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UBC Theses and Dissertations

Synthesis, characterization, and reactivity with dioxygen, of Ru(OEP)(DPS)₂ and Ru(OEP)(DecMS)₂ [OEP=… Pacheco-Olivella, Arsenio Andrew 1986

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SYNTHESIS, CHARACTERIZATION, AND REACTIVITY WITH DIOXYGEN, OF Ru(OEP)(DPS)2 AND Ru(OEP)(DecMS)2 [OEP= dianion of octaethylporphyrin; DPS= diphenylsulphide; DecMS= decylmethylsulphide] by ARSENIO ANDREW PACHECO-OLIVELLA B.Sc, The University of B r i t i s h Columbia, 1982 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (department of Chemistry) We accept t h i s t h e s i s as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA OCTOBER 1986 © Arsenio Andrew Pacheco-Olivella, 1986. In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department The University of British Columbia 1956 Main Mall Vancouver, Canada DE-6(3/81) i i ABSTRACT The complexes Ru(OEP)(DPS)2 (1) and Ru(OEP)(DecHS)2 (2) were prepared i n vacuo on a 100-mg scale by treatment of the dimeric species [Ru(0EP)]2 (3) with a C H 2 C I 2 solution containing a s l i g h t excess of the appropriate thioether [0EP= dianion of octaethylporphyrin; DPS= diphenylsulphide; DecMS= decylmethyl-sulphide]. In vacuo r e c r y s t a l l i z a t i o n , from n-heptane i n the case of 1, and from n-pentane/methanol f o r 2, gave a n a l y t i c a l l y pure material i n 40 and 80 % y i e l d s , respectively. Both products were characterized by X-ray d i f f r a c t i o n analysis, uv/vis absorption and nmr spectrometry, as well as elemental analysis. Variable temperature nmr studies were ca r r i e d out with both complexes. JL was found to be i n thermodynamic equilibrium with 3, the dimer being favoured at about 80° C, and 1 at lower temperatures. Sharp nmr signals f o r the OEP protons of both e q u i l i b r a t i n g species, even at 80° C, indicated that exchange between them was slow on the nmr time scale; but, broadening and eventual coalescence at 80° C of the nmr signals f o r free and coordinated DPS suggested that the a x i a l ligands of JL were quite l a b i l e . Cooling solutions of 2 caused the thioether methylene signals to broaden, and at -60" C the signals due to the methylenes cl o s e s t to the sulphur s p l i t into broad doublets, t h i s r e s u l t i n g from the p r o c h i r a l nature of DecMS. The f a c t i i i that only one nmr signal was observed f o r these methylene protons at room temperature implies rapid alternate coordination of the sulphur lone p a i r s . The c r y s t a l structures of 1 and 2 revealed Ru-S bond lengths t y p i c a l of Ru complexes containing trans-thioethers. The bond distances and angles of the porphyrin core were t y p i c a l of those of monomeric Ru(Porp) complexes. Dv/vis absorption, and nmr spectrometric studies, showed that 1 was extremely a i r - s e n s i t i v e i n solution, r e a d i l y giving [Ru(0EP)0H]20 and free DPS. Dv/vis absorption, nmr, and gc/mass spectrometric studies revealed that 2 reacted with dioxygen over a period of months to give Ru(OEP)(DecMS)(DecMSO) and Ru(OEP)(DecMS0)2 as major products, as well as Ru(OEP)(CO)L (L= DecMS and DecMSO), and two other u n i d e n t i f i e d Ru(Porp) complexes as minor by-products [DecMSO= decylmethylsulphoxide]. In the presence of excess DecMS 2 catalyzed slow autoxidation of the free ligand to give DecMSO, DecMS02, and didecyldisulphide; the rate of t h i s reaction was increased by addition of small quantities of HOAc [DecMS02 = decylmethyl-sulphone]. A major Ru(Porp) end-product both i n the presence and absence of HOAc was Ru(OEP)(CO)L, the CO coming from Ru* I (Porp)-mediated decarbonylation reactions. i v TABLE OF CONTENTS ABSTRACT i i TABLE OF CONTENTS i v LIST OF TABLES v i i i LIST OF FIGURES i x LIST OF ABBREVIATIONS AND SYMBOLS xv ACKNOWLEDGEMENTS x v i i CHAPTER I: INTRODUCTION 1 1.1 General Introduction 1 1.2 Reactivity of Ruthenium Porphyrins with Dioxygen . 4 1.3 Transition Metal Catalyzed Autoxidation of Thioethers 9 CHAPTER I I : EXPERIMENTAL 13 2.1 Materials 13 2.1.1 Solvents 13 V 2.1.1.1 Degassed Solvents 13 2.1.2 Gases 14 2.1.3 Sulphur Containing Ligands 14 2.1.3.1 Decylmethylsulphoxide 15 2.1.3.2 Decylmethylsulphone 16 2.1.4 Ruthenium Complexes 17 2.1.4.1 Rua (C0)12 17 2.1.4.2 Ru(OEP)(CO)py 17 2.1.4.3 Ru(OEP)py2 18 2.1.4.4 [Ru(0EP)]2 18 2.1.4.5 Ru(0EP)(DPS)2 19 2.1.4.6 Ru(0EP)(decMS)2 20 2. 2 Instrumentation 22 2.2.1 O l t r a v i o l e t / V i s i b l e Absorption Spectroscopy (Dv/Vis) 22 2.2.2 Infrared Spectroscopy (Ir) 24 2.2.3 Nuclear Magnetic Resonance Spectroscopy (Nmr) 24 2.2.4 Gas Chromatography/Mass Spectrometry (GC/MS) 25 2.2.5 Elemental Analysis 25 2.2.6 X-Ray Cryst a l Structure Determinations . . . 25 2.3 Special Experimental Techniques and Equipment . . . 26 2.3.1 High Pressure Synthesis of Ru3(CO)i2 . . . . 26 2.3.2 Photolysis 30 2.3.3 Anaerobic Manipulations 32 2.3.3.1 Glove box 32 2.3.3.2 O i l D i f f u s i o n Pump 33 v i 2.3.3.3 Synthesis and i n Vacuo Manipulation of Ru(0EP)(DPS)2 and Ru(OEP)(decMS)2 . . 33 2.3.3.4 Anaerobic Uv/Visible Absorption and Nmr Spectroscopy Determinations . . . 36 CHAPTER II I : PHYSICAL CHARACTERIZATION OF Ru(OEP)(DPS)2 AND Ru(0EP)(DecMS)2 RESULTS AND DISCUSSION . . . . 39 3.1 OV/Visible Absorption Spectra 39 3.2 1 H Nmr Spectra 46 3.2.1 General Comments 46 3.2.2 Temperature Dependence Studies . . . . . . . 49 3.2.2.1 Spectrum of Ru(OEP)(DPS)2 49 3.2.2.2 Spectrum of Ru(OEP)(DecMS)2 56 3.3 Cryst a l Structures of Ru(OEP)(DPS)2 and Ru(0EP)(DecMS)2 58 CHAPTER IV: REACTIVITY OF Ru(OEP)(DPS)2 AND Ru(OEP)(DecMS)2 WITH DIOXYGEN 68 4.1 Ru(0EP)(DPS)2 68 4.2 Ru(0EP)(DecMS)2 71 4.2.1 Ru(OEP)(DecMS)2 i n the Absence of Added Free DecMS 71 4.2.2 Ru(0EP)(DecMS)2 i n the Presence of Added Free DecMS 80 v i i CHAPTER V: CONCLUSIONS AND SUGGESTIONS FOR FURTHER STUDIES 92 APPENDIX: ADDITIONAL INFORMATION ON THE CRYSTAL STRUCTURES OF Ru(OEP)(DPS)2 AND Ru(OEP)(DecMS)2 95 A.1 C r y s t a l Structure Determinations . . 95 A. 1.1 Ru(OEP)(DPS)2 , By Dr. S. R e t t i g 95 A. 1.2 Ru(OEP) (DecMS)2 , By Dr. J . Ibers 95 A.2 Crys ta l lographic Bond Distances and Angles . . . . 98 A . 2 . 1 Ru(OEP)(DPS)2 98 A. 2.2 Ru(OEP) (DecMS)2 . . . 105 REFERENCES 112 v i i i LIST OF TABLES TABLE I Assignments f o r the Major Uv/Vis Absorption Bands of Ru(0EP)(DPS)2 and Ru(OEP)(DecMS)2 40 TABLE II Some Ru(OEP)LL' Complexes L i s t e d i n Order of Increasing Wavelength of the Soret 44 TABLE III Ru-S Bond Lengths f o r Some Complexes Containing Ru-S Bonds 62 TABLE IV Averaged Bond Lengths (A) and Angles (deg) f o r the Porphyrin Core of Some Ru(Porp) Complexes 66 TABLE V Bond Lengths (A) with Estimated Standard Deviations i n Parentheses 98 TABLE VI Bond Angles (deg) with Estimated Standard Deviations i n Parentheses . 100 TABLE VII Intra-annular Torsion Angles (deg) with Standard Deviations i n Parentheses 103 TABLE VIII Bond Lengths (A) with Estimated Standard Deviations i n Parentheses 105 TABLE IX Bond Angles (deg) with Estimated Standard Deviations i n Parentheses 107 TABLE X Dihedral Angles (deg) between the 24-Atom Core and the Pyrrole Rings I l l i x LIST OF FIGURES Figure 2.1. Numbering Scheme Used f o r the Thioether Skeleton.. 15 Figure 2.2. (a) Control Panel f o r the Baskerville and Lindsay High pressure Reactor: (1) Main Power Switch; (2) Agitator Solenoid Switch; (3) Heater Switches; (4) Bomb Temperature Set-Point Indicator; (5) Bomb Temperature Gauge; (6) Set-Point Control and Bomb Thermocouple Ca l i b r a t i o n Screws, (b) Carrying Hoop. (c)Exploded View of the Reaction Chamber: (1) Bomb Casing; (2) Alignment Spot; (3) Agitator Assembly; (4) Bomb Cover; (5) Gas E x i t Port; (6) Gas E x i t Tube Retaining Bolt; (7) Bomb Stem; (8) Thermocouple Port; (9) Thermocouple Sheath. (See Section 2.3.1 f o r Explanations) 27 Figure 2.3. The Ba s k e r v i l l e and Lindsay High Pressure Apparatus as i t Appears When F u l l y Assembled: (1) Heater; (2) Bomb Cover Hold-Down Block; (3) Bomb Cover Hold-Down Bolts; (4) Gas E x i t Tube and Control Valve; (5) Agitator Relay Solenoid; (6) Bursting Cap Assembly; (7) Gas Entry Tube and Control Valve; (8) Bursting Cap; (9) Bomb Pressure Gauge; (10) Thermocouple. Inset: Correct Order f o r the Tightening of the Bomb Cover Hold-Down Bolts. (See Section 2.3.1 f o r Explanations). . . . 28 X Figure 2.4. Exploded View of the Photolysis Apparatus Used i n the Synthesis of Ru(0EP)py 2 . (1) High Intensity Light Source. (2) Pyrex Inner Jacket. (3) Reaction C e l l . (4) Outer Cooling Jacket (Not Used). (5) Condenser. (A) Argon Inlet. (B) Outlet Sidearm. (C) Argon Outlet. The Inlets and Outlets Are Capped with Rubber Septa. (See Section 2.3.2 f o r Explanations) 31 Figure 2.5. Vacuum Transfer Cross Set up f o r Synthesis of Ru(0EP)(Thioether)2. Taps ( l ) - ( 3 ) Were Kontes High Vacuum Teflon Valves. (4) Magnetic S t i r r i n g Bar. (See Section 2.3.3.3 f o r Explanations) 34 Figure 2.6. Apparatus Used to Obtain (a) Uv/vis Absorption, and (b) Nmr Spectra under Anaerobic Conditions, as Described i n Section 2.3.3.4. (1) 1.0 mm C e l l . (2) 0.1 mm C e l l . (3) Reservoir Bulb. (4), (5) Connections to the Transfer Cross. (6) Sealing Point 37 Figure 3.1. Uv/vis Absorption Spectrum of Ru(OEP)(DPS)2 (Extinction C o e f f i c i e n t s f o r the Major Bands Are Lis t e d i n Section 2.1.4.5; Assignments f o r the Porp. Transitions Are L i s t e d i n Table I) 41 Figure 3.2. Uv/vis Absorption Spectrum of Ru(OEP)(DecMS)2 (Extinction C o e f f i c i e n t s f o r the Major Bands Are Listed i n Section 2.1.4.6; Assignments f o r the Porp. it—jt* Transitions Are Lis t e d i n Table I) 42 Figure 3.3. Room Temperature 400 MHz 1H Nmr Spectrum of Ru(0EP)(DPS)2 i n C G D G (the Exact Peak Positions, 8 ppm, fo r a l l the Signals Are Li s t e d i n Section 2.1) 47 Figure 3.4. (a) Room Temperature 400 MHz 1 H Nmr Spectrum of Ru(0EP)(DecMS)2 i n C G D G (b) Room Temperature 400 MHz 1 H Nmr Spectrum of Free DecMS i n C G D G (the Exact Peak Positions, 8 ppm, f o r a l l the Signals Are Li s t e d i n Section 2.1; See Figure 2.1 f o r the Thioether Skeleton Numbering Mode) 48 Figure 3.5. 300 MHz *H Nmr Spectra of Ru(OEP)(DPS)2 i n Toluene-da at Decreasing Temperatures; From Bottom to Top: (a) Room Temperature; (b) 0° C ; (c) -20° C (the Exact Room Temperature Peak Positions, 8 ppm, f o r a l l the Signals Are Li s t e d i n Section 2.1) 50 Figure 3.6. 300 MHz 1 H Nmr Spectra of Ru(OEP)(DPS)2 i n Toluene~d8 at Increasing Temperatures; From Bottom to Top: (a) Room Temperature; (b) 30° C ; (c) 50° C ; (d) 80° C (the Exact Room Temperature Peak Positions, 8 ppm, fo r a l l the Signals Are Li s t e d i n Section 2.1) 51 Figure 3.7. 300 MHz 1 H Nmr Spectra of Ru(OEP)(DecMS)2 i n Toluene-ds at Decreasing Temperatures; From Bottom to Top: (a)Room Temperature; (b) 0° C ; (c) -20° C ; (d) -60° C (the Exact Room Temperature Peak Positions, 6 ppm, f o r a l l the Signals Are Lis t e d i n Section 2.1; See Figure 2.1 f o r the Thioether Skeleton Numbering Mode).. 57 x i i Figure 3.8. ORTEP Drawing of the Ru(OEP)(DPS)z C r y s t a l Structure, Using the Labe l l i n g System Employed i n the Text. The Same Drawing Appears i n the Appendix with the More Complete Numbering System Supplied by the Crystal lographer 59 Figure 3.9. ORTEP Drawing of the Ru(OEP)(DecMS)2 Crystal Structure, using the Lab e l l i n g System Employed i n the Text. Another Drawing of the Same Structure Appears i n the Appendix with the More Complete Numbering System Supplied by the Crystallographer 60 Figure 3.10. Some Complexes Containing Ru-S Bonds f o r Which Crysta l Structures Have Been Obtained. References and Ru-S Bond Lengths Are Li s t e d i n Table III 61 Figure 4.1. (a) 400 MHz iH Nmr, and (b) Uv/vis Absorption Spectra of the F i n a l Products of the Air-Oxidation of Ru(0EP)(DPS)2 69 Figure 4.2. Typical Uv/vis Absorption Spectral Changes upon Exposure of Ru(OEP)(DecMS)2 to A i r . (1) Before and Immediately a f t e r Exposure to A i r . (2) After One Day. (3) After Two Days. (4) Af t e r Four Days. (5) After One Week 72 Figure 4.3. Uv/vis Absorption Spectrum of a 0.188 mM Ru(0EP)(DecMS)2 Solution a f t e r Three Months of Exposure to A i r (1), and at Increasing Time Intervals A f t e r Adding an Excess of Approximately 103 of Free DecMS: (2) After about 3 h; (3) After 1 Day 73 x i i i Figure 4.4. 300 MHz 1 H Nmr Spectra of: (a) the 0.188 mM Ru(OEP)(DecMS)2 Solution Mentioned i n Figure 4.3 a f t e r Three Months of Exposure to A i r , Concentrated and the Residue Redissolved i n C G D 6 ; (b) a Ru(OEP)(DecMS)2 Solution to which Four Equivalents of DecMSO Have Been Added. (See Figure 2.1 f o r the Thioether Skeleton Numbering Mode) 75 Figure 4.5. Uv/vis Absorption Spectral Changes upon T i t r a t i o n of a Solution Containing 0.129 mM Ru(OEP)(DecMS)2, and 22.2 mM Free DecMS, with Aliquots of a 26.9 mM Solution of Free DecMSO. Spectrum (10) Was Obtained a f t e r a Total Addition of 940 uL of the DecMSO Solution. . . . . . . 76 Figure 4.6. 400 MHz 1 H Nmr Spectrum of Ru(OEP)(DecMSO)2. The Dnlabelled Signals Are at Exactly the Same Positions as those Assigned to the T a i l of the DecMS Decyl Chain i n the i H Nmr Spectrum of the Ru(OEP)(DecMS)2 Complex. (See Figure 2.1 f o r the Thioether Skeleton Numbering Mode).. . 78 Figure 4.7. (a) Uv/vis Absorption Spectral Change Observed upon Bubbling CO through the 0.188 mM Ru(OEP)(DecMS)2 Solution Mentioned i n Figure 4.3, a f t e r the Latter Had Been Exposed to A i r f o r Three Months, (b) The Same Experiment Followed by 300 MHz IH Nmr 79 Figure 4.8. Mass Spectra of Some of the Products of Ru(OEP)(DecMS)2-Mediated Air-Oxidation of DecMS: (a) Didecyldisulphide; (b) Decylmethyldisulphide; (c) Didecylsulphide; (d) [ C i o H 2 i S ] 2 82 x i v Figure 4.9. Uv/vis Absorption Spectrum of a Solution I n i t i a l l y Containing 0.246 mM Ru(OEP)(DecMS)2 and 15.5 mM DecMS, a f t e r One Week of Exposure to A i r 83 Figure 4.10. Uv/vis Absorption Spectra of a Solution I n i t i a l l y Containing 1.24 mM Ru(OEP)(DecMS)2, 174 mM DecMS, and 0.175 mM HOAc, (a) a f t e r 24 h. of Exposure to Ai r , (b) a f t e r One Week of Exposure to A i r . (Samples Were A r b i t r a r i l y Diluted to Obtain Spectra on Scale). . 85 Figure 4.11. GC Trace Showing the Product D i s t r i b u t i o n of the Thioether Oxidation Described i n Figure 4.10. The Integrals of the Major Peaks Are Given as Percent Fractions of the DecMS Peak Intensity 86 Figure 4.12. Uv/vis Absorption Spectrum of a Solution I n i t i a l l y Containing 1.58 mM Ru(OEP)(DecMS)2, 4.2 mM HOAc, and 170 mM DecMS, a f t e r Four Hours of Exposure to A i r . (The Sample Was A r b i t r a r i l y Diluted to Obtain an On-Scale Spectrum) 88 Figure A . l . Ru(OEP)(DPS)2 Skeleton Numbering mode Used i n Tables V-VII 97 Figure A.2. Ru(OEP)(DecMS)2 Skeleton Numbering Mode Used i n Tables VIII-X 105 XV LIST OF ABBREVIATIONS AND SYMBOLS Where possible, a l l abbreviations used are those recommended by the "ACS Handbook f o r Authors" (1st Ed., 1967). The following i s a l i s t of sp e c i a l i z e d abbreviations and symbols used i n t h i s t h e s i s . Symbol or Abbreviation Meaning Porp Porphyrin dianion OEP Octaethylporphyrin dianion TPP Tetraphenylporphyrin dianion TMP Tetramesytylporphyrin dianion MPIX Mesoporphyrin IX dianion PPh3 Triphenylphosphine PhaPO Triphenylphosphine oxide R 2 S Thioether R 2 S O Sulphoxide R2SO2 Sulphone DMSO Dimethylsulphoxide DPS Diphenylsulphide DPSO Diphenylsulphoxide DPSO2 Diphenylsulphone DecMS Decylmethy1sulphide x v i Symbol or Abbreviation Meaning DecMSO Decylmethy1sulphoxide DecMS02 Decylmethylsulphone DMA Dimethylacetamide L ( i n a chemical formula) Ligand GC Gas chromatography MS Mass spectrometry ppm, or 6 ppm Chemical s h i f t i n parts per m i l l i o n r e l a t i v e to TMS s Singlet d Doublet t T r i p l e t q Quartet qn Quintet sex Sextet A Wavelength A » a x Wavelength at an absorption maximum Imp. Impurity USP U.S. Pharmacopoeia CP Chemically Pure x v i i ACKNOWLEDGEMENTS As i s the case with a l l s c i e n t i f i c endeavours, t h i s thesis was a team e f f o r t . In the broadest sense the present research was guided by the documented r e s u l t s of a l l past studies. More s p e c i f i c a l l y , I am greatly indebted to many people who have contributed d i r e c t l y i n one way or another. F i r s t , I wish to thank Dr. B. R. James, my research supervisor, f o r h i s expert guidance and enthusiasm; i t has been a pleasure to work fo r him. Second, I wish to thank my colleagues i n both the D. Dolphin and B. R. James research groups f o r contributing to an open and f r i e n d l y environment i n which to work. Of these I am es p e c i a l l y indebted to my good f r i e n d Dr. M. Camenzind f o r sharing with me hi s considerable p r a c t i c a l knowledge. I also wish to thank Drs. S. R e t t i g and J. Ibers f o r t h e i r prompt determination of the c r y s t a l structures of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)z . The techni c a l s t a f f at OBC also played a fundamental r o l e i n my research by always providing s k i l l f u l work, and very often useful suggestions as well. F i n a l l y , I would l i k e to thank my family, e s p e c i a l l y my parents and my brother f o r u n f a i l i n g support, and my wife, Muriel, who helped not only by being there f o r better or f o r worse, but also by lending her a r t i s t i c t a l ents i n doing the i l l u s t r a t i o n s f o r the thesis, an enormous task. 1 CHAPTER I  INTRODUCTION 1•1 General Introduction Studies of ruthenium porphyrins date back to 1969 when complexes were f i r s t synthesized by researchers i n bioinorganic chemistry to serve as models f o r n a t u r a l l y occurring i r o n porphyrin systems.