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The coordination and organometallic chemistry of ruthenium porphyrin species Alexander, Christopher Scott 1995

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THE COORDINATION AND ORGANOMETALLICCHEMISTRY OF RUTHENIUM PORPHYRIN SPECIESByCHRISTOPHER SCOTT ALEXANDERB.Sc., The University of Guelph, 1984M.Sc., The University of Guelph, 1986A THESIS SUBMITTED TN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinTHE FACULTY OF GRADUATE STUDIES(Department of Chemistry)We accept this thesis as conformingto the required standardTHE UNIVERSITY OF BRITISH COLUMBIAAugust 1995© Christopher Scott Alexander, 1995In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature)________________________________Department of L4The University of British ColumbiaVancouver, CanadaDate O_fDE-6 (2188)AbstractTreatment ofRu11(porp)L2complexes with FIX acids in C6H yields the correspondingparamagnetic Ru”Qorp)X2complexes, where porp = the 2, 3, 7, 8, 12, 13, 17, 18-octaethylporphyrin dianion(OEP), L= pyridine(py), X Cl; and porp = the 5, 10, 15, 20-tetramesitylporphynn dianion(TMP), L = CH3N, X= Cl or Br. The 3 day reactions ( at roomtemperature) proceed via the paramagnetic Ru(porp)X(L) intermediates, as demonstrated byisolation of Ru(OEP)Cl(py) and Ru(TMP)Br(CH3CN). The Ru(OEP)Cl(py) complex wasalso produced in situ by the reaction of Ru(OEP)C12with Ru(OEP)py2.Reduction of thedihalo species with anhydrous ammonia yields the paramagnetic Ru(porp)X(NH3species.Cyclic voltammograms of the Ru(porp)X2complexes (where porp = OEP, X = Cl; porp= TPP (TPP 5, 10, 15, 20-tetraphenylporphyrin dianion), X = Cl; porp = TMP, X Br andCl) show reversible Ru”(porp) /RuT(porp) couples in the range of 1.22 to 1.35 V, reversibleRu(IV)fRu(ffl) couples from 0.41 to 0.64 V, and a third irreversible response (tentativelyassigned to the Ru(jorp)/Ru(porp) couples) in the range of -0. 82 to -0.56 V vs. Ag/AgCI.The reversible Ru”(porp)/Ru”(porp) couples of Ru(OEP)Cl(NH3)andRu(TMP)Cl(N113)were measured at 1.31 and 1.45 V vs. AgIAgC1, respectively, while thereversible Ru(IV)/Ru(ffl) couples were found at 0.74 and 0.85 V. Reversible signals(tentatively assigned as the Ru(ffl)/Ru(ll) couples) were also observed at -0.51 and -0.42 Vvs. AgIAgC1 for the OEP and TIVIP complexes, respectively.The diamagnetic Ru(TMP)R2complexes (R = Me, Ph) were isolated from the reaction‘aof Ru(TMP)X2(X = Br, Cl) with an excess ( 6 equivalents) of the corresponding RLireagents. On the other hand, the products of the reactions of Ru(OEP)C12with the alkylatingagents RM [where n 1, R = neopentyl (Np), M = Li; n = 1, R = benzyl (Bz), M = K; n = 2,R = 2-methyl-2-phenylpropyl (neophyl), M = Mg] and reactions of Ru(TMP)X2(X = Cl, Br)with NpLi were dependent on the ratios of the starting material. In situ experiments reveal theimportance of the reducing power of these alkylating agents, as complexes of oxidation statesll-IV were observed, with the yield of the Ru(ll) products increasing as the ratio ofNpLiIRu(OEP)Cl2increased. The paramagnetic Ru(OEP)Np and Ru(OEP)(neophyl), and thediamagnetic, lithium-bridged dimer [Ru(OEP)Np]2Q.-Li),were isolated from these reactionsand unambiguously characterized by microanalysis, UV/visible and ‘H NIvER spectroscopies,and X-ray crystal diffraction. The Ru(OEP)Np species is also produced along withRu(OEP)(NH3)2from the reaction of Ru(OEP)Cl(NH3)with 1 equivalent of NpLi.The paramagnetic nature of the new Ru(TMP)C12,Ru(OEP)Cl(py), Ru(TMP)Cl(NH3,Ru(TMP)Br(NH3)and Ru(OEP)Np and Ru(OEP)(neophyl) species is evidenced by theirbroad, temperature-dependent ‘H NIVIR spectra and the solution magnetic susceptibilities ofRu(TIVIP)C12(2.5 B.M.), Ru(TMP)Cl(NH3(1.61 B.M.), Ru(OEP)Np (2.4 B.M.) andRu(OEP)(neophyl) (2.2 B.M.).The lithium-bridged species is of a unique type among metalloporphyrin complexes, andthe structure is maintained in solution; however, oxidation by air or by H20 gave[Ru(OEP)OH]2(i-O)and Ru(OEP)Np, respectively.The Ru(TMP)R2species (R = Me, Ph) react with CO at 1 atm under laboratory light toyield Ru(TMP)(CO)2via the corresponding Ru(TMP)(COR)R intermediate. The conversionII’of Ru(TMP)(COPh)Ph is light-dependent and thus this benzyol species was produced inalmost quantitative yield by performing the reaction in the dark, and was identified bymicroanalysis, IR and ‘H NIv[R spectroscopy. The Ru(TMP)Me2species also undergoes aphoto-reaction with dioxygen to produce Ru(TMP)CO(L), where L is tentatively assigned asMeOH.The Ru(TMP)R2complexes (R = Ph, Me) undergo thermal decomposition underanaerobic conditions to yield the corresponding five-coordinate, paramagnetic Ru(TMP)Rspecies, as does Ru(OEP)(COPh)Ph to give Ru(TMP)Ph. The in situ Ru(OEP)Np2complexthermally decomposes to give a 50:50 mixture of Ru(OEP)Np and Ru(OEP)=CHC(CH3).Allthese reactions proceed by the rate-determining homolysis of the axial metal-carbon bond, andEyring plots of the first-order rate constants (k1) obtained at various temperatures yieldactivation parameters for cleavage of the various Ru-R bonds [Ru(TMP)Ph2,zSH, 33 kcalmof’ , AS,= 6.9 e.u. ; Ru(TMP)(COPh)Ph, AH, = 22, AS, = -11; Ru(TMP)Me2,AH1 = 22,-17; Ru(OEP)Np2,IJ1, = 16, AS, = -27], The bond dissociation energies (BDE) ofthese bonds are then estimated by an established method (i.e. BDE = AH,- 2 kcal mof’), andthe accuracy of these estimates is discussed in light of the kinetic results.lvTable of ContentsABSTRACT.iiLIST OF FIGURES xLIST OF TABLES xivNUMBERING SCHEME FOR PORPHYRINS xviLIST OF ABBREVIATIONS xviiACKNOWLEDGMENTS xxiiDEDICATION xxiii1. INTRODUCTION TO RUTHENIUM PORPHYRIN CHEMISTRY I1.1 RUTHENIUM(II) DERIVATIVES 41.1.1 Synthesis and physical properties 41.1.2 Reactivity of Ru(porp)CO complexes 61.1.3 Reactivity of Ru(porp)L2complexes 101.1.4 Reactivity of [Ru(porp)12and Ru(TMP) 161.2 RUTHENTUM(0) Mfl) RUTHENTUM(I) DERIVATIVES 211.3 RUTHENTUM(III) DERIVATIVES 231.3.1 Synthesis and physical properties 231.3.2 Reactivity 251.4 RUTHENIUM(IV) DERIVATIVES 261.4.1 Synthesis and physical properties 261.4.2 Reactivity of Ru(IV) complexes 321.5 RUTHENTUM(VI) DERIVATIVES 341.6 CATALYTIC REACTIVITIES OF RUTIIENTUM PORPHYRiNCOMPLEXES 36V1.6.1 Decarbonylation. 361.6.2 Oxygenation/oxidation 381.6.3 Hydrogenase models 391.7 SCOPE OF THIS THESIS 401.8 REFERENCES FOR CHAPTER 1 422. GENERAL EXPERIMENTAL PROCEDURES 502.1 MATERIALS 502.1.1 Solvents 502.1.2 Gases 502.1.3 Reagents 512.1.4 Ruthenium precursor complexes 512.1.5 Preparation of dichloro(octaethylporphyrinato)ruthenium(IV) 522.1.6 Preparation of tetramesitylporphyrin 532.1.7 Preparation of bis(2-methyl-2-phenyl-propyl)magnesium(II) 542.1.8 Preparation of neopentyllithium (I) 552.1.9 Preparation of Na(naphthalenide) 552.2 METHODS 562.2.1 Instrumentation 562.2.2 Cyclic voltammetry 562.2.3 Special techniques 592.2.4 Anaerobic columns 602.3 PREPARATION OF NEW RUTHENIUM PORPHYRIN COMPLEXES 612.3.1 Preparation of (neopentyl)(octaethylporphyrinato)ruthenium(III) 612.3.2 Preparation of neophyl(octaethylporphyrinato)ruthenium(III) 622.3.3 Preparation of [Ru(OEP)Np12(p.-Li) 632.3.4 Preparation of lrans-dichloro(tetramesitylporphyrinato)ruthenium(IV) 642.3.5 Preparation of ammine(chloro)(tetramesitylporphyrinato)ruthenium(Ill).... 652.3.6 Preparation of bisphenyl(tetramesitylporphyrinato)ruthenium(IV) 65vi2.3.7 Preparation of benzoyl(phenyl)(tetramesitylporphyrinato)ruthenium(IV).... 662.3.8 Preparation of dimethyl(tetramesitylporphyrinato)ruthenium(IV) 672.3.9 Kinetics of the decomposition of Ru(TMP)Ph2 682.3.10 Kinetics of the decomposition of Ru(TMP)(COPh)Ph andRu(TMP)(Me) 682.3.11 Kinetics of the decomposition of Ru(OEP)Np2 692.4 REFERENCES FOR CHAPTER 2 703. HALO(PORPHYRINATO)RUTHENIUM DERIVATIVES 713.1 Ru(IV)(PORP)X2DERIVATIVES (PORP = OEP AND TMP) 713.1.1 Preparation of Ru(OEP)X2derivatives 723.1.2 Preparation and characterization of Ru(TMP)C12 753.1.3 Electrochemistry of Ru(porp)X2complexes 833.2 Ru(PORP)X(L) DERIVATIVES (L = NH3, Py, X = HALOGEN) 893.2.1 Preparation of Ru(porp)X(NH3complexes (porp = OEP, X= Cl; porp =TMP,X=ClandBr) 913.2.2 Characterization ofRu(TMP)Cl(NH3and Ru(TMP)Br(NH3) 923.2.3 Preparation and characterization of Ru(OEP)Cl(py) 973.2.4 Attempts to prepare Ru(OEP)Cl 1013.2.5 Electrochemistry of the Ru(III) derivatives 1073.3 THE OXIDATION OF Ru(II) COMPLEXES REVISITED 1103.4 REFERENCES FOR CHAPTER 3 1164. ALKYL COMPLEXES OF RUTHENIUM OCTAETHYLPORPHYRIN 1204.1 REACTION OF Ru(OEP)X2WITH NEOPENTYL LITHIUM 1224.1.1 Reaction with two equivalents of neopentyllithium 1234.1.2 Thermal decomposition of Ru(OEP)Np2 1284.1.3 Reaction with three equivalents of neopentyllithium 1354.1.4 Reaction with 4 equivalents of neopentyllithium 1404.2 REACTION OF Ru(OEP)Cl(NH3)WITH NEOPENTYLLITITILJM 143vu4.3 REACTION OF Ru(OEP)Cl2WITH (NEOPHYL)2Mg.1484.4 REACTION OF Ru(OEP)C12WITH BENZYLPOTASSIUM 1494.5 CHARACTERIZATION OF ISOLATED COMPLEXES 1534.5.1 Preparation and isolation ofRu(OEP)CHC(CH3),Ru(OEP)Np andRu(OEP)(neophyl) 1534.5.2 Spectral characteristics 1554.5.3 Crystal structures of Ru(OEP)Np and Ru(OEP)(neophyl) 1624.5.4 Preparation and characterization of [Ru(OEP)Np]2(p.-Li) 1664.5.5 Crystal Structure of[Ru(OEP)NpJ2(.t-Li) 1684.6 REACTIVITY OF [Ru(OEP)Np]Q.t-Li) 1714.6.1 Reaction with 02 1714.6.2 Reaction with H20 1744.6.3 Reaction with NH3 1764.7 REFERENCES FOR CHAPTER 4 1805. ORGANOMETALLIC COMPLEXES OF (TETRAMESITYLPORPHYRINATO)RUTHENIUM 1835.1 INTRODUCTION 1835.2 PREPARATION AND CHARACTERIZATION OF Ru(TMP)R2COMPLEXES 1845.3 REACTION OF Ru(TMP)X2(X= Cl or Br) WITH NpLi 1905.4 REACTION OF Ru(TMP)R2(R= Me, Ph) COMPLEXES WITH CO 2015.5 KINETICS OF THE DECOMPOSITION OF THE Ru(TMP)R2COMPLEXES 2095.5.1 Thermal decomposition of Ru(TIvIP)Ph2 2145.5.2 Thermal decomposition of Ru(TMP)(COPh)Ph 2175.5.3 Thermal decomposition ofRu(TMP)Me2 2205.5.4 Determination of the strength of Ru-R bonds (R= Ph, PhCO and Me) 2235.6 PHOTOREACTIONS OF Ru(TMP)Me2 2265.7 REFERENCES FOR CHAPTER 5 234VIII6. GENERAL CONCLUSIONS AND RECOMMENDATIONS FOR FUTUREWORK 238APPENDIX A: TEMPERATURE DEPENDENCE’S OF THE ISOTROPICPROTON SHIFTS 243APPENDIX B: KINETIC DATA FOR THE ANAEROBIC THERMOLYSIS OFRu(PORP)R2COMPLEXES 254APPENDIX C: X-RAY CRYSTALLOGRAPIC ANALYSIS OF Ru(OEP)Np ...248APPENDIX D: X-RAY CRYSTALLOGRAPHIC ANALYSIS OFRu(OEP)(NEOPHYL) 256APPENDIX E: X-RAY CRYSTALLOGRAPHIC ANALYSIS OF[Ru(OEP)Np12(i.t-Li) 265APPENDIX F: X-RAY CRYSTALLOGRAPHIC ANALYSIS OFRu(TMP)Ph2 274lxList of FiguresFigure 1-1: The structures of, a) porphine dianion, b) heme, c) free-base porphyrins usedin the work 2Figure 1-2: Molecular orbital diagram for [Ru(OEP)]2 15Figure 1-3: Structure of Ru2DPB (DPB = diporphyrinatobiphenylene tetraanion) 17Figure 1-4: The possible ground state configurations for the three lowest levels of a d4metal in a tetragonally distorted octahedral crystal field 32Figure 2-1: Electrochemical cell used for cyclic voltammetry 57Figure 2-2: Anaerobic glassware; a) NIVIR tube, b)UV/visible cell 59Figure 2-3 : Apparatus used for the chromatographic purification of air-sensitivecompounds 60Figure 3-1: UV/visible spectrum ofRu(TMP)C12(10 .tM in CH21) 78Figure 3-2: ‘H NMR spectrum (300 MHz) ofRu(TMP)C12in C6D at 200 C 79Figure 3-3: Plot of the isotropic chemical shift vs. lIT (K’) for Ru(TMP)Cl2 81Figure 3-4: Cyclic voltammogram of Ru(TMP)C12 83Figure 3-5: Cyclic voltammograms of Ru(OEP)C12(0.5 mM) 88Figure 3-6: UVlvisible spectrum of Ru(TMP)Cl(NH3) 92Figure 3-7: ‘H NMR spectrum (300 MHz) of Ru(TMP)Cl(NH3in C6D taken at293 K 94Figure 3-8: ‘H NMR spectrum (300MHz) of isolated Ru(TMP)Br(NH3)in C6D taken at293 K 95Figure 3-9: Plot of isotropic chemical shift vs. l/T (K) for Ru(TMP)Cl(NH3 96Figure 3-10: ‘H NIVIR spectrum (300 MHz) of Ru(OEP)Cl(py) in C6D taken at293 K 99Figure 3-11: ‘H NMR spectrum (C6D,20 °C, 300 MHz) of the products of the reactionof Ru(OEP)C12with 1 equivalent of sodium naphthalenide 105Figure 3-12: Cyclic voltammogram of Ru(OEP)Cl(NH3) 108xFigure 4-1: ‘11 NMR (C6D)spectrum of the products of the reaction of Ru(OEP)C12with 2 equivalents ofNpLi 124Figure 4-2: First-order plot for the thermal decomposition of Ru(OEP)Np2at 38° C... 129Figure 4-3: Eyring plot for the decomposition of Ru(OEP)Np2 132Figure 4-4: Reaction profile for the decomposition of Ru(OEP)Np2,showing therelationship between the bond dissociation energy (BDE) and the enthalpies ofactivation (t\H) 133Figure 4-5: ‘H NIvIR spectrum of the products of the reaction of Ru(OEP)C12with 3equivalents ofNpLi 136Figure 4-6: ‘H NIv1R spectrum of the products of the reaction of Ru(OEP)C12 with 4equivalents ofNpLi 141Figure 4-7: Proposed structure for the co-product of the reaction of Ru(OEP)C12withfour equivalents ofNpLi 142Figure 4-8: ‘H NMR spectrum (C6D)of the products of the reaction ofRu(OEP)C1(NH3)with one equivalent ofNpLi 144Figure 4-9: ‘H NMR spectrum ofRu(OEP)(NH3)2produced in situ by the reaction of[Ru(OEP)12with anhydrous NH3 145Figure 4-10: ‘H NMR spectrum of Ru(OEP)Np(NH)produced in situ by the reaction ofRu(OEP)Np with anhydrous NH3 147Figure 4-1 la: ‘H NMR spectrum of the products of reaction of Ru(OEP)C12with 2equivalent of BzK after 30 mm 150Figure 4-12: ‘H NIvIR spectrum (C6D,300 MHz) ofRu(OEP)CHC(CH3isolated fromthe reaction of Ru(OEP)C12with 2 equivalents ofNpLi 156Figure 4-13: ‘H NMR spectrum (C6D,300 MHz) of Ru(OEP)Np (T=22° C) 157Figure 4-14: ‘H NMR spectrum (C6D,300 MHz) of Ru(OEP)(neophyl) (T50° C)... 158Figure 4-15: Isotroic chemical shift vs. lIT for Ru(OEP)(neopentyl) in CDC13 161Figure 4-16: Isotropic chemical shift vs. lIT for Ru(OEP)(neophyl) ind8-toluene 161Figure 4-17: ORTEP diagram of Ru(OEP)Np; thermal ellipsiod 33% 163Figure 4-18: ORTEP diagram of Ru(OEP)(neophyl); thermal ellipsoids 33% 165Figure 4-19: ‘H N1\4R spectrum (C6D,300 MF{z) of [Ru(OEP)Np]2(.i-Li) 167xiFigure 4-20: ORTEP Diagram of[Ru(0EP)Np]2(.t-Li);thermal ellipsoids 33% 169Figure 4-21: 1H NIVIR spectrum (C6D,300 1VIHz) of the products of the reaction of[Ru(OEP)Np1(p.-Li)with 02. Spectra were collected: a) within 5 minutes; b)after 2 days 172Figure 4-22: ‘H N1VIR (300 MHz) spectral changes observed over time for the reaction of[Ru(0EP)Np](.t-Li)( 3mM) in water-saturated ( 30 mM) C6D 175Figure 4-23: 1H NEVIR spectrum (C6D,300 MHz) of [Ru(OEP)Np]2(p.-Li) ( 7mM)under anhydrous NH3 177Figure 5-1: ‘H N1VIR spectrum (C6D,300 MHz) ofRu(TMP)Ph2 186Figure 5-2: ‘H NMR spectrum (C6D,300 Mz) ofRu(TMP)Me 187Figure 5-3: a) ORTEP diagram of Ru(TIVIP)Ph2.b) Proposed structure; thermalellipsoids 33% 188Figure 5-4: ‘H NMR spectrum (C6D,300 IVIHz) of the products of the reaction ofRu(TMP)C12with 2 equivalents NpLi 192Figure 5-5: 1H N1VIR spectrum (C6D,300 MHz) of the products of the reaction ofRu(TMP)Cl2with 3 equivalents ofNpLi 194Figure 5-6: ‘H NMR spectrum (C6D,300 MHz) of the products of the reaction ofRu(TMP)Br2with 7 equivalents of neopentyl lithium 197Figure 5-7: a) ‘H N[VIR spectrum (C6D,300 IVIHz) of Ru(TMP)(COPh)Ph 204Figure 5-8: 1 N’R spectrum (C6D,300 MHz) ofRu(TMP)Me2under C0(1 atm) for 5days 206Figure 5-9: 1H NIVIR spectrum (d8- toluene, 300 MHz) of Ru(TIVIP)Me prepared via theanaerobic thermolysis ofRu(TMP)Me2at 1110 C for 24 h 211Figure 5-10: ‘H NMR spectrum (d8- toluene, 300 MHz) of Ru(TMP)Ph prepared via theanaerobic thermolysis ofRu(TMP)Ph2at 1110 C for 24 h 212Figure 5-11: UV/visible absorbance changes (measured at 25° C) for the thermolysis ofRu(TMP)Ph2at 111° C 214Figure 5-12: First-order plot for the thermal decomposition of Ru(TMP)Ph2in toluene at111°C 215xl’Figure 5-13: Eyring plot for the decomposition of Ru(TMP)Ph2 217Figure 5-14: First-order plot for the thermal decomposition of Ru(TMP)(COPh)(Ph) indg-toluene at 800 C 218Figure 5-15: Eyring plot for the decomposition of Ru(TMP)(COPh)Ph 219Figure 5-16: First-order plot for the thermal decomposition of Ru(T1VIP)Me2in toluene at70°C 220Figure 5-17:Eyring plot for the decomposition of Ru(TMP)Me2 224Figure 5-18: ‘H NMR spectrum(d8-toluene, 300 mHz) of Ru(TMP)CO(MeOH)produced by the photolysis of Ru(TMP)Me2under 1 atm 02 228Figure C-i: PLUTO Plot showing the numbering scheme of Ru(OEP)Np 248Figure C-2: Stereoview of Ru(OEP)Np 249Figure D-1: PLUTO Plot showing the numbering scheme for Ru(OEP)(neophyl) 256Figure D-2: Stereoview of Ru(OEP)(neophyl) 257Figure E- 1: ORTEP plot of a monomeric unit of [Ru(OEP)NpJ2(.t-Li) 265Figure E-2: Stereoview of[Ru(OEP)Np12(t-Li) 266Figure F-i: PLUTO Plot showing the numbering scheme of Ru(TMP)Ph2 274Figure F-2: Stereoview of Ru(TMP)Ph2 275XIIIList of TablesTable 3-1: Reduction potentials of Ru(IV)(porp)X2complexes (± .01 V vs. Ag/AgCl)... 84Table 3-2: Reduction potentials for Ru(ffl)(porp)X(L) complexes (± 0.01 V vs.Ag/AgC1) 108Table 4-1: Rate constants for the decomposition of Ru(OEP)Np2at varioustemperatures 132Table 4-2: ‘H NMR spectra of the discussed Ru(OEP) complexes 179Table 5-1: Selected dimensions for some ruthenium porphyrin complexes 189Table 5-2: ‘H NIVIR (C6D,300 MHz) signals observed following the reaction ofRu(TMP)Cl2 with 2 equivalents of neopentyllithium 193Table 5-3: Observed rate constants for the decomposition ofRu(TMP)Ph2 at varioustemperatures in toluene 216Table 5-4: Observed rate constants for the thermolysis ofRu(TMP)(COPh)Phin toluene 219Table 5-5: Observed rate constants for the thermolysis ofRu(TMP)Me2ind8-toluene atvarious temperatures 223Table 5-6: Bond dissociation energies for the axial Ru-R bonds of some Ru(porp)R2complexes 225Table C-i: Experimental Details for the X-ray diffraction analysis of Ru(OEP)Np 250Table C-2: Atomic coordinates and Beq 252Table C-3: Bond Lengths (A) 253Table C-4: Bond Angles (0) 254Table C-5: Least Square Planes 255Table D-1: Experimental Details for the X-ray diffraction analysis ofRu(OEP)(neophyl) 258Table D-2: Atomic coordinates and Beq 260xivTable D-3: Bond Lengths(A).261Table D-4: Bond Angles (°) 262Table D-5: Least Square Planes 264Table E- 1: Experimental Details for the X-ray difiiaction analysis of[Ru(OEP)Np]2(p-Li) 267Table E-2: Atomic coordinates and Beq 269Table E-3: Bond Lengths (A) 270Table E-4: Bond Angles (°) 271Table E-5: Least Square Planes 273Table F-i: Experimental Details for the X-ray diffraction analysis ofRu(TMP)Ph2 276Table F-2: Atomic coordinates and Beq 278Table F-3: Bond Lengths (A) 279Table F-4: Bond Angles (°) 280Table F-5: Least Square Planes 281xvNumbering Scheme for Porphyrins.8 (pyrrole)20\ / 1O(meso)19—N Nz18’ 1217 15 13Note: Carbons 2, 3, 7, 8, 12, 13, 17 and 18 are referred to as the pyrrole positions andcarbons 5, 10, 15 and 20 are referred to as the meso positions.xv’List of AbbreviationsA absorbanceA Angstrom unit (100 meter)Anal. calcd analysis calculatedatm atmosphereBDE bond dissociation energyB.M. Bohr magnetonbr broad, in NN’IR spectroscopyBu normal butyltBu tert-butylBzK benzyl potassiumC degree Celsiuscarbon-13 isotopem-CPBA meta-chloroperbenzoic acidcm centimetercm’ wave number, in JR spectroscopyCV cyclic voltammogramd day, deuterium or doublet, in NIVIR spectroscopyDMA N, N’-dimethylacetamide (CH3CON(CH)2DMF N, N’-dimethylformamide (HCON(CH3)2xviiDMSO dimethylsulfoxide ((CH3)2S0)DPB diporphyrinatobiphenylene tetraanione electronE potentialchange of potentialEl electron impact mode in mass spectroscopyeq. equationEt ethyle.u. cal mol’ IC’FT Fourier transformg gramGC gas chromatography‘H protonactivation enthalpyh hourhv light energyHz HertzIR infraredK equilibrium constant or degree Kelvink kinetic rate constantk0b observed kinetic rate constantkeal kilocaloriesmitL ligand7Li lithium-7 isotopeM metal or molaritym multiplet in NMR spectroscopym meta-proton on an aryl or pyridine ringm-CPBA meta-chloroperbenzoic acidMe methyl (CH3-)MeO methoxy (CH3O-)mg milligrammL millilitermmol millimolemol moleMS mass spectroscopymV millivoltsnaph naphthalenenm nanometerNp neopentylNp neopentyl radicalNpLi neopentyllithiumNMR nuclear magnetic resonanceo ortho-proton on an aryl or pyridine ringOCP 5, 10, 15, 20-tetra(2, 6-dichlorophenyl)porphyrinato dianionxixOEP 2, 3, 7, 8, 12, 13, 17, 18-octaethylporphyrinOFP 5, 10, 15, 20-tetra(2, 6-fluorophenyl)porphyrinato dianionp para-proton on an aryl or pyridine ringPh phenyl (C6H5-)Pfr phenyl radicalPhIO iodosobenzeneporp generic porphyrinato dianionppm or ö chemical shift in parts per million relative to TMSpy pyridinepyrr pyrrole positions on the porphyrinq quartet in N?v’IR spectroscopyR alkyl or arylRLi organolithiumRMgX Grignard reagentRT room temperatureS spin states second or singlet in NMR spectroscopyLS activation entropyT temperatureT1 spin lattice relaxation timeTBAP tetra-n-butylammonium perchiorateTBHP tert-butyl hydroperoxidexxTEMPO tetramethyl- 1 -piperidinyloxyTHF tetrahydrofuranTMP 5, 10, 15, 20-tetramesitylporphyrinato dianionTMS tetramethylsilaneTPP 5, 10, 15, 20-tetraphenyporphyrinato dianionUV ultra-violetV voltsX halidev Infrared frequencywavelength of a principle absorption peak in UV/vis spectroscopyJ.Leff effective magnetic moment.tL microliterc molar absorptivity (extinction coefficient)xx’AcknowledgmentsFirst, I would like to thank my supervisor Professor Brian James, whose continuoussupport made this work possible. I would also like to thank all the members of the Jamesresearch group who have come and gone over the years. Special thanks go to Don Yapp,Ken MacFarlane, Grant Meng and Richard Schutte for lending an ear and helping mework through some of the more confusing aspects of this work. I would also like to thankProfessor Micheal Fryzuk and his group, for allowing liberal access to their glove box.Specifically I would like to thank Guy Clentsmith and Dave McConville, andMurugesipilai Mylvaganum for their help when I was working in their labs.I would like to thank all the members of the Department staff who provided serviceover the years. The number of people who helped is far to many to list here, however Iwould mention Dr. S. Rettig for the X-ray crystallography, Peter Borda for the elementalanalysis, Dr. N. Burlinson, Marietta Austria and Liane Darge for their help with NEVERspectroscopy and S. Rak for glass blowing.Finally, I would like to thank my wife Christine for her Job-like patience andsupport.xxiiFor Christinexxii’Chapter 11. Introduction to Ruthenium Porphyrin ChemistryThe study of the chemistry of porphyrins and metalloporphyrins has been vigorouslypursued since chlorohemin was first crystallized in 18521 and progress in the field has beenwell documented.2 The impetus for this research stems from the interest in biologicallyimportant proteins such as oxygen carriers (hemoglobin), electron-transfer cytochromesand oxygen reducing enzymes (cytochrome P-450) as these species contain themetalloporphyrin unit heme3 at the active site of the molecule. Workers have alsoattempted to derive insight into other porphyrin-like systems such as chlorophyll4andvitamin B12.5 To this end, many porphyrin and metalloporphyrin model complexes havebeen prepared, and extensive research into