B 1 + 3 2 and, =  *  A.B.P. Lever, J. Chem. Educ., 45,711(1968). [see also: Yu-Sheng Dou, J. Chem. Educ., 67, 134 (1990)].  188  -  A-5:  2 and SbF 5 2 Made from Ni, F ) 6 Low Temperature Magnetic Data of Ni(SbF  Temperature [K]  mol 3 [cm ] x 106 1  Peff B1a  81.83  17140  78.06 74.19  17930  3.35 3.35  18740  3.33  69.72  19830  65.19  21030  3.33 3.31  60.15  22660  55.00 47.90 40.60 30.80 26.00 21.00 15.90 10.30 7.16 6.30 5.18 4.40  24620  3.30 3.29  27610  3.25  32010  3.22  41040 47840  3.18  57360  3.15 3.10  73240  3.05  105600  2.95  140500  2.84  153800  2.78  174200  2.69  191900  3.96 3.46  201700  2.60 2.53  207900  2.40  3.11  215800  2.32  2.89 2.79  219900  2.25  221800  2.22  a Uncorrected for TIP  189  A-6:  2 and SbF 5 in HF 2 Made from NiF ) 6 Low Temperature Magnetic Data of Ni(SbF  Temperature [K]  XMCOff  mol 3 [cm ] x 106 4  Peff  B1a  81.83  12000  2.80  78.06 74.19  12490  2.79 2.79  69.72  13170 14000  65.19  14900  60.15  16130  2.79 2.79  55.00  17750  2.79  47.90  20070  2.77  40.60  23450  2.76  31.23  30160  2.74  26.40  35040  2.72  21.00  43070  2.69  15.90 10.75  55980 78900  2.67 2.60  7.16  114600  2.56  6.15  132600  2.55  5.16  151700  2.50  4.40  173500  2.47  4.04  190700  2.48  3.70 3.29  199400  2.43 2.36  3.11  211000 218100  2.89  225600  2.28  a Uncorrected for TIP  190  2.79  2.33  A-7:  Low Temperature Magnetic Data of 6 F)(SbF 3 Au(SO )  Temperature [K]  ol a 4 m 3 [cm XMCOff x 106 ]  ff [j.t]  81.78  410  0.52  74.24  460  0.52  69.72  560  65.25  630  0.56 0.58  60.21  0.58  54.20  690 820  47.40  980  0.61  40.00  1250  0.63  30.85  1820  0.67  25.60  2340  20.60  3070  0.69 0.71  15.85  4240  0.73  10.30  7010  0.76  6.84  11500  0.79  6.30  14800  0.86  4.32  20570  0.84  4.20  21090  0.84  3.37  22170  0.77  2.69  24300  0.72  a Experimental MW of compound  =  1 734.88 g mol  191  0.60  A-8:  Crystal Structures of Some Arene-Sn(U) Complexes  Cr3)  (b)  ) 4 nC1 (Aid C S H (a) 6  ) 4 nCJ (AICJ C S 4 H 26 ) 3 p-(CH  CI(3  C(2)  (d)  I 1 2 (AIC ) 2 SnCI 4 ) H 6 (c) [(C  192  Sn(AICI H 6 C 2 ) H4 6 C  (1)  A-9:  (C Symmetry) Qualitative MO Diagram of [(arene)Ga] Complex 6  E  a LUMO HOMO e  a  a  Ga  v 6 c  193  APPENDIX B  B-i:  F) at Magnetic Field 3 Ni(SO Low Temperature Magnetic Data of 2  Temperature [K]  XMCOff  x 106 1 mol 3 [cm ]  =  eff [IB]a  81.61  15470  3.18  77.72  16310  3.18  74.19  17180  3.19  69.49  18380  3.20  65.19  19700  3.21  59.86  21590  3.22  54.00  23950  3.22  47.60  27460  3.23  40.02  33160  3.26  30.35  45210  3.31  25.75  3.39  20.48  55730 73180  15.75  104700  3.63  10.42  200000  4.08  7.04  417400  4.85  6.30  534400  5.19  5.18  726200  5.49  4.78  813200  5.58  4.40  873100  5.54  4.32  879100  5.51  3.37 2.89  963100  5.10  1017000  4.85  2.69  1041000  4.73  a Uncoffected for TIP  194  7501 G  3.46  B-2:  F) at Magnetic Field 3 Pd(SO Low Temperature Magnetic Data of 2  Temperature [K]  mol 3 [cm J XMCOff x 106 1  =  1 4 ff 1JLB]a  81.50  18900  3.51  77.89  19840  3.52  70.17  22590  3.56  60.50  27090  