* This continued to be the ra t i o n a l e of most, i f not a l l , studies c a r r i e d out on ruthenium porphyrins throughout the 1970's, and many of the more recent papers s t i l l mention the p o t e n t i a l analogy with the iron porphyrins, at l e a s t i n passing. 2 Although many valuable insights have come out of these studies, advances i n the f i e l d , e s p e c i a l l y i n the l a s t seven years, have probably served more to h i g h l i g h t fundamental differences between the ruthenium and iron porphyrins than to draw analogies between them. This should not be considered a setback, and indeed studies of ruthenium porphyrins have proved valuable i n two ways. To begin with, exploring the differences has i t s e l f led to a better understanding of the i r o n systems, and why they are unique. In addition, as synthetic methods have improved i t has become possible to synthesize a whole range of novel complexes, which often bear l i t t l e r e l a t i o n to natural systems, but which nevertheless exh i b i t i n t e r e s t i n g properties of t h e i r own. Work done on one such complex, RuOEP(PPh3)2, by 2 workers in this laboratory, f i r s t aroused interest in the possible synthesis and properties of RuOEP(R2S)2 complexes.3 A solution of RuOEP(PPh3)z exposed to dioxygen in the presence of excess PPh3 was found to catalyze autoxidation of the PPh3 to Ph3P0: Evidence available at the time suggested that t h i s reaction proceeded v i a an i n i t i a l outer sphere oxidation of the RuOEP complex by dioxygen according to the following scheme: (Toluene) PPha > PhsPO (eq. 1.1) RuOEP(PPh3 )2 , 02 (1) Rui i 0EP(PPh3 )2 + 02 ^ [ R u i i i 0 E P(PPh3 ) 2 ] + + 0 2 -(2) 0X~ + UzO > HO2 • + 0 H -( 3 ) 2 H O 2 - > H2O2 + 02 (4) H2O2 + PPhs > PhsPO + H2O cont 3 ( 5 ) 2[RuHiOEP(PPh3 ) 2 ] + + PPha + 2 0 H " > 2 R u i i 0EP(PPh3 )2 + PhsPO + H2O Scheme 1.1. Autoxidation of PPh3 catalyzed by RuOEP(PPh3)z In t h i s scheme, i n order to favour formation of H2O2, the low standard p o t e n t i a l f o r step (1) (superoxide r e a d i l y reduces Ru(III)) would be overcome by the favourable steps ( 2 ) and ( 3 ) . The p o s s i b i l i t y of f i n d i n g an analogous system, i n which thioether autoxidation to sulphoxides might be catalyzed by RuOEP(R2S)2 complexes v i a H2O2, was an i n t r i g u i n g one f o r many reasons. F i r s t l y , H2O2 i s known to oxidize organic sulphides. 4 Secondly, there have been comparatively few studies done on homogeneous c a t a l y s i s of thioether autoxidations to sulphoxides using transitionmetals,5 , e and to our knowledge only three thus f a r have yielded promising r e s u l t s . 5 , G , 7 Furthermore, a l l of these systems require a coreductant (such as an alcohol or dihydrogen) to reduce the higher oxidation state metal complex back to the lower valent dioxygen-sensitive species (cf. steps (1) and ( 5 ) i n scheme 1.1); there i s no well established precedent f o r reduction of the metal complex by the organic sulphide i t s e l f as there i s i n the phosphine case (cf. step ( 5 ) i n scheme 1.1). Would t h i s be f e a s i b l e within a porphyrin system? Such a reaction could be of p r a c t i c a l i n t e r e s t , and would almost c e r t a i n l y have i n t e r e s t i n g mechanistic implications. F i n a l l y , there have been no previous reports on 4 the preparation or characterization of Ru(Porp) (R2S )2 complexes, and hence the p o s s i b i l i t y of synthesizing and characterizing such compounds was i n i t s e l f an i n t e r e s t i n g and challenging proposition. This thesis i s primarily concerned with t h i s l a s t objective; chapter II w i l l deal with the synthetic methods used to prepare two Ru(OEP)(R2S)2 complexes, Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2, while chapter III w i l l describe experiments done to p h y s i c a l l y characterize these two complexes. To date, only preliminary experiments have been c a r r i e d out to study the r e a c t i v i t y of the two complexes with dioxygen, and some of these w i l l be described i n chapter IV. I t i s hoped that t h i s thesis w i l l serve as the f i r s t step i n a series of studies aimed at addressing a l l of the points described above. To further a i d future research i n t h i s f i e l d , a review of the l i t e r a t u r e published to date on the r e a c t i v i t y of ruthenium porphyrins with dioxygen, and on t r a n s i t i o n metal-catalyzed autoxidation of thioethers, i s presented i n sections 1.2 and 1.3 of t h i s chapter. 1- 2 Rea c t i v i t y of Ruthenium Porphyrins with Dioxygen In recent years, knowledge has accumulated on the int e r a c t i o n of ruthenium porphyrins with dioxygen, and some general patterns can now be observed. A b r i e f review of the studies done to date w i l l serve to point these out. Interest i n the subject dates back to the e a r l i e s t studies done. In a paper published i n 1971, Chow and Cohen 8 commented on 5 the high s t a b i l i t y of RuTPP(GO)EtOH to a i r oxidation when compared to the then known iron(II) porphyrin systems. The s t a b i l i t y was r a t i o n a l i z e d i n terms of the larger ruthenium d-orbitals ( t 2 g 6 ) leading to higher ligand f i e l d s t a b i l i z a t i o n by the porphyrin, as well as to more e f f i c i e n t metal-to-porphyrin K backbonding. Subsequently synthesized new ruthenium porphyrin complexes have continued to be found l e s s a i r sen s i t i v e than t h e i r iron counterparts, and the i n i t i a l explanation i s widely accepted. Of note, a l a t e r studyS showed that Ru(Porp)(CO)L compounds themselves are much more re s i s t a n t to electrochemical oxidation than the c a r b o n y l - f r e e Ru(Porp)L2 complexes. I t was proposed that t h i s was due to e f f i c i e n t JC-backbonding from the ruthenium d- o r b i t a l s to the c a r b o n y l ir * o r b i t a l s ; t h i s would decrease the e l e c t r o n d e n s i t y around the metal, thus s t a b i l i z i n g the lower oxidation state (a well-known p r o p e r t y of the CO ligand). In s p i t e of t h e i r lower oxidation p o t e n t i a l r e l a t i v e to Ru(Porp)(CO)L compounds, the f i r s t Ru(Porp)L2 compounds i s o l a t e d also tended to be rather stable to a i r o x i d a t i o n * 0 These complexes, which mostly had nitrogen bases as the a x i a l ligands, reacted slowly and i r r e v e r s i b l y i n a i r to give uncharacterized products. 1 0 In addition, a l l of these compounds were s u b s t i t u t i o n a l s r e l a t i v e l y i n e r t ; Ru(TPP)py , f o r instance, took a week under a CO atmosphere to give the (carbonyl)pyridine product. a Interest i n re v e r s i b l e oxygenation led workers i n our 6 laboratories to synthesize and t e s t derivatives containing more l a b i l e ligands i n the hope of obtaining useful models of b i o l o g i c a l oxygen transport systems. 1 0. 1 1 • 12 Reversible binding of oxygen was demonstrated by spectrophotometric and tensiometric methods f o r Ru(OEP)(CH3CN)2 i n the solvents DMA, DMF, and pyrrole,1 0 and f o r Ru(MpIX)(DMF)2 i n DMF.12 The l a t t e r system was stable only at low temperatures; at room temperature, i r r e v e r s i b l e oxidation was observed. Even i n the OEP systems, i r r e v e r s i b l e oxidation eventually took place, and a l l attempts made to date to i s o l a t e products of r e v e r s i b l e oxygenation have led to i r r e v e r s i b l e o x i d a t i o n . 1 3 When attempts were made to observe r e v e r s i b l e oxygenation i n RuMb (apomyoglobin reconstituted with Ru(II)) only rapid, i r r e v e r s i b l e , oxidation to the met-form, RuMb+, was observed, even at 0° C.12 One key problem i n the protein work was that the Ru(II) e x i s t s i n a 6-coordinate, low spin geometry, unlike the Fe(II) i n deoxymyoglobin. Although RuMb f a i l e d to provide a useful model f o r the natural i r o n system, a l l the studies on r e v e r s i b l e oxygenation, taken together, provided much information on the r e a c t i v i t y of Ru(Porp) systems with dioxygen. One important observation was that the r e a c t i v i t y i s very solvent-dependent;! 1 more recent reports continue to make t h i s p o i n t , 1 4 and i t must be kept i n mind i n the planning of any experiment involving a Ru(Porp) complex, even i n the preparation of a complex believed to be a i r - s t a b l e . 7 The studies of rev e r s i b l e binding of dioxygen were also the f i r s t to demonstrate that Ru(Porp) species could i n t e r a c t with dioxygen e i t h e r by inner sphere or outer sphere processes. Complexes which at f i r s t interacted r e v e r s i b l y with dioxygen were eventually i r r e v e r s i b l y oxidized by i t , presumably v i a an inner sphere reaction. But the attempt to get RuMb to bind 02 r e v e r s i b l y showed that oxidation can take place without i n i t i a l coordination of dioxygen as well. In t h i s case, very rapid oxidation to RuMb+ was observed, even though the precursor RuMb was known to be r e l a t i v e l y i n e r t to s u b s t i t u t i o n . 1 2 The oxidation mechanism had to involve an outer sphere process. Later work done by B i l l e c k e et a l . * 5 on Os(Porp)py f t, and i n less d e t a i l on other Os and Ru porphyrin systems, demonstrated more cases where s u b s t i t u t i o n a l l y i n e r t complexes could be oxidized v i a an outer sphere mechanism. In addition, t h i s work gave evidence that the reaction proceeded v i a the i n i t i a l formation of superoxide and [M* 11 (Porp)py 2 ]+, followed by disproportionation of the superoxide to hydrogen peroxide and dioxygen. In Fe(II) porphyrin systems, the f i n a l products of i r r e v e r s i b l e oxidation following i n i t i a l dioxygen binding (inner sphere process) have long been known to be complexes of the general formula [ F e 1 1 I (Porp)L ]20, the so-called u-oxo dimers. i e It was i n i t i a l l y thought 1 0 that the products of the si m i l a r i n t e r a c t i o n i n the ruthenium systems would be the analogous Ru(III) u-oxo dimers; however, since 1981 papers published by 8 two groups 1*. i T , 18, have reported on the synthesis and characterization of several Ru(IY) u-oxo dimers, some of which were then shown to be the end products of the 02 reactions studied previously.13. 1 * The Ru(IV) u-oxo dimers have been found to be quite stable, and i t seems that they w i l l be, i n general, the common products of inner sphere oxidations of Ru(II) porphyrins by dioxygen. One important exception to t h i s suggestion has come to l i g h t very recently. In O 2-oxidations of Ru 1 1 (TMP)Ii2 , i n which the s t e r i c bulk of the mesityl groups i n h i b i t s u-oxo formation, a Ru(VI) trans-dioxo product has been reported. 1 9 . 2 0 it, seems probable that studies of t h i s species w i l l have important t h e o r e t i c a l and p r a c t i c a l implications; indeed, i n t h e i r 1985 paper,20 Groves and Quinn report that Ru(TMP)(0)2 i s a c a t a l y s t f o r the aerobic epoxidation of o l e f i n s , and they have c i t e d evidence to suggest that trans dioxo complexes may be intermediates i n the oxidation of other ruthenium porphyrins to u-oxo dimers. Thus there are two general mechanisms by which ruthenium(II) porphyrins i n t e r a c t with dioxygen. The f i r s t i s favoured i n complexes having l a b i l e a x i a l ligands, which would therefore suggest that binding of dioxygen at the metal i s a c r i t i c a l step. In general, the end product of t h i s type of i n t e r a c t i o n w i l l be a Ru I V(Porp) u-oxo dimer; however, f o r s t e r i c a l l y hindered porphyrins such as TMP, Ruv* (Porp)(0)2 i s the oxidation product. The second mechanism involves outer sphere oxidation of the Ru(porp)L2 complex to give, at l e a s t i n i t i a l l y , 9 [Rui 1 1 (Porp)L23+ and superoxide. This l a t t e r mechanism i s the one invoked i n scheme 1.1 f o r the Ru(OEP)(PPh3)2-catalyzed oxidation of PPh3. Clearly, any attempts to f i n d s i m i l a r c a t a l y s t s w i l l need to consider ways of avoiding the competing inner sphere reaction. 1.3 Transition Metal Catalyzed Autoxidation of Thioethers As mentioned previously, few studies have been done on the subject of t r a n s i t i o n metal-catalyzed autoxidation of thioethers to sulphoxides and sulphones, perhaps because several reasonably e f f i c i e n t methods already e x i s t f o r carrying out these reactions, both on preparative and on i n d u s t r i a l s c a l e s . * ! 2 1 Nevertheless, i n t e r e s t i n the f i e l d remains, and i n f a c t two out of the three major studies done, have been done i n i n d u s t r i a l research l a b o r a t o r i e s .5 , 6 The two most detailed studies c a r r i e d out so f a r are those of R i l e y and Shumate,5 and Gamage.7 R i l e y and Shumate observed that cis-RuCl2(DMS0)4 and trans-RuBr 2(DMS0)4 catalyzed very s e l e c t i v e oxidation of sulphides to sulphoxides under 100 p s i of 02 at 100°C. This reaction only proceeded i n a l c o h o l i c solvents, and when done i n isopropanol was found to be i n h i b i t e d by acetone. From k i n e t i c 10 studies and product analysis, the following mechanism was proposed: (1) "Ru(II)" + 02 > "Ru(IV)" + (2) R 2 S + H2O2 > R2SO + H2O (3) "Ru(IV)" + R1R2CHOH > "Ru(II) + RiR2C=0 + 2H+ Scheme 1.2. Autoxidation of R 2 S catalyzed by "Ru(II)" No conclusions were drawn as to the nature of the actual c a t a l y t i c species, but i t was noted that the presence of added R 2 S enhanced the reaction rate, and t h i s was c i t e d as evidence that the c a t a l y t i c species contained one or more R 2 S ligands. In a very recent paper, R i l e y and O l i v e r have provided evidence which suggests that the all-trans - R 1 1 X 2 (SR2 )z (DMS0)2 species are the ground-state c a t a l y t i c species; further investigations are under way. 2 2 In the study done by Gamage,7 RhCl3(DMS0 )3 was found to catalyze autoxidation of diphenyl sulphide to the corresponding sulphoxide i n DMA solvent. In t h i s case, H2 was used as the coreductant, following e a r l i e r work on the use of H2 with Rh(III) to reduce DMSO to the s u l p h i d e . 