the structure, physical properties and thereactivity of these species has been done. While this work has improved ourunderstanding of the functions of the naturally occurring systems, it has also providedinteresting and varied chemistry in itself.The porphine dianion, illustrated in Figure 1-1 a is the structural template for allporphyrin ligands. Typically, these tetradentate dianionic ligands bind via the 4 nitrogenatoms with the metal sitting approximately in the center of the macrocycle. This restrictsany subsequent ligand binding to the axial sites. This constraint has led to someinteresting chemistry involving strong trans effects and radical mechanisms (see chapters 4and 5). Metalloporphyrin complexes have extensive ic-systems involving the 11 double12-a) b)octaethylporphyrinA=H, B=CH2CH3tetraphenylporphyrinc) A A=, B=HtetramesitylporphyrinA=Ø-, B=HFigure 1-1: The structures of a) porphine dianion, b) heme, c) free-base porphyrinsused in the work.BBB A B2bonds illustrated in Figure 1-la, and this feature results in very distinctive electronicspectra which have often proven very useftil in the characterization of these complexes.Protoporphyrin IX is the porphyrin ligand found in naturally occurring systems. Theheme moiety, shown in Figure 1-ib, is composed of an iron(II) ion inserted into thecentral cavity of this porphyrin. This group in turn is found within large proteins andusually constitutes the active site of the system. To say the least, these are very complexsystems, and initial work in the field focused primarily on isolating the heme moiety inorder to study its reactivity in the absence of the protein. Alternatively, workconcentrated on preparing analogues of protoporphyrin IX and heme, and studying theproperties of these systems. By altering the functional groups around the periphery of theporphyrin, researchers have managed to create a multitude of derivatives with which towork. Figure 1-1 c illustrates the porphyrin ligands that were involved in the present work.Today, metalloporphyrin complexes representing almost the entire periodic table ofelements have been prepared, although iron complexes have been by far the mostextensively studied. Although a great deal has been learned from this work, many of theintermediate species described in the iron chemistry have been proposed by indirectevidence. This is due to the short lifetime of these species. In an attempt to overcomethis problem, researchers in this and other laboratories have undertaken the task ofpreparing and studying porphyrin complexes of ruthenium, which lies directly below ironin the periodic table. The hope was that these species would exhibit chemistry that was ofdirect relevance to the iron systems, yet would provide added stability so that analogues ofthe latent intermediates proposed in the iron work could be directly observed or isolated.3The first ruthenium porphyrin complex was described in 1969,6 although it was notcorrectly characterized as Ru(TPP)(CO)(EtOH) until two years later.7 Studies thatfocused primarily on Ru(II) complexes continued throughout the 1970s. However, agreat deal of progress has been made since that time and, as of today complexes inoxidation states of 0-VI (except for V) have been isolated or detected. Complexes withC-, N-, P-, As-, 0-, S-, and halogen-donor ligands have been prepared, including somepossibly biologically relevant species containing small diatomic gases such as 02, N2, andCO. The purpose of this chapter is to provide the reader with a brief summary of theprogress made in this field with the hopes of providing some perspective for materialdiscussed in subsequent chapters.1.1 Ruthenium(ll) Derivatives1.1.1 Synthesis and physica’ propertiesComplexes of this oxidation state constitute the largest class of ruthenium porphyrinsystems and are inevitably the starting point for any work in this field. This is becausealmost every successful insertion of ruthenium into a free-base porphyrin has resulted inthe formation of a Ru(II)(porp)(carbonyl) complex.7’8These preparations involverefluxing solutions of ruthenium precursors such as Ru3(CO)12,RuC13(H20), or[RuCI2(CO)3}and a free base porphyrin under CO or N2 gas (eq. 1.1). The solvents usedare usually high boiling and non-coordinating such as toluene or mesitylene. In the4N orCORu3(CO)12 + H2porp 2 Ru(porp)(CO)L 11refluxfinal product, the coordination site trans to the carbonyl ligand can be vacant, but oftencontains a weakly coordinating sixth ligand (such as an alcohol) that is picked up duringthe final work-up. Attempts to metallate the porphyrins, using precursors such asRuC12(DMSO)4or Ru(DMSO)62,to give products without an axial carbonyl ligand wereunsuccessfhl.9 The only exception where metalation resulted in a product other than acarbonyl complex involved insertion ofRu3(CO)12 into the N, N-bridgedtetraphenylporphyrin to give the carbene complex shown in reaction 1.2.10 Mechanismsfor these reactions (eq. 1.1 and 1.2) have not been reported.R•R RcJII IIC Ru3(CO)12THFR=p-CIC6H4 1.2At this time, numerous Ru(porp)CO complexes have been prepared including someof the more exotic systems such as the “picnic basket8e,hl or “picket porphyrincomplexes. Consequently, the 11, physical’2and electrochemical’3properties of these species have been well documented.All of the known carbonyl complexes exhibit remarkable chemical stability and forexample, can be easily handled under aerobic conditions. This stability has been attributedto the strong Ru to L back-bonding from the dir orbitals of the ruthenium to the empty 7r5orbitals of the carbonyl group. This interaction is well documented in organometallicchemistry and can be verified by a study of the vibrational spectra of these compounds.The net result of placing electrons in the ic orbitals is a subsequent weakening of the CObond. This is evident in the energy of the vco stretching frequencies which fall in therange of 1889-1969 considerably lower than the value of 2143 cm’ for free CO.The frequency of this vibration is influenced by the basicity of the porphyrin and the donorproperties of the trans axial ligands.1.1.2 Reactivity of Ru(porp)CO complexesThe ruthenium carbonyl interaction described above causes this bond to be relativelyinert. Accordingly, initial studies of the reactivity of these complexes were limited to anexamination of the exchange of ligands at the sixth axial position. Several in situ studieshave been carried out to inspect these fast equilibrium reactions (eq 3.1).KRu(porp)CO + L q Ru(porp)(CO)L 1.3The magnitude of the equilibrium constant in these systems depends largely on theproperties of the ligand L. For example, studies have demonstrated that there is a directcorrelation between K and the donor number of the ligand L (L=CH3CN, THE andpyridine).’3 Further work, equilibrium constants in the range of 4.2 x iO to 4.3 x iOwere obtained for 20 different nitrogenous bases, and a trend of increasing withincreasing pKa of the ligand was observed. 13e Nitrogen donor ligands are of interest inattempts to understand interactions in proteins.6Neutral oxygen donors tend to bind relatively weakly, while ligands withphosphorus donors exhibit the highest stability presumably due to strong a-donationcoupled with some it-back donation into empty d orbitals of the phosphorus. Overall, thegeneral stability trend increases in the order 0< N<P. 13gThe influence of the carbonyl ligand can also account for the interesting redoxbehavior of these compounds. The it-overlap seems to reduce the energy of the filledmetal d-orbitals to such an extent that the highest occupied molecular orbital of thecomplex resides on the porphyrin rather than on the ruthenium. Thus, the first oxidationoccurs on the porphyrin ring to give the it-cation species [Ru(ll)(porpjC0].’3”4In themajority of other Ru(II) species, the first oxidation results in the Ru(III) product.Exceptions involve ligands which are also strong it- backbonders, such as PF3.’5 The it-cation radical species produced by chemical oxidation with Br2 have been used as modelsfor peroxidase compound j 14a,bThe effect of the Ru to carbonyl it-backbonding on the site of reduction is less clear.The lowest unoccupied orbitals on the metal are the d2 and the orbitals which wouldnot be expected to have any it-overlap with the axial ligand(s). Thus the energy of theseorbitals would be affected only by crystal field and a-bonding effects. No clear trend as tothe site of reduction and the properties of axial ligands has been presented and this seemsto depend more on the properties of the porphyrin itself. Indeed, the site of reduction hasbeen shown to occur on the porphyrin ring for Ru(TPP)C0 to give the it-anion radicalspecies, 13k while evidence has been presented to suggest that the first reduction of7Ru(OEP)CO is metal-centered.’31While the carbonyl species provided an interesting study in themselves, theirinherent stability initially proved to be an obstacle to preparing complexes with a morediverse set of ligands. Several methods have since been developed to remove the carbonylgroup.(1) Direct substitution of the CO with strongly coordinating ligands such asphosphines,7”36’nitrosyl,’7jsocyades72el6a8and nitroaromatic compounds such asnitobenzene.19Ru(porp)CO + L Ru(porp)L2L= PR, NO, RNC, PhNO, AsPh3 1.4(2) Photolysis in coordinating solvents to give Ru(porp)(solvent)2.7lhOhvRu(porp)CO . Ru(porp)(solvent)2solventsolvent = pyridine, DMSO, DMA, THF, CH3N, pyrrole 1.5(3) Reaction with strong oxidizing agents.This gives two categories of products. Pseudo-dimeric Ru(IV) species bridged byan oxygen atom result when Ru(porp)CO complexes are oxidized using oxidants such asm-chloroperbenzoic acid in a non-coordinating solvent (eq. 1 .6).21 The same reaction (forthe OEP species) performed in methanol or ethanol yields the Ru(VI) dioxo product8m-CPBARu(porp)CO [Ru(porp)L]20porp = OEP, TPP, TPrP *L = OW, OW or halides 1.6shown in reaction 1 722 In this case the weakly coordinating alcohols inhibit formation ofthe p.-oxo dimers, but this dioxo species is extremely sensitive and will degrade to the poxo dimer upon exposure to H20.m -CPBARu(OEP)CO trans .-Ru(OEP)(O)2 1 7EthanolFor sterically hindered porphyrins (e.g. Th4P, OCP**), formation of the I.t-oxospecies is not possible, and only the Ru(VI) dioxo complex is formed during thesereactions, regardless of the solvent used.The I.t-oxo dimers proved to be almost as stable as the parent carbonyl complex andonly react with strong reducing agents (see section 1.4.2). The Ru(VI) dioxo speciesturned out to be relatively strong oxidants, transferring one or both oxygen atoms to avariety of substrates. These reactions can occur stoichiometrically andJor catalytically (inthe presence of a suitable oxygen atom donor) and, in either case, various rutheniumporphyrin products of oxidation state (II) and (IV) can be isolated23”4( see also section1.4.1).Methods 1 and 2 above afford a new class of Ru(ll) complexes of general formula5, 10, 15, 20-tetra-n-propylporphyrinato dianion5, 10, 15, 20-tetra(2,6-dichlorophenyl)porphyrinato dianion9Ru(porp)L2(L= strongly coordinating ligand or solvent, L CO). The products obtainedby photolysis (method 2) require an input of energy to effect replacement of the CO bondand are consequently far less stable than the parent carbonyl. The reactions described inmethod 1 proceed thermally under relatively mild conditions and are usually carried out atroom temperature. It seems that strong a-donor- and/or strong t-acceptor-ligandsfacilitate cleavage of the Ru-CO bond yielding complexes that are almost as stable as thecarbonyl complexes. In the following section we will outline the reactivity of theseRu(OEP)L2complexes.1.1.3 Reactivity of Ru(porp)L2complexesThe axial ligands in these complexes exhibit varying degrees of lability and mayundergo one or both of the substitution equilibria shown in equation 1.8. 16c,18,19,20b,25 TheL’ L’Ru(porp)L2LRu(porp)LI)LRu(porp)L’2 1.8products isolated from these reactions depend on the nature of both the outgoing and theincoming ligands and both the monosubstituted and disubstituted products have beenobserved or isolated. Complexes with strong a-donor and/or strong 7-acceptor ligandssuch as the bis(phosphine) 16b-d and bis(nitrosobenzene)’9species tend toward substitutionofjust one axial ligand unless ligands of comparable strength are introduced. Forexample, Ru(OEP)(PhNO)2will react with pyridine to give a quantitative yield ofRu(OEP)(PhNO)py. However a mixture of Ru(OEP)(PhNO)PPh3and Ru(OEP)(PPh3)2was isolated when the same complex was reacted with PPh3. Futhermore, the reaction10with 1 atm of CO gave only Ru(OEP)(CO)2.These results illustrate the differences in thetrans-effect of the incoming ligand L’ and are consistent with the known it-acid strengthsof these species (CO > PPh3 >py). The trans-influence of the nitrosobenzyl ligand is alsoevident as these reactions undoubtedly occur via an SN1 type reaction involving the five-coordinate Ru(OEP)(PhNO) intermediate. A dissociative equilibrium has also beenimplicated in the Ru(TPP)(PPh3)2catalyzed decarbonylation of aldehydes26.This processis examined more closely in section 1.6.1.The Ru(porp)L2products obtained by photolysis are even more labile than theproducts obtained by the thermal reactions and tend towards substitution of both axialligands. Complexes of the more labile ligands (e.g. THF, CH3N) will react even withsmall, diatomic molecules such as 02, N2 and H2. For example, solutions ofRu(OEP)(CH3CN)2in weakly coordinating solvents such as DMA, DMF and pyrrolereversibly bind dioxygen at room temperature and 1 atm pressure.20b The solvents play akey role in this reaction because the same complex gives [Ru(OEP)J20under thecorresponding conditions in toluene. When exposed to air, solutions (CD2I)of theRu(TMP)(CH3CN)2immediately displayed H NMR peaks attributed to theruthenium(IV) mono oxo species which continues to react to produce the ruthemum(VI)dioxo product as shown in reaction .9 As mentioned previously, the bulkytetramesitylporphyrin does not permit close enough approach of two Ru(TMP) moietiesto form a p.-oxo species. Equation 1.10 illustrates reactions of Ru(porp)L2complexes11L= CH3N, porp= TMP 1.9with In all but one case the coordinated dinitrogen was confirmed byJR spectroscopy, and Ru(TIvIP)(N2)THF has been structurally characterized by X-raycrystallography.28Ru(porp)L2+ N2 Ru(porp)(N2)Lporp L vN(cm)OEP THF 2110DMFTMP DMF 2108Et20 2116Et3N 2147THF 2116 1.10The Ru(OEP)(THF)2complex will activate dihydrogen when THF solutions of thiscompound are stirred in the presence of excess KOH under 1 atm ofH2 to give the monohydride product, as shown in reaction 1-1 1.29 This reaction is assumed to proceed viainitial formation of ther2-dihydrogen intermediate followed by proton abstraction fromthe acidic dihydrogen complex by OFf This intermediate has been observed in situ at78° C by reaction of the hydride with the appropriate acid.3° The hydride complexes[Ru(porp)(THF)Hf are thermally stable both in the solid state and in solution. However,dihydrogen is produced at room temperature upon reaction of the complexes with acids orupon oxidation. Section 1.6.3 describes how this knowledge led researchers to catalytic12H=PhCOOH,L=THF 1.11processes for oxidizing H2 to II or reducing H to H2.In 1979 it was reported that Ru(OEP)(THF)2in solution could reversibly bindC2H4.9 The resulting olefin complex can be formulated as the Ru(IV)metallocyclopropane or the it-ethylene species, as illustrated in reaction 1.12. The latterTHF H2C—CH H C=CHTHF 1.12formulation was tentatively favoured, and this was later confirmed when theRu(OEP)(C2H4)complex was isolated in an separate procedure.3’The lability of the axial ligands of some Ru(II)(porp)L2complexes is even evident inthe solid state. Pyrolysis under high vacuum of complexes with non bulky porphyrinligands leads to the dimeric complex illustrated below (equation 1.13)32 In an interestingvariation, some mixed Ru-Os analogues of the dimer were prepared by vacuum pyrolysisof the mixture of the appropriate starting materials.33 For complexes with bulkyporphyrin ligands, dimerization is not possible and a monomeric product results.2200 CRu(porp)(py)2 [Ru(porp)]2io torrporp= OEPorTPP 1.1313For example, an amorphous powder ofRu(TMP)((CH3CN)2yields the four-coordinate,14-electron species Ru(TMP) under the same conditions as shown above.2It should be noted that the pyrolysis products described above are realized only forcomplexes containing the most labile axial ligands; that is to say, complexes prepared bythe photolysis procedure. Pyrolysis of certain diphosphine complexes (equation 1.14)resulted in removal of only one phosphine,34and in one case, no phosphines: pyrolysis ofRu(TPP)(PPh3)2resulted in sublimation of the complex rather than cleavage of the Ru-Pbond.34 This was unexpected since toluene solutions ofRu(TPP)(PPh3)2exhibited moredissociation than the OEP analogues. 16dRu(porp)(PR3)2 i Ru(porp)(PR3)porp TMP, R= tBu; porp= OEP, R= PPh3 1.14Perhaps surprisingly, the Ru2(II,II) complex, [Ru(porp)12proved to beparamagnetic. This can be explained if the molecular orbital picture for these species isconsidered. Figure 1.2 illustrates the molecular orbital overlap expected for a transitionmetal-metal bonded species, as applied to the ruthenium dimers.32b Each ruthenium atomis formally in a 2+ oxidation state and hence contributes six d-electrons to the molecularorbitals of the complex. Thus, the expected electron configuration of these complexes isa(2)it(4)ô (2) ö*(2)t*(2). The ruthenium(II,II) dimers are therefore expected to have atriplet ground state with a metal-metal double bond. The solution magnetic momentmeasured for [Ru(OEP)]2 2.8 B .M. )32a is consistent with 2 unpaired electrons, and14the Ru-Ru bond length obtained from the crystal structure (2.4 A)32b is consistent with abond order of 2./IIII 7* %_____,_&t1I, _._•‘.____xy 4], _..v= xyxz,yz ..iL. _1L?’ - ‘‘_1.L. —.Lxz,yzz2—-< / ‘>._il_2%%% %__iL..__iL_ _/IIIiaiRu Ru=Ru RuI I I IFigure 1-2: Molecular orbital diagram for [Ru(OEP)]2.The oxidation of these complexes can also be interpreted in terms of the MOdiagram of Figure 1-2. Cyclic voltammetric measurements reveal four oxidations and tworeductions, all reversible on the voltammetric time scale.35 The first two oxidations aremetal-centered while the other couples are thought to be porphyrin-centered.Vibrational36and EXAF measurements37on the first two oxidation products reveal areduction of the bond order from 2 to 1.5 and finally 1 with each successive oxidation.This corresponds to the removal of first one, and then two electrons from the it orbitals.Furthermore, the predicted electron configurations for neutral, 1+ and 2+ oxidation stateswere all confirmed by X-ray absorption near edge spectroscopy.37151.1.4 Reactivity of jRu(porp)12and Ru(TMP)The discovery of the [Ru(porp)]2and Ru(TMP) products from vacuum pyrolysiswas a major synthetic milestone in ruthenium porphyrin chemistry. Both compounds arecoordinatively unsaturated and, as such, are extremely reactive. Products with oxidationstates of 0, II- IV and VI have been obtained including a number of new organometalliccompounds. With the preparation of the complexes of higher or lower oxidation states,came new avenues for the synthesis of ruthenium(II) compounds (for examples seesections 1.2 and 1.3.2).The ruthenium porphyrin dimer species react rapidly with air to give the same p-oxodimers previously seen upon oxidation of the carbonyl complexes. The mechanism of thisreaction has not been clearly elucidated although putative intermediates such asRu(OEP)02,Ru(TPP)02and the bridged [Ru(TPP)O]2have been observed by IRspectroscopy, albeit under somewhat extreme conditions.38 If handled under strictlyanaerobic conditions, the dimers serve as excellent synthetic precursors, leading toruthenium-olefin, -carbene, -alkyl and -dihalo products. Moreover, previously unseenRu(II)(porp)L2species are also afforded by reaction with the ligand of interest in noncoordinating solvents. For example, Ru(OEP)(NH3)2was observed by H NMRspectroscopy in this thesis work by placing a sample of the dimer under anhydrousammonia in C6D. A summary of the reactions of [Ru(OEP)J2is shown in Scheme 1-i”’ (see also chapter 4 of this thesis for a description of the neopentyl (Np) work).16A special class of the dimeric complexes are the “cofacial” species which involvetwo porphyrin rings bridged by a variety of functional groups covalently bonded to theperiphery of the porphyrin.40 An example of this is theRu2(DPB) complex shown inFigure 1-3. This complex is prepared in a completely analogous fashion to the dimersdescribed above (by vacuum pyrolysis of theRu2(py)4DPB ) and displays physicalproperties similar to those of its non-bridged cousins. However, due to the rigid cofacialconfirmation exacted by the bridging porphyrin, they display some unique reactivity.Addition of an excess of some standard donor ligands L (L=py, THF, etc.) yields theexpectedRu2(L)4DPB) products. However, addition ofjust 2 equivalents of theappropriate ligands results in some remarkable reactivity with hydrogen and dinitrogen.For example, addition of 2 equivalents of 1-tert-butyl-5-phenylimidazole to a H2-saturated benzene solution ofRu2(DPB) affords the dihydrogen-bridged productrepresented in reaction 1.15.41 The JD-H splitting of 15 Hz observed in the H NIvIRspectrum of the hydrogen deuteride analogue coupled with a spin lattice relaxation time T1of 132 ms is consistent with a dihydrogen structure rather than a di-rutheniumFigure 1-3: Structure of Ru2DPB (DPB = diporphyrinatobiphenylene tetraanion).17H2C—CH H2CCHScheme 1-1: Reactions of [Ru(OEP)]2.RcR CH2N orNpRNp2NpLi/02H01C6] 2+Ru(II)(OEP)L2Na/K [c] 2-THFX2Ru(IV)(OEP)X2X Cl, BrX= OW, 0R[[18Im*1.-.—.EE-r..—iE+ H2/benzene I II II Im* 112LzE Itli L- p—Im* 115Im* 1-tert-butyl-5-phenylimidazolemonohydride formulation. The bridging nature of the H2 bond was based upon theequivalency of the two porphyrin rings in the 1 H NIVIR spectrum, observed even at80°C. This would not be the case if the dihydrogen was coordinated to just one metalcenter. Of course, a fast exchange of the dihydrogen between the ruthenium atoms cannot be ruled out. The properties of the outer axial ligands seem to play a key role in thischemistry. The Ru2(DPB) showed no reactivity with H2 in the absence of the imidazolederivative, nor did any reaction occur when PPh3 was used as an axial donor.The dihydrogen bridge can be replaced by dinitrogen upon exposure to 1 atm ofnitrogen gas.42 Once again, a bridging structure is proposed based upon the symmetry ofthe porphyrin rings in the 1H NMR spectrum. This compound presents a characteristicv stretch at 2112 cm4 in the Raman spectrum which is at the higher end of the range forlinear dinitrogen complexes (2060- 2150 cm’)42 (see also eq. 1.10). Possibly the moststriking property of this complex is its unusual stability. The N2 was not dislodged after 5freeze-pump-thaw cycles, and the complex is completely air-stable in the solid state andtakes several hours to decompose in solution.The monomeric, 14-electron, “bare” ruthenium(II) porphyrin complex, Ru(TMP),also exhibits some rich reactivity. 