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Synthesis and characterisation of ruthenium octaethylporphyrin complexes Sishta, Chand 1986

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SYNTHESIS AND CHARACTERISATION OF RUTHENIUM OCTAETHYLPORPHYRIN COMPLEXES By CHAND SISHTA B.Sc.(Honours), University of New Brunswick, 1984 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Department of Chemistry) We accept t h i s thesis as conforming to the required standard. THE UNIVERSITY OF BRITISH COLUMBIA May 1986 © C h a n d Sishta, 1986 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. I t i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of CHEMISTRY The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date )E-6 (3/81) Abstract The synthesis and characterisation of some higher valent Ru octaethylporphyrin complexes are discussed. These complexes, Ru(OEP)(X)(X«) (X=X'=Br,Cl and X=SbF6,X'=THF) are of the oxidation state IV and I I I , respectively, with either a t r i p l e t d 4 , S=l intermediate spin ground state (for X=X'=Br, CI) or a d 5 , S=l/2 low spin (for X=SbF6,X'=THF) ground state. The a l t e r n a t i v e R u 1 1 1 or R u 1 1 7T-cation r a d i c a l formulations are ruled out. The f i r s t Ru-X bond frequencies (X=Br,179 cm - 1;X=Cl,289 cnf^KBr) i n Ru-porphyrin systems are assigned. The NMR data indicate that contact contributions dominate the i s o t r o p i c s h i f t s but dipo l a r relaxation i s responsible f o r the relaxation of the resonances observed. The metal-porphyrin Tf-bonding a r i s e s from ligand-to-metal charge t r a n s f e r i n a l l three complexes and the Ru I I I :(SbF 6) complex l i k e l y has a p-fluoro bridge with f sb-F = 6 5 0 c 1"" 1/ Nujol. The simple preparative reactions have high y i e l d s (>8 0%) and the s t a b i l i t y of these complexes make them excel-lent precursors f o r further chemistry i n high-valent ruthenium porphyrins. i i To my Parents and Bhavini i i i Table of Contents P a g e Abstract i i Table of Contents i v L i s t of Tables v i L i s t of Figures v i i L i s t of Abbreviations x Acknowledgements x i i Chapter I: Introduction 1 References . 7 Chapter I I : Experimental 9 A. Reagents and Solvents 9 B. Physical Measurements 11 C. Preparation of Ruthenium Complexes . 14 References 25 Chapter I I I : The Characterisation of Ru I V(OEP)(X) 2 and Ru I : t I(OEP) (SbF 6) (THF) 26 I I I . l : Analysis of the data for Ru I V(OEP) (X) 2 26 v A. Nuclear Magnetic Resonance Spectroscopy 2 6 B. Optical Spectra 42 C. Infrared/Resonance Raman Spectroscopy 4 2 D. Mass Spectroscopy . 44 E. Magnetic S u s c e p t i b i l i t y , and Electron i v Paramagnetic Resonance Spectroscopy 48 III.2: Analysis of the Data for Ru I i : I(OEP) (SbF 6)(THF) 49 A. Nuclear Magnetic Resonance Spectroscopy 49 B. Electron Paramagnetic Resonance Spectroscopy 55 C. Optical Spectra 60 D. Mass Spectroscopy 60 E. Infrared Spectroscopy 63 References 65 Chapter IV: The Chemistry of Ru I V(0EP)(X) 2 Complexes 68 References 73 Chapter V: Conclusion 74 Appendix I: The Oxidation Chemistry of Ru I I I(0EP) (PPh 3) (Br) 76 Appendix I I : Tabulation of Spectroscopic Data f o r Ru Porphyrin Complexes 81 v L i s t of Tables T a b l e page 111.1 T x Data f o r Ru I V(OEP) (Br) 2 35 111.2 Tx Data for Ru I V(OEP) ( C I ) 2 36 111.3 Data for the Curie Plot of the Isotropic s h i f t vs Inverse Temperature f o r Ru(OEP) (X) 2 complexes 39 111.4 T1 Data f o r Ru 1 1 1(OEP)(SbF 6)(THF) . . . 53 111.5 Data f o r the Curie Plot of the Isotrop i c S h i f t vs Inverse Temperature f o r Ru(OEP) (SbF 6) (THF) 56 A . I I . l Tabulation of *H NMR Data f o r Ru Porphyrin Complexes 81 A.II.2 Tabulation of Resonance Raman/Infrared Data f o r Ru Porphyrin Complexes . . . . 82 v i L i s t of Figures  Figure Page 1 . 1 The Heme Unit of Naturally Occurring Henoproteins (protoporphyrin IX d i c a r -boxylic acid) 2 1 . 2 Highly Symmetric Synthetic Porphyrins used i n Research with Model Complexes . 4 I I . 1 Apparatus used for the Transfer of Solvents and Reagents under Anaerobic Conditions 1 0 I I . 2 An Anaerobic Optical C e l l 1 2 1 1 . 3 Temperature-controlling Oven Apparatus for the Vacuum Pyro l y s i s of Ru(OEP) Complexes 1 6 1 1 . 4 Apparatus for Photolysis of Ru(OEP) Complexes 2 0 1 1 1 . 1 A View of the Ethyl Groups with the Pyrrole Ring as the Mirror Plane of Symmetry 2 6 1 1 1 . 2 Theoretical XH NMR Spectra for OEP Complexes 2 7 1 1 1 . 3 Ligand F i e l d S p l i t t i n g diagram for a Ru 1 1, d 6 Low Spin Octahedral Complex with Axial D i s t o r t i o n 2 S 1 1 1 . 4 The MO Diagram for Ru(OEP)(X) 2 type of Complexes 3 0 v i i III.5 •'•H NMR Spectrum of Ru(OEP)(Br) 2 . . . . 31 II I . 6 XK NMR Spectrum of Ru(OEP) (CI) 2 . . . . 32 111.7 Plot of the Signal Intensity vs delay D2 to Obtain the T x Value for Ru(OEP)(X) 2 . 37 111.8 The Three Possible d - o r b i t a l Occupancies of Ru I V, d 4 Paramagnetic Complexes . . . 34 111.9 Curie Plot f o r Ru(OEP)(Br) 2 i n the Temp-erature Range -50 to +50 °C 4 0 111.10 Curie Plot f o r Ru(0EP)(Cl) 2 i n the Temp-erature Range -50 to +50 °C 41 111.11 The Optical Spectrum of Ru(0EP)(X) 2 Complexes i n CH 2C1 2 43 111.12 Resonance Raman Spectrum of Ru(0EP)(Br) 2 45 111.13 Resonance Raman Spectrum of Ru(OEP)(Cl) 2 46 111.14 Mass Spectrum of Ru(0EP)(X) 2 Complexes . 47 111.15 XH NMR Spectrum of Ru(OEP)(SbF 6)(THF) i n CDC13 51 111.16 Plot of the Signal Intensity vs the delay D2 to Calculate Values f o r Ru (OEP) (SbF 6) (THF) 54 111.17 Curie Plot f o r Ru(OEP)(SbF 6)(THF) f o r the Temperature Range -50 to +50 °C . . 57 111.18 1 9 F NMR Spectrum of Ru(OEP)(SbF 6)(THF) . 58 111.19 EPR Spectrum of Ru(OEP)(SbF 6)(THF) i n 1:1 THF: Toluene 59 111.20 Optical Spectrum of Ru(OEP)(SbF 6)(THF) . 61 111.21 Mass Spectrum of Ru(OEP)(SbF g)(THF) . . 62 v i i i III.22 Nujol Mull Infrared Spectrum of Ru(OEP) (SbF 6) (THF) 64 A I . l *H NMR Spectrum of [Ru(OEP)Br] 20 . . . . 78 AI.2 Optical Spectrum of [Ru(OEP)Br] 20 . . . 79 ix L i s t of Abbreviations and Symbols atm atmosphere br broad CHC13 chloroform CH 2 Cl2 dichloromethane CH3CN a c e t o n i t r i l e C6 H6 benzene cm"1 wavenumber °C degrees centigrade CO carbon monoxide 1 D deuterium d doublet EtO ethoxide EtOH ethanol eV electron v o l t FT Fourier transform GHZ gigahertz HBr hydrogen bromide HC1 hydrogen chloride *H proton K degrees Kelvin m multiplet mCPBA meta-chloroperbenzoic acid MeOH methanol mg milligram mL m i l l i l i t r e s X mm millimeters ms milliseconds mW m i l l i w a t t nm nanometer OEP octaethylporphyrin dianion PhIO iodosylbenzene porp porphyrin dianion PPh 3 triphenylphosphine PR3 trialkylphosphine ppm parts per m i l l i o n py pyridine Ru ruthenium s s i n g l e t SbF 6 hexafluoroantimonate(V) anion t t r i p l e t THF tetrahydrofuran TMP tetramesitylporphyrin dianion TMS tetramethylsilane spin l a t t i c e relaxation TPP tetraphenylporphyrin dianion jj[eff magnetic moment \) inf r a r e d frequency \ m a x absorption maximum X magnetic s u s c e p t i b i l i t y x i Acknowledgements I would l i k e to thank Drs. B.R. James and D. Dolphin f o r t h e i r patience and support when each was needed and f o r show-ing me that chemistry i s not everything i n l i f e ! I also wish to thank Dr. F. Aubke and Dr. M. Camenzind for many i n t e r e s t -ing discussions on f l u o r i n e chemistry and general t h e o r e t i c a l / p r a c t i c a l chemistry, respectively; and l a s t l y , my wife f o r her enduring love and support. x i i Chapter I; INTRODUCTION The i n s e r t i o n of ruthenium into the porphyrin core with triruthenium dodecacarbonyl (Ru 3(CO) 1 2) r e s u l t s i n a metal-carbonyl complex 1 of the type Ru 1 1(porphyrin)CO which, be-2 cause of the usual synergic Ru-CO bonding , e f f e c t i v e l y t i e s up one a x i a l l i g a t i o n p o s i t i o n . Consequently, the early research 3 i n ruthenium porphyrin chemistry focused on the ligand trans to the CO since the trans e f f e c t 4 l a b i l i s e s the ligand at t h i s p o s i t i o n . The porphyrins used were not the natu r a l l y occurring porphyrins (which may contain reactive v i n y l groups, see Figure 1.1) but instead were the e a s i l y synthesised, highly symmetric macrocycles octaethylporphyrin 5 (H 2OEP), tetraphenylporphyrin 6 (H 2TPP), and tetramesitylporphyrin 7 (H2TMP); these systems, because of t h e i r high symmetry (see Figure 1.2), s i m p l i f i e d charac-t e r i s a t i o n by spectroscopic methods. There are two known methods f o r the decarbonylation of Ru(porphyrin)CO complexes: photolysis of the CO precursor in donor solvents such as pyridine, a c e t o n i t r i l e or tetrahydro-furan leads to Ru(porp)(solvent) 2 8 complexes that are pri m a r i l y used as s t a r t i n g materials for other systems; or a l t e r n a t i v e l y , the addition of t e r t i a r y phosphines (PR 3) to the CO complex can form Ru(porp)(PR 3) 2 complexes. 9 - 1 1 While some Ru(porp)(PR 3) 2 species exhibit the a b i l i t y to decarbony-1 C H = C H 2 H C H . C H = C H . ( C H 2 ) 2 C O O H H ( C H ^ C O O H Figure 1.1: The heme unit of naturally occurring hemo-proteins (protoporphyrin IX dicarbox y l i c acid) 2 l a t e aldehydes c a t a l y t i c a l l y , 1 2 ' 1 3 Ru 1 1 1(OEP)(PPh 3)(Br) (obtained by t r e a t i n g Ru(OEP)(PPh 3) 2 with H B r / a i r ) , 1 4 when oxidised with excess meta-chloroperbenzoic acid (mCPBA) or iodosylbenzene (PhIO), forms a highly oxidised, monomeric complex containing a metal-oxo species formulated as the 7T-cation r a d i c a l [0=Ru I V(OEP 7T-cation radical) ]Br. Both Ru I i : [(OEP) (PPh 3) (Br) and [0=RuIV(OEP+.) ]Br 1 5 ' 1 6 i n the presence of mCPBA or PhIO were found to activate the C-H bonds of organic substrates r e s u l t i n g i n c a t a l y t i c oxidation. As documented i n Appendix A.I of t h i s t h e s i s , a l l attempts in t h i s present study to i s o l a t e the R u I V TT-cation r a d i c a l com-plex led to a mixture of R u I V p-oxo bridged "dimers" and triphenylphosphine oxide (0=PPh3) formed by oxidation of the li b e r a t e d PPh 3: excess mCPBA r"j j~J 2Ru I I ] C(0EP) (PPh 3)Br B r — R u I V — 0 — R u I V — B r + 2 0=PPh3 or PhIO U U ( t i ) = OEP"2 Appendix A.I also documents the oxidation of the Ru(OEP) (CH 3CN) 2 complex using excess mCPBA. At eit h e r ambient (19°C) or low (-60°C) temperatures, the primary products were u-oxo dimers, i n d i c a t i n g that the dimers are extremely stable "thermodynamic" sinks for Ru(OEP) chemistry. 