2 3 The following 11 mechanism was proposed f o r the sulphide oxidation: (1) RhUiDMSO + DMA Rh 1 1 1 DMA + DMSO (2) Rh 111 DMA + H2 > [Rh1 DMA] + 2H+ (3) [Rh1 DMA] + 02 > Rhui ( 0 2 2 ~ ) (DMA) (4) Rhin (0 22-)(DMA) + H2 > [Rh1 DMA] + Hz 02 (5) H2O2 + DPS > H2O + DPSO Scheme 1.3. Autoxidation of DPS catalyzed by Rh(I)/Rh(III) Steps 1 and 2 are the ones that generate the 0 2 - s e n s i t i v e c a t a l y s t . The c a t a l y s i s operates v i a steps (3)-(5). Two other reactions, (6) and (7) (scheme 1.4) constitute an i n t e r e s t i n g side reaction, whereby the solvent i s oxidized s e l e c t i v e l y to a hydroperoxide: (6) Rhiu (0 22-)(DMA) > [Rhi ] + CH3G0N(CH3 )CH2 00H (7) [RW ] + DMA + 02 > Rhin ( 0 2 2 - )(DMA) Scheme 1.4. Reduction of Rh 1 1 1 with DMA Studies done on the atmospheric pressure reaction i n C2H4CI2, were not successful. Interestingly, more basic dialkylsulphides were not oxidized by the RhCl3(DMS0)3 system. This suggested that, i n t h i s case, coordination by sulphides inactivated a p o t e n t i a l l y c a t a l y t i c system. Some other reports are worthy of mention. The f i r s t , by Ledl i e et a l . , 6 reported that di-n-butyl sulphide and di e t h y l sulphide could be oxidized to t h e i r corresponding sulphones i n high y i e l d s using t r a n s i t i o n metal cata l y s t s ; the former substrate was treated with 100 p s i of a i r at 100°C using RuCl3 as a cat a l y s t , while the l a t t e r was treated with 1 atm of oxygen at 75*C using RuCl3(Et2S)3 as a cat a l y s t . In both cases, the solvent was ethanol, and acetaldehyde d i e t h y l acetal was an observed coproduct. Studies done on the atmospheric pressure reaction showed that the sulphoxide was an intermediate product. Attempts at using other solvents were much less e f f e c t i v e ; reasonable y i e l d s of sulphoxides were obtained using various Ru complexes i n benzene, but i n these cases a serious side-reaction was oxidation at the a-carbon of the thioether. Another report of note i s one by Henbest and Trocha-Grimshaw i n 1974 .24 i n t h i s case, IrHCl2(DMS0)3, Rh(III) chloride, and H [ R h C l 4(DMS0)2], were found to be e f f e c t i v e as ca t a l y s t s f o r the oxidation of sulphoxides to sulphones i n aqueous a l c o h o l i c solutions. The complexes did not oxidize sulphides and, i n fa c t , i n t h e i r presence were inactive f o r sulphoxide oxidation, again suggesting that sulphide coordination poisoned the catalyst. 13 CHAPTER II  EXPERIMENTAL 2.1 Materials 2.1.1 Solvents Spectral or reagent grade solvents were obtained from Al d r i c h , BDH, or Fisher Chemical Co. A l l solvents except f o r methanol and deuterated solvents were f i l t e r e d through a column of a c t i v i t y I alumina p r i o r to use. Methanol was always spectral grade, and was used without further p u r i f i c a t i o n . Deuterated solvents were used without further p u r i f i c a t i o n . 2.1.1.1 Degassed Solvents Where anaerobic conditions are sp e c i f i e d , the desired solvent was degassed by submitting i t to 3-6 "freeze/pump/thaw" cycles (caution- see note i n section 2.3.3.3 regarding the freezing and thawing of solvents, such as alcohols, which have high c o e f f i c i e n t s of thermal expansion). Thereafter, a l l manipulations were done using techniques described i n section 2.3.3. 14 2.1.2 Gases Argon, carbon monoxide, dinitrogen, and dioxygen were supplied by Union Carbide of Canada Ltd. Dinitrogen f o r the glove box was pr e p u r i f i e d grade. Argon and dinitrogen used f o r other i n e r t atmosphere manipulations were USP grade, and the argon was further p u r i f i e d by passing i t through a drying tower containing d r i e r i t e (CaSO-O, and a deoxygenation tower containing BASF ca t a l y s t R3-11. Dioxygen was also USP grade, while carbon monoxide was CP grade; both were used without further p u r i f i c a t i o n . 2.1.3 Sulphur Containing Ligands Diphenylsulphide (DPS), diphenylsulphoxide (DPSO), and diphenylsulphone ( D P S O 2), were obtained from A l d r i c h Chemicals, and were used without further p u r i f i c a t i o n . Decylmethylsulphide (DecMS) was obtained from F a i r f i e l d Chemicals, and was f i l t e r e d through a c t i v i t y I alumina p r i o r to use. The product thus obtained was found by GC/MS to contain trace amounts (approximately 1 %) of impurities with the general formula C 1 1 H 2 4 S , C 1 0 H 2 2 S , and C 9 H 2 0 S . The syntheses of decylmethylsulphoxide (DecMSO) and decylmethylsulphone (DecMSG*2) were previously reported by Riley and Shumate,5 but t h e i r report included neither preparative d e t a i l s nor physical characterization. The procedures described below were based on standard methods f o r preparation of sulphoxides and sulphones. 4 2.1.3.1 Decylmethylsulphoxlde To a s t i r r e d solution containing 6.09 g (32.4 mmol) of DecMS i n 18 mL acetone at 0° C were added 3.5 g (approximately 31 mmol) of 30% aqueous H2O2, slowly over a period of several hours. The reaction was followed by t i c (Merck s i l i c a gel 60, 0.2 mm thickness, coated with F254 fluorescent indicator; 2:1 C H 2 C I 2:acetone was used as the developing solution). After 36 h the solution volume was reduced to approximately 3 mL using a rotary evaporator, and the concentrate cooled f o r 4 h at 5° C. The r e s u l t i n g s o l i d white mass was f i l t e r e d o f f , redissolved i n 25 mL C H 2 C I 2 , then dried over MgS04. The solution was f i l t e r e d , the solvent removed under vacuum at 40° C, and the product then r e c r y s t a l l i z e d three times from n-hexane/CH2CI2, and dried i n vacuo f o r 20 h. Melting Point- 53-54° C. Figure 2.1. Numbering Scheme Used f o r the Thioether Skeleton. 16 Analysis- Calculated f o r C11H24OS (204.37 g/mol): C, 64.65%; H, 11.84%. Found: C, 64.41%; H, 11.77%. Nmr- (6ppm i n C G D G ) ; (see fig u r e 2.1 f o r the thioether skeleton numbering mode): (CH3*10), 0.930 t; (CH2#3-9), 1.06-1.39 m; (CH2#2), 1.51 qn; ( C H 2*1), 1.95 m, 2.07 m; (CHstfl'), 1.84 s. A l l integrations were i n agreement with these assignments. 2.1.3.2 Decylmethylsulphone A solution containing 5.00 g (26.6 mmol) decMS, 10 mL acetic acid, and 6.0 g (approximately 53 mmol) 30% H2O2 was s t i r r e d at room temperature f o r 16 h, at which time t i c analysis, as described f o r the decMSO preparation, indicated that no s t a r t i n g material was l e f t , and that one new product was present. The solution was evaporated to dryness. The r e s u l t i n g white s o l i d was redissolved i n 40 mL C H 2 C I 2 , and washed, f i r s t with 10 mL water, then with 10 mL saturated -aqueous NaHC03, then twice more with water. The CH2 C I 2 layer was then dried over MgS04, f i l t e r e d , and evaporated to dryness. Afte r r e c r y s t a l l i z i n g three times from n-hexane/CH2 C I 2 , the product was dried i n vacuo f o r 24 h. Melting Point- 74° C. Analysis- Calculated f o r C11H24SO2 (220.37 g/mol): C, 59.95%; H, 10.97%. Found: C, 59.66%; H, 11.10%. Nmr- (8ppm i n CeDe): (CHstflO), 0.925 t; (CH.2#8,9), 1.03 d(br); (CH2#3-7), 1.09-1.38 m; (CH2#2), 1.50 qn; (CH2#1), 2.32 t; (CH3#1'), 2.04 s. A l l integrations were i n agreement with these 17 assignments. 2.1.4 Ruthenium Complexes Ruthenium was obtained on loan from Johnson, Matthey Ltd, i n the form of RuCl3-3H2 0 (approximately 40 % by weight). H 2 O E P was kindly provided by Dr. D. Dolphin of t h i s department. 2.1.4.1 Ru 3(C0) n Ru 3 (C0),2 was synthesized on a 4-g scale by a high pressure method previously described by other workers.25 The equipment used i s described i n section 2.3.1. The product thus obtained was often contaminated with green and v i o l e t impurities, but dark orange c r y s t a l s of the desired product could be extracted into hexanes from the crude material, using a Soxhlet extraction apparatus. Y i e l d ( P u r i f i e d product)- 80 %. Ir Spectrum- In n-hexane: 2061, 2031, 2011cm-i, due to CO stretching; i n good agreement with the l i t e r a t u r e . 2 6 2.1.4.2 Ru(OEPHCO)py Metallation of OEPH2 using Ru (CO) was according to the well established procedure described by Antipas et a l . 2 7 Analysis- Calculated f o r C42H49N5ORU (740.1 g/mol): C, 68.10%; H , 6.62%; N, 9.46%. Found: C, 67.87%; H , 6.84%; N, 9.46%. Dv/vis- ( C B H G , Amax.nm (log €)): 549 (4.39); 518 (4.18); 396 (5.53) (Soret). The 6-values f o r the a and P bands (see section 18 3.1 f o r "the band nomenclature), which were obtained with a 1.0 mm c e l l agree c l o s e l y with the l i t e r a t u r e , 2 7 but the value f o r G (Soret), obtained with a 0.10 mm c e l l , i s high by approximately 30 %. For a discussion of t h i s r e s u l t , see section 2.2.1. 2.1.4.3 Ru(0EP)py 3 Ru(0EP)py 2 was prepared by photolysis of Ru(OEP)(CO)py using a procedure described by Antipas et a l . 2 7 The photolysis apparatus used i s described i n section 2.3.2 of t h i s t h e s i s . Analysis- Calculated f o r C4 6H5 4NeRu (791.1 g/mol): C, 69.78 %; H, 6.83 %; N, 10.62 %. Found: C, 69.44 %; H, 6.73 %; N, 10.78 %. Nmr- (6ppm i n C G D G ) : OEP; (CHa) 1.92, t; (CEfe ) 3.87, q; (H-meso), 9.65, s. Pyridine; (Ho), 1.97, m; (Hm), 4.04, m; (Hp), 4.65, m. These values are i n good agreement with the l i t e r a t u r e . 2 7 Ov/vis Spectrum- ( C G H S , Amax.nm (log € ) ) : 521 (4.71); 495 (4.16); 450 (4.21); 395 (5.11) (Soret). As with Ru(OEP)(CO)py, only the € values obtained using a 1.0 mm c e l l ( X ^ 495, 450) agreed well with the l i t e r a t u r e ; 2 7 those obtained with a 0.10 mm c e l l (\= 521, 395) were found to be too high. This w i l l be discussed i n section 2.2.1. 2.1.4.4 r R u(0EP ) l 2 Following a procedure recently described by Collman et a l . , 2 8 100-300 mg of Ru(0EP)py 2 were pyrolyzed i n vacuo 19 (2x10-5 t o r r ) at a temperature of 220° C. The progress of the reaction was followed by monitoring the pressure within the vacuum manifold with a Penning gauge (Bendix GPH 320 gauge; GPH 001 high vacuum discharge tube). Onset of reaction was characterized by a dramatic increase i n pressure as the pyridine was evolved, followed by a steady return to the s t a r t i n g pressure as the reaction approached completion. The a i r -se n s i t i v e product was stored i n a dry, oxygen-free glove box (see section 2.3.3.1). Although elemental analysis showed the product to be a n a l y t i c a l l y pure, nmr spectra i n v a r i a b l y showed traces (< 1 %) of the s t a r t i n g material. Y i e l d (crude product)- 92 %. Analysis- Calculated f o r C7 2H8 8NsRu2 (1265.8 g/mole): C, 68.10 %; H, 6.99 %; N, 8.84 %. Found: C, 68.29 %; H, 7.00 %; N, 9.00 %. Nmr- (6ppm i n C G D G ) : (CH3 ), 3.43, t; ( C H 2 a ) , 11.08, sex; ( C H 2 M , 25.75, sex; (H-meso), 10.13, s; i n good agreement with the l i t e r a t u r e (the two methylene protons are anisochronous, and so give r i s e to separate s i g n a l s ) . 2 8 Uv/vis Spectrum- ( C G H G , A*ax,nm): 650; 624; 545; 527; 503; 373, (Soret); i n good agreement with the l i t e r a t u r e . 2 * 2.1.4.5 Ru(0EPUDPS)2 Using the equipment and procedures described i n section 2.3.3.3, 78 mg (0.42 mmol) of DPS were added to 100 mg (0.079 mmol) of [Ru(0EP)]2, together with 20 mL of dry C H 2 C I 2. The 20 solvent was slowly removed, under vacuum at room temperature, while the solution was s t i r r e d . As the solution became more concentrated, the colour changed from brownish green to bright red. When a l l of the solvent had been removed (approximately 45 min were needed), the red s o l i d was dissolved i n 30 mL of n heptane, and the mixture f i l t e r e d to remove trace Ru(0EP)py 2. The solution volume was reduced to 14 mL under vacuum, and the solution allowed to r e f l u x u n t i l no s o l i d was detectable (caution- see note i n section 2.3.3.3 about heating solutions closed systems); the solution was then l e f t to stand overnight at room temperature. The c r y s t a l s thus obtained were suitable f o r an X-ray structure determination. Y i e l d ( p u r i f i e d product) 42 %. Analysis- Calculated f o r C 6 0 H 6 4 N 4 S 2 R U (1006.4 g/mol): C, 71.61 %; H, 6.41 X; N, 5.57 %. Found: C, 71.87 %; H, 6.53 % N, 5.80 %. Nmr- (6ppm i n C G D G ) : OEP; (CH3 ), 1.93, t; (CH2), 3.90, q; (H-meso), 9.50, s. DPS; (Ho), 4.04, br; (Hm), 6.08, br; (Hp), 6.37, br. The integrations were i n agreement with these assignments. Dv\vis Spectrum- ( C G H G , \rnax,nm ( l o g € ) ) : 527 (4.28); 502 (4.07); 408 (5.38) (Soret). 2.1.4.6 Ru(OEP)(DecMS)2 To 75.7 mg (0.0598 mmol) of [Ru(0EP)]2, were added 67.4 mg (0.359 mmol) of DecMS, and 5 mL of CH2CI2, using the procedure 21 described i n section 2.3.3.3. The colour of the solution immediately changed from brownish green to red. The solvent was removed under vacuum at room temperature, and the r e s u l t i n g o i l heated to 50° C under dynamic vacuum f o r an hour to remove excess DecMS. The reddish-purple s o l i d was now dissolved i n 8 mL of n-pentane, and the mixture f i l t e r e d to remove trace Ru(0EP)py a . To the f i l t r a t e were added 50 mL of MeOH, which formed a separate layer below the pentane layer. The two layers were allowed to stand f o r 20 h at room temperature, and then a further 10 h at 5° C. Crystals formed at the solvent/solvent interface, and then dropped to the bottom of the f l a s k . These c r y s t a l s were a n a l y t i c a l l y pure even when they were f i l t e r e d o f f aerobically, although uv/vis absorption spectrometric analysis (\naz,nm) of the air-exposed f i l t r a t e , which contained a small amount of complex s t i l l i n solution, suggested the presence of a Ru 1 1 (0EP)(C0)L complex (these complexes have very c h a r a c t e r i s t i c uv/vis absorption s p e c t r a ) . 2 8 The source of carbonyl may well be the solvent; Ru-complex catalyzed decarbonylation of methanol has been observed previously i n our l a b o r a t o r i e s , 3 0 and i s es p e c i a l l y p l a u s i b l e here given that Ru(OEP)(DecMS)2-promoted decarbonylation was observed under many conditions i n the course of the present studies (see chapter IV). Crystals of Ru(OEP)(DecMS)2 suitable f o r X-ray c r y s t a l structure analysis were obtained by r e c r y s t a l l i z i n g from n-propanol, but the y i e l d from t h i s procedure was considerably lower than f o r the one described above. 22 Y i e l d - R e c r y s t a l l i z a t i o n from MeOH/n-pentane: 81 %, from n-propanol: 40 %. Analysis- Calculated f o r C 5 8 H 9 2 N 4 S 2 R U (1010.4 g/mol): C, 68.93 %; H, 9.18 %; N, 5.54 %. Found: C, 68.94 %; H, 9.19 %, N, 5.35 %. Nmr- (6ppm i n C G D G ) : OEP; ( C H 3 ) , 1.99, t; ( C H 2 ) , 3.98, q; (H-meso), 9.70, s. DecMS; (CH3 #1'), -2.51, s; (CH2 #1), -2.46, t (br); (CH2 #2), -1.17, qn (br); (CH2 #3), -0.30, qn; (CH2 #4), 0.30, qn; (CH2 #5), 0.72ppm, qn; (CH2 #6), 1.00, qn; (CH2 #7), 1.13, m; (CH2 #8), 1.21, m; (CH2 #9), 1.29, sex; (CH3 #10), 0.93, t . The integrations were i n agreement with these assignments. Uv/vis Spectrum - ( C G H G , \ma* ,nm (log €)): 525 (4.42); 498 (4.16); 408 (5.23) (Soret). 2.2 Instrumentation 2.2.1 U l t r a v i o l e t / V i s i b l e Absorption Spectroscopy (Uv/Vis) Uv/vis absorption spectra were recorded on a Cary 17 spectrophotometer. Quartz c e l l s nominally of 1.0 mm and 0.10 mm path length were used. Results obtained were found to be very reproducible; p l o t s of absorbance vs concentration based on f i v e data points including (0,0) consistently gave c o r r e l a t i o n c o e f f i c i e n t s of 1.00 f o r experiments done i n a i r , and of 0.988 or better f o r i n vacuo experiments. Ru(Porp) solutions used f o r aerobic determinations were t y p i c a l l y made up i n 50-100 mL 23 volumetric f l a s k s , using about 10 mg of complex; f o r anaerobic determinations, f o r p r a c t i c a l reasons, solutions were made up i n 10 mL portions using 1-6 mg of Ru(Porp). The greater scatter observed f o r the anaerobic determinations could be attributed d i r e c t l y to the greater error associated with weighing a smaller amount of complex. The exti n c t i o n c o e f f i c i e n t s f o r known complexes obtained using 1.0 mm c e l l s d i d not d i f f e r s i g n i f i c a n t l y from l i t e r a t u r e values; the same was not true of those obtained using 0.10 mm c e l l s , which were about 34 % higher on the average than the l i t e r a t u r e values. The source of such a large discrepancy i s not clear ; i t may be that the recorded l i t e r a t u r e 2 ? data f o r the Soret bands i s incorrect, but u n t i l t h i s i s ascertained the large deviations from the l i t e r a t u r e values make the exti n c t i o n c o e f f i c i e n t s obtained with a 0.1 mm c e l l inadequate f o r i d e n t i f i c a t i o n of a p a r t i c u l a r complex. S t i l l , the advantage of being able to obtain l i n e a r and reproducible absorbance vs. concentration p l o t s of r e l a t i v e l y highly concentrated Ru(Porp) solutions makes the technique valuable f o r many applications where r e l a t i v e changes i n spectra only are required. The baseline f o r each spectrum was obtained from a blank solution a f t e r each run; matched c e l l s were not used. Spectra f o r Ru(OEP)(DPS)2 and [Ru(0EP ) ]2 were obtained i n -vacuo using the apparatus described i n section 2.3.3.4. In addition, the spectra f o r Ru(OEP)(DPS)2 were obtained i n the presence of a 50-fold excess of free DPS. A l l other spectra 24 could be obtained a e r o b i c a l l y i f s u f f i c i e n t l y concentrated samples were used, and i f spectra were obtained immediately a f t e r sample preparation. 2.2.2 Infrared Spectroscopy (Ir) The i r spectra f o r Ru 3(CO) u were obtained on a Nicolet 5DX single beam i r spectrometer, operating i n Fourier transform mode. Samples were dissolved i n n-hexane, and observed as t h i n f ilms between KBr plates. 