20c,28 It is extremely sensitive to 02 and immediatelyforms the Ru(VI) dioxo product when exposed to air. Under anaerobic conditions, the19complex will react with even the weakest of donor ligand yielding Ru(II)(TMP)L2products. For example, even the weak bis(diethylether) adduct was obtained uponaddition of a 102 M solution ofEt20 in benzene.Of special note is the reaction of Ru(TMP) with dinitrogen. In benzene solution orin the solid state, Ru(ThIP)(N2)immediately forms upon exposure of the complex to 1atm of nitrogen gas. The characteristic v stretch of this complex appears at 2203 cm’which is believed to be the highest energy observed for any known dinitrogen complex.Clearly the effect of coordination on the bond order of the N-N bond is small (VNN= 2331cm1 in free N2) presumably because the two trans-N2ligands are competing for the it-electron density of the metal.The Ru(TMP) analogue of the it-ethylene complex shown in reaction 1.12 has beenisolated from the reaction of Ru(TMP)(N2)with ethylene gas. Moreover, a series of it-complexes of this type was prepared by treatment of the dinitrogen complex with ethylene,cyclohexene, phenylacetylene and diphenylacetylene.43 The reaction of the complex withunsubstituted acetylene did not give the expected ic-acetylene complex but instead lead tothe bridging carbene structure shown below. This formulation was suggested by amolecular weight determination, coupled with appearance of a signal— Ru —HCCH H-CRu — C—H{Ru(TMP)} benzene—Ru— 1.1620at 264 ppm in the ‘3C NMR spectrum, such a low field signal being characteristic ofcarbene complexes.1.2 Ruthenium(O) and Ruthenium(1) derivatives.To date, the only Ru(O) porphyrin complexes reported are the Ru(O) porphyrindianions, [Ru(porp)]2 (porp= OEP, TPP), which are prepared as potassium salts by thereduction of the dimer, [Ru(porp)]2with Na/K alloy or K metal in THF (see scheme1.1)31a Their formulation was based largely on their subsequent reactivity: thedianions are very reactive towards electrophiles and several organometallic derivativesincluding alkyls, olefins, and carbenes have been prepared. These reactions aresummarized in scheme 1.2.Ruthenium(I) species have been prepared electrochemically and observed only insitu. The one-electron reduction of Ru(TPP)L2complexes (L= phosphine’‘1BuCN)generated [Ru(TPP)L2]which was assigned as a Ru(I) system based on the absence ofa signal in the ESR spectrum.16aSimilarly, the one-electron reduction of the carbonylanalogues of general formula Ru(OEP)(CO)L will in some cases lead to a Ru(I)product, the site of reduction being dependent upon the axial ligand L.4521THFA + + 2THF[ Et i-iI I RCr%VjTHFRH -1 7 HH20 RCHC12[] 4 K2[Ru(TPP)]N.BrCH2CHrR R% ICII Hc2CCHIIScheme 1-2: Reactivity ofK2[Ru(TPP)] (adapted from ref. 44).221.3 Ruthenium(Ill) Derivatives1.3.1 Synthesis and physical propertiesSeveral of these species have now been characterized, including the crystalstructures of two organometallic complexes in this work. The ruthenium(ffl) porphyrincomplexes exhibit paramagnetic properties with a spin state of S = 1/2 which is consistentwith a low spin d5 system. In this section we will outline the different approaches topreparing these complexes.1) Chemical oxidation of Ru(II) precursorsThe ruthenium(II) carbonyl complexes can be oxidized by 02, Cl2, or Br2 in thepresence of CN to produce the dicyano adduct shown in reaction 1.17.7,46 Someair or Br2Ru(porp)C0KCNK[Ru(porp)(CN)2]porp= OEP, TPP 1.17Ru(III)(porp)(PR3)X(X halogen) species can be prepared by oxidation ofRu(porp)(CO)PR or Ru(porp)(PR3)2with X2 or02/HX. 13i,47 Air-oxidation ofRu(TPP)(TIIF)2in the presence of ethanol yields Ru(III)(TPP)(OEt)(EtOH) (reaction1.18).21b The solvent plays a key role in this reaction because in the absence of EtOH theonly product is the p.-oxo dimer.23Ru(TPP)(OEt)(EtOHRu(TPP)(THF)2[Ru(TPP)O]2 1.18In scheme 1-1 (p. 18), the oxidation of the Ru2(II,II) dimers to give theRu2(III,III)dimeric products was illustrated. This oxidation is performed chemically by reacting the[Ru(OEP)]2precursor with two equivalents of AgBF4,yielding [Ru(OEP)]2(BF4).352) Electrochemical oxidation of Ru(II) precursorsIn section 1.1.2 some of the observations for the electrochemical oxidation ofRu(porp)(CO)L complexes were introduced. The first oxidation occurs on the porphyrinring yielding the it-cation radical product [Ru(II)(porpj(CO)L], while the secondoxidation occurs on the metal center to give the Ru(III) it-cation radical[Ru(III)(porpj(CO)L].’3’In contrast to the mono-carbonyls, most Ru(porp)L2complexes experience the first oxidation on the metal center to give the Ru(ffl) productand the second oxidation on the porphyrin ring. 13h, 14c, 16a,48 In one notable study,intramolecular electron transfer from the metal to the porphyrin was induced uponaddition of tertiary phosphines to [Ru(II)(OEP)(CO)py];’3’addition of a 2-fold excessor more ofPR3 (R= Ph or n-butyl) resulted in the formation of [Ru(III)(OEP)(PR3)2].This electron transfer was considered to be triggered by the loss of CO ligand uponcoordination of the phosphine. A similar ligand-induced electron transfer mechanism hasbeen proposed for the mode of operation of some cytochromes.49241.3.2 ReactivityTheRu2(Ill,ffl) dimer has proven to be a useful synthetic precursor; for example,thioether adducts of oxidation state (III) have been prepared by reacting [Ru(OEP)](BF4)2with the thioether of interest (equation 1.1 9)24 Reaction of the same complex with[Ru(OEP)](BF4)2+ SR’ R” [Ru(OEP)(SRR”)2](BF4)R’= R”= Et, MeR’ = Me, R’ = n-decyl 1.19Grignard reagents affords some Ru(III) organometallic products (reaction 1 .20).° ThecofacialRu2(DPB) (see figure 1-3, p. 18) analogues have also been prepared in thismanner.51 The Ru(porp)R complexes are also formed by the thermolysis of the ruthenium(IV), Ru(OEP)R2complexes (see section 1.4.2). 52,53 The Ru(OEP)Me[Ru(OEP)]2(BF4)+ 2RMgX 2Ru(OEP)RR = Me, Et, Ph, p-tol 1.20complex exhibits some interesting chemistry when reacted with strongly coordinatingligands such as pyridine or phosphine; the Ru(ffl) undergoes disproportionation to giveRu(II) and Ru(IV) products as shown in reaction 1.21 •52 This reaction appears to be2Ru(OEP)Me + 2PPh3 ‘ Ru(OEP)Me2+ Ru(OEP)(PPh3) 1.21unique for alkyl complexes. Reaction of phosphines or pyridine with the Ru(ffl) phenylderivatives simply results in the coordination of the added ligand at the 6th site to yieldRu(OEP)(Ph)L species. 52One of the cyano ligands of [Ru(OEP)(CN)2reaction 1.17) can be displaced bypyridine to give Ru(III)(OEP)(CN)(py), which can be subsequently reduced by25thiophosgene to yield the thiocarbonyl derivative shown in reaction 1.22.46 This speciesCsC12Ru(OEP)(CN)(py) Ru(OEP)(CS)(py) 1.22is analogous to Ru(OEP)(CO)py and it is therefore interesting to note that the CSstretching frequency of 1283 cm’ for this complex is actually slightly higher than the 1274eni1 observed for matrix-trapped CS. Furthermore, the energy of this vibration is notdrastically affected when the trans pyridine ligand is replaced by a variety of phosphines,pyridines, and imidazole derivatives, energies in the range of 1274 -1290 cm1 beingmeasured for the CS stretch in these complexes.54 Clearly, the M-L backbondingobserved for the carbonyl complexes does not occur for the CS analogues.1.4 Ru(IV) Derivatives1.4.1 Synthesis and physical propertiesThe Ru(IV) d4 species can be divided into two categories: monomeric complexes,and the p-oxo dimers described previously (see sections 1.1.2). The latter are diamagneticwhile the former exhibit paramagnetic or diamagnetic properties depending on the axialligands. We will briefly describe the various methods for obtaining these complexes.1) Oxidation of Ru(II) complexesTreatment of the Ru2(II,ll) dimers with HX or X2 (X= Br or Cl) yields the dihaloproducts Ru(OEP)X2shown in scheme 1.1 (page 17).39a)55 Alternatively, some of themonomeric Ru(porp)L2complexes with weaker axial ligands (e.g. L = N2,CH3N) can be26used in place of the Ru2(II,II) dimers.55 Generally, this alternate method has to be usedwhen dealing with the bulkier porphyrins where the dimeric precursors are notavailable. Of course this reaction is not general for all Ru(II) complexes. The readermay remember from section 1.3.1, that reaction of the carbonyl or phosphine adductswith HX/02 results in the isolation of only Ru(III) products.47 Several of theseparamagnetic Ru(OEP)X2compounds have now been synthesized and characterizedand the structure has been verified with an X-ray crystal structure for Ru(TPP)Br2.39bReaction of the dihalo complexes with Grignard or organolithium reagentsresults in the formation of the diamagnetic Ru(IV)(porp)R2compIexes.39’52 Thispreparation is an attractive alternative to the reaction of RX withK2[Ru(porp)] (seescheme 1.2, p. 22) because the dihalo species are more robust and easy to handle. Itshould be noted that some Ru(III)(porp)R products are also isolated from thesereactions.56 In chapters 4 and 5 studies of these reactions are described.Several different oxidation reactions to generate the ruthenium I.t-oxo dimer havenow been identified. The various approaches are summarized in Scheme 1-3. Thestrength of the oxidant required is clearly dependent on the nature of the axial ligandpresent.27Ru(porp)CO Ru(porp)L2 VC [Ru(porp)]2\ 02 (air)peracid 02 (air)[Ru(porp)]20porp= OEP, TPP, etc. L= THF, CH3NScheme 1-3: Oxidation pathways for the synthesis of ruthenium p-oxo complexes.2) Oxidation of Ru(III) precursorsPhoto-induced air-oxidation of the organometallic Ru(III)(OEP)R complexes(where R = aryl) yields the .t-oxo dimer products (reaction 1.23).39l52 It is interesting tonote that the Ru-C bond remains intact in these reactions.Ru(OEP)R O2h(:ir) [Ru(OEP)R]20 1.233) Reduction of Ru(VI) complexesThe Ru(VI) dioxo species described previously (sections 1.12 and 1.13) can transferone or both oxygen atoms to a variety of different substrates. Whether these reactionsproceed stoichiometrically or catalytically is contingent upon the reaction conditionsand/or the substrate itself in any case, a variety of Ru(II) and Ru(IV) products can beisolated from these reactions.Treatment of benzene solutions of Ru(TMP)(O)2with isopropanol results in theformation of the bis(isopropoxy) compound (equation 1.24).” The formulation of this28Ru’ (0)2 + 3Me2CHOH —‘ Ru’ (OCMe2)+ Me2CO + 2H0‘Ru’ Ru(TMP) 1.24paramagnetic product has been confirmed by X-ray crystallography.5mBoth theisopropoxy complex and the dioxo species catalytically oxidize isopropanol to acetone andit follows that each species probably figures prominently in the catalytic cycle. Researchcontinues in these laboratories to elucidate the mechanism of this catalysis.In a similar reaction, a paramagnetic Ru(IV) product results from the reaction ofphenol with Ru(TMP)(0)2(equation 1.25). The Ru(II) bis(hydroquinone) intermediate‘Ru’ (0)2PhOH‘Ru’ (-0H)2 02 ‘Ru’ (0-©-OH)2‘Ru’=Ru(TMP) 1.25was observed by ‘H NMR spectroscopy when the reaction was carried out under oxygen-free conditions.58 Preliminary kinetic measurements give a rate law of that is 1St order inboth the ruthenium complex and phenol (i.e. rate = k[Ru(TMP)(0)21[phenol] (k = 0.069M’s’)), which is consistent with an attack of the ruthenium dioxo species by phenol in therate-determining step. It is interesting to note that the putative mono-oxo intermediatethat is expected in such a reaction was never observed suggesting that the mono-oxocomplex reacts more quickly than does the dioxo species.The crystal structure of a trimetallic bis-p.-oxo ruthenium porphyrin speciesappeared in the literature,59 the species being prepared by reaction ofRu(TPP)(0)2withiron(II) salicylidene. The presence of three metal centers make it difficult to assess theelectronic configuration of the ruthenium in thisd5-d4Fe-0-Ru”-0-Fe system.29Simple paramagnetism is not indicated, however, because there seems to be exchangecoupling as evidenced by variable temperature magnetic moment measurements.The first diarylamido ruthenium porphyrin complex Ru(3,4,5MeOTPP*)(NPh2)was also prepared via reduction of the dioxo precursors withPh2NH,6° although theauthors did not report on the fate of the oxygen atoms. This complex, like the dialkyl anddiaryl species, was diamagnetic.In section 1.1.3 the in situ observation by NMR spectroscopy of Ru(IV)(TMP)(O)during the air-oxidation ofRu(TMP)(CH3CN)2was noted. The identical NIVIR spectrumwas also obtained for the species formed during carethi titration of Ru(TMP)(O)2oneequivalent ofPPh3,with concomitant production of the phosphine oxide.27 An OEPanalogue this mono-oxo complex, Ru(OEP)(O)(EtOH), was later isolated from thereaction Ru(OEP)(O)2with an excess of olefins in ethanol.22 Both these monooxocomplexes exhibit paramagnetic properties consistent with 2 unpaired electrons.The reader may note that the detection of the monooxo complexes during thephosphine and olefin reacions implies that the dioxo species is more reactive than themonooxo species. This is in direct contrast to the observation made for the reaction ofRu(TMP)(O)2with phenol (reaction 1.25). It is thus becoming apparent that the relativereactivity of the second oxo moiety is probably (and not surprisingly) greatly affected bythe ligand trans to it.5, 10, 15, 20-tetra(3, 4, 5-trimethoxypheuyl)porphyrinato dianion304) Magnetic properties of the Ru(IV) derivativesThe magnetic properties of the Ru(porp)L2 (where L = monoanionic ligand)complexes can be accounted for in terms of simple crystal field theory. Figure 1-4illustrates three possible ground state configurations for a d4 system in a tetragonallydistorted crystal field. Cases 1 -4a and 1 -4b represent the splitting that occurs when anoctahedral field experiences elongation along the axial positions. Case c is the resultof an axial compression. The configuration in 1 -4a is the only arrangement thataccounts for the diamagnetism exhibited by species such as the dialkyls and diaryls.The paramagnetism of the complexes such as the halides and the alkoxides can berationalized if one considers the it-overlap between the filled p orbitals on the ligandand the d, d orbitals on the metal. This overlap apparently destabilizesconfiguration 1 -4a (d,, d,j4 to such an extent that this spin-paired configuration is nolonger energetically more favourable than the high spin configuration of Figure 1-4b.The splitting pattern in 1 -4c would also account for paramagnetic behavior; however,it is considered unlikely, because this configuration arises from a shortening of theaxial bonds or alternatively from the presence of stronger field ligands along the z axis.Most crystal structures reveal that the axial bonds are in fact longer than the equatorialporphyrin bonds,52 and both halogens and 0-atom ligands fall below the N-donatingporphyrin ligand in the spectrochemical series.31— xy __i_ xy :1_ _1___IL -.1_, yz.i.L. -i—,IL.a) b) c)Figure 1-4: The possible ground state configurations for the three lowest levels of ad4 metal in a tetragonally distorted octahedral crystal field. The xly axles are defined bythose which include the four Ru-N bonds.1.4.2 Reactivity of Ru(IV) complexesThe t-oxo dimers are relatively inert; however, treating these complexes with strongreducing agents produces a number of Ru(II) complexes. For example, reaction of[Ru(porp)O]2with NaBH4in THF yields Ru(ll)Qorp)(THF)2.1bOxidation ofRu(porp)(CO)L to the .t-oxo dimer, followed by NaBH4reduction, may prove to be auseful alternative method for obtaining Ru(II)(porp)L2derivatives. Reduction of[Ru(TPP)OEt]20with zinc amalgam, followed by treatment with thiophosgene, results inthe formation of thiocarbonyl species (equation 11 )Zn(Hg)[Ru(TPP)(OEt)]20 Ru(TPP)(CS)L2)C1CSsolvent L 1.26Cyclic voltammetric traces of the dihalide complexes exhibit a reversible oxidationand a reversible reduction peak.55 The electronic and ESR spectra of solutions of theoxidized product of Ru(OEP)C12(produced by bulk coulometry) reveal that oxidationoccurs at the porphyrin ring to give [Ru(IV)(OEPjCl2].On the other hand, bulk32reduction results in reduction of the metal center to give a Ru(III) product; this reductioncan be achieved chemically by treatment with anhydrous ammonia which gives themonohalide species shown in reaction 1 The supposed oxidized co-product(hydrazine) has not been detected. The coordinated ammine can be removed by reactionwith HF to give the five-coordinate Ru(OEP)X species.552NH3Ru(porp)X2 Ru(porp)(NH3)X+ 1/2N2H4+ HXporp = OEP, TMP X= BR, Cl 1.27The Ru(porp)R2complexes undergo thermal homolysis of the Ru-C bond to givethe five-coordinate Ru(porp)R species. Kinetic analyses of this process have furnished theRu-C bond strengths for a number of different alkyl and aryl ligands;52’3 three suchsystems have been studied in this thesis (chapter 4 and 5). The Ru-Me bond ofRu(TMP)Me2was found in this work to be homolytically cleaved on exposure to light aswell as by the thermal process.Electrochemical or chemical oxidation of the Ru(OEP)R2complexes induces one ofthe axial R groups to migrate to a porphyrin nitrogen atom, as illustrated in reaction 1.28below.6’ The product is paramagnetic and the charge on the metal has been assigned as-&+1.28Ru(III). This behavior has been observed for other organometallic porphyrin species andhas been implicated in the “suicide deactivation” of cytochrome P450.62 The migration33step has been compared to classical reductive elimination, and possibly occurs because ofthe instability of a Ru(V) species formed upon oxidation. Several N-aryl complexes havebeen prepared by oxidation of the Ru(porp)(aryl)2precursor with AgBF4 and the existenceof Ru(N-Ph-OEP)Ph has been unambiguously verified by an X-ray crystal structure.6mThe methyl analogue has also been prepared although, in this case, the Ru(N-Me-OEP)Medecomposes over a period of days to produce a methylene bridged product shown inreaction 12961eMeH,H-H•129Me MeThe reduction of Ru(OEP)R2complexes has also been studied and ultimately resultsin cleavage of one Ru-C bond to give the Ru(II)(porp)R monoanion. For example,treatment ofRu(OEP)Me2with one equivalent ofNa(naphthalenide) results in homolysisof the Ru-Me bond.6 In the case of the aryl species, two equivalents ofNa(naphthalenide) are required before heterolytic cleavage of the Ru-C bond took place togive [Ru(II)(OEP)Phf and Ph. 61a,b The difference in the reactivity of the reduced alkyland aryl species was not accounted for, although all reductions were considered to occurat the metal center.1.5 Ru(V1) DerivativesTo date, the only Ru(VI) complexes characterized are the diamagnetic, d2, transRu(porp)(O)2species. The first such complex encountered was Ru(TIVIP)(O)2,and34throughout this chapter several processes that lead to this species have been outlined. Thekey to its formation is the sterically hindered tetramesitylporphyrin which prohibits anyintermolecular reaction between Ru(TMP) moieties. In Scheme 1 4 20c,23a,27 the variousroutes leading to this complex are summarized. Recently a number of other iransRu(porp)(O)2species have been prepared and results suggest that Scheme 1-4 applies tothe majority of bulky porphyrin systems. For example, Ru(OCP)(O)2has been preparedby the m-CPBA oxidation of the carbonyl precursor as well as the air-oxidation ofRu(ocpxcH3cN)2.57a63In another study the dioxo derivatives of two atropisomers ofa chiral ruthenium “picket fence” porphyrin complex were isolated from the m-.CPBAoxidation of the carbonyl complexes.23 There are however some exceptions toScheme 1-4. The dioxo complex was not formed when Ru(OFP*)(CO)(NMeIm) wasreacted with tBUOOHSf It seems that the four, highly electronegative 2,6-difluorophenylgroups increase the oxidation potential to the extent that the tBUOOH is no longer astrong enough oxidant to achieve the Ru(VI) state.Ru(TMP)CO L Ru(TMP)L2 vac Ru(TMP)peracVRu(TXO)2/2(air)L= THF, CH3NScheme 1-4: Oxidation pathways for the production of ruthenium porphyrin dioxocomplexes.* 5, 10, 15, 20-tetra(2, 6-difluorophenyl)porphyrinato dianion.35As previously mentioned, dioxo derivatives the of non-hindered rutheniumporphyrin systems (e.g. with OEP, TPP), have been obtained only from the m-CPBAoxidation of the carbonyl precursors and only in alcoholic solvents.22 In non-coordinatingsolvents only the 1.1-oxo dimer is formed.Much of the reactivity of these dioxo species has been discussed in section 1.4.1.These complexes are highly reactive and have a propensity for transferring one or bothoxygen atoms to, or dehydrogenating, a range of organic compounds. Furthermore, in thepresence of suitable oxygen donors, some of these reactions become catalytic. This aspectof the dioxo chemistry has captured the imagination of a number ofworkers and intensestudy of the efficiency and selectivity of these catalytic reactions is ongoing.” Thispotential for catalytic oxidation is looked at more closely within the follow section.1.6 Catalytic Reactivities of Ruthenium Porphyrin ComplexesBecause of their relation to biological catalysts, the ability of metalloporphyrincomplexes to function as catalysts is an obvious area of investigation. Rutheniumporphyrins have proven to be remarkably efficient catalysts for reactions such asdecarbonylation26and oxygenation.64 Modest success has also been achieved in mimickingthe functions of hydrogenase enzymes.30’51651.6.1 DecarbonylationIn section 1.1.1 we noted the high affinity of the Ru porphyrin moiety for carbonmonoxide, as well as the photolytic process for removing coordinated CO. In light of this36behavior, workers in these laboratories recognized early on that these systems heldpromise as catalysts for the decarbonylation of organics. Hence, the catalyticdecarbonylation of DMF upon prolonged photolysis of Ru(porp)(CO)(EtOH) in DMF wasachieved.9 The basic steps for this process seem quite straightforward and are shown inScheme 1-5 below.Ru(porp)(ETOH)CO+ DMF -EtOHRu(porp)(DMF)2 Ru(porp)(CO)(DMF) + HNMe2Scheme 1-5: Proposed cycle for the photolytic decarbonylation of DMF usingRu(porp)(CO)(EtOH) as a catalyst.This reaction in turn led to the discovery of the highly efficient catalyst systemRu(TPP)(PPh3)2fPBufor the decarbonylation of aromatic and aliphatic aldehydes.26Turnover numbers of up to 2 x ioi h have been achieved depending on the substrate andthe reaction conditions. This decarbonylation reaction is not light-dependent and proceedsbecause of the lability of the carbonyl ligand when trans to a strong phosphinea-donor. The mechanism involves free-radical pathways; however, the details have notbeen worked out.26’6hv, + DMF, -Co371.6.2 Oxygenation/oxidationSeveral ruthenium porphyrin systems have been found to catalyze oxygenation ordehydrogenation reactions. Substrates such as thioethers,23,39d4,5786467phosphines23a27,64,68 alcohols,”57’64olefins8’6479and even saturated hydrocarbons6467b9have allbeen successfully oxidized by these systems. In fact, in some cases these catalysts havedemonstrated such remarkable efficiency and selectively, that they promise to make theirway onto the shelves of synthetic laboratories. For example, the02-oxidations of somecholesteryl andA5-steroid derivatives show remarkable efficiency, stereoselectivity andregioselectivity when catalyzed by Ru(TMP)(O)2;64’9 99 % f-epoxidation ofspecifically the 5,6 double bond in yields exceeding 90 % was realized with certain dienecontaining steroids. In another case, an enantiomeric excess of4l % was obtained uponthe02-oxidation of benzyl(methyl)(phenyl)phosphine catalyzed by a chiral picket-fenceruthenium porphyrin dioxo system. 