1 7 3 R R R R R = CH 2CH 3, R'= H :octaethylporphyrin R = H, R*= phenyl :tetraphenylporphyrin R = H, R'= 2,4,6-trimethylbenzyl (or mesitylene): tetramesitylporphyrin Figure 1.2: Highly symmetric synthetic porphyrins used i n research with model complexes. 4 I t was apparent that the formation of a high oxidation state complex would be greatly assisted by the formation of a might i n t e r f e r e i n the subsequent p u r i f i c a t i o n of any new high valent Ru(OEP) complexes. Although the chemistry of Ru(OEP) has expanded greatly from the i n i t i a l work on the C0-complexes, r e l a t i v e l y l i t t l e research on ligand systems other than those noted above has been c a r r i e d out u n t i l recently. Collman et a l . have published i n the past two years the preparation of Ru I I I :(OEP) (EtO) (EtOH) and several new Ru(OEP)(R)(R') compounds (where R=R'= alkyl,R=vacant with R'= carbene or c a r b o x y l a t e ) 1 7 - 1 9 v i a a novel K 2[Ru°(porp)] complex. Some of the transformations indicate that new and e x c i t i n g organometallic chemistry i s possible at ruthenium porphyrin centres. Also, Groves and Quinn have recently pub-l i s h e d the preparation of Ru V I(TMP) ( 0 ) 2 2 0 (a di-oxo complex) and noted i t s a b i l i t y to oxidise o l e f i n s to epoxides. 2 1 In l i g h t of these developments, i t was hoped that the a v a i l a b i l i t y of a Ru I 3 : i (0EP)X complex (X=halide) would allow for further study of the a c t i v a t i o n of C-H bonds i n organic substrates by ruthenium porphyrins. Collman et a l . 2 2 d i s -covered an excellent R u 1 1 precursor that was obtained by the vacuum p y r o l y s i s of Ru 1 1(OEP)(py) 2. This novel compound, [Ru(0EP)] 2 , had no a x i a l ligands and was found to be dimeric: Ru III precursor which contained no oxidisable ligands that D )= OEP -2 u 0 5 The work described i n t h i s thesis shows that upon oxidation of the dimer, novel Ru I V(OEP)X 2 (X= Br, CI) complexes are formed instead of the hoped for Ru I I I(OEP)X complex. Although these R u I V complexes did not catalyse the oxidation of or-ganic substrates, they did lead to the synthesis of many new ruthenium porphyrin complexes. 2 3 The chemistry and charac-t e r i s a t i o n of these new compounds and t h e i r conversion into other compounds w i l l be discussed i n t h i s t h e s i s . 6 References 1. Fleischer,E.B.;Thorp,R.;Venerables,D.,J.Chem.Soc., Chem.Commun.,1969.475. 2. Collman,J.P.;Hegedus,L.S..Principles and Applications of  Oraanotransition Metal Chemistry.University Science Books, M i l l Valley,California,1980,p.29. 3(a).Eaton,S.S.;Eaton,G.R.,Inorg.Chem.,16,72(1977).(b)Faller, J.W.;Chen,C.C.;Malerich,C.J.,J.Inorg.Biochem.,11,151(1979). (c)Eaton,G.R.;Eaton,S.S.,J.Am.Chem.Soc.,97,235(1975). 4. Cotton,F.A.;Wilkinson,G..Advanced Inorganic Chemistry: A  Comprehensive T e x t . 4 — ed.,Wiley Interscience,New York,1980,p.1199. 5. Paine,J.B.,III;Dolphin,D.,J.Org.Chem.,41,3857(1976). 6. Adler,A.D.;Longo,F.R.;Finarelli,J.D.;Goldmacher,J.;Assour, J.;Korsakoff,L.,J.Org.Chem.,32,476(1967). 7. Groves,J.T.;Nemo,T.E.,J.Am.Chem.Soc.,105,6243(1983). 8. Antipas,A.;Buchler,J.W.;Gouterman,M.;Smith,.P.D.,J.Am.Chem. SOC.,100,3015(1978). 9. James,B.R.;Mikkelsen,S,R.;Leung,T.W.;Williams,G.M.;Wong,R., Inorg.Chim.Acta,85,209(1984). 10. Barley,M.;Dolphin,D.;James,B.R.;Kirmaier,C.;Holten,D.,J. Am.Chem.Soc.,106,3937(1984) . 11. Ariel,S.;Dolphin,D.;Domazetis,G.;James,B.R.;Leung,T.W.; Rettig,S.;Trotter,J.;Williams,G.,Can.J.Chem.,62,755(1984). 12. Domazetis,G.;Tarpey,B.;Dolphin,D.;James,B.R.,J.Chem.Soc., 7 Chem.Commun.,939(1980). 13. Domazetis,G.;James, B. R.;Tarpey,B.;Dolphin,D..ACS Symposium  Ser..152 fCatal.Act.Carbon Monoxide).1981,p.243. 14. James,B.R.;Dolphin,D.;Leung,T.W.;Einstein,F.W.B.;Will i s , A.C.,Can.J.Chem.,62,123 8(1984). 15. Dolphin.D.;James,B.R.;Leung,T.W.,Inorg.Chim.Acta, 79,25(1983) . 16. Leung,T.W.;James,B.R.;Dolphin,D.,Inorg.Chim.Acta, 79,180(1983). 17. Collman,J.P.;Barnes,C.E.;Brothers,P.J.;Collins,T.J.;0zawa, T.;Ga1lucei,J.A.;Ibers,J.A.,J.Am.Chem.Soc..106.5151(1984). 18. Collman,J.P.;Brothers,P.J.;McElwee-White,L.;Rose,E.; Wright,L.J.,J.Am.Chem.Soc.,107,4570(1985). 19. Collman,J.P.;Brothers,P.J.;McElwee-White,L.;Rose,E., J.Am.Chem.Soc..107.6110(1985). 20. Groves, J.T. ;Quinn,R. ,Inorg.Chem. ,23., 3844 (1984) . 21. Groves,J.T.;Quinn,R.,J.Am.Chem.Soc.,107,5790(1985). 22. Collman,J.P.;Barnes,C.E.;Swepston,P.N.;Ibers,J.A.,J.Am. Chem.Soc.,106,3 500(1984). 2 3.Sishta,C.;Ke,M.;James,B.R.;Dolphin,D.,J.Chem.Soc.,Chem. Commun.,787 (1986). 8 Chapter I I : EXPERIMENTAL. A. Reagents and Solvents. Tetrahydrofuran (BDH,analytical reagent grade), aceto-n i t r i l e (Eastman,spectroscopic grade) and dichloromethane (Fisher,reagent grade) were refluxed under argon over calcium hydride ( F i s h e r , p u r i f i e d grade) p r i o r to f r e s h l y d i s t i l l i n g i nto storage f l a s k s . Toluene (Fisher, reagent grade) and hexanes (BDH,Omnisolv grade) were also d i s t i l l e d from calcium hydride p r i o r to use. A l l the above solvents were stored over molecular sieves (MCB,4A p e l l e t s ) and THF was stored i n the dark to prevent peroxide products from forming ( a l l the above solvents were used without t e s t i n g further for p u r i t y ) . Pyridine (BDH,reagent grade) and benzene (Fisher,ACS grade) were stored over activated molecular sieves without any previous p u r i f i c a t i o n . Methanol (BDH,Omnisolv grade) and ethanol (Fisher,reagent grade) were used as obtained. Deuterated solvents for NMR studies were also given spe-c i a l treatment: benzene-dg (SCI Isotopes,99.5% D) and dichloromethane-d 2 (MSD Isotopes,99.8% D) were vacuum d i s -t i l l e d into anaerobic sample storage b o t t l e s i n which ac-t i v a t e d molecular sieves had been previously prepared. The NMR solvents were freeze-pump-thawed t h r i c e p r i o r to use to remove any a i r or highly v o l a t i l e impurities. The apparatus used f o r vacuum tra n s f e r of solvents and reagents i s shown i n 9 TO VACUUM LINE (B-19 SOCKET) VorihQ'-TPTgy1 ACTIVATED MOLECULAR SIEVES Figure I I . i : Apparatus used for the tran s f e r of solvents and reagents under anaerobic conditions. 1 0 Figure II.1. Methanol-d 4 (KOR Isotopes, 99.5% D) and chloro form-d-^ (MSD Isotopes, 99.8% D) were "used as obtained. Triphenylphosphine was supplied from MCB Chemical Co. sodium ethoxide was obtained from A l d r i c h Chemical Co. and both were used as supplied. Sodium d i t h i o n i t e was used as i tained i n i t s p u r i f i e d grade from J.T.Baker Chemical Co. Ruthenium t r i c h l o r i d e trihydrate was supplied on loan by Johnson Matthey Limited and octaethylporphyrin was kindly supplied by Dr. T i l a k Wijesekera. Argon was supplied from Linde and, when needed for rigorous conditions, p u r i f i e d by passing sucessively throu an activated molecular sieve column and a Redox c a t a l y s t column (Fisher S c i e n t i f i c ) to remove moisture and oxygen, respectively. Carbon monoxide was also supplied from Lind and used as obtained. Anhydrous HBr^gj was obtained from Matheson and technical grade H C l ^ was supplied by BDH Chemical Co. Nitrous oxide was supplied as the p u r i f i e d grade by Linde. The hydrogen halide and N 20 gases were used as supplied. B. Physical Measurements. Optical spectra were obtained using a Cary 17D s p e c t r -photometer with 0.1,0.5 and 10 mm pathlength quartz c e l l s . Anaerobic spectra were recorded using an anaerobic spectro 5 mm TEFLON STOPCOCK B - 1 4 CONE (CAPPED WHEN IN USE) • QUARTZ C E L L WINDOW Figure II.2: An anaerobic o p t i c a l c e l l 12 photometer c e l l (see Figure II.2). A l l i n f r a r e d spectra un-less indicated otherwise were obtained using a Nicolet 5 DX-FT spectrometer u t i l i s i n g i n a l l cases cesium iodide windows and Nujol. Nuclear magnetic resonance spectra were obtained on a Varian XL-300 FT spectrometer. Electron paramagnetic resonance measurements were made on a Varian E3 spectrometer u t i l i s i n g a l i q u i d nitrogen Dewar for low temperature (77°K) spectra. Anaerobic EPR and NMR spectra were obtained using anaerobic c e l l s s i m i l a r to that shown i n Figure 11.2. A Kratos-AEI MS902 mass spectrometer operating i n the electron impact (70 eV), d i r e c t i n s e r t i o n mode at 200-300°C source temperatures was used for mass spectral data. Microanalyses were performed by Peter Borda of t h i s department. Magnetic s u s c e p t i b i l i t i e s were measured using Evans' method, 1 the d a t a being recorded on an XL-300 NMR spectrometer. Equivalent con-d u c t i v i t y measurements were made i n CH3CN, CH 2C1 2, or CHC13 using a c e l l with a c e l l constant (K) of 1.0 cm"1 and a RCM 15B1 Conductivity bridge from the Arthur H. Thomas Company. The resistance of the appropriate samples were measured and converted to conductivity u s i n g : 2 K x 10 3(conversion factor L-^cm3) Conductivity = 1 • 1 • . • • » concentration of solution x measured r e s i s t a n c e High pressure chemistry was ca r r i e d out using a Baskerville 13 and Lindsay High Pressure Hydrogenation autoclave. C. Preparation of Ruthenium Complexes. Dodecacarbonyltriruthenium(O) (1). This s t a r t i n g material was prepared i n e a r l i e r studies at a y i e l d of 40% using Mantovani's method, 3 but a new proce-dure based on Bruce's method 4 was developed. RuCl 3.3H 20 (3 g) and methanol (200 mL) were placed into a high-pressure autoclave and s t i r r e d at 150°C under 70 atm of c0(g) f o r twenty-four hours. The reaction mixture was vented and f i l -tered to y i e l d crude Ru 3(CO) 1 2. The f i l t r a t e was then re-placed into the autoclave with yet another 3 g of RuCl 3.3H 20 and repressurized under the conditions described previously. This process was continued u n t i l a l l avai l a b l e t r i c h l o r i d e was exhausted. The crude Ru 3(CO) 1 2 was p u r i f i e d by extraction into hexanes using a Soxhlet apparatus and, upon cooling to -20 °C overnight, bright yellowish c r y s t a l s were obtained which were f i l t e r e d and a i r dried (80% y i e l d ) . "Mco)™ 2058' 2020 a n d 1995 cm~1' 14 Carbonvl(ethanol)(octaethylporphyrinato)ruthenium(II) (2). This precursor was made according to the method developed by Barley et a l . 