2.2.3 Nuclear Magnetic Resonance Spectroscopy (Nmr) The spectra of Ru(OEP)(DPS)2 and of Ru(OEP)(DecMS)2 were i n i t i a l l y recorded on a Bruker WH-400 FT instrument, i n order to give maximum resolution f o r peak assignment. The spectrum of Ru(OEP)(DecMS)2 was completely assigned using spin decoupling and, where peaks were too close together f o r spin decoupling, spin t i c k l i n g . In the l a t t e r case, the procedure used i n practice was to s e l e c t i v e l y i r r a d i a t e a single peak of a p a r t i c u l a r signal i n several d i f f e r e n t runs, each time varying the i n t e n s i t y of the radiation. At the low i n t e n s i t y end, no change i n the res t of the spectrum was observed; at the high end, a l l adjacent signals were affected. At intermediate i n t e n s i t i e s , several spectra were obtained where the affected signals could be unequivocally assigned to protons adjacent to those being i r r a d i a t e d . Variable temperature studies on Ru(0EP)(DPS)2 and Ru(OEP)(DecMS)2 were performed using a Varian 25 XL-300 FT instrument. Other experiments involving Ru(OEP)(DPS)2 or Ru(OEP)(DecMS)2 were c a r r i e d out on the 300 or 400 MHz instrument according to a v a i l a b i l i t y . Nmr spectra f o r routine characterization of Ru(Porp) complexes other than the thioether ones were recorded using a Bruker WP-80 FT instrument. 2.2.4 Gas Chromatography/Mass Spectrometry (GC/MS) GC/MS analysis of the products of DecMS autoxidation i n the presence of Ru(OEP)(DecMS)2 (see chapter IV) was c a r r i e d out using a Varian V i s t a 6000 Gas chromatographer, and a Vermag R10-10 mass spectrometer. The GC conditions were as follows: 30 m x 25 mm DB-1 c a p i l l a r y column with a 0.25 um f i l m thickness; sample volume, 2 uL; i n j e c t o r temperature, 280° C; oven temperature program, 120° C f o r 5 min, increased at a rate of 30° C/min u n t i l 250° C was reached, then held f o r 20 min. 2.2.5 Elemental Analysis Elemental analyses were c a r r i e d out by Mr. P. Borda of t h i s department. 2.2.6 X-Ray Cryst a l Structure Determinations The X- ray c r y s t a l structure determination of Ru(OEP)(DPS)2 was c a r r i e d out by Dr. S. J. R e t t i g of t h i s department. The c r y s t a l structure of Ru(OEP)(DecMS)2 was solved by Dr. J. A. Ibers of Northwestern University, Evanston, 111. Experimental d e t a i l s f o r the solution of both structures are included i n an 26 appendix. 2.3 Special Experimental Techniques and Equipment 2.3.1 High Pressure Synthesis of Ru 3(CO), 2 The high pressure apparatus used i n the synthesis of RujCCO), was designed and made by Baske r v i l l e and Lindsay Ltd. of England, and i s i l l u s t r a t e d i n figures 2.2 and 2.3. The reaction chamber i s transportable, and s o l i d s and l i q u i d s could be loaded and emptied i n the main laboratory (caution- remove the bomb cover i n the fume hood a f t e r using the apparatus f o r carbonylation reactions!). The rest of the high pressure apparatus i s housed i n two dedicated rooms, with the source gas cylinder and control panel i n one room, and the bomb assembly i n the other. The procedure used to assemble the apparatus i s as follows. The reaction chamber was lowered into the heating block using the removable carrying hoop, and taking care to a l i g n the f l a t spot (2) on the casing (shown i n fi g u r e 2.2c) with the corresponding f l a t spot i n the heater cavity. At t h i s point the carrying hoop could be removed, and the bomb cover rotated so that the gas e x i t tube could be e a s i l y f i t t e d to the gas ex i t port. The hold-down block was screwed as f a r as i t could go on to the bomb casing, but making sure that the gas e x i t tube was not obstructed by the hold-down b o l t s ( i t i s not necessary f o r the block to be screwed down the whole way). Using a torque F i g u r e 2.2. (a) C o n t r o l P a n e l f o r t h e B a s k e r v i l l e and L i n d s a y H i g h p r e s s u r e R e a c t o r : (1) Main Power S w i t c h ; (2) A g i t a t o r S o l e n o i d S w i t c h ; (3) Heate r S w i t c h e s ; (4) Bomb Temperature S e t -P o i n t I n d i c a t o r ; (5) Bomb Temperature Gauge; (6) S e t - P o i n t C o n t r o l and Bomb Thermocouple C a l i b r a t i o n Screws, (b) C a r r y i n g Hoop. ( c ) E x p l o d e d View o f t h e R e a c t i o n Chamber: (1) Bomb C a s i n g ; (2) A l i g n m e n t Spot; (3) A g i t a t o r Assembly; (4) Bomb Cover; (5) Gas E x i t P o r t ; (6) Gas E x i t Tube R e t a i n i n g B o l t ; (7) Bomb Stem; (8) Thermocouple P o r t ; (9) Thermocouple Sheath. (See S e c t i o n 2.3.1 f o r E x p l a n a t i o n s ) . 28 F i g u r e 2.3. The B a s k e r v i l l e and L i n d s a y H i g h P r e s s u r e Apparatus as i t Appears When F u l l y Assembled: (1) He a t e r ; (2) Bomb Cover Hold-Down B l o c k ; (3) Bomb Cover Hold-Down B o l t s ; ( 4 ) Gas E x i t Tube and C o n t r o l V a l v e ; (5) A g i t a t o r R e l a y S o l e n o i d ; (6) B u r s t i n g Cap Assembly; (7) Gas E n t r y Tube and C o n t r o l V a l v e ; (8) B u r s t i n g Cap; (9) Bomb P r e s s u r e Gauge; (10) Thermocouple. I n s e t : C o r r e c t Order f o r t h e T i g h t e n i n g of t h e Bomb Cover H o l d -Down B o l t s . (See S e c t i o n 2.3.1 f o r E x p l a n a t i o n s ) . 29 wrench, the cover hold-down bol t s were tightened i n 10 f t - l b increments, and i n a r a d i a l pattern (see inset i n figur e 2.3), to 50 f t - l b s . The l a t t e r sequence i s extremely important: uneven  tightening of the hold-down bolts could lead to damage of the  cover seal, and to dangerous leakage of CO. With the hold-down block i n place, the gas e x i t tube and thermocouple could now be inserted into t h e i r respective ports. The gas e x i t tube re t a i n i n g bolt, and a l l fastenings other than the bomb cover hold-down bolts, were simply tightened as much as was practicable with the appropriate t o o l s . The agitator relay solenoid, which activates the agitator to move up and down, was lowered into place and connected, and the bursting cap assembly screwed on to the top of the bomb stem. Before t h i s was tightened completely, the gas entry tube should be screwed i n hand t i g h t to ensure that proper alignment i s possible. At t h i s point, with the apparatus f u l l y assembled, a complete check was car r i e d out to make sure that a l l the bo l t s were f u l l y tightened. Then with the gas outl e t valve t i g h t l y closed and the i n l e t valve open one half of a turn, the bomb was pressurized using the flow regulating valve i n the adjacent room. With the main power switch on the control panel turned on, the agitator could be activated by turning on the solenoid switch. The system was allowed to s i t f o r 15 min to ensure that no s i g n i f i c a n t drop i n pressure was observed. If no leaks were observed, the desired temperature was set using the set-point control screw, and then the two heaters were turned on. 30 At the end of the reaction, the two heaters and the agitator were turned o f f , and the bomb was allowed to cool to room temperature (usually several hours were required). The main power switch was turned o f f , and the pressure i n the bomb released by opening the e x i t valve ( t h i s could be done from outside the room using an extension arm; the CO vent was at a window on the opposite end of the room). Disassembly of the apparatus was the exact reverse of assembly. 2.3.2 Photolysis The apparatus used i n the photolytic synthesis of Ru(0EP)py 2 i s i l l u s t r a t e d i n fi g u r e 2.4. The high i n t e n s i t y l i g h t source used was a 450 watt Hanovia mercury vapour lamp (Fisher Co.). Because l i g h t from t h i s source i s r i c h i n uv, which was found to promote destruction of the porphyrin ring, a uv-absorbing pyrex inner cooling jacket was used. The reaction c e l l was f i l l e d such that when the inner cooling jacket assembly was i n place, the solution reached to within approximately 1 cm of sidearm (B). Argon or dinitrogen entering at (A) served to keep an i n e r t atmosphere blanket over the reaction mixture, to agitate the mixture, and to purge i t of carbon monoxide. The condenser served to minimize loss of solvent during the course of the reaction. The exhaust from the condenser at (C) was vented outside of the laboratory. The whole apparatus, as drawn i n figure 2.4, was enclosed i n a s t e e l cabinet during photolysis, to prevent uv i r r a d i a t i o n of laboratory personnel. ) 31 V J F i g u r e 2 . 4 . E x p l o d e d V i e w o f t h e P h o t o l y s i s A p p a r a t u s Used i n t h e S y n t h e s i s o f R u ( 0 E P ) p y 2 . (1) H i g h I n t e n s i t y L i g h t S o u r c e . (2) P y r e x I n n e r C o o l i n g J a c k e t . (3) R e a c t i o n C e l l . (4) O u t e r C o o l i n g J a c k e t (Not U s e d ) . (5) C o n d e n s e r . (A) A r g o n I n l e t . (B) O u t l e t S i d e a r m . (C) A r g o n O u t l e t . The I n l e t s and O u t l e t s a r e Capped w i t h Rubber S e p t a . (See S e c t i o n 2 . 3 . 2 f o r e x p l a n a t i o n s ) . 32 2.3.3 Anaerobic Manipulations Because many of the compounds prepared i n t h i s project were a i r - s e n s i t i v e to some degree, a va r i e t y of techniques was used i n t h e i r manipulation. Compounds moderately a i r - s e n s i t i v e i n solution, such as Ru(0EP)py 2, were handled under a blanket of p u r i f i e d argon, using a hybrid of commonly used Schlenk and syringe techniques. 3! [Ru(0EP ) ]2 and Ru(OEP)(DPS)2 were both extremely a i r -s e n s i t i v e i n solution, and were more conveniently handled i n -vacuo using techniques described below. Although Ru(OEP)(decMS)2 was not found to be overly a i r - s e n s i t i v e i n hydrocarbon solvents, i t was found to be somewhat more reactive toward a i r i n other solvents such as alcohols. Because i t was no more d i f f i c u l t to use the vacuum techniques described f o r Ru(OEP)(DPS)2 than the less rigorous i n e r t atmosphere techniques, i n general a hybrid of techniques was used according to convenience. 2.3.3.1 Glove box [Ru(0EP ) j2 i s dioxygen-sensitive i n the s o l i d state, and so was stored and transferred from container to container i n a D r i -Lab HE-43-2 glove box. The dinitrogen atmosphere within the box was continuously r e c i r c u l a t e d through a Dri-Train HE-493 p u r i f i c a t i o n tower packed with 2.4 Kg of 3 A molecular sieves, 1.5 Kg of 7A molecular sieves, and 2 Kg of Ridox deoxygenation catalyst. The pressure within the box was monitored 33 automatically by a Pedatrol HE63-P automatic pressure c o n t r o l l e r . This treatment kept the concentration of 02 and H2O below lppm, as evidenced by the long l i f e t i m e of an exposed 25-Watt l i g h t bulb filament within the box.32 2.3.3.2 O i l D i f f u s i o n Pump The high vacuum necessary f o r the synthesis of [Ru(0EP)]2 was obtained using an a l l - g l a s s o i l d i f f u s i o n pump made i n t h i s department. The o i l used was Dow Corning 704 s i l i c o n e d i f f u s i o n pump f l u i d . 2.3.3.3 Synthesis and i n Vacuo Manipulation of Ru(OEP)(DPS)2 and  RufOEP)(DecMS)2 Figure 2.5 shows the apparatus used i n a t y p i c a l synthetic procedure f o r Ru(OEP)(DPS)2 or Ru(OEP)(DecMS)2. In preparation f o r the reaction, f l a s k (A) was charged with [Ru(0EP)]2 i n the glove box, and f l a s k (B) with the desired dry solvent, which was then degassed. Flask (A) was evacuated, and the low v o l a t i l i t y thioether was introduced into i t s sidearm (with a l l taps closed), before assembling the whole apparatus. A f t e r assembly, tap 3 was opened to degas the thioether, while the sidearm of the reaction vessel was cooled with a cotton swab dipped i n l i q u i d dinitrogen, to prevent trace evaporation ( t h i s i s more important i n the case of DecMS which i s more v o l a t i l e ) . After approximately 20 min, tap 3 was closed, and tap 2 opened to allow solvent to condense into sidearm (A). Tap 1 was then 34 F i g u r e 2.5. Vacuum T r a n s f e r C r o s s Set up f o r S y n t h e s i s of R u ( O E P ) ( T h i o e t h e r ) 2 . Taps ( l ) - ( 3 ) Were Kontes H i g h Vacuum T e f l o n V a l v e s . (4) Mag n e t i c S t i r r i n g Bar. (See S e c t i o n 2.3.3.3 f o r E x p l a n a t i o n s ) . 35 opened, and the f l a s k tipped to allow the accumulating solution of thioether to flow into i t . When a l l of the thioether had been transferred, f l a s k (A) was cooled with l i q u i d dinitrogen u n t i l the desired amount of solvent transferred over, at which time taps 1 and 2 could be closed, and tap 3 reopened. From t h i s point on, the reaction vessel could be heated or cooled as desired, and solvents could be added or removed by the vacuum tran s f e r process as proved necessary, while always keeping the reaction vessel under vacuum. Three cautionary notes must be mentioned. F i r s t , although the Kontes type high-vacuum valves were found to hold a dynamic vacuum down to l x l O - 5 t o r r consistently, under s t a t i c vacuum they were much les s r e l i a b l e . They were found to hold around 6 x l 0 _ 4 t o r r f a i r l y consistently f o r the period of time i t took to transfer solvent; however, an e f f o r t was made to minimize the time that tap 3 remained closed, or the time that f l a s k (B) was o f f the l i n e while changing solvents, when the complexes i n f l a s k (A) were i n solution. The second note involves the freezing and thawing of alcohols, and even of C H 2 C I 2. These solvents have f a i r l y high c o e f f i c i e n t s of thermal expansion, and can e a s i l y fracture a f l a s k i f proper care i s not taken. To prevent t h i s p o s s i b i l i t y , f l a s k (B) was never f i l l e d beyond the point indicated by the dotted l i n e i n figur e 2.5, when suspect solvents were used. In the case of the r e c r y s t a l l i z a t i o n of Ru(OEP)(DecMS)2, where 50 ml of MeOH had to be degassed, a 250 ml round bottom f l a s k was used. One f i n a l note involves the 36 heating of f l a s k (A) during r e c r y s t a l l i z a t i o n of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2. Care should be taken not to heat the solution too f a r beyond the solvent's ambient pressure b o i l i n g point, as t h i s could r e s u l t i n an explosion. In any case, an explosion s h i e l d i s recommended. 2.3.3.4 Anaerobic Uv/Visible Absorption and Nmr Spectroscopy  Determinations Anaerobic u v / v i s i b l e absorption and nmr spectroscopy determinations were made using the apparatus outlined i n figures 2.6(a) and (b). In preparation f o r a uv/vis experiment, the bulb was charged with the necessary amount of complex. The apparatus was assembled, and connected by j o i n t (4) to the transfer cross shown i n f i g u r e 2.5, replacing f l a s k (A). The desired solvent was now vacuum transferred over as described previously, and the solution spectrum obtained f o r the Q bands using the 1.0mm c e l l , and f o r the Soret using the 0.10mm c e l l . (Note- the solvent was always c o l l e c t e d i n the re s e r v o i r bulb; the quartz c e l l s should never be cooled or heated r a p i d l y as t h i s w i l l often crack them). Because the c e l l had to be detached from the dynamic vacuum source while the spectrum was taken, i t was best to obtain the spectrum immediately, e s p e c i a l l y since solutions required f o r u v / v i s i b l e spectroscopy of porphyrins tend to be rather d i l u t e , and even traces of oxygen could have a detectable e f f e c t on the a i r - s e n s i t i v e compounds. For nmr determinations, the s o l i d sample was introduced into the tube shown i n 37 F i g u r e 2.6. A pparatus Used t o O b t a i n (a) U v / v i s A b s o r p t i o n , and (b) Nmr S p e c t r a under A n a e r o b i c C o n d i t i o n s , as D e s c r i b e d i n S e c t i o n 2.3.3.4. (1) 1.0 mm C e l l . (2) 0.1 mm C e l l . (3) R e s e r v o i r B u l b . ( 4 ) , (5) C o n n e c t i o n s t o t h e T r a n s f e r C r o s s . (6) S e a l i n g P o i n t . 38 figure 2.6(b); the tube was then attached to the transfer cross v i a sidearm (5) i n order to add the degassed solvent. Once the desired amount of solvent had been transferred, the tube was flame sealed at (6). The t e f l o n valve allowed f o r preparation of samples from [Ru(0EP ) ]2 , which was loaded as a s o l i d i n the glove box; the valve also allowed f o r the addition of excess thioether to the s o l i d sample, using the technique described i n section 2.3.3.3. 