16eSeveral oxidizing agents varying from TBHP, to lutidene-N-oxide, to 02 (air) havebeen used as the source of oxygen in these reactions. The last mentioned oxidant is ofparticular interest as it is cheap and abundant. A good review of all these catalyticoxidation systems has appeared recently in the literature and so the discussion isconcluded here and the reader is referred to this source.64381.6.3 Hydrogenase modelsAlthough dihydrogen is thermodynamically unstable in the presence of oxygen, it iskinetically inert and will not react unless activated by a suitable catalyst. Natural enzymesknown as hydrogenases occur in some micro-organisms and serve to mediate theconsumption and production of dihydrogen7°It is recognized that transition metalcomplexes can generally activate dthydrogen, and so researchers look to these systems tomimic this behavior. Metalloporphyrins react with dihydrogen and are therefore suitablecandidates for investigation.In section 1.1.3 we outlined the reactivity ofRu(OEP)(THF)2with dihydrogen. Fromthe knowledge of this chemistiy, a hypothetical catalytic cycle for the oxidation of dihydrogenhas been outlined (Scheme 1-6).° Each step in the cycle was demonstrated in solution and itwas believed that if a suitable chemical oxidant could be found the catalysis cycle could berealized. The electrochemical catalytic oxidation of dihydrogen was achieved in basic solutionswhen Ru(OEP)(THF)2was adsorbed onto a edge-plane graphite electrode.3°The activecatalyst was thought to be the [Ru(OEP)}2dimer because electrodes treated with this speciesgave the same results. Although the mechanism of this dihydrogen oxidation remains unclear,the fundamental reactions of Scheme 1-6 most likely apply at some points of the true catalyticcycle.39HTH Ka -+ H+THF+H2 -H2 +e -eTHF H+ 1/2H2 4THF THFScheme 1-6: Hypothetical cycle for the oxidation ofH2 catalyzed byRu(TMP)(THF)2.In a related study51, some derivatives of the cofacial Ru2(DPB) system were foundto fi.inction as catalysts for the reduction of acids to produce dihydrogen. This is animportant process considering the potential of dihydrogen as an clean, alternative fuel.Acidic solutions ofRu2(DPB)R (R= Me, p-tolyl, 3,5-bis(trifluoromethyl)phenyl) incontact with a mercury pool electrode gave modest catalytic production ofH2 (4.3 to16.5 turnovers/h). The mechanism of this reaction has not been solved, although initialreduction of the metalloporphyrin complex seems to be a prerequisite to the evolution ofH2 gas.1.7 Scope of this ThesisThe main focus of this thesis was the study of a-bonded organometallic complexesof ruthenium porphyrins, an area that has recieved increasing attention because of its40possible significance to the understanding of related biological systems.7’ At the beginningof this work, great strides had been made in these and other laboratories as to thesynthesis of these complexes via the reaction of Ru(porp)X2(X= Cl, Br) withorganolithium or Grignard reagents to obtain Ru(porp)R (n= 1 or 2) comp1exes.39’526The previous work had primarily involved aryl complexes, with the methyl and ethylspecies being the only alkyl species prepared. It was therefore of interest to apply thischemistry to a number of different alkylating agents in an attempt to obtain a more diverseset of Ru(porp)(alkyl) (n=1 or 2) complexes. Furthermore, no Ru(TMP)R (n=1 or 2)complexes had been prepared at the outset of this thesis work; such complexes holding thepromise of interesting and possibly varied chemistry because of the steric constraintsimposed by the bulky porphyrin. Thus, the objectives of the work were the synthesis,physical and structural characterization, and reactivity evaluation of Ru(OEP)(alkyl)2andRu(TMP)R2complexes.411.8 References for Chapter 11 Teichmann, L. Z Ration. Med., 3, 375 (1852). From reference 2b, vol 1.2a) Porphyrins andMetalloporphyrins, Smith, K.M. Ed, Elsevier, Amsterdam, 1975.b) The Porphyrins, Dolphin, D. Ed., Academic, New York, 1978, vols. 1-7,.c) Porphyrin Chemistry Advances, Longo, F.R. Ed., Ann Arbor Science, Michigan,1979.d) Berezin, B.D. Coordination Compounds ofPorphyrins and Phthalocyanines, JohnWiley & Sons, New York, 1981.e) Mashiko, T.; Dolphin D. 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Acta., 141, 13 (1988).20a) Hopf, F.R.; O’Brian, T.P.; Schiedt, W.R.; Whitten, D.G. J. Am. Chem. Soc., 97, 277(1975).b) Farrell, N.; Dolphin, D.; James, BR. J. Am. Chem. Soc., 100, 324 (1978).c) Camenzind, M.J.; James, B.R.; Dolphin, D. J. Chem. Soc., Chem. Commun., 1137(1986).21a) Sagimoto, H.; Higashi, T.; Mori, M.; Nagano, M.; Yoshicla, Z-I.; Ogoshi, H. Bull.Chem. Soc. Jpn., 55, 822 (1982).b) Collman, J.P.; Barnes, C.E.; Brothers, P.J.; Collins, T.J.; Ozawa, T.; Gallucci, J.C.;Ibers, J.A. J. Am. Chem. Soc., 106, 5151 (1984).22 Leung, W-H.; Che, C-M. .1. Am. Chem. Soc., 111, 8812 (1989).a) Groves, J.T.; Quinn, R. Inorg. Chem., 23, 3844 (1984).b) Rajapakse, N.; Ph.D. Thesis, University of British Columbia, 1990.c) Le Maux, P.; Bahari, H.; Simonneaux, G. J. Chem. Soc., Chem. Commun., 1287(1994).4524 a) Pacheco, A.A. Ph.D. Thesis, University of British Columbia, 1992.b) Pacheco, A.A.; Rettig, S.J.; James, B.R. Inorg. Chem. 34, 3477 (1995).25 Barringer, L.T. Jr.; Rillema, D.P.; Ham, J.H. J. Inorg. Biochem., 21, 195 (1984).26a) Domazetis, G.; Tarpey, B.; Dolphin, D.; James, B.R. J Chem. Soc., Chem.Commun. 939 (1980).b) Domazetis, 0.; James, B.R.; Tarpey, B.; Dolphin, D. ACS Symp., Ser. No. 152, 243,1981.27 Groves, J.T.; Akin, K-H. Inorg. Chem., 26, 3831 (1987).28 Camenzind, M.J.; James, B.R.; Dolphin, D.; Sparapany, J.W.; Ibers, J.A. Inorg. Chem.,27, 3054 (1988).29 Coliman, J.P.; Wagenknecht, P.S., Lewis, N.S. .1. Am. Chem. Soc., 114, 5665 (1992).30 Coilman, J.P., Wagenknecht, P.S.; Hutchison, J.E.; Lewis, N.S.; Lopez, M.A.; Guilard,R.; L’Her, M.; Bothner-By, A.A.; Mishra, P.K. J. Am. Chem. Soc., 114, 5654 (1992).31 Coilman, J.P.; Brothers, P.J., McElwee-White, L.; Rose, E; Wright, L.J. J. Am. Chem.Soc., 107, 4570 (1985).32a) Coliman, J.P.; Barnes, C.E.; Collins, T.J.; Brothers, P.J.; Gallucci, J.; Ibers, J.A. J.Am. Chem. Soc., 103, 7030 (1981).b) Coliman, J.P.; Barnes, C.E.; Swepston, P.N.; Ibers, J.A. .1 Am. Chem. Soc., 106,3500 (1984).a) Coliman, J.P.; Barnes, C.E.; Woo, L.K. Proc. Nati. Acad. Sc., US.A., 80, 7684(1983).b) Coliman, J.P.; Arnold, H.J.; Fitzgerald, J.P., Weissman, K.J. J. Am. Chem. Soc., 115,9309 (1993).Sishta, C.; Camenzind, M.J.; James, B.R.; Dolphin, D. Inorg. Chem., 26, 1181 (1987).Coilman, J.P.; Prodolliet, J.W.; Leidner, CR. I Am. Chem. Soc., 108, 2916 (1986).4636 Tait, C.D.; Gamer, J.M.; Coliman, J.P.; Sattelberger, A.P.; Woodruff, W.H. J. Am.Chem. Soc., 111, 7896 (1989).37Hitoshi, A.; Zisk, M.B.; Hedman, B.; McDevitt, J.T.; Coilman, J.P.; Hodgson, K.O. J.Chem. Soc., Chem. Commun., 1360 (1989),38 Lewandowdki, W. J. Inorg. Chem., 10, 6 (1994).a) Sishta, C.; Ke, M.; James, B.R.; Dolphin, D. .1. Chem. Soc., Chem. Commun., 787(1986).b) Ke, M.; Sishta, C.; James, B.R. ; Dolphin, D.; Sparapany, J.W.; Ibers, J.A. Inorg.Chem., 30, 4766 (1991).c) James, B.R.; Pacheco, A.; Rettig, S.S., Thorburn, I.S.; Ball, R.G.; Ibers, J.A. J. Mol.Catal., 41, 147 (1987).d) James, B.R.; Pacheco, A.; Rettig, S.J.; Ibers, J.A. Inorg. Chem., 27, 2414 (1988).° a) Coliman, J.P.; Kim, K.; Garner, J.M. J. Chem. Soc., Chem. Commun., 1711(1986).b) Coilman, J.P.; Kim, K.; Leidner, C.R. Inorg. Chem., 26, 1152 (1987).41 Coilman, J.P.; Hutchison, J.E.; Wagenknecht, P.S.; Lewis, N.S.; Lopez, M-A.; Guilard,R. J. Am. Chem. Soc., 112, 8206 (1990).42 Coliman, J.P.; Hutchison, J.E.; Lopez, M.A.; Guilard, R.; Reed, R.A. I Am. Chem.Soc., 113, 2794 (1991).‘ Rajapakse, N.; James, B.R.; Dolphin, D. Can. J. Chem., 68, 2274 (1990).Coilman, J.P.; Brothers, P.J.; McElwee-White, J.; Rose, E. J. Am. Chem. Soc., 107,6110 (1985).“ Hu, Y. Ph.D. Thesis, University of Huston, 1993. From Dissertation Abstracts, orderno. ACC 9236155‘ Smith, P.D.; Dolphin, D.; James, B.R. J. Organomet. Chem., 208, 239 (1981).4747James, B.R.; Dolphin, D.; Leung, T.W.; Einstein, F.W.B.; Willis, AC. Can. J. Chem.,62, 1238 (1983).48 Barley, M.H.; Dolphin, D.; James, B.R. J. Chem. Soc., Chem, Commun., 1499 (1984).49Dolphin, D.; Felton, R.H. Acc. Chem. Res., 7, 26 (1974).° Collman, J.P.; Rose, E.; Venburg, G.D. .1. Chem. Soc., Chem. Commun., 11(1994).51 Coilman, J.P.; Ha, Y.; Wagenknecht, P.S.; Lopez, M-A.; Guilard, R. J. Am. Chem.Soc., 115, 9080 (1993).52Ke M. Ph.D. Thesis, University of British Columbia, 1988.Ke, M.; Rettig, S.J.; James, B.R.; Dolphn, D. J. Chem. Soc., Chem. Commun., 1110(1987).Rachlewicz, K.; Grzeszczuk, M.; Latos-Grazynski, L. Polyhedron, 12, 821 (1993).Sishta, C. Ph.D. Thesis, University of British Columbia, 1990.56a)Seyler, J.W., Leidner, C.R. Inorg. Chem., 29, 3636 (1990).b) Seyler, J.W., Safford, L.K.; Leidner, CR. Inorg. Chem., 31,4300 (1992).a) Rajapakse, N.; James, B.R.; Dolphin, D. Stud. Surf Sc Catal., 55, 109 (1990).b) Cheng, S.Y.S.; Rajapakse, N.; Rettig, S.J.; James, B.R. J. Chem. Soc., Chem.Commun., 2669 (1994).58 Rajapakse, N.; James, B.R.; Dolphin, D. In New Developements in Selective Oxidation,Centi, 0 and Trifiro, F. Eds., Elsevier Science, Amsterdam, 1990, p 109.Schulz, L.D.; Fallon, G.D.; Moubaraki, B.; Murray, K.S.; West, B.O. J. Chem. Soc.,Chem. Commun., 14, 971 (1992).60 Huang, J-S.; Che, C-M.; Li, Z-Y.; Poon, C-K. Inorg. Chem., 31, 1313 (1992).61a) Seyler, J.W.; Leidner, C.R. J. Chem. Soc., Chem. Commun., 1794 (1989).b) Seyler, J.W.; Fanwick, P.E.; Leidner, C.R. Inorg. Chem., 29, 2021 (1990).48c) Seyler, J.W.; Safford, L.K.; Fanwick, P.E.; Leidner, CR. Inorg. Chem., 31, 1545(1992).62a) Ortiz de Montellano, P.R.; Kunze, K.L. J. Biol. Chem., 255, 5578 (1980).b) Lavallee, D.K. The Chemistry and Biochemistry ofN-SubstitutedPorphyrins, VCH,New York, 1987.63 Leung, C-M.; Yeung, C-H.; Poon, C-K. Polyhedron, 12, 2311(1993).64Mlodnicka, T; James, B.R. In Metalloporphyrin Catalyzed Oxidations, Montanari, F.and Casella, L. Eds., Kluwer Academic Publishers, 1994, p. 121, and references therein.65 Coilman, J.P.; Wagenknecht, P.S.; Hembre, R.T; Lewis, N.S. J. Am. Chem. Soc., 112,1294 (1990).66 Belani, R.M.; James, B.R.; Dolphin, D.; Rettig, S.J. Can. J. Chem., 66, 2072 (1988).67a) Higuchi, T.; Ohsake, H.; Hirobe, M. Tetrahedron Lett., 32, 7435 (1991).b)Ohtake, H.; Higuchi, T.; Hirobe, M. J. Am. Chem. Soc., 114, 10660 (1992).68 a)James, B.R.; Mikkelsen, S.R.; Leung, T.W.; Williams, G.H.; Wong, R. Inorg. Chim.Acta., 85, 209 (1984).b) James, B.R. Cheng, S.Y.S. Unpublished results.69 a)Leung, T.W.; James, B.R.; Dolphin, D. Inorg. Chim. Acta., 79, 180 (1983).b) Groves, J.T.; Quinn,, R. .1 Am. Chem. Soc., 107, 5790 (1985).c) Tavares, M.; Ramasseul, R.; Marchon, J-C. Catal. Lett., 4, 163 (1990).d) Marchon, J-C; Ramasseul, R. Synthesis, 389 (1989).e) Higuchi,T.; Ohtake, H.; Hirobe, M. Tetrahedron Lett., 30, 6545 (1989).f) Ohtake, H.; Higuchi, T.; Hirobe, M.; Tetrahedron Lett., 33, 2521 (1992).Schlegel, H.G.; Schneider, K. Hydrogenases: Their Catalytic Activity, Structure andFunction, Schiegel, H.G., Schneider, K. Eds. Verlag: Erich Goltze KG, Gottingen,1978. From reference 30.71 Setsune, J-I.; Dolphin, D. Can. J. Chem., 65, 459 (1987).49Chapter 22. General Experimental Procedures2.1 Materials2.1.1 SolventsAll solvents were purchased from Aldrich, BDH, Eastman, Fisher or Mallinckrodtchemical companies. Benzene, toluene, hexanes, pentane, diethyl ether and TF1F were alldistilled from Nalbenzophenone and used immediately. Alternatively, the solvents were storedin an anaerobic glass bomb under vacuum and over sodium metal or molecular sieves(Davidson type 4A) and were condensed when needed onto reagents by standard vacuumtechniques. Solvents handled in this way were rendered gas free by a minimum of four freeze-pump-thaw cycles. Similarly, CH21 and CHC13were distilled from, or stored over, CaB2.Deuterated solvents (C6D ,CDC13 ,CD21d8-toluene) were supplied by MSD Isotopes orIsotech Inc. and were dried and stored in a fashion analogous to that used for the nondeuterated analogues.2.1.2 GasesAnhydrous HBr, HCI, and NH3 were obtained from Matheson Ltd. and were usedwithout further purification.Nitrogen, Ar, CO and 02 (minimum purity 99.99%) were purchased from Linde (UnionCarbide Inc.). These gases were dried where necessary by passing them over molecular sieves50(Davidson type 3A). Prepurified N2 was purchased from Linde and used as received in theNitrogen Glove-Box.2.1.3 ReagentsRuthenium was supplied on loan from Johnson Matthey Ltd. or Colonial Metals Inc. asthe trichloride (40 % by weight). Lithium metal was obtained from Fisher Scientific as metalrods stored in paraffin oil. The desired amount of metal was cut from the rod, hammered flatand then cut into small strips which where washed in hexanes under argon prior to use.Magnesium turnings (BDH) were washed in 1 M HC1, rinsed with distilled water andmethanol, and then dried on the vacuum line for 16 h before use.Mesitaldehyde and pyrrole were purchased from Aldrich Chemical Company and werevacuum distilled immediately prior to use. Neopentyl chloride, 1-chloro-2-methyl-2-phenyl-propane and p-chloranil were also supplied by Aldrich and were used as received. Borontrichloride methanol complex (Aldrich) was used as supplied but within a month of beingreceived. Methyllithium (Aldrich, 1.4 M in diethyl ether) was stored in the glove box andused as supplied. Phenyllithium (Aldrich) ( 1.9 M in diethyl ether) was standardized beforeeach use by reacting 1.0 mL aliquots with excess H20 and titrating for the LiOH produced.The free-base porphyrinH2OEP was kindly provided by Dr. T. Wijesekera.2.1.4 Ruthenium precursor comp’exesThe complexesRu3(CO)12,Ru(OEP)CO(py),2Ru(OEP)py23[Ru(OEP)]2,31’[Ru(TPP)]2,4Ru(TMP)C05,and Ru(TMp)(CH3CN)56were all made in good yield and51purity according to the literature procedures. Ru(TPP)Cl2was provided by Dr. M. Ke,formally of these laboratories.2.1.5 Preparation of dichloro(octaethylporphyrinato)ruthenium(IV)The Ru(OEP)C12was prepared by a slightly modified version of the literatureprocedure.7 The [Ru(OEP)]2(105 mg) was measured into a 100 mL reaction bomb fittedwith a Teflon stopper and this vessel was then evacuated on the vacuum line. In a secondsuch bomb, approximately 25 mL of freshly distilled CH21 was saturated with HC1 bybubbling the anhydrous gas through the solution for 5 mm. This vessel was placed on thevacuum line and the solution was evacuated by two freeze-pump-thaw cycles. TheCH21/HCI was vacuum transferred onto the [Ru(OEP)]2and the reaction was heated to 600C for 1 h in the sealed bomb. After this period, the reaction flask was cooled, opened to theatmosphere, and the products were precipitated by adding approximately 75 mL of coldhexanes. The deep red product was reprecipitated from CHC13/hexanes, filtered through afit, washed with cold pentane (3 x 15 mL) and then dried on the vacuum line at 60° Covernight. Yield 99 mg (85%).Anal. calcd. forC36H44NRuC12.H0:C, 60.58; H, 6.35; N, 7.85 Found: C, 60.91, H,6.18, N 7.69.1H-NIvIR (6, CDC13 20° C): 59.20 (s, 16H, -CH2); 0.81 (s, 4H, meso); 0.67 (s, 24H, -CH3).The data are in close agreement with those in the literature.7522.1.6 Preparation of tetramesitylporphyrinTheH2TMP was prepared by a slightly modified version of the method described byLindsey and Wagner.8 Mesitaldehyde (7.4 mL, 50 mmol) and pyrrole (3.5 mL, 50 mmol)were dissolved in approximately 1 L of freshly distilled CHC13 and the resulting solutionwas de-oxygenated by bubbling dry Ar through the solution for 15 mm. BF3MeOH (3.7mL of a 8.87 M solution in MeOH) was then added by syringe and the reaction mixturewas stirred at room temperature for 1 Yz h. At the end of this period, p-chloranil (9.22 g)was added and the solution was refluxed for an additional 2 1/2 h. The product solutionwas then cooled to room temperature and the solvent was removed on the Rotovap leavinga solid mixture which was washed with cold MeOH (100 mL) and collected on a fit. Thematerial in the frit was dissolved in a minimum of toluene and charged onto an alumina(act. I) column. The first band off the column wasH2TMP which was isolated by removalof the solvent on the Rotovap. The product was washed with cold MeOH and dried on thevacuum line at 80° C overnight. Yield 1.3 g (12.8%).‘H-NMR (ö, CDC13 20° C): 8.63 1 (s, 8H, pyrr,); 7.27 (s, 8H, rn-H); 2.62, (s,24H,p-CH3);1.855 (s, 12H, o-CH3).The data are in close agreement with those in the literature.8532.1.7 Preparation of bis(2-methyl-2-phenyl-propyl)magnesium(II)The preparation of the (neophyl)2Mgwas an adaption (devised by Professor Legzdins ofthis department) of the general literature procedure for preparing the dialkylmagnesiumspecies.9 The following procedure was carried out under dried Ar.Magnesium turnings (3.5 g) were added to approximately 50 mL of freshly distilledEt20 in a three neck, round-bottom flask. 1, 2-Dibromoethane (0.1 mL) and 1-chloro-2-methyl 2-phenylpropane (15.0 mL) were mixed with approximately 60 mL of freshly distilledEt20 in a dropping funnel fitted in the reaction flask. The solution in the drop funnel was thenslowly added (5 mm) to the round-bottom flask, and the resulting solution was refluxed for 16h. After being cooled, the reaction solution was filtered through celite to remove any MgC12.The celite was washed with freshly distilled Et20 until the volume of the filtrate wasapproximately 110 mL.The concentration of (neophyl)MgC1 was then determined by reacting 1.0 mL aliquotsof the solution with water and titrating for the MgC1(OH) produced (with 0.100 M aqueousHCI). The concentration was 0.482 M; yield 57%.A solution of 1,4-dioxane (9.2 mL, 2 equivalents) in 10 mL ofEt20was placed in adropping funnel and slowly added (25 mm) to the vigorously stirred (neophyl)MgCI solution.The resulting suspension of Mg(1,4-dioxane)2Clwas allowed to digest overnight. This solidmaterial was then separated by centrifuge and the remaining solution was filtered through afl-it. The required white product was precipitated by addition of hexanes to the filtrate in theglove-box, purified by three reprecipitations from diethyl ether/hexanes and then collected by54filtration and washed with hexanes before being dried at 700 C on the vacuum line overnight.Yield 5.lg (19%).2.1.8 Preparation of neopentyllithium (I)The neopentyllithium was prepared by a slight modification of the general literatureprocedure for preparing the organolithium reagents.’° Neopentyl chloride (4.66 g) was mixedwith 100 mL of freshly distilled hexanes in a 300 mL bomb and the solution was deoxygenatedby bubbling dried Ar through the solution for 10 mm. Li metal (1.0 g) was then added to theneopentyl chioride/hexanes solution and the bomb was sealed. As a precautionary measure,the reaction solution was subjected to four freeze-pump-thaw cycles before the reaction vesselwas finally charged with Ar ( 1 atm). The reaction solution was then magnetically stirredand the vessel heated in an oil-bath to 550 C for one week. The resulting purple solution wastaken into the glove-box and filtered through celite yielding a clear, colourless filtrate. Thewhite product was precipitated from the filtrate by reducing the volume of solvent toapproximately 10 mL on the Rotovap. The neopentyllithium (NpLi) was collected byfiltration and dried on the vacuum line overnight. Yield 2.0 g .(59 %).1H-NtvlR (ö, C6D): 1.12 (br s, 9H, -CH3); -0.72 (br s, 2H, -CH2).2.1.9 Preparation of Na(naphthalenide)Tha following procedure was carried out under dry Ar. Sodium ( 0.5 g) was added toa glass bomb filled with 100 mL of freshly distilled THF. To this was added 0.6 g ofnaphthalene (freshly sublimed). The resultant green solution was stirred for 2 d and then55stored over the sodium and under Ar until needed. The concentration ofNa(Naph) was testedprior to use by reacting 1 mL aliquots with H20 and then titrating for the NaOH produced.2.2 Methods2.2.1 InstrumentationUV/ visible spectra were measured using either a Hewlett Packard 8452A or a PerkinElmer 552A spectrophotometer. Solid state infrared spectra (KBr pellets) were measuredusing a Nicolet 5DX FT-IR or a ATI Mattson Genesis Series FTIR. spectrophotometer. NIVIRspectra were obtained using either a Varian XL-300 MHz FT-NIVIR, a Bruker WH-400 MHzFT-NMR or an AC-200 MHz FT-NMR. All ‘H and‘3C{’H}-NMR spectra were assignedreferenced to an external standard of TMS. The7Li-NMR spectrum was referenced to a D20solution of LiC1. Mass spectra were obtained using a Kratos-AEI MS902 mass spectrometerusing electron impact (El, 70 eV), and a direct insertion mode at 473- 573 K sourcetemperature. GCMS data were determined using a Carlo Erbo/Kratos Fractovap series 4160gas chromatograph with a Kratos MS 80 mass spectrophotometer.Elemental analysis were performed by P. Borda of this department. All X-ray crystalstructures determinations were carried out by S.J. Rettig of this department.2.2.2 Cyclic voltammetryCyclic voltammetric measurements were carried out using an EG&G PARC model 175universal programmer (to control the potential sweep), in conjunction with a model 173 PARpotentiostat equipped with a model 176 current-to-voltage converter and a model 17856electrometer probe. Voltammetric responses were recorded on a Hewlett Packard model7005B X-Y chart recorder. Scan speeds up to 500 mV/s could be reliably measured with thisapparatus.The three electrode cell, designed by Dr. A. Pacheco formally of these laboratories”was constructed by S. Rak of this department and was designed for use with minimal volumes(as little as 2.0 mL) of test solution (see Figure 2-1). The working electrode consisted of aplatinium bead extending from the end of a flame-sealed glass tube. This bead was placed inthe test solution and was connected through the seal to a length of platinum wire thatextended out the opposite end. A second length of platinum wire (coiled at one end) servedas the auxiliary electrode with the coiled end placed in the test solution while the opposite endextended out of the cell.Working Electrode (Pt)Auxilary Electrode (Pt)Figure 2-1: Electrochemical cell used for cyclic voltammetry.Reference Electmde (Ag)Sat’d KCI, Ag(N03)(aq)Agar PlugLuggin Capillary57The Ag/AgC1 reference electrode was prepared in these laboratories and consists of a 17cm length of glass tubing which was stoppered at one end with a KC1-saturated, agar plug thatserves as a salt-bridge. The tube was then filled with an aqueous solution of KC1 (saturated)and a drop of saturated AgNO3(a was added to precipitate AgCl. A silver wire was insertedinto the tube through a rubber septum, and the tube was then sealed by securing the septum tothe end of the electrode with wire. Such an electrode could be stored for about 6 weeks withthe agar plug immersed in a saturated KC1(aq) solution.All electrochemical experiments were carried out in CH21 solution with approximately0. 