5 V(C0)~ 1 9 2 2 c n " 1 -Bis(triphenylphosphine)(octaethylporphyrinato)ruthenium ( I I )  (3) . This complex was also prepared by a l i t e r a t u r e method. 6 Analysis C 7 2H 7 4N 4P 2Ru(1158 g/mole),calculated:C=74.65, H=6.4 6,N=4.85% ;found:C=74.73,H=6.50,N=4.85%. NMR(C 6D 6,anaerobic): 1.70(t), CH 3; 3.68(g), CH 2; 4.20(d), o-H; 6.2-6.8(m), m-,p-H; 9.16(s), meso-H. (Triphenylphosphine)(octaethylporphyrinato)ruthenium(II) (4 1 . 200°C,2 h , l x l 0 " 5 t o r r R u 1 1 (OEP) (PPh 3) 2 • R u 1 1 (OEP) (PPh 3) + (PPh 3) A f a r simpler method to prepare t h i s compound than that published by James et a l . 7 i s v i a p y r o l y s i s of the b i s -phosphine complex (3). Ru(OFP)(PPh 3) 2 (100 mg,0.1 mmoles) w a s placed into a 10 mm diameter t e s t tube which has a vacuum l i n e attachment (see Figure II.3). By use of an engraver, t h e p a r t i c l e s which adhered to the walls were agitated to the 15 TO TEMPERATURE CONTROLLER POWER SUPPLY TEMPERATURE CONTROLLING THERMOMETER . B-14 CONE (TO VACUUM LINE) ^ 5 mm GLASS VALVE B^14 CONE/SOCKET GLASS REACTION FLASK TEMPERATURE CONTROLLING OVEN TEMPERATURE SET DIAL Figure I I .3 : Temperature-controlling oven apparatus for the vacuum p y r o l y s i s of Ru(OEP) complexes. 16 bottom of the tube. The purple powder was then heated at 200°C at l x l O " 5 t o r r vacuum for two hours using a temperature c o n t r o l l i n g tube oven (Kugelrohr oven from Buchi). The l i b e r a t e d triphenylphosphine appears as a white residue at the mouth of the.oven and the five-coordinate phosphine com-plex remains at the bottom of the tube. (95% y i e l d ) . Analysis f o r C 5 4H 5 9N 4PRu(896g/mole),calculated:C=72.40, H=6.59,N=6.2 6%;found:C=72.49,H=6,70,N=6.13%. NKR(C 6D 6,anaerobic): 2.02 ppm(t), CH 3; 3 . 9 2 ( g ) , CH 2; 4.45(d), o-H; 6.4 5(m), m-H; 6.68(d), p-H; 9.50, meso-H. MS(70 ev EI): 895 m/e,Ru(OEP)(PPh 3) +; 634,Ru(OEP)+, 262,PPh 3 +. Bromo(triphenylphosphine^ (octaethylporphyrinato)  ruthenium f l i p (5). CH 2C1 2 R u 1 1 (OEP) (PPh 3) + HBr/0 2 • R u 1 1 1 (OEP) (PPh 3) Br + HO*2 An improvement over a previous method reported 6 for t h i s compound i s the use of the monophosphine complex (4) instead of the bisphosphine complex ( 2 ); t h i s avoids separation of the oxidised phosphine formed during the reaction. A 10 mL sol u t i o n , made by bubbling anhydrous HBr^gj to saturation into CH 2C1 2, was added to 100 mg (0.1 mmoles) of (4.) under i n e r t conditions v i a vacuum transfer. A f t e r exposure to a i r , the reaction mixture was cooled to ice-bath temperature, and 17 cold hexanes added to p r e c i p i t a t e the product. The pr e c i p i t a t e was then r e c r y s t a l l i s e d twice from C H 2 C l 2 - h e x a n e s to y i e l d a reddish powder (95% y i e l d ) . Analysis for C 5 4H 5 gN 4RuPBr(975g/mole),calculated:C=66.53, H=6.06,N=5.75,Br=8.11%,found:C=66.3 3,H=6.24,N=5.49,Br=7.8 5%. Bis(pyridine)(octaethvlporphyrinato)ruthenium(II) ( 6 ) . hv,24 h,Ar Ru 1 1(OEP)(CO)(EtOH) + 2 Py « R u 1 1 (OEP) (Py) 2 + CO + EtOH This compound was prepared according to the method pub-li s h e d by Antipas et a l . 8 using the photolysis c e l l diagrammed i n Figure II.4. A Hanovia 450 Watt mercury vapor lamp with a quartz water-cooler jacket was used for the photolysis(90% y i e l d ) . NMR(C6D6, anaerobic): 2.03 ppm(t),CH 3; 2.26(d),m-H; 3.97(q),CH 2; 4.17(m),o-H; 4.33(d),p-H; 9.74(s),meso-H. Analysis f o r C 4 6H 5 4N gRu(791g/mole),calculated:C=69.79,H=6.83, N=10.62%;found:C=69.39,H=6.83,N=10.72%. Bis(acetonitrile)(octaethylporphyrinato)ruthenium(II) ( 7 ) . 1W,24 h,Ar Ru 1 1 (OEP) (CO) (EtOH) +2CH 3CN- R u 1 1 (OEP) (CH 3CN) 2 + CO + EtOH This complex was prepared using a photolysis procedure 18 (see preparation of 6) adapted from that used by Walker. Ru(OEP)(CO)(EtOH) (130 mg,0.2 mmoles) was placed i n a tes t tube and CH3CN (10 mL) added. Although the CO complex does not f u l l y dissolve, the photolysis causes the a c e t o n i t r i l e t c re f l u x and thus dissolve the s t a r t i n g material. A f t e r photolysis for 12 hours under argon, the solut i o n was slowly cooled to room temperature under a purge of argon and the product p r e c i p i t a t e d as large, shiny purple c r y s t a l s . These were f i l t e r e d under argon, washed with a c e t o n i t r i l e and dried on a vacuum l i n e at room temperature at an 80% y i e l d . This method r e s u l t s i n the presence of a small amount (5%) of the CO complex. Samples suitable for microanalysis and future X-ray c r y s t a l structure determination were obtained by adding dry, anaerobic CH3CN (2 mL) to samples of the dimer [Ru(0EP)] 2 (10 mg,0.008 mmoles) under anaerobic, vacuum conditions. The solution was then refluxed under vacuum and cooled slowly overnight to p r e c i p i t a t e large, shiny purple c r y s t a l s which were f i l t e r e d , dried under vacuum at room tem-perature and stored under H2(g)-D ( C = N ) = 2 2 6 0 cm"1. NMR(CD2C12, anaerobic): -2.70 ppm(s),CH3CN; 1 .95(t),CH 3 ; 3.98(q),CH 2 ; 9.96(s),meso-H. Analysis f o r C4 t )H 5 0N 6Ru (7l6g/mole) , calculated: C=63 . 69 , H=6. 98 , N=11.73%;found:C=63.82,H=7.11,N=11.80%. 19 COOLING WATER IN ARGON GAS INLET COOLING WATER OUT ARGON GAS OUTLET GLASS REACTION FLASK WATER JACKET FOR COOLING MERCURY VAPOR LAMP Figure II. 4 : Apparatus for photolysis of Ru(OEP) complexes, 20 B i s r ( o c t a e t h v l p o r p h v r i r . a t o ) r u t h e n i u m ( I I ) 1 . (8) . 200°c,2 h,lxl0~ 5torr 2 R u 1 1 (OEP) (Py) 2 ^ [ R u I 3 : ( O E P ) ] 2 + 4 Py T h i s d i m e r i c complex was prepared from complex 6 a c c o r d i n g t o the method of Collman e t a l . 1 0 . N M R ( C 6 D 6 , a n a e r o b i c ) : 3.52 ppm(t),CH 3; 10.22(s),meso-H;11.2l (n),CH 2; 26.13(m),CH 2. A n a l y s i s f o r C 7 2H 8 8NgRu 2(1268g/mole),calculated:C=68.14, H=6.94,N=8.83 %;found:C=68.4 9,H=7.01,N=8.91%. D i b r o n o { o c t a e t h v l p o r p h v r i n a t o ) r u t h e n i u m ( I V ) ( 9 ) . 1/2 [ R u 1 1 ( O E P ) ] 2 + HBr/Br 2* ^ Ru I V(OEP) ( B r ) 2 + KBr * see chapter IV To 8. (100 mg r0.08 mmoles) , 10 mL of a s o l u t i o n , made by b u b b l i n g anhydrous HBr^gj t o s a t u r a t i o n i n CH 2C1 2, was addeu v i a vacuum t r a n s f e r . The r e d s o l u t i o n was then exposed t o t h e a i r , c o o l e d t o i c e - b a t h temperature, and c o l d hexanes added to p r e c i p i t a t e s m a l l r e d d i s h c r y s t a l s which were f i l t e r e d and r e c r y s t a l l i s e d from CH 2C1 2/ hexanes. The sample was d r i e d a t room temperature under vacuum. Large c r y s t a l s s u i t a b l e f o r ar, X-ray c r y s t a l s t r u c t u r e d e t e r m i n a t i o n were grown u s i n g v a p c u r d i f f u s i o n of n-pentane i n t o CHC1 3 s o l u t i o n s of (9) under a e r o b i c c o n d i t i o n s (90% y i e l d ) . A n a l y s i s f o r C 3 6H 4 4N.RuBr 2(791g/mole),calculated:C=54.55, 21 H=5.56,N=7.08,Br=2 0.08%;found:C=54.35,H=5.70,N=7.00,Br=2 0.091 EPR signals were unobserved at ambient or low(77 K) temperatures in 1:1 toluene .'dichloromethane. NMR(CDC13,aerobic,19 °C): 60.lppm(broad),CH 2(16);7.10(br), CH 3(24);3.90(br),meso-H(4). Magnetic s u s c e p t i b i l i t y : / i e f f = 2-5 B.M. using 2% t-butyl alcohol i n CH 2C1 2. MS( EI, 70eV,280°C): 1268 m/e,[Ru(OEP)] 2 +; 634,Ru(OEP) +; 80,HBr +. Conductivity(at 20 °C): 0.5(CH 2C1 2) and 12(CH3CN) ohm~1M"1cm. UV/VIS(CH 2C1 2,aerobic):360 nm,sh(log € =4.75),398,Soret(4.90); 505(4.23); 535(4.16). Dichlorofoctaethylporphyrinato)ruthenium(IV) f l O ). This compound was prepared using the method described for the dibromo analogue but using HCl^gj i n place of HBr^g^ (90% y i e l d ) . Analysis f o r C 3 6H 4 4N 4RuCl 2(703g/mole),calculated:C=61.23, H=6.24,N=7.94,Cl=10.07%;found:C=60.98,H=6.17,N=7.83,Cl=9.88%. EPR signals were unobserved at ambient or low(77 K) temperatures i n 1:1 toluene:dichloromethane solutions. NMR(CDC13,aerobic,19 °C): 57.2 ppm,CH2(16); 8.00,meso-H(4); 6.44,CH 3(24). Magnetic s u s c e p t i b i l i t y : f l e f f - 2.6 B.M. using 5% t-butyl 22 alcohol i n dichloromethane. MS(EI,70 eV,300°C): 1268 m/e,[Ru(OEP)] 2 +; 634,Ru(OEP) +. Conductivity(at 20°C): 0.7 ohm~ 1M" 1cm(CH 2C1 2); 14 ohm"1 M - 1cm(CH 3CN). UV/VIS(CH 2C1 2,aerobic): i d e n t i c a l to that of the dibromide analogue. T e t r a h y d r o f u r a n ( h e x a f l u o r o a n t i m o n a t e ( V ) ) ( o c t a e t h y l p o r p h y r i n - a t o ) r u t h e n i u m ( I I I ) (11). Ru I V(0EP) ( C l ) 2 + AgSbF 6 + THF ^» Ru I I J(0EP) (SbF 6) (THF) + 1/2 C l 2 + AgCl* * see Chapter IV In a Schlenk fl a s k , 10 (100 mg,0.13 mmoles) and s i l v e r hexafluoroantimonate(V) (86 mg,0.25 mmoles) were dissolved i n dry, degassed THF (50 mL). The r e s u l t i n g red suspension v a s s t i r r e d under dry argon for t h i r t y minutes and then f i l t e r e d through a Schlenk f i l t e r to remove the suspended reaction products (presumably AgCl). n-Pentanes (100 mL) were then cannulated into the f i l t r a t e with s t i r r i n g to p r e c i p i t a t e t h e product as a brown powder. This was r e c r y s t a l l i z e d twice f r o r , THF/n-pentanes and dried under vacuo at 80°C f o r s i x hours (90% y i e l d ) . Analysis for C 4 0H 5 2N 4RuSbF 6O(941g/mole),calculated:C=51.0 6 , H=5.53,N=5.95%;found:C=51.19,H=5.65,N=5.87%. NMR (CDCl-j, anaerobic, 19 °C):17.5 ppm, CH 2 (8) ; 6. 24 ,meso-H (4 ) ; 23 3.80,CH 2(S;;2.00,THF(4);1.89,CH 3(24); -1.05,THF(4). EPR s i g n a l s were unobserved at room temperature but a t 77 K,g =2.3 and g =2.8 were measured u s i n g an 1:1 THF (I t o l u e n e , anaerobic s o l u t i o n . C o n d u c t i v i t y ( a t 20°C): 9.0 ohm"1M~1cm i n C H C l 3 . UV/VIS(CHC1 3,anaerobic)t386 S o r e t ( l o g £ =4.94);501(4 528 (4.01). 