39 CHAPTER III  PHYSICAL CHARACTERIZATION  OF Ru(OEP)(DPS)2 AND Ru(OEP)(DecMS)2 RESULTS AND DISCUSSION 3.1 UV"/Visible Absorption Spectra The uv/vis absorption spectra f o r Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2 are shown i n figures (3.1) and (3.2). Several of the observed bands are common to a l l metalloporphyrin spectra, and can be l a b e l l e d using the well established nomenclatures 3 l i s t e d i n table I. A l l of these bands have been attributed to JC-IC* t r a n s i t i o n s on the porphyrin r i n g . 3 3 In addition to these prominent peaks, there are also several weaker underlying bands whose o r i g i n i s less c e r t a i n . The presence of such "extra" bands appears to be t y p i c a l f o r Ru(II) porphyrins and some other metalloporphyrins, and attempts have been made to provide t h e o r e t i c a l explanations f o r t h e i r presence.2 7, 3 3 These bands w i l l not be discussed further here, except to say that they are very l i k e l y of charge-transfer o r i g i n , and that they represent a perturbation of the t y p i c a l porphyrin spectrum ( i e : a spectrum having only the types of bands mentioned i n table I) by a metal center. Another better understood way i n which the Ru(II) center a f f e c t s the porphyrin spectrum i s that the metal causes the two Q bands to s h i f t hypsochromically r e l a t i v e to those of free base 40 TABLE I Assignments f o r the Major Dv/Vis Absorption Bands of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2 A (nm) Q Bands B Bands Q(0,0) Q(l.O) B(0,0) B(1,0) N Complex (a) (3) (Soret) Ru(0EP)(DPS)2 528 502 408 389 353 Ru(0EP)(DecMS)2 525 498 407 388 354 See sections 2.1.4.5 and 2.1.4.6 f o r molar ex t i n c t i o n c o e f f i c i e n t s of the Q bands and the Soret. 4 1 Mnm) 400 500 600 F i g u r e 3 . 1 . U v / v i s A b s o r p t i o n Spectrum of Ru(OEP)(DPS ) 2 ( E x t i n c t i o n C o e f f i c i e n t s f o r t h e M a j o r Bands Are L i s t e d i n S e c t i o n 2 . 1 . 4 . 5 ; Assignments f o r t h e Porp. TI—K* T r a n s i t i o n s Are L i s t e d i n T a b l e I ) . 42 M n m ) 4 0 0 5 0 0 6 0 0 F i g u r e 3.2. U v / v i s A b s o r p t i o n Spectrum of Ru(OEP)(DecMS)2 ( E x t i n c t i o n C o e f f i c i e n t s f o r t h e Major Bands Are L i s t e d i n S e c t i o n 2.1.4.6; Assignments f o r t h e Porp. 7r-7t* T r a n s i t i o n s Are L i s t e d i n T a b l e I ) . 43 porphyrins and of many other metalloporphyrins. A l l free-base porphyrins, as well as porphyrins containing group IA-VA metals of valences I-V respectively, have the Q(0,0) band between 570 and 600nm. Ru(II) porphyrins, and some other porphyrins with t r a n s i t i o n metal centers, have t h e i r Q bands s h i f t e d below 570nm. This i s attributed to metal to porphyrin J C - J C * backbonding, which tends to r a i s e the energy of the lowest T C * o r b i t a l of the p o r p h y r i n . 2 7 , 3 3 The degree to which the Q bands are s h i f t e d depends greatly on the a x i a l ligands. Antipas et a l . 2 7 prepared several Ru* I (OEP) and Os* I (OEP) complexes, and showed a c o r r e l a t i o n between the degree of metal to a x i a l ligand TC backbonding (predicted by i t e r a t i v e extended Huckel c a l c u l a t i o n s ) , and the extent to which the Q bands were sh i f t e d . E s s e n t i a l l y , the more metal to a x i a l ligand TC backbonding, the le s s blue-shifted were the Q bands. I t would be tempting to extrapolate from these r e s u l t s and t r y to estimate the degree of metal to a x i a l ligand i t backbonding f o r the thioether complexes; however, the donor atom of the a x i a l ligands i n t h i s case i s a t h i r d row element, whereas a l l of the complexes studied by Antipas et a l . had a x i a l ligands with second row donor atoms. This raises the p o s s i b i l i t y that the larger sulphur o r b i t a l s also a f f e c t the degree to which the Q bands s h i f t . U n t i l t h i s point i s more c a r e f u l l y investigated, such extrapolation i s unwarranted. Comparison of data f o r complexes with second and with t h i r d row a x i a l - l i g a n d donor atoms reveals an i n t e r e s t i n g trend. 44 TABLE II Some Ru(OEP)LL' Complexes L i s t e d i n Order of Increasing Wavelength of the Soret A. nm Complex Soret P a Refs. Ru(OEP)(NO)(OMe) 392 539 572 27 Ru(OEP)(CO)MeOH 393 517 549 28 Ru(OEP)(CO)EtOH 393 515 548 29 Ru(OEP)(CO) 393 512 547 29 Ru(OEP)(CO)(DecMSO) 395 518 549 (See Ch. IV) Ru(OEP)py 395 495 521 27 Ru(OEP)(CO)py z 396 518 549 27 Ru(OEP)[P(pCH3 0 P h ) 3 ] 2 396 505 533 34 Ru(OEP)(DecMSO)2 398 525(Br) (See Ch. IV) Ru(OEP)(CO)(DecMS) 401 518 549 (See Ch. IV) Ru(OEP)(DecMS)(DecMSO) 404 498 525 (See Ch. IV) Ru(0EP)(C0)(PPh3) 407 525 555 29 Ru(OEP)(DecMS)2 407 498 525 Ru(OEP)(DPS)2 408 502 528 Ru(OEP)(CO)(PnBu 3) 408 528 555 29 Ru(0EP)(PPh3)2 420 518 532 29 Rii(OEP)(PnBu 3)2 428 511 535 29 45 Table II l i s t s some of the Ru* I (0EP)L2 complexes i s o l a t e d to to date i n order of increasing wavelength of t h e i r Soret bands. It i s s t r i k i n g that a l l of the f u l l y characterized complexes (with the exception of Ru(OEP)[P(pCH3 0Ph)3]2), i n which P or S i s the donor atom of at lea s t one a x i a l ligand, have spectra with the Soret bands above 400nm, whereas a l l of the complexes i n which both the donor a x i a l atoms are second row elements, have spectra with Soret bands below 400nm. Moreover, within a series such as Ru(OEP)(PPhs)2, Ru(OEP)(PPh3)C0, and Ru(OEP)(CO)L, where L i s a ligand with a second row donor element, \ (Soret) decreases stepwise ( i n the c i t e d example X (Soret) goes from 420, to 407, to about 393nm). Such a trend could be a useful i n d i c a t i o n of whether a ligand i s bonding v i a a second row or a t h i r d row element, i n the case where a p a r t i c u l a r ligand has both available. Some examples of t h i s came up i n the present research; f o r example, complexes of the form Ru(OEP)(DecMS)(DecMSO) and Ru(OEP)(DecMSO)2 were prepared i n s i t u by t i t r a t i o n of Ru(OEP)(DecMS)2 with DecMSO (see chapter IV). The Soret band s h i f t e d from 407nm f o r the b i s -sulphide complex, to 404nm f o r the sulphide/sulphoxide, and to about 398nm f o r the b i s sulphoxide complex. Based on t h i s information, one might predict that f o r the l a s t two complexes, the sulphoxides are probably 0-bonded rather than S-bonded. Such predictions are supported by nmr studies, and could be v e r i f i e d by i n f r a r e d spectroscopy, though t h i s has not been done to date. 46 3.2 I H Nmr Spectra 3.2.1 General Comments Figures 3.3 and 3.4a show the room temperature 1H nmr spectra of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2, respectively. Two points about these spectra are immediately s t r i k i n g . The f i r s t i s that i n both spectra some of the peaks show broadening; t h i s i s e s p e c i a l l y noticeable i n the spectrum of Ru(OEP)(DPS)2, and suggests possible exchange processes. To address t h i s l a t t e r point, the temperature dependence of the spectra was studied. The r e s u l t s of these experiments are described i n section 3.2.2. The second point worthy of mention i s the remarkable complete re s o l u t i o n of a l l the signals of the bound DecMS ligand. I t i s not that t h i s r e s u l t i s surprising; the dramatic e f f e c t of r i n g currents on chemical s h i f t s has been known f o r three d e c a d e s , 3 5 i 3 6 • 3 7 and was f i r s t recognised i n porphyrins as early as 1959. 3 8 Nevertheless, few porphyrin complexes have been prepared i n which such a large space influenced by the r i n g current i s monitored by nmr s i g n a l s . 3 9 This, coupled with the f a c t that the c r y s t a l structure f o r the complex has been determined, may make t h i s an a t t r a c t i v e system f o r doing t h e o r e t i c a l studies to t r y and improve present models f o r r i n g current e f f e c t s . 4 0 To t h i s end, an e f f o r t was made to assign unambiguously a l l of the Ru(OEP)(DecMS)2 IH nmr signals. 47 ««/— 5 4 3 2 1 ppm F i g u r e 3.3. Room Temperature 400 MHz *H Nmr Spectrum of Ru(OEP)(DPS ) 2 i n CSDG ( t h e E x a c t Peak P o s i t i o n s , 6 ppm, f o r a l l t h e S i g n a l s Are L i s t e d i n S e c t i o n 2.1). 48 F i g u r e 3.4. (a) Room Temperature 400 MHz 1 H Nmr Spectrum of Ru(OEP)(DecMS)2 i n CeDe (b) Room Temperature 400 MHz I H Nmr Spectrum of Fr e e DecMS i n C6D6 ( t h e E x a c t Peak P o s i t i o n s , 8 ppm, f o r a l l t h e S i g n a l s Are L i s t e d i n S e c t i o n 2.1; See F i g u r e 2.1 f o r t h e T h i o e t h e r S k e l e t o n Numbering Mode). 49 The extent to which the nmr signals of bound DecMS are spread out r e l a t i v e to those of the uncoordinated ligand (figure 3.4b) serves as a v i v i d reminder of the p o t e n t i a l which metalloporphyrins have f o r use as d e r i v a t i z i n g agents, to aid i n the characterization of compounds which would otherwise have l H nmr spectra with unresolved signals. Again t h i s i s by no means a new i d e a , 4 0 but i t i s now becoming a p r a c t i c a l one, since simple synthetic procedures are available f o r the preparation of diamagnetic metalloporphyrin complexes from r e l a t i v e l y stable s t a r t i n g materials, such as Ru(0EP)py 2. 3.2.2 Temperature Dependence Studies 3.2.2.1 Spectrum of Ru(OEP)(DPS)2 At room temperature, a l l of the signals i n the Ru(OEP)(DPS)2 spectrum due to the DPS ligands are broad bands without any f i n e structure (figure 3.3). Figure 3.5 shows that as a sample of Ru(OEP)(DPS)2 i s cooled, the ligand phenyl peaks sharpen into two well defined t r i p l e t s and a doublet. No major difference i s detected i n the porphyrin peaks, which are f a i r l y sharp even at room temperature. Another i n t e r e s t i n g point i s that i n the low temperature spectra, two well defined multiplets appear at approximately 6.9 and 7.3 ppm, which are the positions at which the resonances f o r free DPS appear. 4! Figure 3.6 shows the r e s u l t s of heating a sample of Ru(OEP)(DPS)2 from room temperature to 80° C. As the temperature i s increased, the a x i a l 50 i ' ' ' ' i ' ' I I 1 1 ' ' ' i ' ' ' ' 1 1 1 • • 1 1 ' i ' 111 ' 11 M 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I 1 1 1 1 1 1 ' i t O . O 9 . 0 8 . 0 7 . 0 6 . 0 5 . 0 4 . 0 3 . 0 2 0 1 . 0 P P M F i g u r e 3.5. 300 MHz IH Nmr S p e c t r a of Ru(OEP)(DPS)2 i n Toluene-d8 a t D e c r e a s i n g Temperatures; From Bottom t o Top: (a) Room Temperature; (b) 0° C; (c) -20° C ( t h e E x a c t Room Temperature Peak P o s i t i o n s , 6 ppm, f o r a l l t h e S i g n a l s Are L i s t e d i n S e c t i o n 2.1). 51 0) CH, (d) Hota (c) (b) (a) (2) rfg>-C^CH3 H a H«» C H , t i i HJ>UI HJD| Toluene ft / Lbound C H j l . l Tj luene H*0 Imp L f r e e i -L±Ju » « 12 J O ii ie u t2 10 e . 4 { i'ey Figure 3.6. 300 MHz lH Nmr Spectra of Ru(OEP)(DPS)2 i n Toluene-d8 at Increasing Temperatures; From Bottom to Top: (a) Room Temperature; (b) 30° C; (c) 50° C; (d) 80° C (the Exact Room Temperature Peak Positions, 6 ppm, for a l l the Signals Are Listed i n Section 2.1). 52 ligand peaks broaden and s h i f t downfield towards the free DPS positions. At the same time, a s i g n i f i c a n t hump appears underlying the solvent peaks at approximately 7 ppm. In retrospect, t h i s hump i s v i s i b l e even i n the room temperature spectra, though much less evident. At 80° C a l l three peaks due to the bound ligand have coalesced with each other, and with the broad hump (which can now be p o s i t i v e l y assigned to free ligand), to give a single time-averaged peak at approximately 7 ppm. Correspondingly, a small unassigned peak at 3.5 ppm has grown into the t a l l e s t peak i n the spectrum, and three additional peaks, which at room temperature appeared f a i r l y i n s i g n i f i c a n t , have also grown to a prominence equal to that of the peaks due to the Ru(OEP)(DPS)2 complex. These four peaks, at the 80° C temperature, are c l e a r l y i d e n t i f i a b l e as belonging to the paramagnetic [Ru(0EP)]2 complex (the d r a s t i c a l l y s h i f t e d methylene proton peak at 20+ ppm i s e s p e c i a l l y d i a g n o s t i c ; 2 8 see section 2.1.4.4 f o r complete assignment of the room temperature 1U nmr spectrum of [Ru(0EP ) ] 2 ) . Two other points are of importance here. F i r s t , as part of one of the experiments to study the r e a c t i v i t y of Ru(OEP)(DPS)2 with dioxygen, (see chapter IV), an nmr spectrum of the complex i n the presence of a ten-fold excess of free DPS was taken i n vacuo at room temperature. This spectrum showed no peak at 3.5 ppm, sharp unshifted peaks f o r free DPS, and unshifted peaks f o r coordinated DPS, broadened to the same extent as they were i n the absence of excess free ligand. The f i n a l important 53 observation i s that although s l i g h t l y broadened, a l l of the porphyrin signals due to [Ru(0EP)]2 and Ru(OEP)(DPS)2 remain separate up to and including 80° C, suggesting that exchange between these species i s slow, even at the highest temperatures. A l l of the above observations can be explained i n terms of a minimum of two e q u i l i b r i a , outlined i n scheme 3.1: (1) Ru(0EP)(DPS)2 u> ^ Ru(0EP)(DPS) + DPS Ki (=k,/k-, ) (2) 2Ru(0EP)(DPS) ^ * [Ru(0EP)]2 + 2DPS K2 (=k a/k- 2) Scheme 3.1. Equations proposed to explain the observed temperature dependence of the nmr spectrum of Ru(OEP)(DPS)2 At room temperature, the combined equilibrium Ki Kz must incorporate f a i r l y slow exchange between Ru(OEP)(DPS)2 and [Ru(0EP ) ] 2 , since the porphyrin peaks f o r these two compounds are very sharp. The s i g n i f i c a n t broadening of the a x i a l ligand peaks can be explained, on the other hand, i f Ki i s assumed to be small, while ki and k-l are assumed to be much larger than k 2 and k - 2 . For peak broadening to be observed, two conditions should be f u l f i l l e d . 4 2 F i r s t , the protons on any i n d i v i d u a l molecule must be capable of changing t h e i r environment rapidly r e l a t i v e to the l i f e t i m e of the nmr excited state. Second, these protons must spend somewhat comparable times i n each 54 environment; otherwise, even though exchange might be rapid, the o v e r a l l average spectrum observed would be almost indistinguishable from that r e s u l t i n g from the proton being i n the more favourable environment. If ki<<k-i, then i n any given time period the protons on OEP would spend most of t h e i r time as Ru(OEP)(DPS)2, so that the averaged positions of the corresponding peaks would be i d e n t i c a l to the positions expected i f no averaging occurred. On the other hand, equilibrium (2) provides a pool of free ligand with which Ru(OEP)(DPS)2 can exchange, so any given molecule of DPS could d i s s o c i a t e from the complex, be replaced by another DPS molecule, and thus spend s u f f i c i e n t time i n the free state to give averaging. This would account f o r the observed broadening of the signals due to bound and free DPS. When a large excess of the free DPS i s added, the peaks due to free DPS are sharper because, on the nmr time scale, a smaller f r a c t i o n of DPS molecules w i l l spend time attached to the porphyrin complex. As the temperature i s increased, the combined equilibrium K1K2 apparently increases, g i v i n g r i s e to the increase i n i n t e n s i t y of the [Ru(0EP)]2 peaks, even though the rate at which Ru(0EP)(DPS)2 and [Ru(0EP)]2 are interchanged remains low on the nmr time scale. At the same time, both ki and k-i increase to the point where very rapid exchange i s occurring on the nmr time scale; t h i s and the ever increasing pool of free DPS re s u l t s i n a time-averaged peak f o r the DPS signals which i s f a i r l y close to the positions of the signals f o r free ligand. I t i s d i f f i c u l t 55 to say whether a s i g n i f i c a n t amount of Ru(OEP)(DPS) i s present at the higher temperatures; c e r t a i n l y no d i s t i n c t new nmr peaks can be discerned, but the porphyrin peaks of t h i s species might have chemical s h i f t s f a i r l y s i m i l a r to those of Ru(OEP)(DPS)2, and given the poor resolution obtained i n the high temperature spectra, and the rapid exchange between the two species, i t i s possible that the peaks due to both complexes are present, but are indistinguishable from each other. When the nmr sample tube i s cooled, the combined equilibrium K1K2 should s h i f t further to the l e f t . The f a c t that the i n t e n s i t i e s of the signals due to [Ru(0EP)]2 appear e s s e n t i a l l y the same at room temperature and at -20° C implies that [Ru(0EP)]2 and free DPS present are k i n e t i c a l l y trapped at the low temperature. I t i s i n t e r e s t i n g to note that once the sample was allowed to cool a f t e r heating, the brownish colour of the dimer remained f o r several hours, the red colour of the b i s -l i g a t e d complex being f u l l y regained only a f t e r a day or two. The slow reverse reaction (dimer to 6-coordinate complex) explains why during the synthesis of Ru(OEP)(DPS)2, the reaction mixture had to be concentrated before rapid conversion of [Ru(0EP)]2 to Ru(OEP)(DPS)2 was observed. Presumably, i f the reaction mixture used f o r the synthesis had been l e f t for a day or more at the i n i t i a l experimental concentration, i t would have eventually yielded an equilibrium concentration of the desired product. 