1M [Bu4N][ClO (TBAP) acting as the supporting electrolyte. Under these conditionsthe ferrocenium/ferrocene couple appeared at 0.53 ± 0.01 V with a AE (cathode peak - anodepeak) of 0.06-0.07 V. The [Bu4N][ClO was prepared and purified by a standard literatureprocedure’2and the CH21 was stored in a bomb under vacuum over CaH2 until needed.In a typical experiment, 175 mg of[11Bu4N][C104] and 2-4 mg of the test complexwere placed in a small bomb which was then evacuated on the vacuum line. Approximately5.0 mL ofCH21 was then vacuum transferred into the flask and this solution was transferred(by canula) under positive pressure (Ar) to the Ar-purged septum-sealed cell. The referenceelectrode was then inserted into position (see Figure 2-1) and the cell was sealed and thenconnected to the PAR apparatus. A slow flow of Ar was maintained during the course ofmeasurements through the side-arm of the cell.582.2.3 Special techniquesBecause of the air-sensitivity of many of the species studied in this work, much of thework was performed in a dry nitrogen glove-box or on a vacuum line using standard Schienkand syringe techniques. Special anaerobic glassware similar to those represented in Figure 2-2was used to obtain spectroscopic data. Solvents were added to the apparatus in the glove-boxor alternatively on the vacuum line. NN4R spectra were obtained in tubes similar to thatrepresented in Figure 2-2a either under vacuum, or under the gas of choice by applicationthrough the side-arm. Finally, the tube would be made ready for measurements in the NMRmachine by flame sealing it. Alternatively, J-Young tubes (Aldrich) were used. TheUV/visible cell represented in Figure 2-2b was available in quartz or Pyrex with path lengthsof either 0.1 or 1.0 mm. The Pyrex tubes were used for kinetic studies.a)Figure 2-2: Anaerobic glassware; a) NMR tube, b) UV/visible cell.b)592.2.4 Anaerobic columnsCompounds which were purified anaerobically were separated on a column similar tothat represented in Figure 2-3. The solvents used were deoxygenated by bubbling argonthrough the solvent for half an hour prior to use. Drying the solvents was unnecessary. Thealumina was rendered oxygen-free by running deoxygenated solvent down the column for 2-3hours before use. The product solutions were eluted from the column under a constant purgeof argon and the solvent was subsequently removed on the vacuum line.Argon =>Figure 2-3 Apparatus used for the chromatographic purification of air-sensitivecompounds.=Argon602.3 Preparation of New Ruthenium Porphyrin Complexes2.3.1 Preparation of (neopentyl)(octaethylporphyrinato)ruthenium(II1)The following is a typical preparation performed in the glove box. A suspension ofapproximately 82 mg (0.12 mmol) of Ru(OEP)C12tin approximately 10 mL of dry,deoxygenated benzene was prepared and thoroughly mixed with a second solution ofapproximately 27 mg (0.35 mmol) of NpLi dissolved in 5.0 mL of dry, deoxygenated benzene.The reaction was allowed to proceed at room temperature for 0.5 h, thereupon the reactionflask was then sealed with a rubber septum and taken from the glove-box. The reactionsolution was transferred (by canula) onto an anaerobic neutral alumina ( act. I ) column ( seeFigure 2-3) and the Ru(OEP)Np was eluted from the column with benzene and collected in aSchienk tube that had been previously purged with Ar. It should be noted that a faint brownband came off the column first; however, this material contained no porphyrin speicies asjudged by 1H NMR spectroscopy. Furthermore, a brownish/black band remained on thecolumn after the Ru(OEP)Np had been isolated.The benzene was removed from the Ru(OEP)Np fraction on the vacuum line and theproduct was redissolved in a minimum ( 25.0 mL) of dry, deoxygenated hexanes. Thissolution was then transferred to, and sealed in, a reaction bomb fitted with a Teflon stopper.The solvent volume was reduced on the vacuum line until the Ru(OEP)Np had partiallyreprecipitated (15 mL), at which point the precipitated material was redissolved by heatingto 80-90 ° C. The solution was allowed to cool slowly (overnight) to room temperature andtRu(OEP)Br2was also used for this procedure.61then to -72 °C in a dry ice! acetone bath before the solvent was decanted (using a canula)from the X-ray grade red crystals which were dried on the vacuum line overnight. Theproduct was collected and stored in the glove-box. Yield 23.6 mg (29 %).Anal. caled. forC41H55N1Ru: C, 69.93; H, 7.87; N, 7.95. Found: C, 69.60; H, 7.73; N,8.12.1H-NrvIR (3, C6D 200 C): OEP; 2.15 (br s,4H, meso), 13.48 (br S, 8H, CHa), 6.08(br s, 8H, -CHb-), -1.40 (br s, 24H, -CH3). Neopentyl ligand: 5.78 (br s, 9Hs, -CH3).Visible spectrum (toluene, 20° C, (nm), (log 6)): 362(4.84), 392(4.99),503.5(4.19).2.3.2 Preparation of neophyl(octaethylporphyrinato)ruthenium(Ill)The preparation of the Ru(OEP)(neophyl) complex was analogous to that used for theRu(OEP)Np complex. In a typical reaction 96.8 mg (0.137 mmol) of Ru(OEP)C12wasreacted with 63 mg of(neophyl)2Mg(0.2 16 mmol). The column purification was identicalexcept toluene was used instead of benzene as the eluant. Similarly, a small amount ofbrownish material eluted from the column (no porphyrin products) before the redRu(OEP)(neophyl) species which then left a large amount of brownish/black material on thecolumn. Crystals suitable for X-ray analysis were obtained in exactly the same way as for theRu(OEP)Np crystals. Yield 19.1 mg (18.1%).Anal. calcd. forC46H57NRw0.5 H20: C, 71.19; H, 7.53; N, 7.22. Found: C, 71.24; H,7.44; N, 7.28.621H-NIVIR (8, C6D 200 C): OEP; 2.49 (br s, 4H, meso), 14,02 (br S, 8H, CHa), 5.98(br s, 8H, -CHb-), -1.15 (br s, 24H, -CH3). Neophyl ligand: 6.37 (br s, 2H, rn-H), 5.65 (br s,1H,p-H).Visible spectrum (Toluene, 20° C, ? (nm), (log e)): 362(4.59), 392(4.72), 506(4.00).2.3.3 Preparation of [Ru(OEP)NpIz(,.i-Li)2The following is a typical preparation performed in the dry nitrogen glove-box. Asolution of NpLi (5.9 mg (76 p.mol) in 1.5 mL ofC6D)was added dropwise to a secondsolution containing exactly 0.5 equivalents of [Ru(OEP)12(47.5 mg (37.5 mol) in 5 mL ofC6D)while mixing thoroughly and the reaction occured instantaneously as judged by thecolour change (green to burgundy). The product crystallized upon slow evaporation of thesolvent and was then collected by vacuum filtration, taken from the glove box and dried onthe vacuum line overnight. Crystals suitable for X-ray analysis were obtained serendipitouslywhen an NMR solution evaporated to dryness in the glove-box. Yield 23 mg (43%).Anal. calcd. forC82H110NRu2Li:C, 69.17; H, 7.78; N, 7.87. Found: C, 68.92; H,7.76; N, 7.73.1H-NMR (8, C6D): OEP; 8.003 (s, 8H, meso), 3.531 (m, 16H, -CH-), 3.365 (m,16H, -CH2b-), 1.650 (t, 48H, -CH3). Neopentyl ligand; -2.284, (s, 18H, -CH3), -7.447, (s, 4H,-CH2).7Li-NMR(6, C6D 20° C): -14.85 (br s) upfield from aqueous LiBr.63Visible spectrum (benzene, 200 C, Lax (nm)): 382, 510.2.3.4 Preparation of trans-dichloro(tetramesitylporphyrinato)ruthenium(1V)Ru(TMP)(CHCN)(106 mg, 0.110 mmol) was measured into a reaction bomb(100 mL) fitted with a Teflon stopper and the system was then evacuated on the vacuumline. In a second such bomb, approximately 25 mL of freshly distilled benzene wassaturated with HC1 by bubbling the anhydrous gas through the solution for about 5 mm;this vessel was then placed on the vacuum line and evacuated by 2 freeze-pump-thawcycles. TheC6HdHC1 reagent was condensed onto the Ru(TMP)(CH3CN)2and thereaction mixture was heated to 50° C for 3-4 days. After this period, approximately 10mL of theC6H/HC1 solution was removed under vacuum and the products wereprecipitated by adding approximately 75 mL of cold pentanes. The precipitate was filteredthrough a fit and washed with cold pentane. Yield 98 mg (93%).Anal. calcd. forC56H2N4RuC12:C, 70.58; H, 5.50; N, 5.89. Found: C, 70.40; H,5.52;N, 5.81.1H-NMR (, C6D,20° C): 11.25 (s, 8H, rn-H), 3.78 (s, 24H, o-CH3), 3.50 (s, 12H,p-CH3), -55.62 (s, 8H, pyrr.).Visible spectrum (CH2C1, 20° C, Lax (nm), (log e)): 522(4.05); 410(5.24).642.3.5 Preparation of ammine(chloro)(tetramesitylporphyrinato)ruthenium(IEI)Ru(TMP)Cl2(41.7 mg, 43.8 i.tmol) was dissolved in approximately 50 mL benzene andthe solution was then deoxygenated by bubbling Ar through the solution for 5 minutes. TheNH3 was introduced into the reaction by bubbling the anhydrous gas through the solution for10 minutes when the flask was then sealed and stirred at 50° C overnight. The productsolution was purged with Ar (5 mm) whereupon the entire solution was charged onto aneutral alumina (act. I) column. The orange Ru(TMP)(NH3)Clwas the first band eluted fromthe column with benzene and the solvent was removed on the Rotovap (It was sometimesnecessary to run a second column to remove persistent impurities). The product was washedwith cold hexanes, filtered, and dried at 60 ° C on the vacuum line overnight. Yield 14.0 mg(34%).Anal. calcd. forC56H5NRuC1: C, 71.97; H, 5.93; N, 7.49. Found: C, 71.88; H, 5.93;N, 7.41.1H-NI\’IR (ö, CDC13 22° C): 3.87 (s, 4H, rn-Ha); 3.80 (s, 4H, rn-Hi.,); 0445 (s, 12H,p-CH3); 0.377 (br s, 12H, o-CH3J; -0.826 (br s, 12H, o-CH3b); -32.41 (br s, 8H, pyrr.).Visible spectrum (Toluene, 20° C, Amax (flm), (log s)): 416(5.34), 536(4.15)2.3.6 Preparation of bisphenyl(tetramesitylporphyrinato)ruthenium(1V)The Ru(TMP)C12(102 mg, 0.107 mmol) was dissolved in approximately 10 mL offreshly distilled toluene. This solution was magnetically stirred under Ar as 0,39 mL of PhLi(1.8 M in Et20, 0.702 mmol) was added using a gas-tight syringe. The solution was allowed65to react for approximately 0.5 h after which time the reaction vessel was opened to the air andthe solvent was removed on the Rotovap. The products were redissolved in a minimum ofCC!4 and charged onto a neutral alumina (act. I) column where Ru(TMP)Ph2separated andwas the sole product collect from the column upon elution with CC14. A dark brown materialremained on the column. The CC14was removed on the Rotovap and the product wasreprecipitated fromCH21LN4eOH. The final brown powder was collected on a flit and driedon the vacuum line overnight. Crystals suitable for X-ray analysis where obtained by vapourdiffusion of hexanes into a saturated benzene solution of the complex. Yield 34.3 mg (30.7%).Anal. calcd forC68H2N4Ru : C, 78.81; H, 6.03; N, 5.41. Found C, 79.03; H, 6.00, N,5.24.1H-NMR (ö, C6D): TMP; 8.32 (s. 8H, pyrr.), 6.99 ( s, 8H, rn-H), 2.32 (s 12H,p-CH3), 1.86 (s, 24H, o-CH3). Axial phenyls; 5.62 (t, 2H, p-H), 5.31 (t, 4H, rn-H), 2.004 ( d,4H, o-H).Visible spectrum (Toluene, 200 C, ?m (nm), (logE)): 492(4.107); 418(5.016).2.3.7 Preparation of benzoyl(phenyl)(tetramesitylporphyrinato)ruthenium(IV)Ru(TMP)Ph2(13 mg, 13 iimol) was weighed into an anaerobic NMR tube fitted with aTeflon stopper (see Figure 2-2a) which was then evacuated on the vacuum line. Dry,degassed C6D( 1.0 mL) was condensed into the tube and the Teflon stopper was thensealed. Carbon monoxide ( 1.0 atm) was introduced by purging the septa sealed side arm66with the gas for 3 mm and then opening the Teflon stopper to the evacuated tube. The NMRtube was then flame-sealed, wrapped in foil and heated to 35 °C for 10 days, whileperiodically monitoring the progress of the reaction by NMR spectroscopy. At the end of thisperiod, the tube was opened to the atmosphere and the solvent was removed on the Rotovap.The product was washed with approximately 5 mL of cold pentane and then redissolved in asmall amount of benzene. The benzene was removed under a slow flow ofN2 gas and thenproduct was collected and was dried on the vacuum line overnight. Yield 3.6 mg (24 %).Anal. calcd forC69H2N4ORu0.5 H20: C, 77.21; H, 6.00; N, 5.22. Found: C, 77.46; H,6.12; N, 4.90.1H-NMR (ô, C6D): TMP; 8.58 (s, 8H, pyrr.), 7.21, 7.02 (s, 8H, rn-H), 2.40, 2.31,1.62, (s, 36H, o-,p-CH3).Phenyl ligand: 5.46 (t, 1H, p-H), 5.08 (t, 2H, rn-H), 1.18 (d, 2H, oH). Benzoylligand: 5.90 (t, 1H,p-H), 5.51 (t, 2H, rn-H), 3.32 (d, 2H, o-H).IR: vco =1752 cm 1 (KBr).2.3.8 Preparation of dimethyl(tetramesitylporphyrinato)ruthenium(IV)The procedure for preparing the Ru(TMP)(CH3)2was completely analogous to thatused to prepare Ru(Th4P)Ph2except that all manipulations of the product in air were carriedout in the absence of direct light. Typically, 44 mg of Ru(T1VJP)C12(46 i.tmol) was reactedwith 0.16 mL of 1.4 M ( 0.22 mmol.) MeLi solution. Yield 11.7 mg (27 %).Anal. calcd. forC58HN4RwH2O:C, 74.88; H, 6.50; N, 6.05. Found C, 74.46; H, 6.33;N, 5.63.671H-NMR (6, C6D): TMP; 8.39 (s, 8H, pyrr.), 7.05 (s, 8H, rn-H), 2.38 (s, 12H, pCH3), 1.96 ( s, 24H, o-CH3). Axial methyl ligands: 1.87 (s, 6H, Ru-CH3).Visible spectrum (Toluene, 200 C, Lax (mn)(log 6)): 411(4.947); 526(3.976).The ‘H NIVIR and UV/visible spectra compare favourably to those reportedpreviously.’32.3.9 Kineticst of the decomposition of Ru(TMP)Ph2A stock solution of Ru(TMP)Ph2was prepared by dissolving approximately 0.6 mg ofthe solid in 50 mL of dry degassed toluene. The concentration of the solution (1.2 x iü M)was determined from the UV/visible absorption spectrum. The solution was prepared andstored in the dry nitrogen glove-box until needed.In a typical experiment, a few mL of the stock solution were placed in an anaerobicUV/visible cell, sealed and then taken from the glove-box. The reaction was initiated bysubmerging the cell in a thermostated oil-bath. Timing of the reaction was not started untilthe cell had been submerged for 200 s to allow the solution to reach the bath temperature.The rate of the reaction was monitored periodically by quenching the reaction in cold waterand then measuring the absorption spectrum.2.3.10 Kinetics of the decomposition of Ru(TMP)(COPh)Ph and Ru(TMP)(Me)2Because of the light-sensitivity of the title complexes, the thermal decomposition couldThe rate constants obtained for all 1St order kinetic analyses are considered accurate to ± 5%.68not be studied by UV/visible spectroscopy. Therefore, the reaction was monitored by ‘HNMR spectroscopy. In a typical experiment, approximately 0.6 mL ofd8-toluene wascondensed onto approximately 1.5 mg of the complex. The NMR tube was then filled withN2(g), flame sealed and the placed in the NIVIR probe which was thermostated at the desiredtemperature. Spectra were measured periodically to monitor the progress of the reaction, andthe time dependence of the reaction was determined by plotting the integration of the pyrrolepeaks with time.2.3.11 Kinetics of the decomposition of Ru(OEP)Np2Because it could not be isolated, the Ru(OEP)Np2was generated in situ. In a typicalkinetic experiment, 5.0 mg of Ru(OEP)C12(7.1 i.tmol) was suspended in 2 mL C6D. Tothis was added 1.95 equivalentst of NpLi (1.1 mg in 1.0 mL C6D)to produce Ru(OEP)Np2and Ru(OEP)Np in varying yields (as judged by integration). The presence of the latterspecies had no effect on the rate of the reaction. The initial concentration ofRu(OEP)Np2was then estimated as a fraction of the Ru(OEP)Cl2added based on the relative integration ofthe two products (i.e. Ru(OEP)Np2 [Ru(OEP)Cl ]ipjt). The solution was‘.Ru(OEP)Np + Ru(OEP)Np2} 2heated to the desired temperature in the NIVIR probe and the disappearance of theRu(OEP)Np2was followed by monitoring the integration of the neopentyl methyl signal withtime.of more than 2 equivalents of NpLi results in the production of [Ru(OEP)Np]z(ji-Li)2.This species appears toundergo a slow yet competitive reaction with Ru(OEP)Np2as it was difficult to obtain reproducible results in the caseswhere various amounts of this lithiated species were present.692.4 References for Chapter 2‘Bmce M. I.; Matison J. G.; Wallis R. C.; Patrick J. M. ; Skelton B.W.; White A. H. J. Chem.Soc., Dalton Trans., 2365 (1983).2Barley M.; Becker, J. Y.; Doma.zetis, G.; Dolphin D.; James, BR. Can. J. Chem., 61, 2389(1983).3a) Antipas, A.; Buchier, J. W.; Gouterman, M.; Smith, P. D. J. Am. Chem. Soc., 100, 3015(1978).b) Coliman, J.P.; Barnes, C. E.; Collins, T. J.; Brothers P. J.; Gallucci, J.; Ibers, J. A. J. Am.Chem. Soc., 103, 7030 (1981).‘ Coliman, J.P.; Barnes, C.E.; Swepston, P.N.; Ibers, J.A. J. Am. Chem. Soc., 106, 3500(1984).a) Caminzend, M. J.; James, B. R.; Dolphin, D.J.; Sparapany, 3. W.; Ibers, J: A. Inorg.Chem., 27, 3054 (1988).b) Barley, M.; Becker, J. Y.; Donazetis G.; Dolphin, D. J.; James, B. R. Can. J. Chem., 61,2389 (1983).6Rajapakse, N. Ph.D. Dissertation, University of British Columbia, 1990.‘ Shista C.; Ke M.; James B.R.; Dolphin D. J. Chem. Soc., Chem. Commun., 787 (1986).8 Lindsey, J.S.; Wagner, R. W. .1 Org. Chem., 54, 828 (1989).9a) Anderson, R.A.; Wilkinson, G. J.Chem. Soc., Dalton Trans., 809 (1977).b) Anderson, R.A.; Wilkinson, G. Inorg. Synth., 19, 262 (1979).10 Brandsma, L.; Verkruijsse, H. In Preparative Polar Organometallic Chemistry 1,Springer-Verlag, Berlin, 1987, chapter 1.Pacheco, A.A. Ph.D. Thesis, University of British Columbia, 1992.12 Sawyer, D.T.; Roberts, J.L.Jr. In Experimental Electrochemistryfor Chemists, John Wileyand Sons, New York, N.Y. (1974), p 212.13 Venburg, GD. Ph.D. Thesis, Stanford University, 1990.70Chapter 33. HaIo( porphyrinato)ruthenium derivatives3.1 Ru(IV)(porp)X2Derivatives (porp = OEP and TMP)In the mid-i 980s, workers in these laboratories discovered that the reaction of the[Ru(porp)]2(porp OEP, TPP) complexes with FIX acids (X= F, Cl, Br) yields thecorresponding Ru(IV) dihalo products (reaction 3.1).’ The stoichiometry of the reaction[Ru(porp)J2+ 4HX ‘ 2Ru(porp)X + ‘4H’porp = OEP; X= Br, Cl, Fporp = TPP; X Br, Cl 3.1suggests that the acid is the oxidizing species, although, the dihydrogen from the reducedH was not detected. la,2 Later work revealed that this chemistry could be extended toinclude a more diverse set of Ru(II) complexes (reaction 3 .2),2 although the reaction is notcompletely general as, for example, the treatment of Ru(TMP)py2with HC1 resulted in noreaction.2 Furthermore, reactions 3.1 and 3.2 were reportedly accelerated when airRu(porp)L2+ 2FIX Ru(porp)X2+ 2L + ‘211’porp = TMP; X=Br; L= vacant, N2,CH3Nporp OEP; X=Cl; L= py, CH3N 3.2was introduced after an initial anaerobic reaction with the acid. This suggests that 02 isinvolved in the oxidation of some intermediate species formed from the reaction with HX.When this thesis work began, the dihalo complexes were primarily of interest asprecursors in the synthesis of the organometallic complexes discussed in chapters 4 and 5.71However, the chemistry of reactions 3.1 and 3.2 proved to be somewhat unpredictable inthat the rates vary significantly from those described previously. This section outlinessome of the inconsistencies encountered in this work (as compared to the earlier reports)and modified synthetic procedures are provided. The Ru(TMP)C12complex was alsoisolated and fully characterized for the first time. Included is a study of theelectrochemical properties of a series of these complexes which was undertaken tocomplement the earlier work.3.1.1 Preparation of Ru(OEP)X2derivativesTo date, synthesis of all Ru(OEP)X2complexes (X Br, Cl, F) have involved theoxidation of [Ru(OEP)]2according to reaction 3.1. la,b However, NMR spectral evidencesuggests that Ru(OEP)(py)2can be used as a substitute for the dimer in the preparation ofthese OEP derivatives.2 This is an attractive alternative as it allows one to avoid thesomewhat cumbersome preparation of [Ru(OEP)]2.In the NMR study, a solution ofC6D saturated with HC1 was added toRu(OEP)(py)2under anaerobic conditions. A Ru(III) species was initially observed whichwas tentatively assigned as Ru(OEP)(py)Cl based on the ‘H NIVIR spectrum.2 Thisspecies was then further oxidized to give the final Ru(OEP)C12product. This secondoxidation reaction could apparently be effected aerobically or anaerobically; however, twomechanisms were indicated by the difference in the rates of the two processes. The formerreaction “occurred rapidly” whereas the latter reportedly requires “several hours.” A72subtle but important aspect of this chemistry is that air must be introduced after the HC1 orthe resulting product is [Ru(OEP)(py)2]Cl.Repeated attempts to apply this reaction on a preparative scale (i.e. 100 mgRu(OEP)(py)2in 25 mL benzene saturated with HC1) gave disappointing results. Yieldsof approximately 30% (after workup)t of Ru(OEP)C12were typically obtained after 8 hfor the anaerobic oxidation at room temperature and the introduction of air did notimprove upon this. The best result (70% after work-up) was obtained after four days forthe anaerobic reaction. This result was never duplicated however as yields for reactionsrun for this period were normally on the order of 50 % after work-up. This is partially dueto the tenacity of the Ru(III) coproduct(s) which could only be removed after 2 to 3reprecipitations from chioroform/hexanes resulting in a significant reduction in yield.In an attempt to identify the coproduct(s), the collected filtrate from one of thesereprecipitation procedures was charged onto a neutral alumina column, whereupon threespecies separated on elution with chloroform. Two of these decomposed as they moveddown the column, while the third orange complex was isolated and characterized asRu(OEP)(py)Cl (see section 3.2.3). Thus, Ru(OEP)(py)Cl is indeed formed as at leastone intermediate in this reaction; however, the subsequent oxidation of this species to giveRu(OEP)Cl2took more time than previously suggested (at least on the preparative scale).When performed anaerobically, the reaction perhaps requires in excess of a week (at roomtemperature) to give yields that are comparable to those obtained from the [Ru(OEP)]2+The complex was precipitated by adding hexanes ( 100 mL) and then reprecipitated from CHC13/hexanes (5:100mL).734HC1 reaction. Furthermore, the aerobic reaction did not occur as quickly as previouslyindicated in the in situ NMR experiments. “Occurs rapidly” was interpreted to imply thatthe reaction was complete within minutes; however, this was not the case in the syntheticattempts. Reaction solutions were vigorously stirred in the presence of air for periods ofup to 10 mm with no obvious improvement in yield. This procedure using theRu(OEP)py2precursor was abandoned in the end as the reaction was too time consuming.Some similar inconsistencies with the earlier reports’”2were encountered when[Ru(OEP)]2was used to make Ru(OEP)X2.The original procedure recommends runningthe reaction in a solution of methylene chloride that had been presaturated with theanhydrous HX acid. la,b This solution (20 mL) is then vacuum transferred ontoapproximately 100 mg of the dimer. The reaction reportedly requires 2 h under anaerobicconditions, whereas Ru(OEP)X2is produced “directly” upon exposure of the reactionmixture to air. la,b In the present work, yields of less than 50% were routinely obtainedafter 15 mm for the aerobic process and reaction times of approximately 24 h were neededto achieve acceptable yields (> 80%) for the anaerobic reaction when performed at roomtemperature. The time for the latter process could be reduced to approximately 1 h if thereaction was carried out at 60° C and this was the procedure that was ultimately adoptedfor repetative preparations of the Ru(OEP)X2(X Cl, Br) in this work.3.1.2 Preparation and characterization of Ru(TMP)C12When this thesis work began, the series of Ru(porp)X2complexes listed in reactions3.1 and 3.2 had been isolated and fully characterized. Notably absent from this work were74data for the complete characterization of Ru(TMP)C12although this species had beenobserved in situ by ‘H NMR from the reaction ofRu(TMP)(CH3CN)2with HC1.2 Thisomission has become of some concern as this complex was recently reported to act as acatalytic precursor in a very efficient oxidation system for saturated hydrocarbons;3again,the only evidence given for the involvement of this Ru(OEP)C12species was the ‘H NMRspectrum. Therefore, it was of interest to isolate and fully characterize this species.The preparation ofRu(TMP)X2complexes (X= Br, Cl) by oxidation ofRu(TMP)(CH3CN)2with 2HX (reaction 3.2)2 again required extended reaction times;otherwise a significant amount of a Ru(III) reaction intermediate was isolated along withthe Ru(TIVIP)X2complexes. For example, the ‘H NIVIR spectrum of the product mixtureisolatedt after reacting Ru(TMP)(CH3CN)2with HBr for 4 hours (RT) exhibits the desireddibromo complex; however, a Ru(III) co-product is also evident, making up about 50 %(as judged by integration) of the total isolated This species is most likelyRu(TMP)(CH3CN)Br as the MvIR spectrum (ö(ppm) -31.2, H,,; -0.42, 0.28, o-CH3;0.42, p-CH3;4.02, 4.16, rn-H) is typical of a Ru(III) complex ofC4 symmetry for thisporphyrin (see section 3.2.2). The Ru(TMP)X2products could be separated from theRu(Ill) co-products by reprecipitating several times from a benzene/hexanes system;however, this reduces the overall yields of the dihalo products considerably. Alternatively,the product mixture could be redissolved in HX/benzene and allowed to re-reactanaerobically for 2-3 more days yielding analytically pure Ru(TMP)X2as the sole product.Products were isolated by adding 100 mL cold pentane, filtering through a flit and then washing the productmixture with several portions (Sx 5 mL) of cold hexanes.ttThj represents much less than the total Ru(llI) product as much of this material was lost upon work-up.75Consequently, for the purposes of this work, these reactions were routinely run for 3-4days under anaerobic conditions.The Ru(TMP)Cl2complex was successfully isolated in 93% yield by theprocedure outlined above. The elemental analysis is consistent with this compositionand the spectral characteristics compare favourably with those of the Ru(TMP)Br2analogue, prepared previously from the reaction of Ru(TMP)(CH3CN)2with HBr.2The electronic absorption spectra of metalloporphyrin complexes featureabsorbances due to it to it transitions on the porphyrin ligand4 (the weaker d to dtransitions at the metal are not seen), although just two of these tend to dominate thespectra. The first arises from an electronic excitation from the highest occupiedmolecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) on theporphyrin. This normally results in the absorption of light in the region of 500 to 600nm giving maxima which are commonly referred to as the Q-band(s). Quite often twopeaks are observed for this transiton due to overlap with two distinct vibrational states.A second transition from the (HOMO- 1) to the LUMO appears in the range of 380 to420 nm and this is commonly referred to as the Soret band. The Q-bands typicallydisplay molar absorptivities of the order of I 0’ (cm’M’) while the Soret peaks areapproximately 10 times more intense. There are often other features apparent in thesespectra that are worthy of note (eg N, L and M bands found to the blue of the Soret76band);4however, for the purposes of this work the discussion will be limited to theabsorbances described above.Figure 3-1 shows the visible spectrum of Ru(TMP)C12in CH21. The Soretband is found at 410 nm while one Q-band is evident at 522 nm. These energies aresimilar to those reported for Ru(TMP)Br2(416 and 518 nm in CH2I). A red shift ofabout 12 nm is observed for the Soret band upon changing the porphyrin from OEP1ato TMP [Note: A similar comparison can not be made for the Q-bands as the OEPcomplex shows two absorbances (505 and 535 nm)’ whereas the TMP complex showsonly one (522 nm)]. However, the red shift is due to the change in porphyrin ligandrather than any interaction with the metal as a similar shift is observed for thecorresponding free base porphyrins (i.e. H2OEP max(Soret) = 400 nm; H2TMP?,(Soret) = 418 nm). The general difference in absorption energies of the octaalkyl4band the tetraphenyl-type porphyrins has been noted previously.The NMR spectrum of Ru(TMP)C12(Figure 3-2) agrees well with those reportedin the previous studies.”3 The broad peaks and wide range of shift positions aresuggestive of a paramagnetic system, and the magnetic moment of 2.5 B.M. (measuredby Evan’s method)5clearly indicates two unpaired electrons. Unpaired electrons affectthe NMR experiment in two ways. First, they create local magnetic fields that are ofan appreciable magnitude and cause a considerable change in the chemical shifts ofthe systems. The two terms that are normally applied to describe this effect are dipolarand contact shifts.77a, C.) I 0 Co.2 1.5I0.5 0 350Wavelength(nm)Figure3-1:UV/visiblespectrumofRu(TMP)C12(10iMinCH21).40045050055060078SFigure3-2:‘HNMRspectrum(300MHz)ofRu(TMP)C12inC6Dat200C;S=solvent.79rn-HF....14Iic-Me...:....I10IIVVIIJIV1JIVI•VljVVIV20100—10—20—30-4oppuThe former is a spacial effect and diminishes as the distance from the site of the loneelectron increases. The contact shift arises from the delocalization of the electronthroughout the porphyrin and the magnitude of this effect is proportional to the (lone)electron density at any given atom in the system. As one can see from Figure 3-2, thecombination of these effects result in shifts that can be well out of the “normal” range (0to 10 ppm) observed for diamagnetic compounds. Unpaired electrons also provide anideal mechanism for the relaxation of protons (after they have been excited by the radiosignal) and this increases the rate of this process so that, more often than not,paramagnetic systems relax too quickly to be detected. Fortunately, metalloporphyrinscomplexes are one of the few exceptions to this rule6 because as the lone electron(s)is(are) delocalized throughout the large conjugated porphyrin system, the rates of protonrelaxation are greatly reduced (Note: these rates are also subject to the same dipolar andcontact terms). However, the effect is still evident in the broadening of the N1\’IR signalsand the general loss of observable proton coupling in these spectra.The chemical shift positions also vary with temperature for paramagneticcompounds. The observable (bulk) effects of paramagnetism decrease as temperatureincreases due to increased randomization of the molecules within the system. At the limitof infinite temperature (i.e., 1/Trn 0), these systems will appear to be diamagnetic. Figure3-3 shows a plot of isotropic shift position (paramagnetic-diamagnetic) vs. l/T. The straightline plots indicate that only one spin state (S= 1) is occupied within the temperature rangestudied (-50 to 20° C). The slight deviation of the intercepts from the expected value ofzero (if real) is not unusual for paramagnetic8010 0-10-20-30-40-50-60-70-80-9000.00050.0010.00150.0020.00251/Temp(K1)Figure3-3:Plotoftheisotropicchemicalshift(calculatedrelativetoRu(TMP)(CH3CN)2)vs.l/T(K’)forRu(TMP)C12.RawdataareavailableinappendixA.Cl) 0 0rn-Ho-,p-Me0.0030.00350.0040.00450.00581metalloporphyrins, and may represent the effects of temperature-independentparamagnetism or spin-orbit coupling.6The Ru(TMP)C12complex is highly symmetrical (D4h) resulting in the appearanceunder ambient conditions of only one signal for the o-methyl (3.8 ppm) and rn-protons(11.25 ppm) of the 4 mesityl groups. On the other hand, when the two faces of theporphyrin are magnetically inequivalent (i.e. C4 symmetry), these protons becomediastereotopic and two signals are observed.Theory suggests that the large upfleld shift for the pyrrole protons (-56.5 ppm) isindicative of charge transfer from the porphyrin to the metal.6 Iterative extended Huckelcalculations yield two sets of orbitals of the correct energy and symmetry to undergo toverlap with the partially filled eg orbitals (d, d) of the ruthenium. They are designated3eg(it) and 4e5(7t*), the former being filled and the latter being empty. The wave functionsfor the 3 eg(t) orbitals have a large amplitude about the pyrrole carbons and theorypredicts that a charge transfer from these orbitals to the metal will cause a shift for protonsat this position that is upfleld from their diamagnetic positions as seen in Figure 3-2.Furthermore, the theory also predicts a shift of equal magnitude in the opposite direction ifan aliphatic group is bonded at the pyrrole position, and this is in fact observed in theNMR spectrum of Ru(OEP)C12as the methylene signals of the 8 pyrrole ethyl groupsappear around 60 ppm (at RT). The NMR spectra of both complexes conform nicely withthe theoretical predictions and presumably indicate that charge transfer from the porphyrinto the ruthenium is operative.823.1.3 Electrochemistry of Ru(porp)X2complexesA brief electrochemical study was conducted on the Ru(OEP)X2(X= Br, Cl)complexes in earlier work in this laboratory2and it was of interest to extend this study toinclude the TMP and TPP congeners in order to determine the effect the porphyrin has on thereduction potentials of these systems. Figure 34 shows the cyclic voltammetric response forRu(TMP)Cl2;the CV was essentially unchanged over several cycles or if the scan wasinitiated in the opposite direction. The analogous plots for Ru(TMP)Br2and Ru(TPP)C12arebasically identical except of course for the shift in the potential of each couple. Thus thereduction potentials for each of the observed couples are listed in Table 3-I alongI!1:6 . - VAACIFigure 3-4: Cyclic voltammogram of Ru(TMP)C12.Data obtained in 0.1 M [(iiBu)4N1[Cl0]in CH21 under an 1 atm Ar at 20° C (scan rate = 20 mV/s).831 St oxidation 1 St reduction 2nd reductionRu”’(por)fRu”(porp) Ru”/RumRu(OEP)C12 -0.821.22 0.41(1.22)l (036)bRu(OEP)Br2’ (1.31) (0.38)Ru(TPP)C12 1.35 0.64 -0.56Ru(TMP)C12 1.26 0.43 -0.82Ru(TMP)Br2 1.26 0.46 -0.71a) All measurements were made in a solution of 0.1 M [(n-Bu)N][ClOfin CH21 at293 K; the ferrocenium/ferrocene couple appeared at 0.53 V under these conditions. b)Data obtained from reference 2.with previously reported data for the Ru(OEP)X2species.2 The measurements were madein a solution of methylene chloride with tetrabutylammonium perchiorate (TBAP) addedas the supporting electrolyte (0.1 M). The test solutions were made up in concentrationsof approximately 0.5 mM and potentials were measured against a AgIAgCl(sat’d)reference electrode, the same conditions used in the previous work.Each complex displays three distinct redox events; one reversible oxidation, onereversible reduction and a second irreversible reduction. Ideally, a redox couple isconsidered to be electrochemically reversible if the difference between the cathode and theanode peak is given by 0.059V/n where n is the number of electrons transferred. Allcouples assigned as reversible in these experiments gave peak differences (Eje-Eaie)Table 3-1: Reduction potentials of Ru(IV)(porp)X2complexes (± .01 V vs.Ag/AgCl).’84between 0.06 and 0.07 V which is typical of a reversible one-electron transfer process.Furthermore, these differences did not change upon varying the scan rate from 20 to 200mVIs, which confirms the reversible nature of the redox couples. The second cathodicpeak is typical of an irreversible process as there is no corresponding anodic peak on thereturn cycle (except for Ru(OEP)Cl2,see Figure 3-5) which suggests that the ‘second’reduced species generally decomposes immediately,In Table 3-1, the reversible oxidation reaction is assumed to occur at the porphyrinring to give a it-cation radical product. This assignment was based on the results obtainedfor the bulk electrolytic oxidation of a solution ofRu(OEP)Br2.The greenish brownproduct solution resulting from this treatment exhibited a visible spectrum that was typicalof a porphyrin radical species,7and more definitely an ESR signal at g = 2.01 wasobserved for the frozen solution (77 K). The oxidation potentials of the other complexeslisted in Table 3-1 all fall within a relatively narrow range (1.20-1.35 V vs Ag/AgC1),attributed also by others8 to generation of a porphyrin it-radical within TPP and OEPsystems (excluding the CO complexes, whose potentials have been reported in the rangeof 0.68-0.82 V vs. AgIAgCl8’9). The site of oxidation has therefore been assigned to theporphyrin ligand in all the systems.In contrast, the first reduction is assigned to the metal center to give a Ru(ffl)product. Bulk electrolytic reduction of Ru(OEP)Br2at 0.186 V produced a species withan electronic absorption spectrum that was identical to that of Ru(OEP)Br.2 Of note, thisbulk process was not reversible. The Ru(III) mono bromo species was thereforeconsidered to be the product of this one-electron reduction reaction even though this85apparently conflicts with the reversibility of the CV reduction. The discrepancy wasexplained by noting the difference in the time-scale of the two experiments:2the reducedspecies observed in the CV (presumably [Ru(OEP)Br2f)exists only for a few secondsbefore it is oxidized back to its original state, whereas the bulk electrolysis proceduretakes about 30 mm which appears to be enough time for the complete dissociation of a Bfligand. A Ru(III) product was also observed in an in situ study of the chemical reductionof Ru(OEP)C12and Ru(TMP)C12with 1 equivalent of sodium naphthalenide [Na(naph)J(see section 3.2.4). The ‘H NMR spectra suggest products ofC4,, symmetry (analogous toRu(OEP)Br).It should be noted that the identification of Ru(OEP)Br is not in itself evidence thatthe initial reduction process occurs at the metal center as cases exist where a change in theaxial ligands results in intramolecular electron transfer between the porphyrin and themetal.8c However, other criteria tend to rule out porphyrin-centered reduction. Theinsensitivity of a redox couple to a change in axial ligands is generally accepted asevidence of a porphyrin-centered event.10 The first oxidation of these complexes hasafready been assigned to the porphyrin and a comparison between the data forRu(TMP)Br2and Ru(TMP)C12(and to a lesser extent Ru(OEP)C12and Ru(OEP)Br2)clearly shows this insensitivity. In addition, there also tends to be a constancy in thepotential difference between porphyrin-centered events. For example, the differencebetween the first porphyrin oxidation and the first porphyrin reduction generallyapproximates to 2.25 V.” For the complexes shown in Table 3-1, the differences betweenthe first oxidation and the first reduction range between 0.71 and 0.83 V; assuming that86the oxidation does indeed occur at the porphyrin, the differences strongly suggest that thefirst reductions are ruthenium-centered.The site of the second reduction listed in Table 3-1 was not unambiguouslyassigned. The differences between these potentials and the porphyrin-centered oxidationpotentials range from 1.91 to 2.08 V which are perhaps close enough to the value of 2.25V to suggest that a porphyrin-centered reduction is feasible. On the other hand, the samereduction potential is relatively sensitive to the axial ligands within Ru(TMP)Br2andRu(TMP)Cl2,implying a metal-centered event.Figure 3-5 displays two cyclic voltammograms obtained for Ru(OEP)Cl2in thiswork which are presented to highlight a feature that was not observed in any of the othersystems (or noted in the earlier work2). A small peak appears at approximately 0.9 Vwhen the scan was initiated towards negative potentials (Figure 3-5b); this peak was notobserved when the scan was initiated in the opposite direction (Figure 3-5a).Furthermore, the signal was only observed when potentials were scanned beyond thesecond reduction, which indicates that this peak arises from a decomposition product ofthis reduction. It is not clear however what this species is. The potential of this oxidationfalls near the range observed for porphyrin-centered oxidations ofRu(II) systems.8 Onthe other hand, the chemical reduction of Ru(OEP)C12with 2 equivalents Na(naph) (atRT) yields in solution a black product with no ‘H NMR signals, consistent with a t-anionradical product as theseRu111(porp) species are expected to be NMR silent.87:1.Q -4I1J1-1.00-1.0Vvs.Ag/AgCIFigure3-5:CyclicvoltammogramsofRu(OEP)Cl2(0.5mM).Datameasuredin0.1M(n-Bu)NClO4inCH2IunderAratmosphereat20°C(scanrate=100mV/s).88It is interesting to note that the data in Table 3-limply that the TMP and OEPporphyrins are not very different in base strength, as the absolute potential for each coupledoes not change significantly upon the change in porphyrin. A correlation betweenporphyrin basicity and redox potentials has been noted previously.10 In contrast, there is adistinct cathodic (negative) shift in the potentials of the metal-centered reductions whenthe porphyrin is changed from TPP to OEP; consistent with the more basic OEP porphyrinincreasing the electron density at the metal making it more difficult to reduce. Theinductive effect of the 3 additional methyl groups of the TMP porphyrin (relative to theTPP) appears to increase the basicity to the extent that the reduction potentials of the OEPand TMP analogues are essentially identical. Direct measurement of the basicity of TMPvia pH titration procedures has not been reported.The effect of changing axial ligands can also be noted from the data of Table 3.1. Acathodic shift is observed upon changing the axial ligands from Br to Cl, reflecting thedecreasing ability of the halogens to stabilize higher oxidation states in the sequence F>Cl> Br> 1.12 Thus chloro species are more difficult to reduce than the analogous bromospecies.3.2 Ru(porp)X(L) Derivatives (L = NB3, py, X = halogen)Two approaches for preparing Ru(III) complexes were developed in theselaboratories in the 1 980s. The preparation of species such as Ru(OEP)Br(PPh3)involvesthe aerobic oxidation of the bis(triphenylphosphine) Ru(II) precursor in the presence ofHBr as shown in reaction 3•313 On the other hand, the Ru(OEP)X(NH3)complexes892Ru(PPh3)+02+ 2HBr 2RuBr(PPh3)+ PPh3OPPh3 + H20Ru Ru(OEP)were prepared by reduction of the Ru(IV) dihalo derivatives with NH3;the ammineligand was then removed by reaction with hydrofluoric acid to give the 5-coordinateRu(OEP)X species. These two reactions are summarized in equations 3.4 and 352(2) NH3Ru(OEP)X2 1 atm ‘ Ru(OEP)X(NH3)+ HX + (1/2NH4?) 