3.62  54.40  30610  3.65  47.90  36090  3.72  40.30  45460  3.83  31.50  64760  4.04  7.42  875200  7.21  5.64  955100  6.56  4.32  984400  5.83  3.54  998000  5.32  2.60  1006000  4.57  2.20  1010000  4.22  1.84  1013000  3.86  a Uncorrected for TIP  195  9625 G  B-3:  )(SO at ) 6 Pd(JJ)[Pd(IV F 3 Low Temperature Magnetic Data of ] Magnetic Field  Temperature [KJ  =  %25 G  ZMCOff  moP 3 [cm ] x 106 1  eff B]a  82.33  21070  3.73  74.98  23360  3.74  61.00  30070  3.83  48.60  38330  3.86  32.10  59150  3.90  22.30  96310  4.14  12.15  285700  5.27  6.84  537300  5.42  5.08  604400  4.96  a Uncorrected for TIP  196  B-4:  F) 3 Ni(II)[Sn(IV)(SO ] Low Temperature Magnetic Data of 6  Temperature [KJ  XMCOff  x 106 1 mol 3 [cm ]  I.Lff  [1.LBIa  81.56  16610  3.29  77.83  17460  3.30  73.91  18470  3.30  69.49  19560  3.30  65.02  20830  59.98 53.85  22600 24950  3.29 3.29  47.45  28330  3.28 3.28  40.30  33300  3.28  30.70  43750  3.28  25.85  51580  3.27  21.05  63720  3.28  15.50  85710  3.26  10.06  134900  3.30  6.44  223400  3.39  4.46 4.24  321200 340600  3.39  a Uncorrected for TIP Magnetic field = 7501 G  197  3.40  B-5:  F) 3 Cu(II)[Sn(IV)(SO ] Low Temperature Magnetic Data of 6  []a  XMCOff x 106 1 mol 3 [cm ]  ff  81.50  6540  2.06  77.83 74.08  6830 7100  2.06  69.83 65.31  7550  2.05  8010  2.05  60.09 54.10  8600  2.03  9520  2.03 2.02  40.00  10700 12730  30.80  16280  2.00  26.10  19360  2.01  21.35  23630  2.01  16.15  30650  1.99  10.48  46260  1.97  7.19  66730 82150  1.96  5.00 4.78  95270  1.95  98560  1.94  4.32  109700 140500  1.95  168800  1.80  Temperature [K]  47.55  5.84  3.02 2.40  a Uncorrected for TIP Magnetic field  =  9225 G  198  2.05  2.02  1.96  1.84  B-6:  ) )(SO Ag(II)[Sn(W F 3 ] Low Temperature Magnetic Data of 6  Temperature [K]  mol 3 [cm ] x 106 1  ff  [&  81.61  5010  77.55  5230  1.81 1.80  73.68  5490  1.80  69.26  5970  1.82  64.90 59.68  6330  1.81  6890 7710  1.81 1.81  8730  1.81 1.82  53.12 46.94 30.36  10300 13640  25.30  16640  1.83  20.18  1.80  15.05  20070 26320  9.76  39680  1.78 1.76  6.44  57840  1.73  6.15  61370  1.74  5.34  68870  1.72  4.62  77760  1.70  3.96  91000  1.70  3.37  103600  1.67  2.69  112400  1.56  2.50  116200  1.52  40.20  a Uncorrected for TIP Magnetic field = 9225 G  199  1.82  B-7:  F) for the Temperature Range 312 to 4 K 3 Cu(SO Magnetic Data of 2  Temperature [K]  312 300 287 272 240 211 181 152 123 100 81.78 78.06 74.36 69.94 65.77 59.98 55.00 48.10 41.60 31.80 26.65 21.83 16.90 11.13 8.70 5.91 4.20  XMCOff  mol 3 [cm ] x 106 1  Peff  1830 1900 1970 2090 2350 2660 3060 3620 4460 5460 6500 6850 7290 7780 8320 8950 9880 11180 13100 17280 20600 25170 33010 52110 71180 77690  2.08 2.08 2.07 2.08 2.08 2.08 2.07 2.07 2.07 2.07 2.05 2.05 2.07 2.07 2.08 2.06 2.07 2.06 2.08 2.09 2.09 2.09 2.11 2.15 2.22 1.91 1.69  85130  a First ten data points from Ref. 15, Chapter 6. b Corrected for TIP (TIP = 100 x 10*6 3 , Ref 15, Chapter 6) 1 cm mo1 Magnetic Field = 9225 G  200  

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