56 3.2.2.2 Spectrum of Ru(OEP)(DecMS)2 At f i r s t glance, the IH nmr spectrum of Ru(OEP)(DecMS)2 (figure 3.4a) appears very straightforward; c e r t a i n l y the spectrum shows no abnormalities comparable to the broadening of the DPS signals i n the spectrum of Ru(OEP)(DPS)2. Nevertheless, upon closer inspection, i t does appear that the peaks due to the a x i a l ligand methylenes c l o s e s t to the sulphur (5= -2.46, -1.17ppm) are somewhat broadened. Indeed, cooling of the sample made t h i s broadening more pronounced, u n t i l at -60° C, the signals due to (CH2 #1) and (CH2 #2) were each s p l i t into two broad signals, with the remaining a x i a l ligand signals being broadened to a degree dependent on the distance of the corresponding methylenes from the center of the porphyrin r i n g (figure 3.7). The observed low temperature spectrum i s r e a d i l y r a t i o n a l i z e d , given the p r o c h i r a l nature of DecMS. Once a lone p a i r on the sulphur i s used i n a dative bond, the sulphur atom becomes a c h i r a l center. The Ru(OEP)(DecMS)2 complex has two such c h i r a l centers, and can thus presumably e x i s t i n two diastereomeric forms, which could give r i s e to separate nmr signals. In addition, the protons on any given carbon are now diastereotopic, and can also p o t e n t i a l l y give r i s e to separate signals. The f a c t that separate signals are observed at low temperature but not at room temperature suggests that at the l a t t e r rapid exchange takes place between the two sulphur lone pairs, giving r i s e to time averaging of the proton environments. 57 L (d) (c) (b) (a) Toluene u J CH, J CH, (CH34*T)l (CH3»10) (CH2#3-9)L (CH^2)L (CH,«1)L IMJ_LA_J I I . I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I I ' I I ' I I I I ' I II I 1 1 1 1 I 1 10 8 6 4 2 0 - 2 - 4 P P M F i g u r e 3.7. 300 MHz i H Nmr S p e c t r a of Ru(OEP)(DecMS)2 i n Toluene-d8 a t D e c r e a s i n g Temperatures; From Bottom t o Top: (a)Room Temperature; (b) 0° C; (c) -20° C; (d) -60° C ( t h e E x a c t Room Temperature Peak P o s i t i o n s , 6 ppm, f o r a l l t h e S i g n a l s Are L i s t e d i n S e c t i o n 2.1; See F i g u r e 2.1 f o r t h e T h i o e t h e r S k e l e t o n Numbering Mode). 58 The above explanation f o r the low temperature spectra implies that heating the sample should sharpen the ligand methylene nmr signals. Spectra were obtained f o r Ru(OEP)(DecMS)2 at 30, 50, and 80° C. Unfortunately these were broadened and poorly resolved i n a way s i m i l a r to the high temperature spectra of Ru(OEP)(DPS)2. If better resolved spectra could be obtained, perhaps the above prediction could be v e r i f i e d . The high temperature spectra were good enough to show that no broadening due to rapid exchange processes was occurring, and no [Ru(0EP)]2 was being produced i n detectable quantity. 3.3 Crys t a l Structures of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2 The c r y s t a l structures of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2 (figures 3.8 and 3.9) represent the f i r s t reported f o r Ru(Porp) complexes containing sulphur-bound a x i a l ligands; nevertheless, c r y s t a l structures of other types of Ru complexes containing Ru-S bonds have been reported. Some of these complexes, and the corresponding Ru-S bond lengths, are l i s t e d i n table III; figure 3.10 i l l u s t r a t e s the more complicated structures. From table III i t i s evident that Ru-S bond lengths span a f a i r l y wide range, between 2.188 A f o r [Ru(NHa)s(DMSO)]2 + , 4 3 a n d 2.450 A f o r Ru-S(2) i n cis,cis,cis-Ru(S0CPh ) 2(phen) ( P M e 2 P h ) 2 . « « The short Ru-S bond length i n [Ru (NH3)5(DMSO)]2+ and other S-bound sulphoxide complexes has been attributed to an increased bond order due to e f f i c i e n t metal to ligand Tt-backbonding i n these complexes. This e f f e c t i s enhanced i f the sulphoxide i s 5 9 F i g u r e 3 . 8 . ORTEP D r a w i n g o f t h e R u ( O E P ) ( D P S ) 2 C r y s t a l S t r u c t u r e , U s i n g t h e L a b e l l i n g Sys tem Employed i n t h e T e x t . The Same D r a w i n g A p p e a r s i n t h e A p p e n d i x w i t h t h e More Comple te Number ing Sys tem S u p p l i e d by t h e C r y s t a l l o g r a p h e r . 60 F i g u r e 3.9. ORTEP Drawing of t h e Ru(OEP)(DecMS)2 C r y s t a l S t r u c t u r e , u s i n g t h e L a b e l l i n g System Employed i n t h e Text. A n o t h e r Drawing of t h e Same S t r u c t u r e Appears i n t h e Appendix w i t h t h e More Complete Numbering System S u p p l i e d by t h e C r y s t a l l o g r a p h e r . 61 (a) o t Brf-S ( 2 )Et E t S(2)*f S<3) Br \) (b) M e ^ s ( w h 7 s / 3 ) Br-r-Br \ (0 EtS(2—Br, o / L^ (d) 0 t s-y  0 > I PPh3 s-f—CO i CO PPh. <« Me Me I Ph n u ^-^H-siT^o Phcn N Y 0 F i g u r e 3.10. Some Complexes C o n t a i n i n g Ru-S Bonds f o r Which C r y s t a l S t r u c t u r e s Have Been O b t a i n e d . R e f e r e n c e s and Ru-S Bond Lengths Are L i s t e d i n Ta b l e I I I . 62 TABLE III Ru-S Bond Lengths f o r Some Complexes Containing Ru-S Bonds Complex Bond Bond Length (A) Ref. [Ru(NHa)5(DMS0)]2+ 2.188(3) 43 [RuCla(DMS0)3]- 2.252(2)-2.273(5) 45 fac-[Ru(DMS0)3(DMS0)3] 2 + 2.260(3) 46 RuCl2(DMS0 )4 2.277(1) 47 trans - R u B r 2(DMS0 ) 4 2.360(1) 48 (a) Ru-Si 2.269(1) 49 Ru-S2 2.375(Av) Ru-S3 2.218(1) (b) Ru-Si 2.275(2) 49 Ru-S2 2.372(2) Ru-S3 2.235(2) Ru-S4 2.393(2) (c) Ru-Si 2.351(1) 50 Ru-S2 2.338(Av) Ru-S3 2.340(1) Ru(OEP)(DPS)2 2.3706(13) Ru(OEP)(DecMS)2 2.369(11) (cont.) 63 (Table III Cont.) (d) 2.362(1) 51 (e) Ru-Si 2.323(4) 52 R11-S2 2.379(4) (f) Ru-Si 2.399(2) 44 R11-S2 2.450(3) Those complexes i d e n t i f i e d with a lower-case l e t t e r are i l l u s t r a t e d i n figu r e 3.10. 64 trans to a ligand which i s both a o-donor and a non-ic-acceptor, such as a halide or ammine; conversely, the e f f e c t i s decreased i f the sulphoxide i s trans to another 7c-acceptor, such as another sulphoxide.5 3 At the high end of the scale, the long bond length of the Ru-S(2) bond i n cis,cis,cis-Ru(S0CPh)2(phen)(PMe2Ph)2 has been attributed to a decreased bond order caused by the strongly jc-accepting P(Me)2Ph ligand trans to i t . 4 4 The remaining Ru-S bond lengths provide a much narrower range, spanning 2.315-2.404 A. Five of these bonds involve thioether ligands, and i t can be seen that f o r thioether Ru-S bonds trans to other Ru-S bonds, the lengths are e s s e n t i a l l y i d e n t i c a l to those observed i n Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2. In complexes i n which there was no S-bonded or other p o t e n t i a l l y 7c-backbonding ligand trans to the thioether, the thioether Ru-S bond was found to be 0.02-0.05 A shorter, suggesting that thioethers are capable of some J C -backbonding. At t h i s point i t i s worth noting that Fe porphyrins containing S-bound a x i a l ligands are of i n t e r e s t i n biochemical c i r c l e s , as some enzymes are known to contain such units i n t h e i r active s i t e s . 5 4 . 5 5 » 5 6 Dnlike the Ru case, several c r y s t a l structures of Fe porphyrins with S-bound a x i a l ligands have been determined. 5 5! 5 6 In t h e i r 1981 review, Scheidt and Reed note that the Fe-S bond distances f a l l within a very narrow range between 2.324 and 2.360 A, and are r e l a t i v e l y i n s e n s i t i v e to 65 the nature of the sulphur ligand, spin state of the Fe, and coordination number of the complex. 5 5 Although a more recent a r t i c l e 5 6 reports an Fe-S bond length which f a l l s below the suggested range (at 2.298 A), the r e s u l t i n g variance i s s t i l l not great. I t would be i n t e r e s t i n g to see whether a greater variance was found within a series Ru porphyrins spanning a va r i e t y of ligands, coordination numbers, and metal oxidation states, e s p e c i a l l y given the wide range observed f o r Ru-S bonds i n general. Apart from the novelty of the Ru-S bonds, the two structures described do not appear to display any unusual features. The S-Ru-S axis i n both complexes i s not quite orthogonal to the porphyrin plane, but t h i s i s also observed i n other Ru porphyrins containing large a x i a l l i g a n d s , 3 * » 5 7 and i s l i k e l y due to c r y s t a l packing considerations. Table IV l i s t s some parameters of the porphyrin cores of Ru(OEP)(DPS)2, Ru(OEP)(DecMS)2, and some other Ru(Porp) complexes f o r comparison. De t a i l s of the data c o l l e c t i o n procedures, as well as a more extensive l i s t of parameters f o r the two new c r y s t a l structures, are given i n an appendix. TABLE IV Averaged Bond Lengths (A) and Angles (deg) for "the Porphyrin Core of Some Ru(Porp) Complexes Ru(TPP) Ru(TPP) Ru(TPP) ( C 0 ) ( p y ) 5 8 , * (C0)(Et0H )59 , * (OEt)(EtOH )H» $ Ru-N 2.052(9) 2.049(5) 2.040(6) N-Ca 1.370(9) 1.374(8) 1.377(5) Ca — Cm 1.395(10) 1.393(10) 1.398(5) Ca-Cb 1.446(11) 1.437(13) 1.437(13) Cb-Cb 1.333(11) 1.327(12) 1.350(6) Ca-N-Ca 107.8(6) 107.4(6) 106.6(3) N-Ca -Cb 108.3(8) 108.3(6) 109.3(3) N-Ca _Cm 126.4(7) 125.6(6) 125.6(4) Ca -Cb -Cb 107.8(8) 108.0(8) 107.4(4) Ca — Cm— Ca 125.0(7) 126.1(6) 125.6(4) (Cont.) * Data c o l l e c t e d at room temperature. $ Data c o l l e c t e d at -160° C. •c Data c o l l e c t e d at -150° C. See figures 3.8 and 3.9 f o r the porp. skeleton l a b e l l i n g mode. Table IV (cont.) 67 Ru(OEP) Ru(OEP) Ru(OEP) ( P h ) 2 G 0 , T (DPS )2* (DecMS)2 T Ru-N 2.047(3) 2.049(1) 2.046(6) N-Ca 1.377(13) 1.375(2) 1.374(4) Ca —Cm 1.393(3) 1.386(3) 1.389(5) Ca-Cb 1.453(3) 1.456(2) 1.453(5) Cb -Cb 1.364(3) 1.354(4) 1.357(6) Ca -N-Ca 106.6(5) 107.1 106.7(3) N-Ca-Cb 109.8(3) 109.3 109.7(3) N—Ca —Cm 124.7(6) 124.6 124.5(3) Ca-Cb-Cb 106.9(5) 107.1 107.0(3) Ca —Cm ~Ca 127.3(10) 128.3 127.8(4) c 68 CHAPTER IV  REACTIVITY OF Ru(OEP)(DPS)2 AND Ru(OEP)(DecMS)2 WITH DIOXYGEN As was mentioned i n chapter I, the p o s s i b i l i t y that complexes of the general formula Ru(OEP)(R2S)2 might catalyze oxidation by dioxygen of R 2 S provided the i n i t i a l incentive f o r the preparation of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2. This chapter w i l l describe some of the preliminary experiments that have been c a r r i e d out to investigate the r e a c t i v i t y of these two complexes toward dioxygen. 4.1 Ru(0EP)(DPS)2 Reactions of Ru(OEP)(DPS)2 with dioxygen were followed at room temperature using u v / v i s i b l e absorption and nmr spectroscopy. The e f f e c t s of varying Ru(OEP)(DPS)2 concentrations between 10 and 10 - 3 mM, of adding up to an 80-f o l d excess free DPS, and of adding a c e t i c acid to the reaction mixture, were a l l investigated. In every case studied, the f i n a l nmr and uv/vis spectra matched those expected f o r a mixture of [Ru(0EP)(0H)]2 0 and free DPS (figures 4.1a, b).n.«* The reaction was almost invari a b l y over i n minutes, with no intermediates being detected. However, at concentrations below 10 - 2 mM, and i n the presence of a 50-fold excess of free F i g u r e 4 . 1 . (a) 400 MHz I H Nmr, and (b) U v / v i s A b s o r p t i S p e c t r a o f t h e F i n a l P r o d u c t s o f t h e A i r - O x i d a t i o n o f R u ( O E P ) ( D P S ) 2 . 70 ligand, a transient intermediate with a broad Soret at 390 nm was observed by uv/vis spectroscopy. At concentrations of Ru(0EP)(DPS)2 i n the order of 10 -3 mM, -this intermediate was long l i v e d , and complete conversion to the [Ru(0EP)0H]2 0 took approximately two days. The intermediate spectra generated several i s o s b e s t i c points. The observed r e a c t i v i t y of Ru(OEP)(DPS)2 can be r a t i o n a l i z e d i n l i g h t of the r e s u l t s obtained from the temperature-dependence *H nmr studies (chapter I I I ) , which showed the complex to be i n equilibrium with [Ru(0EP ) ]2. The l a t t e r i s known to react r a p i d l y with dioxygen to give [Ru(OEP)OH]2 0 , 6 1 s o that even i f Ru(OEP)(DPS)2 i t s e l f were a i r - s t a b l e , i t could eventually be channelled to the u-oxo dimer v i a [Ru(0EP ) ] 2 . At t h i s point l i t t l e can be said as to the nature of the intermediate observed i n the d i l u t e solutions; however, a second order reaction such as dimer formation would be slow i n such solutions, and i t i s probable that the intermediate i s an oxidized monomeric species. I t should be added that i n the absence of a i r , the spectra observed f o r the d i l u t e solutions (XmaK Soret= 403 nm) were unlike the spectrum of Ru(OEP)(DPS)2 measured at higher concentrations (see section 2.1.4.5), and also unlike the spectrum of [Ru(0EP ) ]2 (see section 2.1.4.4). Whether the 403 nm spectrum was due to reaction of the Ru(OEP)(DPS)2 with trace impurities, or to a x i a l ligand d i s s o c i a t i o n i s uncertain. 71 4.2 Ru(OEP)(DecMS)2 4.2.1 Ru(OEP)(DecMS)2 i n the Absence of Added Free DecMS The r e a c t i v i t y of Ru(OEP)(DecMS)2 with dioxygen was found to be more in t e r e s t i n g , but much more complicated than that of Ru(0EP)(DPS)2. If a solution of Ru(OEP)(DecMS)2, of concentration between 1 and 0.1 mM i n benzene or toluene, i s exposed to a i r , a slow change i s observed i n the uv/vis spectrum, which generates several i s o s b e s t i c points (figure 4.2). In the f i r s t week, the Soret s h i f t s to 404 nm, the two Q bands broaden, the r a t i o of the i n t e n s i t i e s of the a and 0 bands decreases from about 1.8 to 1.5, and a shoulder appears at 549 nm. Addition of an excess of free DecMS at t h i s point leads to slow (a few hours to a day), nearly complete conversion back to the Ru(OEP)(DecMS)2 spectrum, except that the shoulder at 549 nm remains unchanged. If the solution i s l e f t exposed to a i r f o r a longer time the spectrum continues to change, but d i f f e r e n t i s o s b e s t i c points are now observed. This suggests that a t h i r d species i s being formed. A f t e r three months, the (3 peak i s no longer distinguishable, and only a broad band i s seen at 525 nm. The shoulder at 549 nm has become more prominent, and a new shoulder i s v i s i b l e on the Soret at 397 nm; s t i l l , the spectrum of the s t a r t i n g material can be regenerated by adding large amounts of free DecMS to the solution (figure 4.3). Again the reverse reaction takes several hours, and the peak at 549 nm i s not 72 F i g u r e 4.2. T y p i c a l U v / v i s A b s o r p t i o n S p e c t r a l Changes upon Exposure o f Ru(OEP)(DecMS)2 t o A i r . (1) B e f o r e and Immediately a f t e r Exposure t o A i r . (2) A f t e r One Day. (3) A f t e r Two Days (4) A f t e r Four Days. (5) A f t e r One Week. 73 M n m ) F i g u r e 4.3. U v / v i s A b s o r p t i o n Spectrum of a 0.188 mM Ru(OEP)(DecMS)2 S o l u t i o n a f t e r Three Months o f Exposure t o A i r ( 1 ) , and a t I n c r e a s i n g Time I n t e r v a l s A f t e r A d d i n g an Excess of A p p r o x i m a t e l y 103 Q f F r e e DecMS: (2) A f t e r about 3 h; (3) A f t e r 1 Day. 74 eliminated (figure 4.3 shows only part of the process, but the peak at 404 nm can be made to disappear completely). An nmr spectrum of the Ru(OEP)(DecMS)2 solution a f t e r three months i n a i r reveals one major set of porphyrin methyl and methylene peaks; the positions and shapes of these signals are t y p i c a l of Ruii(porp) species (figure 4.4a). 