24 References 1 . Evans,D.F.,J.Chem.Soc.,1959 ,2003. 2. Atkins,P.W..Physical Chemistry.W.H. Freeman and Co.,San Francisco,1978,p.819. 3. Mantovani,A.;Cenini,S..Inorg. Synth..vol XVI;F.Basolo, ed;McGraw-Hill,New York, 1976.p.47. 4. Bruce,M.I.;Matisons,J.G.;Wallis,R.C.;Patrick,J.M.; Skeleton,B.W.;White,A.H. , J.Chem.Soc.,Dalton Trans., 1983.2365. 5. Barley,M.;Becker,J.Y.;Domazetis,G.;Dolphin,D.;James,B.R., Can.J.Chem.,61,2389(1983). 6. James,B.R.;Dolphin,D.;Leung,T.W.;Einstein,F.W.B.;Willis, A.C.,Can.J.Chem.,62,12 38(1984). 7. James,B.R. ;Mikkelsen, S .R. ; Leung, T.W. .-Williams, G .M. ;Wong,R. , Inorg.Chim.Acta,8 5 ,209(1984). 8. Antipas,A. ;Buchler, J.W. ;Gouterman,M. ;Smith,P.D. ,J.Am.Cher,. Soc.,100,3015(1978). 9. Walker,S.G., M.Sc. T h e s i s , U n i v e r s i t y of B r i t i s h Columbia, 1980. 10. Collman,J.P.;Barnes,C.E.;Swepston,P.N.;Ibers,J.A.,J.Am. Chem.Soc.,106,3500(1984). 25 Chapter I I I ; The Characterisation of Ru (OEP)(X) 2 and  Ru I i : I(OEP) (SbF c) (THF) . Section I I I . l ; Analysis of the data for Ru(OEP)(Br) 2 f 9 and  RuroEP) r e p 2 f 1 0 . A.NMR Spectroscopy. The use of 1H NMR i n diagnosing Ru(OEP) complexes i s an indispensable t o o l , as the eight ethyl groups of OEP are sen-s i t i v e probes of the symmetry about the ruthenium: Figure I I I . l : A view of the ethyl groups with the pyrrole as the mirror plane of symmetry. The free r o t a t i o n about the C 1C 2 bond r e s u l t s i n H a and H b being equivalent and the rotation about the C 2C 3 bond results i n the methyl protons also being equivalent. Thus, f o r Ru(OEP) (hyopthetically, without any a x i a l ligands), one ob-serves an A 2B 3 1H NMR pattern for the ethyl groups i n t h e i r 26 usual chemical s h i f t range. Since Ru(OEP) has D 4 n symmetry, the meso protons (H m) would be equivalent and r e s u l t i n a s i n g l e t . The in c l u s i o n of a x i a l ligands w i l l a f f e c t the over-a l l symmetry of the complex i n two general ways: i f both the a x i a l ligands are i d e n t i c a l , then a D n n symmetry w i l l be preserved and an A 2B 3 spectrum would r e s u l t ; however, i f the ax i a l ligands are d i f f e r e n t from each other, then the D n n symmetry i s l o s t and the H a and protons become inequivalent, r e s u l t i n g i n two methylene peaks of equal i n -t e n s i t y (ABX3 spectrum). 1 These differences are diagrammed below: (a) A 2B 3 spectrum (b)ABX 3 spectrum 4 2 ppm 4 2 ppm Figure III.2: Theoretical 1H N M R spectra for OEP complexes:(a)mirror symmetry present (x axis = y axis),(b)no mirror symmetry present. Complexes 9 and iQ, having s i m i l a r nonproton a x i a l ligands, e x h i b i t 1H N M R spectra with only three signals (-CH2,-CH3,-Hm) because a mirror plane of symmetry i s p r e s e n t (see Figure I I I . l ) . The chemical s h i f t s of these three s i g -nals i n D n h symmetry generally depend on the metal's oxida-27 t i o n state and the a x i a l ligands present. A R u 1 1 complex with neutral a x i a l ligands would have a d 6 octahedral (with tetragonal a x i a l stretching distortion) configuration which i s shown i n Figure I I I . 3 : 2 Ru I : c,d 6 d x2_ y2 d 22 d x2_y2,d 22 I 1 I I L • l h (d o r b i t a l s ) . Jld^ Jl_ J J _ i L d x z ' d y z ' d x y I N \K R J t d x z , d xz'~yz no ligand f i e l d octahedral f i e l d tetragonal a x i a l stretching d i s t o r t i o n Figure III.3: Ligand f i e l d s p l i t t i n g diagram fo r a Ru I ] [,d 6 low spin octahedral complex with a x i a l d i s t o r t i o n . A paramagnetic complex such as 9 or 10 has unpaired electrons i n the metal d - o r b i t a l s , and so the chemical s h i f t s are perturbed from t h e i r normal 0-12 ppm diamagnetic range. For paramagnetic s h i f t s , the observed i s o t r o p i c s h i f t i s based on the three sources: 3 ( A H / H ) I S O = ( A H / H ) contact + ^ H / H ) dipolar _ ( ^ H / H ) diamagnetic The contact s h i f t a r ises from the p a r t i a l t r a n s f e r of un-paired spin density into an o r b i t a l centered on the nucleus of i n t e r e s t , and i s proportional to the hyperfine coupling constant A (which r e f l e c t s the unpaired spin density at the 28 nucleus); and i s inversely proportional to the temperature. Dipolar s h i f t s p r i m a r i l y a r i s e from the magnetic anisotropy or inequivalence i n the x,y,z axes of the metal, 4 and are proportional to r where r i s the metal-to-proton nucleus distance. Since the dipolar s h i f t diminishes according to a r ~ 3 function, i t s e f f e c t i s secondary to that of the contact s h i f t i n many cases where paramagnetism i s present. The 1H NMR spectra of 9 and 10 (see Figures III.5 and II I . 6) e x h i b i t a l l the c h a r a c t e r i s t i c s of a L-*-M CT system for metal-porphyrin 7T-bonding. The tran s f e r of spin density between the metal d o r b i t a l s and the molecular o r b i t a l s of the ligand can occur v i a cr- and/or 7T-bonding. For 7T-bonding, eit h e r a ligand-to-metal charge transfer (L-*M CT) or a metal-to-ligand charge transfer ( i e . backbonding) (M—*L CT) i s possible;^ and which process occurs i s dependent on the energy of the metal d o r b i t a l s r e l a t i v e to the porphyrin energy l e v e l s 6 (see Figure I I I . 4 ) . I f the a x i a l ligands exert s i g n i f i c a n t 7T-bonding to the metal, then the eg o r b i t a l s of the metal become d e s t a b i l i s e d and increase i n energy, bring-ing them c l o s e r to the energy l e v e l of the porphyrin egTT* o r b i t a l . 7 In t h i s case, a M-*L charge tr a n s f e r i s l i k e l y , and the transferred charge resides l a r g e l y at the porphyrin meso position, causing the H m e s o -^H NMR signal to s h i f t greatly up-f i e l d of TMS compared to the diamagnetic s h i f t (the positions of the pyrrole hydrogens tend to s h i f t s l i g h t l y downfield at the same t i m e ) . 8 In the case of a weaker7F-donor, the metal e 29 l e v e l s become less d e s t a b i l i s e d and now are nearer to the porphyrin 3e g 7T- o r b i t a l energy l e v e l , r e s u l t i n g i n a L-^M CT. In t h i s case, most of the electron density i s donated from the pyrrole carbons rather than the meso carbons, and thus the ethyl 1H NMR resonances s h i f t downfield while the meso NMR resonance s h i f t s s l i g h t l y u p f i e l d . Thus, the -^H NMR spectra of 9 and 10 exhibit a l l the c h a r a c t e r i s t i c s of a L—»M CT system because the methylene peak appears as a broad s i n g l e t a t ~ 6 0 ppm, the methyl peak at ~7.0 ppm and the meso peak between 3-9 ppm (see Figures III.5 and III.6). The cor-responding diamagnetic positions are +3.97, +2.03 and +9.74 ppm respectively for Ru 1 1(OEP)(py) 2• x 2 - y 2 z 2 py(7T*) 4ea(7T*) r xy(n.b.) (eg> JL a 2u JL JL X Z ' Y Z JL aiu(7T) (ID py (77) porphyrin metal a x i a l ligand Figure III.4: The MO diagram for Ru(OEP)(py) 2 as a model for the Ru I V(OEP)(X) 2 complexes 9 and 10. 6 30 Figure III.5 : The * H NMR spectrum of Ru(OEP)(Br) 2 in CDC13, 300 M H z , 19 °C, under aerobic conditions. CIL cnci 3 JJ J cn. — \ > < — 60.6 60.2 59.8 H » » t ; i » i i l t i » i i i t i t | i i i i | i » i i t i » » i ; i t i t | » i t t i i i i i | i i t t i t t t i | i i i » | » » ' • t 7 . 0 • 0 3 . 0 « . t 9 . 0 » • W Figure III.6: The *H NMR spectrum o f Ru(OEP) ( C l ) 2 in CDC3, 300 MHz, 19 °C, under aerobic conditions. to 5 7 . 8 5 7 . 2 5 6 . 6 CDC1. CM, A J _ _ A ; T » T » | i i > i | i » T i | t t » i | i i i i | » I T t f l i t f | t , » t | i i i i ; » i i t | i i i t | t i t i | i i > i > i » i i t ; i i i t j > i i i ; T t l i ; t l i l | I S O 17 0 I I . 0 1 0 . 0 t . O 0 0 7 . * 0.0 9.9 **• The assignments of the OEP peaks were deduced from the r e l a t i v e i n t e n s i t i e s and by the i n t e g r a t i o n of the signals observed. Although chemical s h i f t s a r i s e mainly from contact e f f e c t s for paramagnetic molecules, r e l a x a t i o n rates are p r i m a r i l y e f f e c t e d by d i p o l a r r e l a x a t i o n terms, 9 which diminish according to r ~ 6 where r i s the metal-to-proton distance. Thus, by studying the s p i n - l a t t i c e r e l a x a t i o n rates (Tj^)" 1 by the inversion-recovery NMR method (as described in the Varian XL-300 NMR operating manual) 1 0 and i n t u i t i v e l y c o r r e l a t i n g these values to ' r ' , one can assign unambiguously the NMR spectra observed (see Tables I I I . l and III.2 and Figure I I I . 7 ) . I f the relaxation rate i s f a s t (short T ^ i e . d t i s small), then the resonant frequency width (dF) i s large, and vice-versa. For t h i s reason, the NMR spectra of 9 and 10 both have broad s i g n a l s with no observed s p l i t t i n g s or couplings. The r e l a t i v e ordering of the ruthenium d - o r b i t a l s i s of considerable i n t e r e s t because, to our knowledge, £ and 12. are the f i r s t intermediate spin, t r i p l e t state S=l, ruthenium porphyrin complexes known. There are three possible orderings of the ruthenium's d - o r b i t a l s energy for a Ru I V, d 4 con-f i g u r a t i o n (see Figure III . 