34Ru(OEP)X(NH3)+ HF b Ru(OEP)X + NH4F 3.5In this section, the reduction shown in reaction 3.4 is revisited and applied to theTMP derivatives to produce the two new complexes, Ru(TMP)Br(NH)andRu(TMP)C1(NH3).When this thesis work began the only Ru(III) derivative of thisporphyrin that had been isolated and characterized was Ru(TMP)Br(PPh3),althoughunfortunately no NMR data were presented for this species.’4 These data are essentialfor comparative purposes in this work. As previously mentioned (section 3.1.1), thenew Ru(OEP)Cl(py) species was also isolated as a coproduct of the anaerobic oxidationof Ru(OEP)py2with HC1, and the preparation and the characterization of this product arealso discussed here. Several unsuccessful attempts to synthesize the OEP monochloroderivative by reaction 3.4 are outlined, as well as some equally unsuccessful attempts toobtain this 5-coordinate species by alternative methods. Finally the electrochemical90properties of Ru(OEP)Cl(NH3)and Ru(TMP)Cl(NH3)are examined by cyclicvoltammetry.3.2.1 Preparation of Ru(porp)X(N113)complexes (porp = OEP, X= Cl; porp = TMP,X = Cl and Br)The Ru(OEP)Cl(NH3)complex could be reliably prepared in 64 % yield using aslightly modified version of the original procedure.2 In a typical synthesis, theRu(OEP)C12starting material (40 - 50 mg) was dissolved in toluene (50 niL) and theresulting solution was then saturated with NH3 by bubbling the anhydrous gas through thesolution for 5-10 minutes. The duration of the reaction was not indicated in the earlierwork but reaction times of more than 12 hours (overnight) were found to greatly improvethe yield. The original procedure also suggested washing the product solution withseveral portions of water, presumably to remove the excess ammonia. Bubbling argonthrough the product solution for approximately 5 miii achieves the same result with noadverse effect on the yield of Ru(OEP)Cl(NH3).Running the product mixture through aneutral alumina column was usually enough to complete the purification. The red productcould be eluted from the column with CHC13 and after the volume was reduced (2-5 mL),the final product was precipitated by adding an excess (40- 50 mL) of cold hexanes.Yields of approximately 33 % could be realized for the synthesis of TMP analoguesby using the same procedure. However, benzene or acetonitrile was needed to elute theproduct off the column in this case as the complex decomposed if CHCI3 was used. Thereason for this became clear when it was discovered that CDC13 solutions of91Figure 3-6: UV/visible spectrum of Ru(TMP)Cl(NH3)taken at 200 C (13 tM intoluene).The Soret band appears at 414 nm while a single Q band is evident at 536 nm. The Soretalso bears a shoulder at 395 nm which may be due to a charge transfer between the metalRu(TMP)Cl(NH3)decomposed when exposed to air (chromatography was routinely donein air); approximately 50 % of the complex is oxidized to Ru(TMP)C12within an hour asjudged by ‘H NMR. This process is probably accelerated on a column. In contrast,anaerobic solutions of the Ru(TMP)X(NH3)complexes were stable. It is not clear whythe same sensitivity to air was not observed for the OEP chloro derivative.3.2.2 Characterization of Ru(TMP)C1(N113)and Ru(TMP)Br(NH3)The Ru(TMP)Cl(NH3)complex was isolated and fully characterized in this study,while the bromo analogue was isolated only as a impure solid. The visible spectrum of theformer is shown in Figure 3-6 and is typical of a normal metalloporphyrin species.21.5C0U,40.50350 400 450 500 550Wave’ength (nm)60092and the porphyrin (section 3 .2.3). The spectrum of the bromo species is almost identical(418 and 536 nm).These paramagnetic Ru(llI) complexes are low spin with 1 unpaired electron asevidenced by the magnetic moment of 1.61 B.M. measured for Ru(TMP)Cl(NH3). Thesimilarity in the NMR spectra of the two complexes (see Figure 3-7 and Figure 3-8)indicates that the bromo complex has the same spin state (S = 1/2). This is consistent withthe observations made for the OEP congeners.2 As with the dihalo derivatives, theseparamagnetic compounds exhibit NIVIR spectra with broad signals at chemical shiftssignificantly shifted from their diamagnetic positions. The plot of the isotropic shift vs.l/T for Ru(TMP)C1(NH3)(Figure 3-9) clearly illustrates that one spin state dominateswithin the measured temperature range (-20 to 500 C). As with the Ru(IV) dichiorospecies, the small positive intercept for the pyrrole signal (if real) may be indicative oftemperature-independent paramagnetism or spin orbit coupling in this complex.A comparison of the NMR spectrum ofRu(TMP)Cl2(Figure 3-2) andRu(TMP)Cl(NH3)(Figure 3-7) clearly demonstrates the loss of symmetry on going fromthe dichloro to mono chioro species. In the spectrum of the latter species, two resonancesare observed for the rn-protons of the mesityl groups (3.87 and 3.80 ppm) while a broadsinglet appears for each of the o-methyl protons ( 0.38 and -0.83 ppm). The magneticinequivalence of these two sets of protons demonstrates the anisochronic nature939o-Me•,I,I,I1,III12QIIbM—2rii-,—i•—irj-1i—r—rFTriri[IiIr1111Jl1VIr)1050—5—10—15—20—25—30PPIb4—35Figure3-7:IINMRspectrum(300MHz)ofRu(TMP)Cl(Nl-13)inC6Dtakenat293K.Ssolvent,x=unknownimpurity.Srn-H‘CI1TrIIIIIII86494.e50—5—10—15—20p-Me—5—30Figure3-8:‘IINMRspectrum(300MHz) ofisolatedRu(TMP)Br(N113)inC6Dtakenat293K.S=solvent,xunknownimpurity.S‘Cx-MeII85420—2PPM9510 0j10-20•—-300-40-50-601/Temp(K1)Figure3-9:Plotofisotropicchemicalshift(calculatedrelativetoRu(TMP)(CH3CN)2vs.l/T(K)forRu(TMP)C1(NH3).RawdataavailableinappendixA.rn-Hp-Meo-Me H3,1.00.00050.0010.00150.0020.00250.0030.00350.0040.004596of the two faces of the porphyrin in this complex. The assignment of the remaining peaksis quite straight forward with the p-methyls appearing as a sharp singlet at 0.44 ppm andthe pyrrole protons appearing as a broad signal at -32.40 ppm. The integrationcorroborates these assignments. As seen in Figure 3-8, the spectrum of Ru(TMP)(NH3)Bris completely analogous to that of the chioro derivative [ö(ppm) rn-H, 3.86, 3.80; o-CH3,0.25, -1.02; p-CH3,0.42; pyrr, -30.21 1. The animine protons are not detected in theNMR spectrum for either of these complexes nor were they observed for the OEPanalogues.2 However, the microanalysis of Ru(TMP)C1(NH3)confirms the presence ofthis ligand, at least in the solid state. It is not unusual for the cL-proton signals to be absentin the NMR spectra of Ru(II1) complexes. For example, the axial methyl protons ofRu(TMP)CH3and Ru(OEP)CH3”5are invisible to NMR as are the methylene protons ofthe neopentyl and neophyl ligands ofRu(OEP)CH2C(CH3andRu(OEP)(CH2C(CH3)Ph)(see Chapter 4). Clearly the cL-protons relax far to quickly tobe detected due to their proximity to the paramagnetic metal centre.3.2.3 Preparation and characterization of Ru(OEP)C1(py)As previously mentioned, Ru(OEP)C1(py) was isolated purely by happenstance froma reaction of approximately 100 mg of Ru(OEP)py2with HC1. The UV/visible,t elementalanalysis,tt and 1H NMR spectra (Figure 3-10) are all consistent with this formulation.Because Ru(OEP)C12was the target complex, the reaction was run for three days at 500 C(nm) = 402 (Soret), 520 (Q-band).ttftj Caled forC41H9N5Ru.0.S H20: C, 65.02; H, 6.65; N, 9.24. Found: C, 65.05; H, 6.86; N, 9.05.97and the Ru(III) product was only isolated in trace amounts (<2 mg). Judging from theresults reported for the in situ N1VIR study (see section 3.1.1), it is likely that this complexcan be prepared in increased yields if the reaction were carried out at room temperaturefor 5 to 10 mm.Figure 3-10 shows the ‘H NIVIR spectrum Ru(OEP)Cl(py). This spectrum is typicalof a paramagnetic Ru(III)(OEP) species ofC4 symmetry. The broad peaks found at 9.9and 6.65 ppm correspond to the OEP methylene signals while the peaks at -2.15 and -4.2ppm can be assigned to the methyl and meso protons, respectively. These signals do notcompare favourably with the shifts reported for the intermediate observed in the originalNIVIR experiment on the Ru(OEP)py2/HC1 reaction (ö CH3= -1.75; -CH2= 12.10, 10.22;Hmeso = -3.98 at 20°C). However, this spectrum was obtained in a solution ofC6Dsaturated with HC1(g) and this perhaps affects the frequency the 1H NIVIR signals. Thebroad signal found downfield at 28.1 ppm (Figure 3-10) is similar to that found for thephenyl rn-protons of Ru(OEP)Ph (ö= 48.8 ppm)’5 and has therefore been assigned to thern-protons of the axial pyridyl ligand. This signal integrates for 2 protons which isconsistent with this assignment. The Ru(OEP)Ph complex also exhibits peaks at -48.8 and-83.1 ppm, attributable to the phenyl p- and 0-proton resonances respectively;’5 however,the corresponding pyridine signals of Ru(OEP)Cl(py) were not observed in the regionbetween 30 to -100 ppm, these peaks perhaps being broadened beyond detection.It is interesting to note that the Ru(OEP)Cl(py) species was also obtained from the insitu reaction of Ru(OEP)C12with Ru(OEP)py2.In this experiment a suspension ( 0.8 mLC6D).98S-Cl-I,11,0f-CH2b-f-CH2-HmesoIIIIIIIlliji‘IIIl1IIIl1IIII02015105OPPH—5Figure3-10:1HNIv1Rspectrum(300 MHz)of Ru(OEP)C1(py)inC6D6takenat293K.S=solvent,1=thepyridinern-H(tentatively).99of the dichioro complex ( 7 .tmol) and the Ru(OEP)py2( 7.6 iimol) were sealed undervacuum in an N?vlR tube. The reaction appears to be slow as the two reagents were theonly species observed in the ‘H NIVIR spectrum after 1 hour; however, within 1 week theRu(OEP)Cl2had disappeared leaving Ru(OEP)Cl(py) and the excess Ru(OEP)py2.In the earlier work, it was hypothesized that the NrvlR spectra of theRu(OEP)X(NI{3)complexes were characteristic of a charge transfer from the rutheniumto the porphyrin2and the same arguments apply here to Ru(OEP)Cl(py). The wavefunctions (Huckel) of the empty 4e5(lt*) (LUMO) orbitals have a large amplitude on themeso carbons and the transfer of unpaired spin into this molecular orbital is predicted toresult in a large upfleld shift for protons and a large downfield shift for methyl groupsattached at this position.1’ The meso signal for the above complex was observed ataround -5 ppm, which is 14 tol5 ppm upfleld from the diamagnetic shifts, consistent withthe theoretical predictions. The methylene resonance of the pyrrole ethyl groups ofRu(OEP)Cl(py) are found 2 and 7 ppm downfield of the diamagnetic signals ofRu(OEP)py2.4As previously stated (section 3.1.2), a downfield shift of the pyrrolemethylene signals is indicative of a transfer of electron density from the porphyrin3eg(7t)orbitals to the metale5(d,, d) orbitals. The same criterion can not be applied to the mesosignals ofRu(TMP)X(NH3);however, the pyrrole signals appear at approximately -32ppm for these complexes, and once again a large upfleld shift for pyrrole protons indicatesa porphyrin to metal charge transfer. The same type of shift is also observed for thepyrrole protons of the Ru(TMP)R complexes (see Chapter 5). On the other hand, there isa downfield shift for the methylene signals and an upfleld shift for the meso signals of the100Ru(OEP)R complexes which implies that both types of charge transfer processes arepresent! It is becoming clear that these predictions may be a little too simplistic to applyto these paramagnetic ruthenium systems.3.2.4 Attempts to prepare Ru(OEP)C1This complex was also of interest as a reagent for the preparation of organometallicspecies as it had been previously demonstrated that the reaction of Ru(OEP)Br(PPh3)withMeLi resulted in a mixture of the products shown in equation 3.6.1c However, initial2RuBr(PPh3)+ 2MeLi RuMe + Ru(PPh3)2+ 2LiBrRu Ru(OEP) 3.6studies on the reactivity of Ru(OEP)Br suggested that this species does not react with thisorganolithium reagent;’6this is curious as the triphenyiphosphine derivative clearly does.Furthermore it is difficult to imagine a mechanism for the reaction of the Ru(porp)X2complexes with organolithium or Grignard reagents (which yield Ru(porp)R (n= land 2)type species)’ that does not involve these 5-coordinate Ru(III) species as intermediates.It was therefore of some interest to determine whether this lack of reactivity extended tothe neopentyllithium reagent used in this thesis work (see chapters 4 and 5).Repeated attempts to prepare Ru(OEP)Cl according to the method illustrated inequation 3.5 (p. 90) proved unsuccessful. The original procedure2described a 2-phaseanaerobic reaction in which an aqueous solution of HF ( 0.5 mL) was reacted with achloroform solution (50 mL) of Ru(OEP)Cl(NH3(20 mg) under anaerobic conditions.The mixture was vigorously stirred for 10 mm at ambient temperature and the product101was then isolated on a neutral alumina column. The only complex isolated in this thesiswork by following this procedure was the Ru(OEP)Cl(NH3)starting material. Prolongedsonication (1/2 h) of the reaction mixture or increasing the duration of the reaction to 21 hhad no effect but to reduce the amount of the retrievable starting material. In everyattempt, a second green product remained on the column during the purification. The datapresented for characterization of the Ru(OEP)X complexes in the original report2 areconsistent with the formulation and it is clear that these complexes were in fact isolated.The reason for the lack of reproducibility of this important transformation remains unclear,despite recent communications with the original author, Dr C. Sishta.A number of alternative procedures were devised in an attempt to obtain these5-coordinate complexes. Vacuum pyrolysis of Ru(OEP)Cl(NH3)was one approach, thehope being that the ammine ligand might dissociate while the chioro ligand would not[phosphine, pyridine and acetonitrile ligands have been removed successfully fromRu(porp) species by such a procedure’4”7]. An NMR sample was therefore heated to220° C and 10 4 torr for 5 h. Unfortunately, but of interest, the experiment revealed that,in addition to the NH3, the chloro ligand was in fact labile under these conditions(presumably lost as Cl2) as the only complex observed in the NIVIR spectrum after thistreatment was [Ru(OEP)]2. In an other experiment, aqueous HC1 (1.0 M) was substitutedfor the HF in the procedure outlined above. However, after about 16 h (overnight) a largepercentage of the complex had been converted to Ru(OEP)C12with the balance remainingunreacted as evidenced by NMR. In retrospect, both of these results could have beenpredicted. For example, the vacuum pyrolysis of Ru(OEP)X2complexes under conditions102similar to those described above also yields the dimeric complex. la It is possible that the5-coordinate Ru(III) complexes (i.e. Ru(OEP)X) are intermediates in these reactions.Moreover, it was demonstrated in the earlier work and reconfirmed here thatRu(OEP)Cl(py) is oxidized by HC1 under anaerobic conditions to give Ru(OEP)C12.Presumably Ru(OEP)Cl(NH3would react similarly, the only significant difference in thisprocedure being the use of aqueous HC1. It is not clear why the HF acid withRu(OEP)Cl(NH3)does not yield Ru(OEP)F2given that this species has been prepared viaa similar process (i.e. reaction of [Ru(OEP)]2with HF). lbBecause of the continuing failure to obtain Ru(OEP)Cl from the ammine derivative,another approach was attempted. As previously mentioned (section 3.1.3), the bulkelectrochemical reduction of a solution of Ru(OEP)Br2(at 0.186 V vs. AgIAgCI) resultedin the formation of Ru(OEP)Br.2 This result suggested that Ru(OEP)Cl might be obtaineddirectly from the dichioro species by reduction with a non-coordinating reagent. Sodiumnaphthalenide is an appropriate choice for this reaction for 3 reasons; it is a strongreducing agent (E° -2.55 V’8), relatively easy to add a controlled amount (i.e.1 equivalent), and the naphthalene coproduct can be easily removed by sublimation. Onepossible complication arises from the fact that the Na(naph) is prepared as a solution inTHF (see Chapter 2 for details) and this could possibly result in the formation of a productwith coordinated THF. However, this is a weak ligand and could probably be pumpedaway easily on the vacuum line. The reduction was therefore attempted on an NMR scaleto test the feasibility of this approach.103In a typical experiment 4-6 mg of Ru(porp)C12(porp OEP or TMP) was weighedinto a Schienk tube fitted with a Teflon stopper. This vessel was then evacuated and 5 to10 mL of dry, degassed benzene was condensed into the tube. One equivalent ofNa(naph) was then added dropwise (by syringe) to the vigorously stirred solution under acontinuous purge of argon. Stirring was continued for 3 h whereupon the solvent wasremoved on the vacuum line and the product was dried at 50° C while pumping overnight.The product was then taken into the glove-box, dissolved in C6D, and the solution sealedin an anaerobic NvIR tube. Figure 3-11 shows the spectrum of product resulting fromtreating Ru(OEP)Cl2in this way.The NMR spectrum in Figure 3-11 is typical of a ruthenium (III) octaethylporphyrincomplex ofC4 symmetryc2l5a(see also section 3.2.3), and the most obvious assignmentfor this is Ru(OEP)Cl(THF). The methylene protons appear at two different frequencies(10.4 and 7.0 ppm) revealing the inequivalence of the two faces of the porphyrin. Thesignal at -1.25 ppm integrates for 24 protons and the shift position is typical of the methylfrequencies for these species. le,2,15a The 0.84 ppm signal is typical of the porphyrin mesoprotons of these complexes while the peak at 14.7 ppm might be due to the THF -CH2protons; each of the signals representing 4 protons consistent with these assignments. Theother expected signal for the THF is not seen but, as previously mentioned (p. 97),protons in close proximity to the paramagnetic metal center are often not observed.Finally, the remaining signals can probably be attributed to unreacted Ru(OEP)C12although these peaks are shifted relative to the frequencies normally observed in C6D104-cH)Il11lIluPIIlpllII1llI1TlT1IIIl1lluIl1ITlJlIlllIIlIllIflIItlJIl1IlIIIluIp111TUll-1614121066420—2PPU—42—illIJI111f‘‘‘I11111TIIIJIIIllIllIllIlTillIIJIIIJ1E—rJrrlII9111111111111111t1I(050403020100PPM—10Figure3-11:1HN’Rspectrum(C6D,20°C,300Mhz) of theproductsofthereactionofRu(OEP)C12withI equivalent ofsodiumnaphthalenide.S=solvent,1axialTHF(3-Cl2)(tentatively),2=unreactedRu(OEP)C12.105(ö(ppm, 200 C) 51.05, -CH2; 13.50, Hmeso; 6.05, CH3).t The shift of these signals maysuggest that Ru(OEP)C12is involved in a rapid exchange equilibrium in solution.Taken by itself, the spectrum in Figure 3-11 supports the proposedRu(OEP)Cl(THF) formulation; however, certain observations create doubt. First, in allother Ru(llI)(OEP)X(L) complexes, the porphyrin meso signals appears upfield of themethyl peaks.2”3 It is not clear why Ru(OEP)Cl(THF) would be an exception to this rule.Of more concern however is the air-sensitivity of this Ru(III) species. WhileRu(OEP)Cl(py) (section 3.2.3), Ru(OEP)Cl(NH,Ru(OEP)Cl(CH3CN),2andRu(OEP)C12are all air stable in solution (even when run through an alumina column), this‘Ru(OEP)Cl(THF)’ species completely decomposed to [Ru(OEP)Cl]2(p.-O)1’’Th(as judgedby ‘H NMR spectroscopy) within an hour of being exposed to air and the decompositionwas accelerated on alumina columns.The 1H NMR specutrum obtained by treating Ru(TMP)Cl2with 1 equivalent ofNa(naph), as described above, suggests an analogous Ru(TMP)Cl(THF) product (ö(ppm,20° C): TMP; -27.2, H; -0.30, 0.79, o-CH3;0.80, p-CH3;4.22, 4.43, rn-H. THE; 15.823-C). This species was similarly air-sensitive and initial attempts to isolate this materialfailed. However, the results suggest that the Ru(Ill) product might be isolable if columnswere run anaerobically.The ‘H NMR spectra of Ru(OEP)X2species are not normally reported in C6D because of the insolubility of thecompounds in this solvent.106The only firm conclusion that can be drawn from these studies is that Ru(III)products (as opposed to a it-anion radicals) ultimately result from the one-electronreduction of Ru(porp)C12.Although initial attempts to isolate these products wereunsuccessful, this route to the Ru(porp)X species shows promise and warrants furtherinvestigation.3.2.5 Electrochemistry of the Ru(III) derivativesThis work was carried out to supplement the earlier studies of the Ru(OEP)Xcomplexes (X = Br and Cl).2 It was also hoped that these data might provide insight intothe nature of the aerobic oxidation reaction mentioned previously.2 Figure 3-12 shows thecyclic voltammetric trace for Ru(OEP)Cl(NR3).The response for Ru(TMP)CI(NH3)isalmost identical in appearance and the potentials obtained for these two species aretabulated in Table 3-2 below.Each complex shows two reversible 1 electron oxidations and one reversible 1electron reduction. As shown in Table 3-2, the 1St and 2nd oxidations are metal-centeredand porphyrin-centered, respectively. These assignments are based on those made for theRu(OEP)Br complex2where bulk electrochemical oxidation yielded products withelectronic absorption spectra that resembled a regular metalloporphyrin for the firstoxidation and a it-cation radical complex for the second. It seems that the redox reactivityof the ammine species in Table 3-2 closely resembles that of the Ru(OEP)Br complexgiven the similarity of the potentials involved. The reversible reductions have not beenassigned; however, these reductions are probably metal-centered as the107V VLAg/AgCIFigure 3-12: Cyclic voltammogram of Ru(OEP)C1(NH3)(0.5 mM). Data obtainedin 0.1 M (n-Bu)4NClO in CH21 under 1 atm Ar at 298 K (scan rate 200 mV/s).Table 3-2: Reduction potentials for Ru(III)(porp)X(L) complexes (± 0.01 V vs.Ag/AgCl).’2nd oxidation 1 St oxidation 1 St reductionRuW(porpjfRuT((porp) Ru”/RuRu(OEP)C1’ 1.20 0.68Ru(OEP)C1(NH3) 1.31 0.74 -0.51Ru(TMP)C1(NH 1.45 0.85 -0.42a) All measurements were made in a solution of 0.1 M (n-Bu)4NClO in CH21 at 293K. b) data obtained from reference 2.108difference between these peaks and the porphyrin-centered oxidation couples isapproximately 1.8 V, considerably lower than the accepted value of 2.25 V for thedifference between the first porphyrin centered oxidation and reduction (section 3.1.3). Ifcorrect, the Ru(III)/Ru(II) couples measured for the Ru(OEP)X(NH3)complexes are themost negative recorded to date; potentials for complexes of the Ru(OEP)LL’ type, forexample (LL’ py, L=L’=SR2or L=py and L’= CH3N), Z Sa, typically fall in the rangeof 0.1 to 0.3 V (vs. AgIAgC1). This presumably reflects the preference for the halide-stabilized higher oxidation state for the ruthenium metal.The results for the two ammine complexes in Table 3-2 contrast with those observedfor the Ru(IV) dichloro species (Table 3-1, p. 84). The potentials of the three redoxevents listed in Table 3-2 display an anodic (positive) shift upon changing the porphyrinfrom OEP to TMP, as perhaps expected for a less basic tetraphenylporphyrin-typederivative. However, within the dichloro species (Table 3-1, p. 84) a change from OEP toTMP resulted in essentially no change in the potentials of the three observed redox events,and it was therefore concluded that the two porphyrins are equally basic. Obviously thecorrelation between base strength and reduction potentials is not that simple. Of note isthe positive shift in the potential of the Ru(IV)/Ru(III) couple upon the replacement ofone chioro ligand with NH3 (0.33 and 0.42V for OEP and TMP derivatives, respectively).This likely reflects mainly the destabilization of the higher oxidation state upon theremoval of one chioro ligand making the complex easier to reduce.1093.3 The oxidation of Ru(II) complexes revisitedThe discrepancy in the reported’2and observed rates of reactions 3.1 and 3.2 (p.71) was the source of considerable frustration in this thesis work. Indeed, there seemed tobe some inconsistencies within the previous account, as the oxidation of Ru(OEP)Br withHBr to give the dibromo product was reported to require 2 h under aerobic conditions,2whereas the ‘double oxidation’ of the Ru(ll) precursors in reaction 3.1 was said to “occurrapidly” when air is introduced into the reaction solution.2 This is something of a paradoxconsidering that the latter process probably involves Ru(III) intermediates that areanalogous to Ru(OEP)Br. One problem with these reactions is the nature of the redoxprocess. For example, J{’ is the obvious oxidant for the anaerobic process and theestablished stoichiometry2shown in reactions 3.1 and 3.2 supports this. However, intenseefforts to observe the expected dihydrogen coproduct during the anaerobic oxidation of[Ru(OEP)]2with HBr were unsuccessful. A suggestion that trace X2 (X = halogen)impurities are the active oxidants was ruled out as reaction with halogens resulted inconsiderable destruction of the porphyrin ligand.lM2In the earlier work,13 the aerobic oxidation ofRu(OEP)(PPh3)2[as outlined inreaction 3.3 (p. 90)] was somewhat unexpected as this complex was relatively air-stable inthe absence of the protic acid (e.g. HC1). The oxidation was initially rationalized in termsof the reaction sequence shown in equations 3.7 to 3913 where the initial outerRu(OEP)(PPh3)2+ 02 - [Ru(OEP)(PPh3)2f+ 02 3.711002 + H HO2 1/2 02 + 1/2 H20 3.8[Ru(OEP)(PPh3)2]- Cl Ru(OEP)Cl(PPh3)PPh3 39sphere electron-transfer equilibrium is thermodynamically unfavourable as indicated by thereduction potentials: the Ru(III)/Ru(II) couple ofRu(OEP)(PPh3)2has been measured at0.16 VSd vs. Ag/AgCI, whereas the standard reduction