6 2 Five signals are seen i n the region between 9.4 and 10.3 ppm. This i s the region where the meso proton s i n g l e t s are usually observed, 6 2 and the f i v e signals can reasonably be assigned to the meso protons of f i v e new complexes; the meso proton signal f o r the s t a r t i n g material i s not detected. It was immediately suspected that two of the new complexes observed i n the nmr spectrum might be Ru(OEP)(DecMS)(DecMSO) and Ru(OEP)(DecMSO)2. As an i n i t i a l t e s t f o r t h i s p o s s i b i l i t y , Ru(OEP)(DecMS)(DecMSO) was prepared i n s i t u by t i t r a t i n g Ru(OEP)(DecMS)2 with DecMSO under an argon atmosphere. The progress of the r e s u l t i n g reaction was monitored by uv/vis spectroscopy (figure 4.5). A large excess of DecMS was added to the reaction mixture to " s t a b i l i z e " the possible Ru(OEP)(DecMS)(DecMSO) intermediate, and prevent further conversion to Ru(OEP)(DecMSO)2 (see below). The observed changes are quite s i m i l a r to those observed i n the f i r s t days a f t e r exposure of Ru(OEP)(DecMS)2 to a i r , except that no peak at 549 nm i s detected. If no excess of DecMS was added to a t i t r a t i o n mixture, then changes s i m i l a r to those observed i n the (a) Ru(OEP)(CO)L Ru(OEP)(DecMSO)2 Ru(OEP)(DecMS)(DecMSO) ? CHj C*H 6 C H , I • 1 • • I ' ' ' ' I ' ' ' ' I 1 ' ' ' I ' ' ' ' I ' 1 ' ' I ' 1 ' ' ) ' ' ' 1 4.5 4.0 J.S 3.0 2.5 2.0 1.5 1.0'PPM T _ T T 10 ~ - i — | — i — I — r S X. fcHjttl')L(Ru(0EP)(DecMS0)2] CHj^JLlRulOEPXDecMSOlj] nipTTniTlim'lI|llll[ll!T]!lll)llMI1lllj111![11U]1!l1)1tH|):i<ill'l|!UI|i:il|llll|l!ll l ' i ' • I ' r - r - i n - - r — r - p r i - i i T - I - T -(b) Ru(OEP)(DecMSO)j Ru(OEP)(DecMS)(DecMSO) Ru(0EP)lDecMS) 2 C H , CH. CH,#V)L[Ru(OEPXDecMSO). (CH^DLtRutOEPXDecMSCjj] I 1 1 1 • I 1 1 " I " 1 11 1 1 1 11 " " I • 1 1 1 I 1 1 1 'T D.5 0 . 0 -0-5 - 1 0 - 1 5 -70 - 2 . 5 W 0 HjO 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 1 1 ' 1 i 1 1 1 1 i 8 6 4 J 0 -2 PPM F i g u r e 4 . 4 . 300 MHz I H Nmr S p e c t r a o f : (a) t h e 0 .188 mM Ru(OEP)(DecMS)2 S o l u t i o n M e n t i o n e d i n F i g u r e 4 . 3 a f t e r Three Months o f E x p o s u r e t o A i r , C o n c e n t r a t e d and t h e R e s i d u e R e d i s s o l v e d i n C6Ds; (b) a Ru(OEP)(DecMS)2 S o l u t i o n t o w h i c h F o u r E q u i v a l e n t s o f DecMSO Have Been Added . (See F i g u r e 2 .1 f t h e T h i o e t h e r S k e l e t o n Number ing Mode) . A(nm) 400 500 F i g u r e 4.5. U v / v i s A b s o r p t i o n S p e c t r a l Changes upon T i t r a t i o n of a S o l u t i o n C o n t a i n i n g 0.129 mM Ru(OEP)(DecMS ) 2, and 22.2 mM Free DecMS, w i t h A l i q u o t s of a 26.9 mM S o l u t i o n of F r e e DecMSO. Spectrum (10) Was O b t a i n e d a f t e r a T o t a l A d d i t i o n of 940 uL of t h e DecMSO S o l u t i o n . 77 spectrum of Ru(OEP)(DecMS)2 l e f t exposed to a i r f o r some months were observed. Ru(OEP)(DecMSO)2 was now prepared i n a way s i m i l a r to that used to prepare Ru(OEP)(DPS)z and Ru(OEP)(DecMS)z . Elemental analysis of the prepared complex gave analysis f o r carbon approximately 1% too low, but the nmr spectrum was clean, and the signals e a s i l y assignable (figure 4.6). This nmr spectrum shows many signals which could correspond to some of those seen i n figure 4.4a. Figure 4.4b shows the nmr spectrum of a sample of Ru(OEP)(DecMS)2 to which 4 equivalents of DecMSO were added, and here meso peaks are seen at approximately 9.7, 9.9, and 10.0 ppm. The 9.7 ppm sign a l can be assigned to a very small amount of Ru(OEP)(DecMS)2, while the signal at 10.0 ppm can be assigned to Ru(OEP)(DecMSO)2 by comparison with the data of figure 4.6. F i n a l l y , i t seems reasonable to assign the signal at 9.9 ppm to Ru(OEP)(DecMS)(DecMSO). S i m i l a r i t i e s between other regions of figures 4.4a, 4.4b, and 4.6, e s p e c i a l l y below -2 ppm, support these assignments. One more product of the reaction of Ru(OEP)(DecMS)2 with dioxygen may be assigned. Most, i f not a l l Ru(0EP)C0(L) complexes known have uv/vis a bands at around 550 nm (see table I I ) , and the bubbling of CO through the solution of four month air-exposed Ru(OEP)(DecMS)2 immediately increased the i n t e n s i t y of the 549nm peak (figure 4.7a). Two Soret bands are v i s i b l e i n the spectrum of the carbonylated solution, one at 78 Figure 4.6. 400 MHz *H Nmr Spectrum of Ru(OEP)(DecMSO)2. The Unlabelled Signals Are at Exactly the Same Positions as those Assigned to the T a i l of the DecMS Decyl Chain i n the iH Nmr Spectrum of the Ru(OEP)(DecMS)2 Complex. (See Figure 2.1 for the Thioether Skeleton Numbering Mode). F i g u r e 4 . 7 . (a) U v / v i s A b s o r p t i o n S p e c t r a l Change Observed B u b b l i n g CO t h r o u g h t h e 0.188 mM Ru(OEP)(DecMS)2 S o l u t i o n Mentioned i n F i g u r e 4 . 3 , a f t e r t h e L a t t e r Had Been Exposed A i r f o r Three Months, (b) The Same Experiment F o l l o w e d by 300 MHz l H Nmr. 80 401, and the other at 395 nm; these are thought to correspond to Ru(OEP)(CO)(DecMS) and Ru(OEP(CO)(DecMSO), respectively. To strengthen t h i s hypothesis, CO was bubbled through a solution of Ru(OEP)(DecMS)2; the Soret s h i f t e d to 401 nm, and then, upon addition of excess DecMSO, to 395 nm. Figure 4.7b shows the nmr spectrum of the four month a i r -exposed Ru(OEP)(DecMS)2 solution a f t e r CO was bubbled through i t . The si g n a l at 10.2 ppm i s now the only one v i s i b l e , providing further evidence that one of the minor reaction products from the a i r oxidation was Ru(0EP)C0(L) (L = DecMS, DecMSO), and also i n d i c a t i n g that a l l the products of reaction could be converted to the carbonylated derivatives. One f i n a l point: the f a c t that only very broad signals are observed i n the region of the Ru(0EP)(C0)L nmr spectrum below 0 ppm, indicates that the non-carbonyl ligands are l a b i l e on the nmr time scale. Such l a b i l i t y has been observed f o r other Ru(Porp)(C0)L systems. 5 9 The other two meso proton signals observed i n the nmr spectrum of figur e 4.4a, found between 9.4 and 9.6 ppm, were not rea d i l y i d e n t i f i a b l e from the experiments performed; indeed, many signals i n spectrum 4.4a remain unaccounted f o r thus f a r . 4.2.2 Ru(OEP)(DecMS)2 i n the Presence of Added Free DecMS The above r e s u l t s were encouraging since they showed that DecMSO could be produced by exposure of Ru(OEP)(DecMS)2 to a i r , and also that the o v e r a l l reaction did not change the oxidation 81 state of at lea s t the bulk of the Ru. To explore the c a t a l y t i c p o s s i b i l i t i e s of the Ru(OEP)(DecMS)2 system, a series of experiments were now ca r r i e d out i n which a 60 to 140-fold excess of free DecMS was added to the metalloporphyrin solution. The changes i n Ru(OEP)(DecMS)2 upon exposure to a i r were then followed by uv/vis spectroscopy, while any products of free DecMS oxidation were detected by GC/MS analysis. In the f i r s t experiment, a benziene solution containing 0.246 mM Ru(OEP)(DecMS)2 and 15.5 mM DecMS was exposed to a i r f o r one week before GC/MS analysis was ca r r i e d out. Comparison with a blank solution containing DecMS, DecMSO, and D e c M S 0 2 , showed that the reaction mixture contained both DecMSO and DecMS02 free i n solution; the integrations f o r the corresponding peaks showed these to be 1.95 and 0.44 % of the i n t e n s i t y of the DecMS peak. In addition to these two peaks, a t h i r d peak with an int e n s i t y 3.02 % that of the DecMS peak was observed, f o r which no standard was available. The mass of the parent peak, and the fragmentation pattern, suggest that t h i s compound i s didecyldisulphide (figure 4.8a ) . B 3 Figure 4.9 shows the uv/vis spectrum of the reaction mixture at the time that the GC/MS analysis was c a r r i e d out. In the second experiment, the oxidation reactions were ca r r i e d out i n the presence of 0.14 equivalents of HOAc ( r e l a t i v e to the Ru(OEP)(DecMS)2 complex) to see i f the reaction rate was affected ( r e c a l l from chapter I that i f superoxide were produced i n an intermediate step, then the 82 (a) Bud I 15 143 40 GO SO IOO 1 2 0 140 43? 160 IftO 200 220 240 Z»0 *s320 540 3*0 360 1 " • " ' • * " I' (b) (C.oHj.lSSCH, C,,HMS21-H|I|I.,U, 1 • 1 " " ' ' • " 1 " " r 1 1 'I i \ •• • • 1 40 60 SO 100 130 140 160 16tJ 2O0 220 240 260 (C) I, 'f 4 0 eo ao too i» i*o ito tao aoo 2 2 0 7 4 0 K O ; /300 3 2 0 S 4 0 (d) c^sr 173 ll „ T , 1ff,, , , , ' ff , , r [ S (C „H 2 , ) ] 2 C ^ S S H ^ 1 ^ 40 60 • 0 IOO I T O 1 4 0 I S O 1BO 2 0 0 2 2 0 2 4 0 6 f ' i r 1 SOO 320 340 360 Figure 4.8. Mass Spectra of Some of the Products of Ru(OEP)(DecMS)2-Mediated Air-Oxidation of DecMS: (a) Didecyldisulfide; (b) Decylmethyldisulfide; (c) Didecylsulfide; (d) [ C 1 0 H 2 1 S 3 2 83 M n m ) 4 0 0 5 0 0 6 0 0 Figure 4.9. Uv/vis Absorption Spectrum of a Solution I n i t i a l l y Containing 0.246 mM Ru(OEP)(DecMS)2 and 15.5 mM DecMS, afte r One Week of Exposure to A i r . 84 oxidation rate might be increased when aci d i s added). A rate increase was indeed observed, and a f t e r 24 h a u v / v i s i b l e analysis showed nearly complete conversion to the Ru(OEP)(DecMS)(DecMSO) spectrum (figure 4.10a). Addition of more DecMS to a portion of the reaction mixture at t h i s point gave, as expected, nearly complete regeneration of the s t a r t i n g spectrum; however, at the time that the GC/MS analysis was ca r r i e d out one and a h a l f weeks l a t e r , the spectrum had changed completely (figure 4.10b), and the change was now e s s e n t i a l l y i r r e v e r s i b l e . 6 4 Looking at figu r e 4.10b, one can recognise the peak at 549 nm as probably a r i s i n g from Ru(OEP)(C0)L, but now a new prominent peak i s v i s i b l e at 615 nm, and i t i s apparent that the reaction mixture i s a complex one. It i s worth mentioning that an i d e n t i c a l spectrum was observed for the solution containing excess DecMS, but no HOAc, a f t e r i t had sat f o r 1.5 months. Indeed, i n retrospect, the 615 peak i s v i s i b l e i n figures 4.9 and 4.10a. The GC trace f o r the HOAc solution i s given i n figure 4.11. The peaks at 222 and 264 were present i n standard solutions of DecMS; they had the same parent mass as DecMS, and s i m i l a r fragmentation patterns, and are probably s t r u c t u r a l isomers of DecMS. The major peak at 1009 corresponds to DecMSO, by comparison with a standard solution. The peaks at 1654 and 2009 represent a b i t of a mystery. They have e s s e n t i a l l y i d e n t i c a l mass spectra, both i n turn i d e n t i c a l to the didecyldisulphide mass spectrum i l l u s t r a t e d i n figure 4.8a. Why two i d e n t i c a l peaks are observed i s not at a l l clear; i t may 85 c o Xi AC \ (a) \ 525 615 Mnm) 400 500 600 c a A(nm) 400 Figure 4 10 Uv/vis Absorption Spectra of a Solution I n i t i a l l y C o n t a i n i n g 1 24 mM Ru(OEP)(DecMS)2, 174 mM DecMS, and 0 175 mM HOAc (a) a f t e r 24 h. of Exposure to Air, (b) after One Week ot E x p o ^ r ^ t o A i r . (Samples Were A r b i t r a r i l y Diluted to Obtain Spectra on Scale). 86 114"S Zi 2* 5 = 0*1 £t42 B»22 10101 t i t 40 13i 19 14»5S 16«38 l&t I? iStZ? r r J—~~" ' • • ' • • • 352 100% " 2 | " 25.2V. 1092 Figure 4.11. GC Trace Showing the Product D i s t r i b u t i o n of the Thioether Oxidation Described i n Figure 4.10. The Integrals of the Major Peaks Are Given as Percent Fractions of the DecMS Peak Intensity. 87 be that one of the peaks a c t u a l l y originates from another compound, such as decanethiol, which i s then converted to the disulphide on the column. On the other hand, given that the experiment was c a r r i e d out only once, i t i s also possible that the r e s u l t i s an irreproducible a r t i f a c t ; further study of t h i s phenomenon i s c e r t a i n l y warranted. The remaining peaks, taken together, account f o r under 4 % of the t o t a l integration; however, they may be of importance i n the eventual understanding of t h i s system. The peak at 1092 corresponds to D e c M S 0 2, by comparison with a standard solution, while the peak at 848 can be assigned to the decylmethyldisulphide by examination of the MS (figure 4.8b). 63 Likewise, the peak at 1784 has been t e n t a t i v e l y assigned to didecylsulphi.de (figure 4.8c). e 3 This leaves two peaks, at 1283 and 1931 unassigned. The MS of these two compounds are again i d e n t i c a l (figure 4.8d) and both are also s i m i l a r , but not i d e n t i c a l to, the MS e a r l i e r assigned to didecyldisulphide (figure 4.8a). With the l a s t two, there are now a t o t a l of four mass spectra e x h i b i t i n g i d e n t i c a l parent ion peaks, and very s i m i l a r or i d e n t i c a l fragmentation patterns. Again, these observations s t i l l await explanation. One other experiment was c a r r i e d out using GC/MS analysis to characterize the products. This time, four equivalents of HOAc ( r e l a t i v e to the Ru(OEP)(DecMS)2 complex) were added to the reaction mixture. In t h i s case, a very rapid reaction ensued, and within 2 h the only product observable i n the uv/vis was 88 A(nm) 4 0 0 5 0 0 6 0 0 F i g u r e 4.12. U v / v i s A b s o r p t i o n Spectrum of a S o l u t i o n I n i t i a l l y C o n t a i n i n g 1.58 mM Ru(OEP)(DecMS)2, 4.2 mM HOAc, and 170 mM DecMS, a f t e r Four Hours of Exposure t o A i r . (The Sample Was A r b i t r a r i l y D i l u t e d t o O b t a i n an On-Scale Spectrum). 89 Ru(OEP)(CO)L (figure 4.12). GC/MS showed that the only observable sulphur products were DecMSO and unreacted DecMS. Although the integrations could not be used as r e l i a b l e measures since they were not corrected f o r varying detector s e n s i t i v i t y , they showed that roughly 2.4 equivalents of DecMS (r e l a t i v e to the Ru(OEP)(DecMS)2 catalyst) were converted to DecMSO. A l l of the above experiments indicate that the system under study i s quite complicated, and very s e n s i t i v e to the exact reaction conditions. Nevertheless, some features f a m i l i a r i n Ru(Porp) and thioether chemistry are evident, and provide at l e a s t reference points f o r further study. The f i r s t f a m i l i a r feature i s the presence of Ru(OEP)(CO)L among the reaction products. Like the Fe(Porp) complexes, most Ru(Porp) complexes bind CO very s t r o n g l y , 6 5 and the presence of any source of CO i n a solution of Ru(Porp) usually r e s u l t s i n i t s carbonylation. Reported sources of CO range from quartz glass, which had adsorbed the gas, 6 6 to acetic anhydride 8 and various aldehydes, 6 5 whose decarbonylation was promoted by the porphyrin complex. The a b i l i t y of Ru(Porp) complexes to decarbonylate HOAc (as they do anhydride) could account f o r the rapid production of Ru(OEP)(CO)L i n the presence of excess of the acid. I t i s not c l e a r at t h i s point whether the decarbonylation reaction i s part of the thioether oxidation cycle or whether i t i s a side-reaction, but i t was found that the decarbonylation does need a i r to proceed. I t i s i n t e r e s t i n g 90 that i n the presence of excess HOAc, DecMSO was the only product of thioether oxidation observed; i t may be that HOAc decarbonylation and the production of the other thioether oxidation compounds are competing reactions. A second f a m i l i a r feature i s the product d i s t r i b u t i o n of the thioether oxidation, which i s s i m i l a r to that observed from f r e e - r a d i c a l autoxidation of a l i p h a t i c t h i o e t h e r s : 6 7 (1) R 'CH2-S-R" — — > R'CH-S-R" chain i n i t i a t i o n (2) R'CH-S-R" + 02 > R'CH(O20-S-R" chain ( 3 ) R'CH(02«)-S-R" + R 'CH2-S-R" > Propa R'CH(02H)-S-R" + R'CH-S-R" gation (4) R'CH(02H)-S-R" + R 'CH2-S-R" > R'CH(0H)-S-R" + R*CH2-S0-R" ( 5 ) R'CH(0H)-S-R" > R'CHO + R"SH ( 6 ) R'CH(0H)-S-R" + R"SH > H2O + complex sulphides Scheme 4.1. Free-Radical Autoxidation of Thioethers While disulphides rather than t h i o l s are the observed by-products i n the system currently under study, i t i s well known that t h i o l s are e a s i l y oxidized to d i s u l p h i d e s , 6 8 and t h i o l s may s t i l l have been the i n i t i a l sulphur products. The s i m i l a r i t y i n product d i s t r i b u t i o n s between the f r e e - r a d i c a l autoxidation and the Ru(OEP)(DecMS)2/O2 system could be interpreted i n many ways. 91 For the moment, only two observations w i l l be made. F i r s t , the observed product d i s t r i b u t i o n suggests that thioether oxidation i n the Ru(OEP)(DecMS)2/02 system occurs both at the S to give DecMSO, and at the a-carbon to give, at lea s t i n i t i a l l y , the a-hydroxylated thioether. Second, extrapolating from the observed s i m i l a r i t i e s between the two systems i n question, aldehydes might be expected to be found among the products of the Ru(OEP)(DecMS)2-mediated DecMS autoxidation. While these products were not detected using the DB-1 GC column, t h e i r presence could account f o r the accumulation of Ru(OEP)(CO)L i n the l a t e r stages of the reactions i n which an excess of HOAc was not present. As aldehyde accumulated, i t could be decarbonylated by the Ru(Porp) species to generate the Ru(OEP)(CO)L species; however, the required accompanying hydrocarbon coproduct (Eq. 4.1) was not detected under the experimental conditions employed. Ru(Porp) + RCH2CHO > Ru(Porp)(CO) + RCH3 (Eq. 4.1) 92 CHAPTER V  CONCLUSIONS AND SUGGESTIONS  FOR FURTHER STUDIES The synthesis of Ru(OEP)(DPS)2 and Ru(OEP)(DecMS)2 from [Ru(0EP)]2 has proven to be a very e f f e c t i v e method f o r obtaining these complexes i n high purity. The variable temperature nmr studies done on Ru(OEP)(DPS)2, on the other hand, served to point out a po t e n t i a l l i m i t a t i o n to the preparation of Ru(0EP)L2 complexes i n general by simple ligand addition to [Ru(0EP ) ]2 . The complex Ru(OEP)(DPS)2 was found to be i n equilibrium with the dimer, and at high temperatures the equilibrium a c t u a l l y favoured the dimer. I t i s apparent that f o r ligands weaker than DPS the [Ru(0EP)]2 could be thermodynamically favoured even at room temperature. The slow exchange between [Ru(0EP)]2 and Ru(OEP)(DPS)2 does suggest that thermodynamically unfavoured Ru* 1 (0EP)L2 complexes could be k i n e t i c a l l y "trapped" i f they could f i r s t be synthesized by a via b l e a l t e r n a t i v e route. Preliminary studies on the r e a c t i v i t y of Ru(OEP)(DecMS)2 with dioxygen indicate that, i n benzene solutions, t h i s complex w i l l catalyze oxidation of free DecMS; however, the oxidation occurs not only at the sulphur to give DecMSO, but also at the ct-carbon to give, at lea s t i n i t i a l l y , the a-hydroxylated 93 thioether. This i s the problem encountered i n the f r e e - r a d i c a l autoxidation of thioethers, and i t was the problem encountered by Ledlie et a l . when they attempted Ru-catalyzed oxidation of thioethers i n benzene sol u t i o n s . 