8 ) . The S=2 configuration i n Figure III.8 argues against a L-»M CT system i n favour of o— bonding because the d x2_ v2 o r b i t a l i s of cr- symmetry, and the o r b i t a l s needed fo r L->M or M-*L CT system are of ea7T/7T* symmetry. Also, that S i s 33 equal to one (two unpaired electrons) from magnetic measure-ments of 1 and 10, indicates that the S=2 high spin con-f i g u r a t i o n i s considered less l i k e l y than the other two (b or c i n Figure III.8). These l a s t two cases are consistent with a L—*M CT picture but are not e a s i l y distinguished using com-mon spectroscopic methods. I f one chooses an a x i a l (a) (b) (c) d z2 d z2 d x 2 - v 2 r — Yd"*2 d r — d r * V 2 d -T -H Z 2 _ L - d x z ' d y z _ L _ l _ d x z ' d y z _ t _ d w ^ . -L_ dxy iL dxy J _ d x z ' d y z Figure III.8: The three possible d - o r b i t a l occupancies of Ru I V, d 4 paramagnetic complexes:(a)an S=2 configuration (b)an S=l ( d X y ) 2 ( d x z ' d y z ^ 2 configuration (c)an S=l ( d x z , d v z ) 3 ( d ^ ) 1 configuration. stretching d i s t o r t i o n instead of an a x i a l compression d i s t o r -t i o n ( i e . Ru-Br,2.55 k vs Ru-N,2.05 A(ave.) for Ru(OEP) ( P P h 3 ) B r ) , 2 7 b then configuration c i n Figure III.8 i s the best representation for a Ru I V,d 4 complex. A Curie Law p l o t of the i s o t r o p i c s h i f t versus T - 1 should r e s u l t i n a s t r a i g h t l i n e only i f one spin state i s populated over the temperature range studied. Another t e s t for Curie behaviour i s that as T - 1-> 0, the i s o t r o p i c s h i f t should approach 0 ppm ( i e . the corresponding diamagnetic position) and, i f both conditions are met, the compound i s said to follow the Curie Law. 1 1 Although a l l the proton 34 Table I I I . l : T1 Data for R u I V ( O E P ) ( B r ) 2 . 5 Interpulse delay fms)fe Intensity (CH 2) Intensity (CH 3) I n t e n s i t y ( H m c _ 0 ) 5.0X10" 2 11.0 -92.0 -2.01 1.OxlO" 1 9.12 -94.0 -2.02 5.OxlO" 1 10.4 -94.0 -2.20 1.0 11.0 -91.2 1.22 4.0 19.8 -75.7 3.06 8.0 26.0 -59.8 7.00 20 47.0 -13.9 13.5 50 80.9 75.4 16.8 80 99.6 137 17.6 100 108 166 17.2 300 123 260 18.2 500 124 270 18.8 i (ns)fi 50.5 79.4 13.0 • i n CDCI3 at 19°C (aerobic sample); i n t e n s i t i e s given peak heights ( a r b i t r a r y scale) • — standard time delay to allow for p a r t i a l relaxation of the spin magnetization vector. — obtained from a computer-aided c u r v e - f i t t e d p l o t of signal i n t e n s i t y vs. interpulse delay u t i l i s i n g the data above. 35 Table III.2: T1 Data for Ru I V(OEP) (CI) 2 .-^  Interpulse d e l a v ( m s ) I n t e n s i t y f C H 2 ) Intensity(CH 2) I n t e n s i t y f H m c _ _ ) 5.0X10" 2 5.32 -80.9 -7.04 1.0X10" 1 5.02 -80.7 -8.24 5.0X10" 1 6.00 -79.2 -6.04 1.0 7.01 -77.4 -6.00 4.0 11.7 -66.7 1.00 8.0 16.5 -52.9 6.00 20 21.3 -46.2 8.11 50 56.4 37.8 20.2 80 83.1 114 22.1 100 89.8 141 22.4 300 102 235 22.0 500 98.9 251 23.0 T x (ms)0- 50.1 89.7 13.2 — i n CDC13 at 19°C (aerobic sample); i n t e n s i t i e s given as peak heights i n an a r b i t r a r y scale. — standard time delay to allow for p a r t i a l r elaxation of t h e spin magnetization vector. — obtained from a computer-aided c u r v e - f i t t e d p l o t of s i g n a l i n t e n s i t y vs. interpulse delay u t i l i s i n g the data above. 36 Figure III.7: Plot of the signal i n t e n s i t y vs. interpulse delay to obtain the corresponding values for 9 and 10. 37 resonances of 9 and 10 gave s t r a i g h t l i n e s for Curie p l o t s , only the CH 3 resonances f o r 9 and 10 and the H m e s o resonance for 10 gave extrapolated intercepts near zero ppm (± 5 ppm) at T - 1 - » 0 (see Table III.3 and Figure III.9 and III.10). The other three peaks (the CH 2 resonance for 9 and 10 and the Hmeso resonance f o r 9) do not follow the Curie Law. The presence of s p i n - o r b i t coupling may be the o r i g i n of the non-Curie behaviour. 1 2 A further point i s that OEP has 22 7F-electrons with a 4n+2 Huckel resonance configuration. I f an electron i s added or removed from the r i n g , the r e s u l t i n g r a d i c a l i s then s t a b i l i s e d by many resonance s t r u c t u r e s . 1 3 Thus, another pos-s i b l e e l e c t r o n i c configuration f o r 9,and 10 i s that of a 77-cation r a d i c a l porphyrin complex, i n which an electron has been removed (oxidation) from the r i n g to the metal centre i n comparison to a Ru I V(OEP) formulation. This would r e s u l t i n a [Ru 1 1 1(0EP(+.))X]X i o n i c complex or an [Ru 1 1 1(OEP(+.))X 2] neutral complex. Morishima et a l . 1 4 have shown that such 7f-cation r a d i c a l complexes, although containing an a x i a l CO ligand, e x h i b i t very broad 1H NMR signals i n the range -60 t o +60 ppm with the -CH2 and -CH3 1H NMR resonances well downfield and the meso-H NMR resonance s h i f t e d well u p f i e l d of TMS. Both 9 and 10 do not exhibit t h i s type of a 1H NMR spectrum and both are non-electrolytes. On the strength of the 1H NMR data, the Ru(0EP)X 2 formulation with an intermediate spin, t r i p l e t ground state 38 Table III.3: Data f o r the Curie Plot of the Isotropic s h i f t vs. Inverse Temperature. shift(CH 3) shift(CH 2) s h i f t ( H m ) T,o c a T-lf- x io+3 K - l ) obsfe/corrS- obs^/corr 0- obsj^/corr 0-L. Data for Ru(OEP)(Br) 2' — --50 4.48 9.69/7.66 83.3/79.3 6.49/-3.30 -30 4.12 8.88/6.85 75.0/71.0 5.79/-3.95 -10 3.80 8.06/6.03 68.0/64.0 4.77/-4.77 10 3.53 7.09/5.06 62.3/58.3 4.16/-5.58 30 3.30 6.92/4.89 57.9/53.9 3.67/-6.07 50 3.10 6.13/4.10 52.9/48.9 3.23/-6.51 (.Data fo r Ru(OEP)(Cl) 2' -50 4.48 9.39/7.36 82.2/78.2 10.9/1.13 -30 4.12 8.49/6.66 74.7/70.7 9.93/0.13 -10 3.80 7.66/5.63 67.7/63.7 9.10/-0.64 10 3.53 6.98/4.95 62.0/58.0 8.44/-1.30 30 3.30 6.43/4.40 57.2/53.2 7.92/-1.81 50 3.10 6.06/4.04 53.9/49.9 7.61/-2.13 — temperature deviation + 0.5 °C. — obtained i n CDC13, aerobic sample. — diamagnetic correction (Ru I I(0EP)(py) 2/C 6D 6, anaerobic): CH3=2.03, CH2=3.97, 11^ =9.74 ppm. 39 2.0 4.0 6.0 T'1, ( x 103 K' 1 ) Figure III.9: Curie Plot for Ru(OEP)(Br) 2 9, i n the temperature range -50 to +50 °C. 40 temperature range -50 t o +50 °C. 41 Ru ,d metal center seems almost c e r t a i n . The a x i a l bonding i s due to cr1 bonding with appreciable 7T donor character, and the metal-porphyrin 7T-bonding i s l i k e l y L-»M CT. B. Optical Spectra. The presence of a porphyrin TT-cation r a d i c a l complex i s inv a r i a b l y indicated i n the v i s i b l e region of the o p t i c a l spectrum: a broad peak at 620-680 nm 1 5 i s c h a r a c t e r i s t i c a l l y diagnostic of a TT-cation r a d i c a l . The absence of such a peak i n the o p t i c a l spectra of 9 and 10 supports the conclusions reached by NMR, and as the o p t i c a l spectra y i e l d no further information except f o r i d e n t i f i c a t i o n purposes, the data are presented i n Figure III.11 without discussion. C. Infrared and Resonance Raman Spectroscopy. The i n f r a r e d spectra of 9 and 10 are both d e f i c i e n t of a c h a r a c t e r i s t i c strong peak at 1520-70 cm"1 which i s t y p i c a l l y present i n OEP 7T-catibn r a d i c a l complexes. 1 6 Thus, the IR spectra of these compounds again support the conclusions from the NMR data. The assignment of the Ru-X bond frequency was investigated because no such halogen frequencies within por-phyrin systems have been reported to date. An assignment was attempted using FT-IR data but the presence of many bands due to water or carbon dioxide i n the far-IR region (some of 42 2.0 4 Figure III.11: The o p t i c a l spectrum of Ru(0EP)(X) 2 complexes in CH 2C1 2. (C = 2.50 xlO" 5 M, pathlength = 1.0 cm). 398 nra (log 6 = 4.90) 1.6 w i . 2 ca cc O I/) CO < 0.8 0.4 360 nm .(4.751 535 nm (4.16) 400 500 WAVELENGTH, nm 6 0 0 which may overlap with any legitimate signals present) made t h i s task i m p o s s i b l e . 1 7 There were no intense peaks i n t h i s region, suggesting that due to the centrosymmetric nature of these compounds, some bands may be present i n the resonance Raman spectra of 9 and 10. Using argon ion laser e x c i t a t i o n at 457.9 nm, a KBr matrix (1 mg sample/100 mg KBr) was found to give the Ru-Br bond frequency at 178 cm"1 (no observable isotope s p l i t t i n g ) and the Ru-Cl frequency at 2 89 cm"1 (again, no isotope s p l i t t i n g observed); both peaks ap-pear as intense, but broad bands (see Figures III.12 and III.13) and the c h a r a c t e r i s t i c 100 cm"1 separation between the bromide and chloride analogues was o b s e r v e d . 1 8 3 The resonance Raman spectra were measured by Dr. Laura Andersson (University of Oregon) to whom I am extremely g r a t e f u l . 1 8 b D. Mass Spectroscopy. A s u r p r i s i n g feature of the mass spectra of 9 and 10 i s that t h e i r most intense peaks are due to the Ru(OEP) unit, with no parent ion being observed; the dimeric [Ru(0EP)] 2 + and the monomeric Ru(OEP)"*" species give r i s e to the most i n -tense s i g n a l s . The only other peaks resulted from the usual fragmentation pattern of the ri n g (see Figure III.14). By mimicking the conditions of a mass spectrometer i n a laboratory experiment, i t was found that 9 and .10 could be converted back to the dimer (8) i n a quantitative y i e l d (see 44 Figure III.13: The Raman resonance spectrum of Ru(OEP)(Cl) 2 in a KBr matrix. (* denotes a matrix RR band). 672 cm" , porphyrin mode o> 289 cn" 1 ,HRu-Cl) WAVENUMBERS, cm I . N T E N S I T Y i f f • f * f 4 f Z f I f f • f t f 4 f Z f f I f f • f t f 4 f 2 f I f f • f t f 4 f Z f f .... ( R « < 0 E P » 2 + i i I i i i i i i i i i I i i i i i i i i i I i i i i i i i i i I i i i i "i i if r^ Mf4"'f'rSt' I I > I I I I I I I I I I I I I I r • I f S f I I f f I I S f I Z f f I Z S f I 3 f f I I S f I I I I I I I I | I I I I I 7 S f I I | I I I I I • f f I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I I | I I I I I I I I • 6 f » f f 9 6 f I f f f ( 3 4 Ru(OEP) + 5 8 9 . , i 11 i i i i [ i i i i i i i i i I i i | i i i i i t i i f | i " ! " . r ^ f V f r i f ^ T ^ ' r ^ h i - | ' i i ' i i i i i i i | 4 f f 4 E f 6 f f S S f t f f I I I I I | I I i S f 7 f f _ 5 2 79 Br (missing i n the c h l o r i d e analogue) H | l l . | J , |,i,l|i,,ill |ln,| , i , | " | 5 f I I i"T- | 't hM ? 'r i"T'i i' i " p i 'l N i i i i i | i i i i i i r f f I S f Z f f Z S f 3 1 7 I i r I 'I I I I I | I I I I I I 3 f f S S f MASS UNITS, m/e F i g u r e III.14: The mass spectrum of R u ( O E P ) ( B r ) 2 . (The c h l o r i d e analogue i s i d e n t i c a l except f o r peak a t 79 m/e). chapter IV). E. Magnetic S u s c e p t i b i l i t y and Electron Paramagnetic Resonance. The s o l u t i o n magnetic s u s c e p t i b i l i t i e s of 9 and 10 were 2.5 and 2.6 B.M., respectively, and were estimated using Xm , the molar s u s c e p t i b i l i t y , 1 9 which was obtained by Evans' method 2 0 (B.M. «= 9.27xl0" 2 4 J T" 1) : 50 uL of a 5% t-butyl alcohol i n CH 2C1 2 solution were added to a long melt-ing point sample tube. 2 or 10 (1-2 mg) and the 5% t-butyl alcohol so l u t i o n (500 pL) were then added to an NMR sample tube and the melting point tube was placed c o - a x i a l l y i n s i d e . The 1H NMR spectrum was obtained immediately, and the separation of the two 1H NMR resonances f o r t-butyl a l -cohol (in two d i f f e r e n t environments) was measured ( t y p i c a l l y 7-9 H z ) . Xg (gram s u s c e p t i b i l i t y ) was c a l c u l a t e d . 2 0 Diamagnetic corrections were made using Pascal's c o n s t a n t s , 2 1 and the r e s u l t i n g s u s c e p t i b i l i t e s were within experimental error of the spin-only value of 2.83 B.M. for an S=l s y s t e m . 2 2 , 2 3 No EPR signals of 9 and 10 at e i t h e r ambient or 77 K in 1:1 toluene:dichloromethane were observed. There are several p o s s i b l e reasons f o r t h i s : the short relaxation tir.es discussed e a r l i e r for the protons would lead to the broaden-48 i n g of any s i g n a l ; secondly, the t r i p l e t s t a t e S=l has z e r o -f i e l d s p l i t t i n g 2 4 which can cause s i g n a l s t o be obscured; l a s t l y , the u n p a i r e d s p i n s can couple with each o t h e r , g i v i n g r i s e t o s p i n - s p i n i n t e r a c t i o n s which can cause a s i g n a l t o be b r o a d e n e d . 2 5 The EPR s p e c t r a of these compounds would have shown t h e presence of a sharp s i g n a l a t g=2.00 i f a 7 T ~ c a t i o n r a d i c a l were p r e s e n t . S e c t i o n I I I . 2 ; A n a l y s i s of the Data f o r R u 1 1 1 f O E P W S b F e ) (THF)  11. A. NMR Spectroscopy. The *H NMR spectrum of Ru(OEP)(SbF 6)(THF), H , d i f f e r s from t h a t of 9 and 10 i n two ways: H has two CH 2 peaks, e a c h i n t e g r a t i n g t o e i g h t protons, showing t h a t no m i r r o r symmetry ( i e . no m i r r o r plane of symmetry) i s p r e s e n t whereas 9 and 10 have such symmetry and e x h i b i t o n l y one CH 2 peak. Secondly, the spectrum of H i s s o l v e n t dependent whereas s p e c t r a of the p r e v i o u s complexes show l i t t l e s o l v e n t dependence. S p e c t r a of H i n CH 3CN-d 3 or MeOH-d4 appear c o m p l i c a t e d with many meso-H peaks s u g g e s t i n g t h a t the S b F 6 u n i t and/or THF can be e a s i l y d i s p l a c e d by s t r o n g l y coor-d i n a t i n g s o l v e n t s . Because of s o l u b i l i t y problems, the 49 measurement of the NMR spectrum of i i i s r e s t r i c t e d to using CDCI3 or polar coordinating solvents; thus, the *H NMR spectrum in CDCI3 i s shown i n Figure III.15. The CH 3 resonance has not s h i f t e d greatly from i t s diamagnetic p o s i t i o n of 2.03 ppm whereas the meso-H and CH 2 peaks have s h i f t e d greatly from t h e i r diamagnetic positions. The meso-H peak has s h i f t e d from 9.74 to 6.25 ppm and the CH 2 peaks are at 3.80 and 17.5 ppm compared to the diamagnetic p o s i t i o n of 3.97 ppm. The presence of two CH 2 peaks and t h e i r p o s i t i o n indicates that the e l e c t r o n i c environment on one side of the porphyrin plane i s d i f f e r e n t from the other side of the porphyrin plane, with one CH 2 peak close to the normal diamagnetic p o s i t i o n of 3.97 ppm. This type of 1H NMR i s s i m i l a r to that of the dimer [Ru(OEP)] 2, (which has two CH 2 resonances;one at 26.1 ppm, the other at 11.2 ppm) and also to that of Ru I I I(0EP) (PPh 3)(Br) (having two CH 2 resonances at 8.8 and 18.5 ppm). 2 7 The separation between the two CH 2 peaks (about 10-15 ppm) i n the l a s t two cases have been ascribed to differences i n metal-porphyrin charge transfer at each CH 2 proton s i t e and a s i m i l a r e f f e c t i s postulated for 11. The assignment of the *H spectra of i i was made using experiments as discussed i n the previous NMR section ( I I I . l . A ) . A s i m i l a r c o r r e l a t i o n between T^'s and r (the metal-to-proton distance) , as observed for 9 and l f j , was found for H (see Table III.4 and Figure III.16), with the exception that for i i , the CH 2 resonance at 17.5 ppm has a 50 Figure III.15: The *H NMR spectrum of Ru(OEP)(SbF 6)(THF) i n CDC13, 300 MHZ anaerobic sample at 19 °C. CDC1. CH, CH. H2o H CH. THF i i i i i i i i i i i i i i i i i i | > i i i | i i i i i i i i i i i i i i i i i i i I i i i i i » i i i j i i IB IB 14 12 10 a ll I I I I I j I I I I I I I I I j I I I I I ' ' ' ' j ' ' ' ' I ' ' ' 1 j ' ' ' ' I / longer relaxation time than the CH 2 protons at 3.8 0 ppm. Since the relaxation, by d e f i n i t i o n , r e f e r s to the rela x a t i o n of a spin with the help of the surrounding l a t t i c e of solvent and other molecules present, the relaxat i o n monitored by the CH 2 protons at 17.5 ppm must be slower than the relax a t i o n for the other CH 2 protons at 3.80 ppm.9 The reason for t h i s difference i n relaxation rates i s not apparent; although, presuming that the dipo l a r relaxation i s s t i l l dominant, the r vector must be shorter f o r the faster relaxing protons as a consequence of the T^'s dependence on r ~ 6 . The presence of an out-of-the-plane Ru would account f o r t h i s shortening of the r m p vector (both the [Ru(OEP)] 2 dimer and Ru I I I(OEP) (PPh 3)(Br) have an out-of-the-plane ruthenium). The use of T 1 experiments to assign a 1H NMR spectrum does not always lead to an unambiguous so l u t i o n ; f o r example, i n t h i s case, the T^ data cannot be used to d i s t i n -guish which CH 2 resonance originates from which side of the porphyrin plane (the SbFg side vs the THF s i d e ) . In such cases, deuterium l a b e l l i n g i s needed for a complete assignment. The p l o t of the i s o t r o p i c s h i f t vs T - 1 gave a str a i g h t l i n e , i n d i c a t i n g that only one spin state i s occupied over the temperature range studied (-50 to +50 °C i n CDC13, see Table III.5 and Figure III.17). The high temperature ex-trapolations to T_1->-0 of the i s o t r o p i c s h i f t s gave values within experimental error (+ 5 ppm) of 0 ppm for a l l the 52 Table III.4: T x Data for Ru (OEP)(SbFg)(THF).— Interpulse CH 2(17.5 ppm) CH 2(3.80 ppm) 1^ CH 3 D3 (ms) Intensi t y - Intensity— Intensity— I n t e n s i t y -OxlO" 1 -91.0 -24.7 -29.7 -209 1.0 -93.0 -20.2 -34.0 -222 4.0 -75.1 -8.00 -30.4 -187 8.0 -48.3 18.2 -20.4 -128 20 4.25 37.0 10.3 -14.0 50 62.0 46.0 14.5 159 80 85.4 47.2 19.9 243 100 93.6 46.0 24.0 272 300 104 61.0 55.4 337 500 103 61.1 55.0 336 (ms)S 34.2 10.3 9.3 44.7 — i n CDCI3 at 19°C (anaerobic sample). — peak height i n an a r b i t r a r y scale. — obtained from a computer-aided c u r v e - f i t t e d p l o t of signal i n t e n s i t y vs. interpulse delay u t i l i s i n g the data supplied above. 53 Figure III.16: Plot of the signal i n t e n s i t y vs. interpulse delay to cal c u l a t e T, values. 54 resonances except that of the H m. The -CH2 and -CH3 data obtained from the Curie plots obeyed the Curie Law within the temperature range studied i n d i c a t i n g that only a single ground state i s populated. The 1 9 F NMR spectrum of H (CDC13, anaerobic) shown in Figure i l l . 1 8 has a lineshape and p o s i t i o n v a s t l y d i f f e r e n t from that of free KSbFg in Freon-11. Free SbF g~ appears as a broad resonance (+ 10 ppm) centered at -119 ppm r e l a t i v e t o Freon-11 2 8;thus, t h i s r e s u l t indicates that the SbF 6 i s coor-dinated (11 i s also a non-electrolyte i n CHC13) and not f r e e as i s suggested by the IR data discussed i n section III.2.E. B.EPR Spectroscopy. The EPR spectrum of l i i s c h a r a c t e r i s t i c of a complex with mirror symmetry (X=YfZ), since one sees two signals: (g ) and ( g ^ ) . 2 9 The spectrum i s shown i n Figure III.19 and was obtained using X-band microwave frequency r a d i a t i o n (9.11 GHz) at 10 mW microwave power and a d i l u t e 1:1 (THF:toluene) solution of H under anaerobic conditions. No signal was ob-served at room temperature but at -196°C (77°K), an intense signal was observed with g at 2530 + 20 G (g=2.8 + 0.1) and g^ at 2950 + 20 G (g=2.3 + 0.1) with no hyperfine s p l i t t i n g s . This spectrum and i t s lineshape are s i m i l a r to that of other Ru I I I(0EP) complexes. 2 7 1 3 The a l t e r n a t i v e , possible formula-55 Table III.5: Data for the Curie Plot of the Isotropic s h i f t vs.Inverse Temperature for 11. shift(CH 3) s h i f t ( H m ) T. °C- T'^-fxlO 3 K"1) obs|/corr? obsj/corr--50 4.48 1.31/-0.72 9.31/-0.43 -30 4.12 1.35/-0.68 8.52/-1.22 -10 3.80 1.41/-0.62 7.64/-2.10 10 3.53 1.35/-0.68 6.96/-2.78 30 3.30 1.42/-0.61 6.47/-3.27 50 3.10 1.43/-0.60 6.07/-3.67 shift(CH 2,17ppm) shift(CH 2,3ppm) obs^/corr- obs^/corr--50 4.48 20.6/16.6 3.41/-0.59 -30 4.12 19.7/15.7 3.53/-0.47 -10 3.80 18.7/14.7 3.71/-0.29 10 3.53 17.8/13.8 3.67/-0.33 30 3.30 17.1/13.1 3.74/-0.26 50 3.10 16.6/12.6 3.75/-0.25 - temperature deviation + 0.5 °C. - obtained i n CDC13, aerobic sample. - diamagnetic correction (Ru 1 1(OEP)(py) 2,c 6D 6, anaerobic): CH3=2.03, CH2=3.97, 1^=9.74 ppm. 56 16 c-it o t o o O CH. CH, 2.0 _j 4.0 3 _j T , ( x 10 K ) 6.0 Figure III.17: Curie Plot for Ru(OEP)(SbF 6)(THF) in the temperature range -50 to +50 C. 57 Figure III.18: The 1 9 F NMR spectrum of Ru(OEP)(SbF 6)(THF), 11,in CDCI3 (obtained at 19 °C at 300 MHz using an anaerobic sample). Figure III.19: The EPR spectrum of Ru(OEP)(SbF6)(THF) in 1:1 THF:toluene (anaerobic) at -196 °C. (9.11 GHz X-band radiation at 10 mW microwave power). t i o n of H as a Ru 1 1(OEP)(SbFg)(THF) cation r a d i c a l complex i s ruled out. Such a r a d i c a l complex would behave from an EPR point of view as an i s o l a t e d organic r a d i c a l which gives r i s e to a sharp signal at g = 2.0 ( 3200 G ). C. Optical Spectra. As discussed i n a previous section ( I I I . l . B ) , the o p t i -c a l spectrum of a cation r a d i c a l i s d i s t i n c t i v e and, since H does not show t h i s c h a r a c t e r i s t i c absorption, a TT-cation r a d i c a l formulation i s ruled out. The o p t i c a l spectrum of 11 i s shown i n Figure III.20. D. Kass Spectroscopy. The usual Ru(OEP) peaks were observed i n the MS along with the peaks for the SbF 6 u n i t . In fact, the fragmentation pattern SbF 3 +, SbF 2 +, and SbF + (178, 159, 140 m/e respectively) i s r e a d i l y observed (see Figure III.21) but the parent SbFg* i s not present, i n d i c a t i n g that the SbFg unit might be thermally decomposed. No parent peak for the complex was present and the THF was the f i r s t fragment observed at m/e of 71. 