6 The low s e l e c t i v i t y f o r S-oxidation makes Ru(OEP)(DecMS)2 i n benzene a poor c a t a l y t i c system f o r conversion of thioethers to sulphoxides. Nevertheless, Ru(OEP)(DecMS)2 i t s e l f deserves more study as a c a t a l y s t f o r several reasons. F i r s t , the f a c t remains that few studies on transition-metal catalyzed autoxidation of thioethers, and no studies to determine the mechanism by which a-carbon oxidation takes place i n such systems, have been done to date. It i s necessary to know how a-carbon oxidation takes place, and why i t i s favoured over S-oxidation, i f better c a t a l y t i c systems are to be designed. A second reason f o r further study i s that d i f f e r e n t (and possibly more favourable) r e a c t i v i t y might be observed i n other solvents. For instance, one might observe r e a c t i v i t y analogous to that observed by R i l e y 5 (see section 1.3) i f the reaction were c a r r i e d out i n isopropanol. Furthermore, two very recent reports by Riley and C o r r e a 6 9 i 7 0 show that f r e e - r a d i c a l autoxidation, at high pressures i n polar solutions, leads s e l e c t i v e l y to sulphoxide production instead of to the mixture of products observed when the reaction i s ca r r i e d out at atmospheric pressures i n non-polar s o l v e n t s . 6 7 This means that the solvent used plays an important r o l e i n determining which s i t e i s oxidized i n the thioether, which strengthens the hope that the same may be true 94 i n •transition-metal catalyzed systems. In addition to the thioether autoxidation c a t a l y s i s , at leas t one other reaction observed during the current research deserves further study. Ru(Porp)-promoted decarbonylation of various organic compounds i s a widely observed phenomenon i n Ru(Porp) chemistry, and s t i l l l i t t l e i s known about the exact mechanism or mechanisms by which t h i s process occurs. Apart from the p o t e n t i a l u t i l i t y of t h i s reaction i n i t s own ri g h t , i t would be useful to know when decarbonylation was l i k e l y to be a serious side reaction i n some other process of in t e r e s t . 95 APPENDIX  ADDITIONAL INFORMATION ON THE  THE CRYSTAL STRUCTURES OF  Ru(OEP)(DPS)2 AND Ru(OEP)(DecMS)2 A.1 Crys t a l Structure Determinations A.1.1 Ru(OEP)(DPS)2. By Dr. S. R e t t i g An Enraf-Nonius CAD4-F diffractometer was used. Data were c o l l e c t e d at 22° C with Mo Ka radiation. The c r y s t a l s are orthorhombic, with a= 9.569(1), b= 22.401(1), c= 23.868(2) A, Z= 4, space group Pbca. The structure was solved by conventional heavy-atom methods and refined by f u l l - m a t r i x least-squares procedures to R= 0.042 and Rw = 0.039 f o r 2424 independent absorption-corrected r e f l e c t i o n s with I> 2o(I). Hydrogen atoms were f i x e d i n calculated positions. A.1.2 Ru(OEP)(DecMS)2. By Dr. J. Ibers An Enraf-Nonius CAD-4 diffractometer and Harris computer were used; programs and methods were standard. 7 1 Data were c o l l e c t e d at -150° C with MoKa r a d i a t i o n . The c r y s t a l s belong to the space group C i - P l , with a= 9.429(3) A, b= 14.198(3) A, c= 21.392(5) A; ct= 87.68(2)°, 0= 79.19(2)°, V= 77.73(2)°; Z= 2. The Ru atom and the 4 N were located by the Patterson function. 96 The rest of the molecule was found from DIRDIF.7 2 Refinement was by f u l l - m a t r i x least-squares methods. F i n a l refinements were on Fo2 , f o r 7279 unique data with Fo2> 3cr(Fo2 ) . H atoms were located from regular difference Fourier Syntheses following the f i r s t anisotropic refinement. Positions were i d e a l i z e d with the use of standard geometry and C-B> 0.95 A, BH= Beq + 1 A2. Positions of H were not varied. 97 Figure A . l . Ru(OEP)(DPS)2 Skeleton Numbering mode Used i n Tables 98 A.2 Crystallographic Bond Distances and Angles A. 2.1 Ru(0EP)(DPS)2 TABLE V Bond Lengths (A) with Estimated Standard Deviations i n Parentheses Bond Length(A) Bond Length(A) Ru-S 2. 3706(13) C(4)-C(5) 1. 387(6) Ru-N(l) 2. 050(3) C(5)-C(6) 1. 383(6) Ru-N(2) 2. 048(3) C(6)-C(7) 1. 455(6) S-C(19) 1. 796(5) C(7)-C(8) 1. 350(6) S-C(25) 1. 798(5) C(7)-C(15) 1. 513(7) N ( l ) - C ( l ) 1. 375(5) C(8)-C(9) 1. 457(6) N(l)-C(4) 1. 376(6) C(8)-C(17) 1. 514(7) N(2)-C(6) 1. 377(5) C(9)-C(10) 1. 389(6) N(2)-C(9) 1. 371(5) C(ll)-C(12) 1. 511(7) C(l)-C(2) 1. 458(6) C(13)-C(14) 1. 477(9) C(l)-C(10)' 1. 386(6) C(15)-C(16) 1. 485(9) C(2)-C(3) 1. 358(6) C(17)-C(18) 1. 508(8) C(2) - C ( l l ) 1. 506(6) C(19)-C(20) 1. 363(7) C(3)-C(4) 1. 453(6) C(19)-C(24) 1. 382(6) C(3)-C(13) 1. 505(7) C(20)-C(21) 1. 401(7) cont /.. 99 C(21)-C(22) 1.360(8) C(26)-C(27) 1.384(7) C(22)-C(23) 1.358(8) C(27)-C(28) 1.354(9) C(23)-C(24) 1.384(7) C(28)-C(29) 1.362(9) C(25)-C(26) 1.377(7) C(29)-C(30) 1.396(8) C(25)-C(30) 1.372(7) 100 TABLE VI Bond Angles (deg) with Estimated Standard Deviations i n Parentheses Bonds Angle(deg) Bonds Angle(deg) S-Ru-N(l) 97.17(10) Ru-N(2)-C(6) 126. 0(3) S-Ru-N(2) 84.08(10) Ru-N(2)-C(9) 126. 9(3) S-Ru-S' 180 C(6)-N(2)- 107. 1(4) S-Ru-N(l)' 82.83(10) G(9) S-Ru-N(2)' 95.92(10) N ( l ) - C ( l ) - 109. 2(4) N(l)-Ru-N(2) 90.34(14) C(2) N(l)-Ru-S' 82.83(10) N ( l ) - C ( l ) - 125. 1(4) N(l)-Ru-N(l)' 180 C(10)' N(l)-Ru-N(2)' 89.66(14) C(2)-C(l)- 125. 7(4) N(2)-Ru-S' 95.92(10) C(10)' N(2)-Ru-N(l)' 89.66(14) C(l)-C(2)- 107. 1(4) N(2)-Ru-N(2)* 180 C(3) Ru-S-C(19) 115.4(2) C(l)-C(2)- 126. 1(4) Ru-S-C(25) 110.9(2) C ( l l ) C(19)-S-C(25) 103.3(2) C(3)-C(2)- 126. 8(4) Ru-N(l)-C(l) 126.5(3) C ( l l ) Ru-N(l)-C(4) 126.3(3) C(2)-C(3)- 107. 0(4) C ( l ) - N ( l ) - 107.1(4) C(4) C(4) C(2)-C(3)- 128. 1(5) C(13) cont./... 101 C(4)-C(3)- 124.9(5) C(13) N(l)-C(4)- 109.5(4) C(3) N(l)-C(4)- 124.3(5) C(5) C(3)-C(4)- 126.2(5) C(5) C(4)-C(5)- 128.3(5) C(6) N(2)-C(6)- 124.8(4) C(5) N(2)-C(6)- 109.2(4) C(7) C(5)-C(6)- 126.1(4) C(7) C(6)-C(7)- 107.2(4) C(8) C(6)-C(7)- 124.6(5) C(15) C(8)-C(7)- 128.1(4) C(15) C(7)-C(8)- 107.2(4) C(9) C(7)-C(8)- 127.4(5) C(17) C(9)-C(8)- 125.5(5) C(17) N(2)-C(9)- 109.3(4) C(8) N(2)-C(9)- 124.7(4) C(10) C(8)-C(9)- 125.9(5) C(10) C(9)-C(10)- 127.1(4) C ( l ) * C ( 2 ) - C ( l l ) - 113.6(4) C(12) C(3)-C(13)- 112.5(6) C(14) C(7)-C(15)- 112.9(5) C(16) C(8)-C(17)- 111.2(5) C(18) S-C(19)-C(20) 116.8(4) S-C(19)-C(24) 123.5(4) C(20)-C(19)- 119.6(5) C(24) C(19)-C(20)- 120.4(5) C(21) C(20)-C(21)- 119.4(6) C(22) cont./... 102 C(21)-C(22)- 120.2(6) C(23) C(22)-C(23)- 120.9(6) C(24) C(19)-C(24)- 119.3(5) C(23) S-C(25)-C(26) 123.1(4) S-C(25)-C(30) 115.6(5) C(26)-C(25)- 121.2(5) C(30) C(25)-C(26)- 119.6(5) C(27) C(26)-C(27)- 120.0(6) C(28) C(27)-C(28)- 120.3(6) C(29) C(28)-C(29)- 121.3(6) C(30) C(25)-C(30)- 117.6(6) C(29) 103 TABLE VII Intra-annular Torsion Angles (deg) with Standard Deviations i n Parentheses Atoms Value(deg) N(2)-Ru-N(l)-C(4) 3.1(4) Ru-N(l)-C(4)-C(5) -3.2(7) N(l)-C(4)-C(5)-C(6) 0.6(9) C(4)-C(5)-C(6)-N(2) 1.0(9) Ru-N(2)-C(6)-C(5) 0.1(7) N(l)-Ru-N(2)-C(6) -1-7(4) N(l)'-Ru-N(2)-C(9) -0.4(4) Ru-N(2)-C(9)-C(10) 0.4(7) N(2)-C(9)-C(10)-C(l)' 0.2(9) C(9)-C(10)-C(l)'-N(l)' 0.1(8) C(10)-C(l)'-N(l)'-Ru 0.2(7) C(l)'-N(l)'-Ru-N(2) 0.3(4) 104 Table's ^ ^ " ( O E P M D e c M S ) * Skeleton Numbering Mode Used i n A.2.2 Ru(OEP)(DecMS)2 105 TABLE VIII Bond Lengths (A) with Estimated Standard Deviations i n Parentheses Bond Length(A) Bond Length(A) Ru-S(l) 2. 376(1) C(ll)-C(12) 1. 448(5) Ru-S(2) 2. 361(1) C(13)-C(14) 1. 447(5) Ru-N(l) 2. 044(3) C(16)-C(17) 1. 451(5) Ru-N(2) 2. 044(3) C(18)-C(19) 1. 450(5) Ru-N(3) 2. 056(3) C(2)-C(3) 1. 354(5) Ru-N(4) 2. 041(3) C(7)-C(8) 1. 361(5) N ( l ) - C ( l ) 1. 371(4) C(12)-C(13) 1. 364(5) N(l)-C(4) 1. 373(4) C(17)-C(18) 1. 350(5) N(2)-C(6) 1. 381(4) C(l)-C(20) 1. 392(5) N(2)-C(9) 1. 379(4) C(4)-C(5) 1. 398(5) N(3)-C(ll) 1. 371(4) C(5)-C(6) 1. 379(5) N(3)-C(14) 1. 370(4) C(9)-C(10) 1. 386(5) N(4)-C(16) 1. 375(4) C(10)-C(ll) 1. 389(5) N(4)-C(19) 1. 371(4) C(14)-C(15) 1. 384(5) C(l)-C(2) 1. 459(5) C(15)-C(16) 1. 392(5) C(3)-C(4) 1. 458(5) C(19)-C(20) 1. 392(5) C(6)-C(7) 1. 451(5) C(2)-C(21) 1. 506(5) C(8)-C(9) 1. 456(5) cont./.. 106 C(3)-C(23) 1. 498(5) C(7)-C(25) 1. 506(5) C(8)-C(27) 1. 503(5) C(12) -C(29) 1. 501(5) C(13) -C(31) 1. 502(5) C(17) -C(33) 1. 499(5) C(18) -C(35) 1. 509(5) C(21) -C(22) 1. 524(5) C(23) -C(24) 1. 531(5) C(25) -C(26) 1. 509(5) C(27) -C(28) 1. 526(5) C(29) -C(30) 1. 525(5) C(31) -C(32) 1. 526(5) C(33) -C(34) 1. 526(5) C(35) -C(36) 1. 522(5) S ( l ) - C(37) 1. 813(4) S ( l ) - C(38) 1. 825(4) S(2)-C(48) 1. 797(4) S(2)-C(49) 1. 810(4) C(38) -C(39) 1. 501(5) C(49) -C(50) 1. 496(5) C(39) -C(40) 1. 527(5) C(50) -C(51) 1. 549(5) C(40) -C(41) 1. 513(5) C(57) -C(52) 1. 514(5) C(41) -C(42) 1. 516(5) C(52) -C(53) 1. 530(5) C(42) -C(43) 1. 523(5) C(53) -C(54) 1. 517(5) C(43) -C(44) 1. 516(5) C(54) -C(55) 1. 511(6) C(44) -C(45) 1. 514(6) C(55) -C(56) 1. 514(6) C(45) -C(46) 1. 504(6) C(56) -C(57) 1. 504(6) C(46) -C(47) 1. 499(6) C(57) -C(58) 1. 499(7) 107 TABLE IX Bond Angles (deg) with Estimated Standard Deviations i n Parentheses Bond Angle(deg) Bond Angle(deg) N(l)-Ru-N( .2) 90.0(1) Ru-N(l)-C(4) 126. 8(2) N(l)-Ru-N< [4) 90.0(1) Ru-N(2)-C(6) 126. 6(2) N(2)-Ru-N( 3) 89.7(1) Ru-N(2)-C(9) 126. 6(2) N(3)-Ru-N< [4) 90.3(1) Ru-N(3)-C(ll) 126. 6(2) N(l)-Ru-N( .3) 178.9(1) Ru-N(3)-C(14) 126. 3(2) N(2)-Ru-N< [4) 179.1(1) Ru-N(4)-C(16) 126. 3(2) N(l)-Ru-S< : D 90.2(1) Ru-N(4)-C(19) 126. 8(2) N(2)-Ru-S| 86.9(1) N ( l ) - C ( l ) - 109. 8(3) N(3)-Ru-S( : D 90.9(1) C(2) N(4)-Ru-S| [1) 94.0(1) N(l)-C(4)- 110. 0(3) N(l)-Ru-S( 2) 90.7(1) C(3) N(2)-Ru-S< [2) 94.7(1) N(2)-C(6)- 109. 4(3) N(3)-Ru-S( :2) 88.3(1) C(7) N(4)-Ru-S( :2) 84.5(1) N(2)-C(9)- 109. 7(3) Ru-S(l)-C( :37) 107.5(1) C(8) Ru-S(l)-C| [38) 111.2(1) N ( 3 ) - C ( l l ) - 109. 7(3) Ru-S(2)-C< '48) 109.0(1) C(12) Ru-S(2)-C| [49) 108.1(1) N(3)-C(14)- 109. 4(3) Ru-N(l)-C( :i> 126.6(2) C(13) cont - / - -108 N(4)-C(16)-C(17) N(4)-C(19)-C(18) C ( l ) - N ( l ) -C(4) C(6)-N(2)-C(9) C ( l l ) - N ( 3 ) -C(14) C(16)-N(4)-C(19) C(l)-C(2)-C(3) C(4)-C(3)-C(2) C(6)-C(7)-C(8) C(9)-C(8)-C(7) C ( l l ) - C ( 1 2 ) -C(13) C(14)-C(13)-C(12) C(16)-C(17)-C(18) 109.6(3) 109.8(3) 106.5(3) 106.7(3) 107.1(3) 106.4(3) 107.1(3) 106.6(3) 107.4(3) 106.7(3) 106.5(3) 107.2(3) 107.1(3) C(19)-C(18)-C(17) N ( l ) - C ( l ) -C(20) N(l)-C(4)-C(5) N(2)-C(6)-C(5) N(2)-C(9)-C(10) N ( 3 ) - C ( l l ) -C(10) N(3)-C(14)-C(15) N(4)-C(16)-C(15) N(4)-C(19)-C(20) C(4)-C(5)-C(6) C(9)-C(10)-C ( l l ) C(14)-C(15)-C(16) C(19)-C(20)-C(l) 107.0(3) 124.6(3) 124.2(3) 124.5(3) 124.7(3) 124.6(3) 124.2(3) 124.3(3) 124.5(3) 127.8(3) 127.6(3) 128.4(3) 127.4(3) cont./.. 109 C(3)-C(4)-C(5) C(7)-C(6)-C(5) C(8)-C(9)-C(10) C( 1 2 ) - C ( l l ) -C(10) C(13)-C(14)-C(15) C(17)-C(16)-C(15) C(18)-C(19)-C(20) C(2)-C(l)-C(20) C(l)-C(2)-C(21) C(4)-C(3)-C(23) C(6)-C(7)-C(25) C(9)-C(8)-C(27) C ( l l ) - C ( 1 2 ) -C(29) 125.7(3) 126.1(3) 125.6(3) 125.6(3) 126.4(3) 126.0(3) 125.7(3) 125.6(3) 124.3(3) 124.0(3) 124.9(3) 124.8(3) 124.4(3) C(14)-C(13)-C(31) C(16)-C(17)-C(33) C(19)-C(18)-C(35) C(3)-C(2)-C(21) C(2)-C(3)-C(23) C(8)-C(7)-C(25) C(7)-C(8)-C(27) C(13)-C(12)-C(29) C(12)-C(13)-C(31) C(18)-G(17)-C(33) C(17)-C(18)-C(35) C(2)-C(21)-C(22) C(3)-C(23)-C(24) 124.3(3) 124.7(3) 124.6(3) 128.6(3) 129.4(3) 127.6(3) 128.6(3) 129.1(3) 128.4(3) 128.2(3) 128.4(3) 113.7(3) 113.4(3) cont./.. 110 C(7)-C(25)-C(26) C(8)-C(27)-C(28) C(12)-C(29)-C(30) C(13)-C(31)-C(32) C(17)-C(33)-C(34) C(18)-C(35)-C(36) C(37)-S(l)-C(38) C(48)-S(2)-C(49) S(l)-C(38)-C(39) C(38)-C(39)-C(40) C(39)-C(40)-C(41) C(40)-C(41)-C(42) C(41)-C(42)-C(43) 112.8(3) 113.5(3) 113.2(3) 112.5(3) 112.0(3) 113.6(3) 98.4(2) 101.0(2) 110.8(3) 112.9(3) 111.8(3) 115.5(3) 112.6(3) C(42)-C(43)-C(44) C(43)-C(44)-C(45) C(44)-C(45)-C(46) C(45)-C(46)-C(47) S(2)-C(49)-C(50) C(49)-C(50)-C(51) C(50)-C(51)-C(52) C(51)-C(52)-C(53) C(52)-C(53)-C(54) C(53)-C(54)-C(55) C(54)-C(55)-C(56) C(55)-C(56)-C(57) 113.6(3) 115.6(3) 114.4(3) 115.6(4) 113.9(3) 112.2(3) 114.1(3) 112.7(3) 114.3(3) 113.5(3) 116.0(3) 114.0(4) I l l TABLE X Dihedral Angles (deg) between the 24-Atom Core and the Pyrrole Rings Dihedral Angle (Deg) N(1),C(1)-C(4) N(2),C(6)-C(9) N(3),C(11)-C(14) N(4),C(16)-C(19) 2.03 2.47 4.29 2.96 112 REFERENCES 1. 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Soc.. 106. 3500 (1984). 29. An extensive compilation of u v / v i s i b l e absorption spectra f o r Ru(0EP)(C0)L complexes can be found i n : M. Barley, J. Y. Becker, G. Domazetis, D. Dolphin, and B. R. James, Can. J.  Chem.. 61, 2389 (1983). 114 30. I. S. Thorburn, Ph. D. Thesis, The University of B r i t i s h Columbia, Vancouver, B. C., Canada, 1985. 31. D.F. Shriver, "The Manipulation of A i r Sensitive Compounds", McGraw-Hill, New York, N.Y., 1969. 32. D. G. Sekutowski, and G. D. Stucky, J . Chem. Ed.. 53(2). 110 (1976). 33. M. Gouterman i n "The Porphyrins," Vol. I l l , D. Dolphin, Ed., Academic Press, Inc., New York, N. Y., 1978, Chapter 1. 34. S. A r i e l , D. Dolphin, G. Domazetis, B. R. James, T. W. Leung, S. J . Rettig, J . Trotter, and G. M. Williams, Can. J. Chem.. 62. 755 (1984). 35. J. A. Pople, J. Chem. Phys.. 24. 1111 (1956). 36. J . S. Waugh and R. W. Fessenden, J. Am. Chem. Soc..' 79. 846 (1957) . 37. C. E. Johnson and F. A. Bovey, J . Chem. 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Williams, "Mass Spectrometry of Organic Compounds", Holden-Day, Inc., San Francisco, Ca., 1967, pp 276-296. 64. Adding a large excess (about 103-10* fold) of DecMS to the solution did produce small shoulders at 407 and 500 nm, suggesting that a small portion of the mixture was s t i l l "active". 65. B. Tarpey, MSc. Thesis, The University of B r i t i s h Columbia, Vancouver, B. C., 1982, and references therein. 66. A. Co r s i n i , H. Mehdi, and A. Chan, Can. J. Chem.. 58. 527 (1980). 67. D. Barnard, L. Bateman, and J . I. Cuneen, i n "Organic Sulfur Compounds", Vol. 1, N. Kharasch, Ed., Pergamon Press, Inc., New York, Oxford, London, Paris, 1961, Chapter 21. 68. D. S. Ta r b e l l , i n "Organic Sulfur Compounds", Vol. 1, N. Kharasch, Ed., Pergamon Press, Inc., New York, Oxford, London, Paris, 1961, Chapter 10. 69. P. E. Correa and D. P. Riley. J. Org. Chem.. 50. 1787 (1985). 70. D. P. Ri l e y and P. E. Correa, J. Chem. Soc.. Chem. Commun.. 1097 (1986). 71. J . M. Waters, and J. A Ibers, Inorg. Chem.. 16. 3278, (1977). 72. P. T. Beurskens, W. P. Bosman, H. M. Doesburg, R. 0. Gould, Th. E. M. van den Hark, P. A. J. Prick, J. H. Noordik, G. Beurskens, V. Parthasarathi, H. J . Bruins Slot, R. C. Haltiwanger, M. Strumpel, and J . M. M. Smits, Technical Report 1984/1, Crystallography Laboratory, Toernooiveld, 6525 Ed Nijmegen, The Netherlands. 

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