60 503 534 T—r T—r T1" 625 ~[—r T—i—r I 1 1 1 675 700 T — r -j—i—i—i—r 500 T—i—i—r 62S T - T - r - r - r 550 675 r~r~ t 0 0 >i0 428 4 0 7 275 ~i *~t—i—i—i—i—i—i—i—r 275 300 ,79 T — | — 1 — 1 — I 1—|—I—I 1—I—| 1 1—I—I—| 1—I—I 1 f - i — i — i — i — i — i — i — i — I — i — r r 326 350 376 159 S b F . 52 I' f l Jl S b F 21 VI40 -r^T—r**-j—i—i—i •!••[—i—r 100 126 400 177 425 450 475 SbF3 ,,„ 212 i , 227 | I ' T i 'i |'"I i i'T"| i I T I | i l i i | i 150 176 200 225 250 MASS UNITS, m/e i—i—r 50 75 F i g u r e I I I . 2 1 : Mass spectrum o f Ru(OEP)(SbF 6)(THF). E.Infrared Spectroscopy. The t y p i c a l 7 T-cation r a d i c a l peak for OEP i s not present in the spectrum of 2 2 , showing again that the cation r a d i c a l formulation i s inappropriate. Based on data for other ji-fluoro metal-SbF 6 compounds, 3 0 the band at 650 cm"1 (Figure III.22) i s assigned to ^(sb-F)* T ^ i s stretching frequency appears to be sharp (and not broad as would be expected for a bridging SbF 6), and i s i n the correct area f o r an i o n i c SbF 6 complex. The IR data indicates t h a t the SbF 6 i s uncoordinated, 3 1 and i s in c o n f l i c t with the 1 9 F NMR, 1H NMR, and conductivity data. These differences i n data may be due to the SbFg being 30 weakly coordinated . 63 Figure III.22: The infrared spectrum of Ru(OEP)(SbF 6)(THF) in a Nujol mull. • J ^ ^ - f - J — ! — « 1 • H 1 1 » — - 4 -1458.7 127Q. 1 l l O l . S 023. OS 740. 38 500.70 301. lO 213 WAVENUMBERS <CM-1> References. 1. Pople,J.A.;Schneider,W.G.;Bernstein,H.J..High Resolution  Nuclear Magnetic Resonance.McGraw-Hill,New York,1959,p.103. 2. Ballhausen,C.J..Introduction to Ligand F i e l d Theory. McGraw-Hill,New York,1962. 3. LaMar,G.N.;Walker,F.A..The Porphyrins.Vol IV,D.Dolphin,Ed., Academic Press,New York,1979,p.61. 4. Jesson,J.P..NMR of Paramagnetic Molecules:Principles and  Applications;G.N.LaMar.Ed..Academic Press,New York, 1973, p.2. 5. Reference 3, p. 67. 6. Adapted from:Antipas,A.;Buchler,J.W.;Gouterman,M.;Smith,P. D.,J.Am.Chem.Soc.,100,3015(1978). 7. Goff,H.;LaMar,G.N.;Reed,C.A.,J.Am.Chem.Soc.,99,3641(1977). 8. Reference 3, pp.74. 9.Swift,T.J..NMR of Paramagnetic Molecules:Principles and  Applications;G.N.LaMar.Ed..Academic Press,New York, 1973, p. 53. 10. Patt,S.,Varian XL-300 NMR Advanced Operations  Manual.Version 4.1,Varian Associates,Palo Alto,1984. 11. Earnshaw,A..Introduction to Magnetochemistrv.Academic Press,London,1968. 12. LaMar,G.N..NMR of Paramagnetic Molecules:Principles and  Appli cat ions;G.N.LaMar,Ed.,Academic Press,New York, 1973. 13. Hoard,J.L..Hemes and Hemoproteins.R.Chance,Ed.,Academic 65 Press,New York,1966. 14. Morishima,I.;Shiro,Y.;Takamuki,Y.,J.Am.Chem.Soc.,106, 7666 (1984). 15. Barley,M.;Becker,J.Y.;Domazetis,G.;Dolphin,D.;James,B.R., J.Chem.Soc.,Chem.Commun.,19,982(1981). 16.Shimomura,E.T.;Phillippi,M.A.;Goff,H.M.;Scholz,W.F.; Reed,C.A.,J.Am.Chem.Soc..103.6778(1981). 17.Banwell,C.N..Fundamentals of Molecular Spectroscopy.2— Ed.,McGraw-Hill Books,Maidenhead,1972,p.112. 18(a).Maslowsky,E.,Jr..Vibrational Spectra of Organometallic Compounds.Wiley-Interscience,New York,1977,(b).Andersson, L., personal communication. 19. Cotton,F.A.;Wilkinson,G..Advanced Inorganic Chemistry:A  Comprehensive T e x t . 4 — Ed.,Interscience Publishers,New York,1966,p.540. 20. Evans,D.F., J.Chem.Soc.,1959,2003. 21. Reference 11, p . 6. 22.Ibid., p . 35. 23. Mulay,L.N.,Anal.Chem.,34,343(1962). 24. Wertz,J.E.;Bolton,J.R..Electron Spin Resonance:Elemental  Theory and Applications;McGraw-Hill Book Co.,New York, 1972,p.227. 25.Ibid.,p. 241. 26.Walling.C..Free Radicals in Solution.Wiley and Sons,New York,1957. 27(a).Collman,J.P.,.Barnes,C.E.;Swepston,P.W.;Ibers,J.A.;J. 66 Am.Chem.Soc..106.3500(1984),(b)James,B.R.;Dolphin,D.; Leung,T.W.;Einstein,F.W.B.;Willis,A.C.,Can.J.Chem.,62, 1238(1984). 28. Wray,V.,Annual Reports on NMR Spectroscopy,G.A.Webb, E d i t o r , V o l 10b,Academic Press,New York,1980. 29. Palmer,G.,Biochem.Soc.Trans.,13,548(1985). 30.Shelly,K.;Bartczak,T.;Scheidt,W.R.;Reed,C.A.,Inorg.Chem., 34/4325(1985). 31. Qureshi, A.M. ; Hardin, A. H. ; Aubke, F. , Can. J . Chem. ,49.,816(1971) . 67 Chapter IV: The Chemistry of the RvpMOEP) complexes 9 and 10. The oxidation of 9 and 10 i n CH 2C1 2 at room temperature using e i t h e r mCPBA or PhIO displayed two trends: at low oxidant to porphyrin r a t i o s (<10:1), no reaction was observed (the resonance f o r free oxidant could be e a s i l y observed using *H NMR) and t h i s behaviour was independent of reaction time or rate of s t i r r i n g . At higher r a t i o s of oxidant to por-phyrin (>15:1), these same conditions resulted i n bleached solutions with concomitant loss of the porphyrin's NMR resonances and o p t i c a l spectra. Clearly, the macrocycle was being destroyed by the oxidants, and the same r e a c t i v i t y was observed f o r two-phase reactions using H 20 2 or t e r t i a r y -butylhydroperoxide i n aqueous media as oxidants. The attempted oxidation of cyclohexene i n CH 2C1 2 (0.1 M) using excess (>20x) mCPBA or PhIO i n the presence of 9 or 10 ( l x l O - 3 M) at 19 °C d i d not r e s u l t i n any oxidised cyclohexene products (as tested by GC), and the macrocycle was s t i l l destroyed. Regrettably, 9_ and JLO do not e x h i b i t any a b i l i t y to catalyse the oxidation of t h i s organic substrate. Solutions of 9 and 10 i n CH 2C1 2 ( l x l O - 3 M) were unaf-fected i n the l i g h t or dark when exposed to a i r . They were also unchanged i n the presence of trace amounts of water but the species were hydrolysed to the u-oxo dimers [Ru(OEP)X] 20 (X=Br or OH) i n excess water (xlOO) as studied by 1H NMR ( s e e 68 Appendix A.I). Exposure to f i v e atmospheres of pure 0 2 or N 20 for two days also resulted i n unreacted solutions of 9 and JLO (again, l x l O " 3 M). Thus, these complexes are i n e r t toward oxidants tested to date. Heating anaerobic NMR samples ( C D C I 3 , l x l O " 4 M) at 100 °C for two hours under l i g h t or dark conditions led to the thermal decomposition of the compounds. The reaction of 9 and 10 (lxlO"" 3 M) with excess sodium d i t h i o n i t e ( Na 2S 2 0 4 ) i n CH 2 C1 2 or with excess sodium borohydride (NaBH4) i n THF led to the rapid formation of Ru 1 1(OEP)(CO) as judged by the 1H NMR spectrum (see Appendix A . I I . l ) . The source of CO for these reactions i s unknown but carbonyl formation i s frequently encountered during experimentation. Solutions of 9 and 10 i n CH 2 C1 2 ( l x l O - 4 M), exposed to one atm of H 2 f o r 12 hours showed no reac-t i v i t y towards dihydrogen, as monitored by v i s i b l e spectroscopy. The presence of the peak for the [Ru(OEP)] 2 dimer i n the mass spectra of 9 and 1 0 indicated that the complexes were being reduced i n the mass spectrometer. By heating these com-pounds (7 mg) i n an anaerobic NMR tube at 200°C and l x l O - 5 t o r r vacuum fo r one hour, the dimer was q u a n t i t a t i v e l y regenerated. The 1H NMR of the pyrolysed product did not have any resonances due to the s t a r t i n g material and only one H m resonance was observed (for the dimer). Although the p r e s s u r e i n the vacuum l i n e did increase during continued pumping (i n d i c a t i n g that a v o l a t i l e material was evolved), the 69 v o l a t i l e has not yet been i d e n t i f i e d . The most l i k e l y pos-s i b i l i t y i s halogen production v i a a r a d i c a l process: l x l 0 ~ 5 t o r r , 2h Ru I V(OEP) (X) 2 • 1/2 [Ru I : E(OEP)] 2 + 2 X*radicals 200°C X 2 The above findings lead one to guestion the o r i g i n of the oxidant f o r the reverse R u 1^—»Ru I V preparative reaction. Using stoicheiometric amounts of B r 2 as the oxidant d i d lead to the R u I V products but with side-products which made p u r i f i c a t i o n d i f f i c u l t . Chromatography under e i t h e r anaerobic or aerobic conditions, using eit h e r alumina or s i l i c a gel ( a c t i v i t y I->-IV) with a v a r i e t y of solvent systems (MeOH: CH 2 C1 2 or neat CH3CN or neat MeOH), always resulted i n decom-posed products. Using excess H X(g)» considered to contain trace amounts of X 2 ( g ) ' 1 ( P u r e * anhydrous HX^gj should be colourless but the gases obtained from suppliers have a f a i n t yellow color) gave clean samples of £ and 1 0 ; indeed, using excess HF(g) to oxidise the dimer did not give the analogous Ru I V(OEP)(F)2 complex because HF^gj does not have any ^2 (g) as a trace impurity. 2 Another possible oxidant f o r the R u I I - » R u I V oxidation was thought to be HX^gj i t s e l f . Gaseous HX could possibly oxidise the [ R u I I ( 0 E P ) ] 2 dimer, consequently forming the R u I V ( 0 E P ) ( X ) 2 compounds and 70 dihydrogen (H 2): anaerobic conditions 4 HX ( g ) + [Ru I 3 :(OEP)] 2 • E» 2 H2 (g) + 2 R u I V ( O E P ) ( X ) 2 Several attempts were made to detect H 2 using the following procedure: i n an i n e r t atmosphere glove box, 2 0 mg of the [Ru(OEP)] 2 dimer was loaded into an anaerobic f l a s k with a side arm septum port (2 mL volume) s i m i l a r to that shown i n figure II.3. A saturated solution of HX^ gj i n CH 2C1 2 (1 mL) was vacuum transferred into the f l a s k containing the dimer and the r e s u l t i n g solution was thawed to allow the reagents to react. Upon refreezing to 77°K to trap out the excess HX^gj and solvent, a 1 mL sample of the vapor phase was withdrawn using a gastight syringe and injected d i r e c t l y into the GC. The formation of ^2(g) c o u l d n o t b e detected by gas chromatography (Carle GC: 6' Porapak Q column, 25°C oven temperature, 20 mL/min gas flow, 1 mL gas samples). I f , ac c i d e n t a l l y , the reaction i s exposed to the a i r before the reagents have had s u f f i c i e n t time to react (about 5 minutes), the corresponding u-oxo dimer [Ru(0EP)X] 20 i s formed. The most l i k e l y source of the oxidant i n the preparative reaction i s trace halogen i n gaseous hydrogen halide. In an attempt to prepare Ru I V(0EP)(X') 2 (X'= SbF 6), two equivalents of s i l v e r hexafluoroantimonate(V) (AgSbFg, 4 mg,0.01 mmoles), and 9 or 10 (4 mg,0.005 mmoles), were reacted i n CDC13 i n an NMR tube and the 1H spectrum of the 71 reaction mixture was obtained immediately. The f a m i l i a r NMR resonances for 9 and 10 were not present i n the spectrum of the reaction mixture and only one porphyrin product (that i s , only one H m resonance) was observed. Further spectroscopic analysis of the new product (11), along with microanalysis, indicated that i t was a R u 1 1 1 complex with only one SbFg unit per ruthenium. This r e s u l t i s s u r p r i s i n g because i t indicates that e i t h e r Ru I V- has oxidised Ag 1 to A g 1 1 , thereby generating a R u 1 1 1 product (the Ag I/Ag 1 1 reduction p o t e n t i a l i s near -2 V ) , 3 or that s i l v e r a s s i s t s the homolytic cleavage of the Ru-X bond (giving R u 1 1 1 and X» r a d i c a l s ) . In l i g h t of the very high energy needed to oxidise Ag 1, the l a t t e r reason i s most l i k e l y the cause of the reduction of ruthenium to R u 1 1 1 . The exact mechanism i s unknown as yet and more work i s needed i n t h i s area to v e r i f y the mechanism. 72 References l.Sharpe,A.G..Halogen Chemistry.V. Gutmann,Ed.,Vol.1,Acedemic Press,New York,1967,pp.1-67. 2.Simons,J.H..Inorg. Synth..H.S.Booth.Ed.,Vol.1,McGraw-Hill,New York,1939,p.135. 3.CRC Handbook of Chemistry and Physics,R.C.Weast.Ed.,63— ed.,CRC Press,Boca Raton,1982,pp. D-162-7. 73 C h a p t e r V : C o n c l u s i o n s and S u g g e s t i o n s for F u t u r e S t u d i e s . The addition of HX ( gj to the [Ru I I(OEP)] 2 dimer r e s u l t s in the formation of highly oxidised, novel complexes of Ru I v. A l l the data obtained to date indicate consistently that these compounds are Ru I V(OEP)(X) 2 (9=Br,10=C1) complexes with a t r i p l e t state, intermediate spin ground state e l e c t r o n i c configuration, and are the f i r s t such ruthenium porphyrins reported. The alternate R u 1 1 1 7T-cation r a d i c a l formulation i s ruled out, and the f i r s t Ru-X IR/RR bond stretching frequencies (KBr p e l l e t s ) have been assigned i n Ru porphyrins (X=Br,179 cm"1;X=C1,289 cm - 1). An analysis of the relationship between metal-axial ligand/metal-porphyrin bonding, and the corresponding 1H NMR spectrum has been attempted. The halide i s predicted to be a weak7T-donor (p7T-d7T donation) to the metal, and consequently, the Ru-porphyrin bonding i s also a ligand-to metal charge transfer (instead of metal-to-ligand back-donation). The i s o t r o p i c s h i f t i s mainly due to contact contributions but di p o l a r relaxation i s the dominant relaxa-t i o n mechanism. The oxidant,responsible for the R u 1 1 to R u I V oxidation i s trace *2(g) * n H x ( g ) a n d * s n o t e i t n e r t n e H X i t s e l f or a i r / 0 2 . Both 2 and i O appear to be e a s i l y reduced by common reducing agents but are ox i d a t i v e l y i n e r t and do not have the a b i l i t y to catalyse the oxidation of cyclohexene in the presence of monooxygen sources such as mCPBA or Phio. S i m i l a r l y , i i i s formulated to be Ru 1 1 1(OEP)(SbF 6)(THF) 74 rather than a R u 1 1 TT-cation r a d i c a l . As with other M(porp) SbF 6 complexes, a j i - f l u o r o bridged Ru-F-SbF 5 type of struc-ture i s favored with Vsb-F " 6 5 0 cm _ 1(Kujol). The e l e c t r o n i c configuration i s that of a R u 1 1 1 , d 5 low spin (S=l /2) complex. The above compounds (9-11) are excellent precursors f o r further study i n high oxidation state Ru porphyrin chemistry because of t h e i r ease of preparation and inherent s t a b i l i t y . One example of t h i s i s the s u b s t i t u t i o n of the a l k y l s i n place of the halides to form the corresponding Ru(OEP)(R) 2 compounds (R=CH 3,phenyl,C 2H 5). 1 Also,the s u b s t i t u t i o n of an halide f o r the SbF 6 unit may form a R u 1 1 1 (porp) (X) complex » and t h i s complex would be an excellent precursor (as 11 may be) f o r studying the c a t a l y t i c oxidation of organic substrates as discussed i n the Introduction. References 1. Sishta,C.;Ke,K.;James,B.R.;Dolphin,D.,J.Chem.Soc.,Chem. Commun.,787(1986). 75 Appendix I:The Oxidation Chemistry of Ru 1- 1 1 (OEP)(PPh 3) (Br) . 5 . The o r i g i n a l method developed by Leung 1 f o r the syn-the s i s of an oxo complex involved s t i r r i n g 5 (100 mg,0.1 mmoles) and mCPBA (100 mg,0.6 mmoles) i n dry, degassed CH 2C1 2 f o r t h i r t y minutes under argon. A green product was then p r e c i p i t a t e d by adding cold hexanes, f i l t e r e d and dried under vacuum. Based on v i s i b l e and ESR spectra, Leung et a l . sug-gested a [0=Ru I V(OEP+.)]Br formulation. 2 Following h i s procedure, a brown powder was obtained which was analysed by spectroscopic techniques. The v i s i b l e spectrum of the brown product (12.) was broad and d i f f u s e ( A m a x = 3 8 4 (log 6 =4.80),502(3.73),and 604(3.62) nm); the mass spectrum displayed peaks f o r only 0=PPh3 (278m/e), and the correspond-ing i n f r a r e d band f o r Uo=p w a s present at 1190 cm - 1. 3 The 1 H NMR spectrum of 12, had two resonances at 7.15 and 7.58 ppm for the 0=PPh3 protons and three proton signals at 9.35, 4.1-4.4, 1.85 ppm (for - 1 ^ , -CH2 (two s i g n a l s ) , and -CH3 respectively) f o r OEP. The %N obtained from microanalysis was very low, and was consistent with the other data which sug-gested contamination of 12 with 0=PPh3. Chromatography was attempted i n order to separate the 0=PPh3 from the porphyrin residue, using e i t h e r s i l i c a gel or alumina ( a c t i v i t y I-IV) and elu t i n g with a CH2Cl2/MeOH s o l -vent system. The NMR spectrum of the CH2Cl2/MeOH (1/25) eluate indicated that two species were present: 0=PPh3 and a 76 diamagnetic porphyrin complex with the same chemical s h i f t s as 12. This solvent system was the only one found to elute a l l of the porphyrin product; unfortunately, i t co-elutes the phosphine oxide. The 1H NMR and v i s i b l e spectra of 12. were i d e n t i c a l to those of the ji-oxo dimer [Ru(OEP)Cl] 2° reported by Collman (see Figures Al.1 and AI.2). 4 A room temperature t i t r a t i o n of 5 ( l x l 0 ~ 4 MJ i n CgD6 with one-electron equivalent aliquots of mCPBA i n C 6D 6 (the reaction being followed by NMR) showed that a small amount (<5%) of a second porphyrin compound was formed upon addition of more than ten equivalents of mCPBA. That t h i s minor product i s not present i n samples which have aged or been p u r i f i e d by chromatography i s s i g n i f i c a n t . Indeed, the same t i t r a t i o n c a r r i e d out at -60 °C gave a better y i e l d (10%) of the minor product as judged by NMR. Due to the complexity of the p u r i f i c a t i o n procedure, and the low y i e l d s for the minor product, a new precursor which had no oxidisable a x i a l ligands was sought. A NMR t i t r a t i o n s i m i l a r to that done f o r 5 was attempted for Ru 1 1(OEP)(CH 3CN) 2 (2) to te s t whether a R u 1 1 1 precursor was r e a l l y needed to study higher oxidation states of Ru. At eit h e r 19 °C or -60 °C, a t i t r a t i o n of 1 ( l x l O " 4 M) with mCPBA i n C 6D 6 and CD 2C1 2 (done i n a septum-capped NMR tube) led to the quantitative formation of the p-oxo dimer [Ru(OEP)X] 20. Because the R u I V J J - O X O dimers are diamagnetic, the s h i f t s due to the three sets of OEP protons w i l l not v a r y 77 Figure A.I.I: The 1H NMR spectrum of [Ru(OEP) (X) ] 20 i n C 6D 6, 300 MHz aerobic sample at 19 °C. (Note: the XH NMR spectrum of 12 i s i d e n t i c a l to that of the spectrum below with the exception that no mCPBA peaks are present.) CO — " — « — 1——. 1— 3 0 0 *oo 5 0 0 b 0 0 WAVULCWTTH. i w greatly as d i f f e r e n t anionic ligands are substituted, and the presence of the d i s t i n c t i v e -^H NMR pattern 9.80,4.20-3.80(two se t s ) , and 1.90 ppm (-JL^, -CH2, and -CH3, respectively) i s representative of these bridged dimers. Thus, i t i s apparent that a precursor which can be e a s i l y oxidised by oxygen-free reagents (to avoid ja-oxo dimer formation) would greatly a i d the synthesis of high oxidation complexes of Ru. References. 1.Leung,T.W., personal communication. 2(a).Dolphin,D.;James,B.R.;Leung,T.W.,Inorg.Chim.Acta,79,25 (1983),(b)Leung,T.W.;James,B.R.;Dolphin,D.,Inorg.Chim.Acta, 29,180(1983). 3. Moyer,B.A.;Sipe,B.K.;Meyer,T.J.,Inorg.Chem.,10,1475(1981). 4. Collman,J.P.;Barnes,C.E.;Brothers,P.J.;Collins,T.J.;0zawa, T.;Gallucci,J.A.;Ibers,J.A.,J.Am.Chem.Soc.,106,5151(1984). 80 Appendix.II: Tabulation of Spectroscopic Data f o r Ru  Porphyrin complexes. Table A . I I . l : Tabulation of -"-H NMR Data. RufOEP) fL) fL') CH^ CH 3 a x i a l liaand L^EtOJ^L^CO, 3- 2 9.74 (S) 4.00(q) 2.03(t) L=L»=PPh 3,^ 2 9.16 (S) 4.20(q) 1.70(t) e L=vacent,L•=PPh3 ,- 4 9.50 (S) 3.92(q) 2.02(t) f L=Br,L'=PPh3,^ 5 9.90 (S) 8.85,18.5(m) 0.53(br) g L=L'=py,^ 6 9.74 (S) 3.97(q) 2.03(t) h L=L'=CH3CN,fe 7 9.96 (S) 3.98(q) 1.95(t) -2 .70,CH3CN Dimer,^ 8 10.2 (S ) 11.2,26.1(111) 3.52(t) L=L'=Br,— 9 3.50(br) 60.1(br) 7.10(br) L=L'=C1,^ 10 8.20(br) 59.7(br) 6.34(br) L=THF,L'=SbFg,— 11 6.24(br) 17.5,3.80(br) 1.89(br) i^ — C 6D 6(7.15 ppm), aerobic sample. — CgDg(7.18 ppm), anaerobic sample. — CDC13(7.25 ppm), aerobic sample. — CDC13(7.25 ppm), anaerobic sample. — phenyl resonances:4.20(d),o-H;6.2-6.8(m),m-,p-H. — phenyl resonances:4.45(m),o-H;6.45(m),m-H;6.68(d),p-H. 3 phenyl resonances:2.72(m),p-H;14.6-14.8,o-,m-H. — pyridine resonances:2.26(d),m-H;4.17(m),o-H;4.33(d),p-H. — THF resonances:2.00,-1.05. 81 Table A.II.2: Tabulation of Resonance Raman/Infrared Data. compound frequency(cm - 1) assignment,"}) Ru 3(CO) 1 2, 1 2058 , 2020,1995 C=0 Ru(OEP)(CO)(EtOH), 2 1922 C=0 Ru(OEP)(CH 3CN) 2, 2 2260 C=N RU(OEP)(Br) 2, 9_ 179 Ru-Br Ru(OEP)(Cl) 2, I Q 289 Ru-Cl Ru(OEP)(THF)(SbF 6), H 650 Sb-F 82 

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