potential of 02 in dry, aproticsolvent occurs at approximately -0.8 Vt vs. Ag/AgC1.2°These numbers translate toequilibrium constants of the order of 10.18. However, the addition ofH was consideredto force reaction 3.7 to the right by stabilizing the superoxide anion and promoting itsdisproportionation to give hydrogen peroxide and dioxygen (reaction 3.8); this isirreversible and rapid, and was considered to provide a kinetic driving force to effect theoverall process. Indeed the introduction ofH has an apparent thermodynamic effect onthe reduction of dioxygen in aprotic solvents as the measured reduction potential increasesto -0.08 V vs. AgIAgClt upon acidification.20 The same driving force was also proposedfor the Ru(0EP)(PPh3)2/Hcatalyzed oxidation of PPh3 to OPh3.21In later work, la attempts were made to generalize this chemistry in order to includea wider scope of Ru(II) precursors; however, as shown in reactions 3.1 and 3.2 (p. 71)these studies resulted in some cases in the overall two-electron oxidation to give theRu(IV) dihalo complexes. Dioxygen reportedly played a role in these reactions (videtValue obtained in dry DMF.111infra); however, the oxidation could also be effected in the absence 02. As previouslydiscussed, the anaerobic reaction in certain cases has been shown to involve twodiscernible oxidation steps in which at least one Ru(III) intermediate is initially detected,which in turn is oxidized to give the final Ru(IV) dihalo products. More specifically,Ru(III) intermediates have been detected in the reaction of [Ru(OEP)]2with HC1 inCH2l,tortreatment of Ru(OEP)py2(see also section 3.1.1) or Ru(TMP)(CH3CN)2with HCI and/or HBr in benzene (section 3.1.2). It is interesting to note that in the lasttwo systems, the Ru(III) intermediates are air-stable (in solution) in the absence of theacid as are some of the other plausible intermediates that have been isolated. For example,two air-stable Ru(III) complexes have now been isolated from the various reactions ofRu(OEP)(py)2with HC1: [Ru(OEP)py2]C1and Ru(OEP)Cl(py). As mentioned in section3.1.1, the latter species is an intermediate en route to the dihalo species and the formercomplex possibly plays a role in this mechanism as well.The introduction of air reportedly accelerates the overall reaction; however, if air isintroduced before the HX acid, products such as [Ru(OEP)Cl]2(p-O) (for the reaction of[Ru(0EP)]2)laand [Ru(OEP)py2]Cl(for the reaction ofRu(OEP)py2)form instead ofthe dihalo species. While 02 clearly effects the Ru(II)/Ru(III) oxidation reaction, theresults suggest that dioxygen also intervenes in the Ru(III)/Ru(IV) oxidations. Thispossibly implies a mechanism similar to that shown for the Ru(II)/Ru(UI) oxidation inreactions 3.7 and 3.8. However, the reduction potentials for the Ru(IV)/Ru(ffl) couple(see Table 3-1 and Table 3-2) reveal that this may not be operative. These values fall intotNo Ru(llI) intermediates were detected when [Ru(OEP)]2was treated with FIX acids in benzene.2112the range of 0.3 ito 0.85 V vs. the AgIAgCl,2making the outer-sphere oxidation ofRu(III)/Ru(IV) even less favourable than the analogous Ru(II)/Ru(III) oxidation (i.e.reaction 3.7). In principal, the overall process could be driven by the reaction of thesuperoxide intermediate with H (reaction 3.8); however, this seems unlikely as the specieswith the most favourable potential, Ru(OEP)(PPh3)Brat 0.31 V2, was not oxidized toRu(IV) under these conditions.’3’22It should be noted that 02 can oxidize Ru(II) and Ru(III) species to oxidation statesof IV and in some cases VI. For systems with sterically unhindered porphyrins such asOEP, the .t-oxo dimer shown in reaction 3.10 results.23 Again noteworthy is02/H I IRu(OEP)L2 HO-P1u—O-1- HL= vacant, THF, CH3N 3.10that water, presumably acting as a source of protons, is necessary to drive this reaction.2Similarly, the Ru(ffl) complex Ru(OEP)(OEt)(EtOH) gives the diethoxy congener of the.t-oxo dimer when methylene chloride solutions of this species are exposed to air.23’ Thep.-oxo dimeric complexes are sterically precluded when bulky porphyrins such as TMP areinvolved and the aerobic oxidation of these systems ultimately results in formation of theRu(VI) dioxo species Ru(TMP)(0)2.4 It is unlikely, however, that these processes, whichclearly involve initial coordination of 02, bear any resemblance to the outer-sphereinitiated oxidation sequence outlined in equations 3.7 and 3.8 as the02-coordinationwould have a profound effect on the thermodynamics of any redox reaction.113Several factors should be considered as possible sources for the inconsistenciesexperienced in the application of reactions 3.1 and 3.2. For example, water may facilitatethe oxidation reaction. A great deal of effort was made to exclude water from the reactionsolvents in these studies (see chapter 2), whereas the same precautions were notnecessarily followed in the earlier work”2. Hydrochloric acid is somewhat more soluble inwater-saturated benzene (0.502 lvi, 200 C, 1 atm) than in dry benzene (0.461 M, 20° C, 1atm)25 and this could increase the rate of the reaction particularly if a proton (waterstabilized) was involved in the rate-determining step.Another possibility is the participation of light in these reactions. This is notunprecedented as the catalytic oxidation of thioethers can involve a light-induced outer-sphere electron transfer to 02. 19a No attempts were made to control the intensity andsource of light in these reactions, and this of course could drastically alter the reactionrate.Finally, an inner sphere mechanism should also be considered for these oxidationreactions. The Ru(TMP)(0)2complex has been reported to oxidize FIX acids to yieldRu(TMP)X2as the metalloporphyrin product.3 Although the details of this reaction werenot reported, the reaction has been shown to be rapid (occurring within seconds) andclean.26 Consequently, the Ru(VI) dioxo species may play an important role in theoxidation reactions of equation 3.2 as applied to the TMP systems. However, thechemistry for complexes of the less bulky metalloporphyrins (e.g. OEP and TPP) is morecomplicated as02-oxidation of these species results in the formation of the114[Ru(IV)(porp)OH]2(p.-O)dimers.23 These species are unlikely to be intermediates in theoverall process because the reaction of HX acids with these complexes results only in theexchange of the axial OH by X anion. 23c However, it is not clear what happens during theoxidation of the Ru(III)(OEP)(X)S complexes (X = halogen, S = labile ligand) with theO2/H system; Ru(IV) or Ru(V) monooxo intermediates such as Ru(porp)(O) orRu(porp)(O)X might evolve, and these might react with FIX in a manner similar to thedioxo species. An analogue of the Ru(IV) species has appeared in the literature in theform of Ru(OEP)(O)(EtOH) although its reactivity with FIX was not reported.27 Theformation of such oxo species would depend on the lability of the axial ligand S, and therates of any such oxidation reaction would be expected to vary with the ligand S.Clearly, more work is needed to optimize the conditions for the oxidation reactions,and several factors implicated above warrant investigation. In the meantime, if theobjective is to obtain analytically pure samples of the Ru(IV) dihalo products in areasonable yield (i.e. 80%), the procedures outlined in this thesis should reliably satisfythis aim.1153,4 References for Chapter 31a) Sishta, C., M Sc. Thesis, University of British Columbia, 1986.b) Sishta, C.; Ke, M.; James, B.R.; Dolphin, D. J. Chem. Soc., Chem. Commun., 787(1986).c) Ke. M.; Ph.D. Thesis, University of British Columbia, 1989.d) Ke. M.; Sishta, C.; James, B.R. ; Dolphin, D.; Sparapany, J.W.; Ibers, J.A. Inorg.Chem., 30, 4766 (1991).2 Sishta, C., Ph.D. Thesis, University of British Columbia, 1990.Ohtake, H.; Higuchi, T.; Hirobe, M. .1. Am. Chem. Soc., 114, 10660 (1992).a) Antipas, A.; Buehler, J.W.; Gouterman, M.; Smith, P.D. J. Am. Chem. Soc., 100,3015 (1978).b) Gouterman, M. In The Porphyrins, Dolphin, D. Ed., Academic Press, New York,N.Y., 1978, vol. 3, chapter 1.a) Evans, D.F. J. Chem. Soc., 2003 (1959).b) Deutsch, J.L.; Poling, S.M., J. Chem. Ed., 46, 167 (1969).c) Sur, S.K. J. Mag. Res., 82, 169 (1989).d) Eaton, S.S.; Eaton, G.R. Inorg. Chem., 19, 1096 (1980).6 La Mar, G.N., Walker, F.A. In The Porpyrins, Dolphin, D. Ed., Academic Press, NewYork, N.Y., 1979, vol 4, chapter 2.a) Fuhrhop, J.H.; Kadish, K.M.; Davis, D.G. .1. Am. Chem. Soc., 95, 5140 (1973).b) Collman, J.P.; Prodolliet, J.W.; Leidner, C.R. J. Am. Chem. Soc., 108, 2916 (1986).8a) Brown, G.M.; Hopf, F.R.; Ferguson, J.A.; Meyer, T.J.; Whitten, D.G.; J. Am. Chem.Soc., 95, 5939 (1973).116b) Barley, M.; Becker, J.Y.; Domazetis, G.; Dolphin, D.; James, BR. J. Chem. Soc.,Chem. Commun., 982 (1981).c) Barley, M.; Becker, J.Y; Domazetis, G.; Dolphin, D., James, B.R. Can. J. Chem.,61, 2389 (1983).d) Barley, M. Ph.D. Thesis, University of British Columbia, 1983.e) Pacheco, A.A., Ph.D. Thesis, University of British Columbia, 1992.a) Brown, G.M.; Hopf, F.R.; Ferguson, J.A.; Meyer, T.J.; Whitten, D.G.; J. Am. Chem.Soc., 97, 5385 (1975).b) Rillema, D.P.; Nagle, J.K.; Barringer, L.F.J.; Meyer, T.S. J. Am. Chem. Soc., 103, 56(1981).c)Kadish, K.M.; Chang, D. Inorg. Chem., 21, 3614 (1982).d) Kadish, K.M.; Leggett, D.J.; Chang, D. Inorg. Chem., 21, 3618 (1982).e) Malinski, T.; Chang, D.; Bottomley, L.A.; Kadish, K.M. Inorg. Chem., 21, 4248(1982).f) Mosseri, S.; Neta, P.; Hambright, P. J. Phys. Chem., 93, 2358 (1989).10 Guilard, R; Kadish, K.M. Chem. Rev., 88, 1121 (1988).“ Felton, R.H. In The Porphyrins, Dolphin, D. Ed., Academic Press, New York, N.Y.,1978, vol 5, chapter 2.‘2Boftemiey L.A.; Olson, L.; Kadish, K.M. In Electrochemical andSpectroelectrochemical Studies ofBiological Redox Components, ACS Series, Kadish,KM. Ed., Am. Chem. Soc., Washington, 1982, vol. 210, chapter 13.13 James, B.R.; Dolphin, D.; Leung, T.W.; Einstein, F.W.B.; Willis, A.C. Can. J. Chem.,62, 1238 (1983).14 Sishta, C.; Camenzind, M.J.; James, B.R.; Dolphin, D. Inorg. Chem., 26, 1181 (1987).15 Ke. M.; Rettig, S.J.; James, B.R.; Dolphin, D. J. Chem. Soc., Chem. Commun., 1110(1987).11716 Sishta, C. Unpublished results.17a) Coilman, J.P.; Barnes, C.E.; Collins, T.J.; Brothers, P.3.; Gallucci, J.; Ibers, J.A. J.Am. Chem. Soc., 103, 7030 (1981).b) Coilman, J.P.; Barnes, C.E.; Swepston, P.N.; Thers, J.A. J. Am. Chem. Soc., 106,3500 (1984).c) Camenzind, M.J.; James, B.R.; Dolphin, D. J Chem. Soc., Chem. Commun., 1137(1986).18 Seyler, J.W.; Lance, K.S.; Leidner, C.R. Inorg. Chem., 31, 4300 (1992).19 a) Pacheco-Olivella, A.A. Ph.D. Thesis, University of British Columbia, 1992.b) Pacheco, A.A.; Rettig, S.J.; James, BR. Inorg. Chem., 34, 3477 (1995).20a) Sawyer, D.T.; Valentine, J.S. Acc. Chem. Res., 14, 393 (1981).b) Sawyer, D.T.; Nanni Jr., E.J.; Roberts Jr., J.L. In reference 12, chapter 24.21 James, B.R.; Ivlikkelsen, S.R.; Leung, T.W.; Williams, G.H.; Wong, R. Inorg. Chim.Acta., 85, 209 (1984).Sishta, C; Camenzind, M.J.; James, B.R.; Dolphin, D. Inorg. Chem., 26, 1181(1987).23 a) Farrell, N.; Dolphin, D.; James, B.R. J. Am. Chem. Soc., 100, 324 (1978).b) Collman, J.P.; Barnes, C.E.; Collins, T.J.; Brothers, P.J.; Gallucci, J.; Ibers, J.A. J.Am. Chem. Soc., 103, 7030 (1981).c)Collman, J.P.; Barnes, C.E.; Brothers, P.J.; Collins, T.J.; Ozawa, T.; Gallucci, J.C.;Ibers, J.A. J. Am. Chem. Soc., 106, 5151 (1984).24 Groves, J.T.; Ahn, K-H. Inorg. Chem., 26, 3831 (1987).25 Seidell, A. Solubilities ofInorganic andMetal Organic Compounds, 3rd Ed., VanNorstrand, New York, 1940, vol I, pp. 567-580.26 James, B.R.; Cheng, S.Y.S. Unpublished results.118611t6861)1188‘111‘•°°Suiay3UVTWD‘aqj11-Ak&InalLiChapter 44. Alkyl Complexes of Ruthenium OctaethylporphyrinThe relevance of organometallic porphryin chemistry to certain aspects of thechemistry of cytochrome P450’ and vitamin B122 has prompted the study of numeroussynthetic models. Early studies focused primarily on iron and cobalt derivatives as theseare the metals found respectively in the biological systems; however, work has beenextended to include the related 4d and 5d metalloporphyrins (Ru, Os, Rh, Ir) as well ascomplexes involving group 4, 6, 10, 12, 13 and 14 metals.3Although the first ruthenium porphyrin was synthesized in 1 969, it was not until the1 980s that the major synthetic hurdles towards the synthesis of organometallic species hadbeen overcome (see chapter 1). Research has since gained momentum and the number ofc- and it- bonded species observed or isolated continues to grow. Today, two generalmethods for preparing alkyl- and aryl-ruthenium porphyrin complexes have beendeveloped: reaction of electrophiles with Ru(0) or Ru(I) precursors,5and treatment of the[Ru(porp)]2(BF4)5b,c,6 and Ru(porp)X2(X halogen)7complexes with Grignard ororganolithium reagents. Because the dihalo complexes were first prepared in theselaboratories, they were the reagents of choice in this work, and they do offer the addedconvenience of air-stability. Reaction 4.1 lists the complexes that had been synthesized inthese laboratories at the outset of this thesis work. As shown, the only dialkyl120Ru(porp)X2+ xs MgXR (or RLi) Ru(porp)R2+ Ru(porp)RXC1, Brporp = OEPR Me, Et, C6H5p -Me-C6H4,m-Me-C6H4,p -MeO-C6H4,p -F-C6H4porp = TPPR=C6H5 4.1derivatives known at the time were Ru(OEP)Me2and Ru(OEP)Et2,both being less stablethan the phenyl derivatives with the latter decomposing rapidly at room temperature togive the five-coordinate Ru(OEP)Et species.67b Thus, one of the goals of this work wasto synthesize and characterize a number of these dialkyl species by applying a number ofalkyl-Grignard and -lithium reagents to reaction 4.1. However, as will be seen, the strongreducing abilities of these reagents, coupled with the intrinsic instability of the Ru-alkylbond (in dialkyl complexes), made this aim difficult and the only products isolated fromthese reactions were the 5-coordinate Ru(III) derivatives.The original method for preparing these complexes involved the addition of excessGrignard (or organolithium) reagent to the Ru(porp)X2precursor under anaerobicconditions, followed by aerobic purification on a neutral alumina column.7’Thisprocedure routinely resulted in yields of approximately 30% of the dialkyl or diaryl specieslisted in reaction 4.1, and it was later discovered that when the purification was performedunder anaerobic conditions, most of the balance of the ruthenium porphyrin ( 50 %)could be isolated as the five-coordinate Ru(porp)R complexes. 7e(1 Prior to this, theseRu(ffl) species had been obtained initially by the thermally induced homolysis of a Ru-Rbond of the Ru(OEP)R2complexes.7b8Although this reaction may be syntheticallyredundant, the kinetic profile of this process allows for determination of the strength of the121Ru-R bond in question.67b8In fact, such an analysis is applied to the transientRu(OEP)Np2tspecies observed during the reaction ofRu(OEP)Cl2with neopentyllithiumdescribed below (section 4.1).It was the general practice during the application of reaction 4.1, to add a 5-foldexcess of the Grignard or organolithium reagent of interest. However, it became apparentduring the course of this thesis work that the products of this reaction depend heavily onthe molar ratio of the starting materials. In this chapter, this dependence as it applies toreactions with neopentyllithium (NpLi), bis(2-methyl-2-phenyl-propyl)magnesium(II)[(neophyl)2Mg] and benzylpotassium is examined. In the course of this study, three newspecies were isolated and characterized including a Li-bridged species which is uniqueamong metalloporphyrin systems.4.1 Reaction of Ru(OEP)X2with neopentyllithium (NpLi)Initial attempts to isolate Ru(OEP)Np2by applying the procedure outlined in theprevious work7’for the corresponding bis(aryl) and bis(methyl) species wereunsuccessful and therefore a series ofNIVIR experiments was carried out to examine thereaction more closely. In a typical experiment, 5-10 mg of Ru(OEP)X2was suspended in1.5-2 mL ofC6D while a second solution of the appropriate amount ofNpLi dissolved inC6D ( 0.5 mL) was also prepared. The NpLi solution was then slowly added to themetalloporphyrin solution with thorough mixing under anaerobic conditions. In selectedexperiments, one equivalent of anthracene was added at this point to act as a ‘Htp neopentyl anion122concentration reference. A portion of this solution was then sealed in an anaerobic NIvIRtube (see Figure 1.2) and the spectrum was obtained.. As previously mentioned, thereaction was dependent on the number of equivalents ofNpLi added with the productschanging considerably upon addition of 2, 3 and 4 equivalents, respectively.4.1.1 Reaction with two equivalents of neopentyllithiumTreatment of Ru(OEP)C12with 2 equivalents ofNpLi results in an immediate colourchange from brown to red-orange. Figure 4.1 shows the resulting NIVIR spectrum wheretwo distinct Ru(OEP) products are visible. The major paramagnetic product accounts forapproximately 72% of the Ru(OEP)C12added and was ultimately isolated and identified asRu(OEP)Np (see section 4.5.1). Several attempts were made to isolate the second minormetalloporphyrin species (formed as 21 % ofRu(OEP)C12added) using anaerobic aluminacolumns although all attempts were unsuccessful, even at -20°C. However, the NrvlRspectrum shows that this complex is undoubtedly Ru(OEP)Np2:it is a diamagnetic speciesof D4h symmetry as judged by the well resolved quartet appearing at 3.65 ppm for themethylene signals of the 8 porphyrin ethyl groups while the remaining porphyrin signalsappear at 9.76 (s, 4H, meso) and 1.77 ppm (t, 24H, CH3). The sharp singlet at -2.42 ppmintegrates for 18 protons and has therefore been assigned to the 6 axial neopentyl methylsignals while the 4 neopentyl methylene protons appear at -1.25 ppm. This latter peakappears immediately adjacent to one of the signals of Ru(OEP)Np and consequently anaccurate integration could not be obtained; however, the position123S-CH3aaL-F12— 2 Np-CH3J•11 I•10 8 6 4 2 0 —2PP14-4Figure 4-1: 1H NMR (C6D,300 MHz) spectrum of the products of the reactionof Ru(OEP)C12(7.2 mg, 5.8 mM after mixing) with two equivalents ofNpLi (1.6mg, 13.7 mM after mixing). S = solvent; 1 = Ru(OEP)Np; 2= anthracene (11p.mol); 3=2, 2, 5, 5-tetramethylhexane; 4= neopentyl chloride. Remaining peaksare assigned to Ru(OEP)Np.Hmo14 12124of this signal relative to that of the neopentyl methyl signals (i.e. downfield) is consistentwith those observed for the methylene and methyl signals of the axial ethyl groups ofRu(OEP)Et2(-2.74 ppm and -4.54 respectively).6’Th Clearly, the proximity of the highlyoxidized Ru(IV) center results in considerable deshielding of the ct-protons. In contrast,the relative positions of these two signals in a similar Ru(ll) species is reversed (seesection 4.5.4).Two major and one minor organic species can also be observed in the N1\4Rspectrum. The peaks at 0.89 and 1.17 ppm are due to the methyl and methylene protonsof 2, 2, 5, 5- tetramethyihexane, respectively, as indicated by GC/MS (see section 4.1.3),while the peaks at 0.78 and 2.98 ppm correspond to those observed for neopentyl chloridewhich is a precursor used in the preparation of the neopentyllithium reagent (see chapter2). The chloride was not present as an impurity in the NpLi (as judged by ‘H NMRspectroscopy), and is produced as a byproduct of the reaction ofNpLi with Ru(OEP)C12.These two organic coproducts respectively account for 6.4 and 10 % of the NpLi added.A small peak at 0.90 ppm (not visible in Figure 4-1 as it is obscured by the 2, 2, 5, 5-tetramethylhexane peak at 0.89) can be assigned to neopentane, most likely formed fromthe reaction ofNpLi with trace amounts of water in the system.Although this system does not lend itself to kinetic analysis, the mechanism almostcertainly involves neopentyl radicals, as the 2, 2, 5, 5-tetramethylhexane is the product ofthe coupling of two of these highly reactive intermediates (reaction 4.2). Radical1252NpCH3 CH3Np2= CHCH2CH3 CH3 4.2processes are not unprecedented in the chemistry of Grignard and organolithium reagentsas radicals are sometimes produced from outer-sphere reduction processes similar to thatshown in equation 4.3 for the present case.9 The exact fate of any Li[Ru(OEP)C12]Ru(OEP)C12+ NpLi LF’ [Ru(OEP)C12f+ Np• 4.3produced is not clear as the [Ru(OEP)C12fions have a lifetime estimated to be on theorder of minutes in CV experiments (see chapter 3). However, the decomposition of thisspecies might be greatly accelerated in the presence of the small lithium ion which couldfeasibly penetrate the inner coordination sphere of the Ru and allow direct attack on theRu-Cl bond (reaction 4.4).[Ru(OEP)C12]Li Ru(OEP)Cl + LiC1 4.4The stepwise metathesis process shown in equations 4.5 and 4.6 could also play arole in the chemistry; however, this only accounts for Ru(OEP)Np2and not for the otherRu(OEP)Cl2+ NpLi ‘ Ru(OEP)(Np)Cl + LiCl 4.5Ru(OEP)(Np)Cl + NpLi Ru(OEP)Np2+LiC1 4.6products. On the other hand, a series of reactions involving the the neopentyl radicaland/or Ru(OEP)Cl intermediates could provide a rationale for formation of all the126products. For example, direct attack of an axial chloro ligand of the dichloro complex byneopentyl radical would account for the neopentyl chloride (reaction 4.7). A metathesisreaction involving the monochloro species could then be invoked to explain the formationof the Ru(III) mononeopentyl species(reaction 4.8). As for the Ru(OEP)Np2product, theRu(OEP)C12+ Np’ Ru(OEP)Cl + NpCl 4.7Ru(OEP)C1 + NpLi ‘ Ru(OEP)Np + L1C1 4.8NMR. evidence suggests that radical attack of the mono(neopentyl) complex is primarilyresponsible for the production of this species (reaction 4.9), because Ru(OEP)Np is theRu(OEP)Np+ Np• Ru(OEP)Np2 4.9only metalloporphyrin product observed in the NMR spectrum when just one equivalentofNpLi is used. If the metathesis process was a major pathway, the ratio of the finalproducts would not be expected to change significantly and one would expect to see someRu(OEP)Np2formed. It therefore seems likely that the bis(neopentyl) species is producedonly when the concentration of Ru(OEP)Np builds to the point that reaction 4.9 becomescompetitive with the other reactions involving the neopentyl radical. Although themetathesis process of reactions 4.5 and 4.6 can not be completely ruled out, the reducingability ofNpLi (i.e reaction 4,3) is probably more important in this synthetic chemistry.The above reactions (eq. 4.3-4.9) are by no means the only conceivable possibilities,but they appear to be the most obvious. Another scenario has also been developed whichmay act in lieu of, or in conjunction with, the above processes. The presentation of this ispostponed until the pertinent data are made available (see section 4.1.3).1274.1.2 Thermal decomposition of Ru(OEP)Np2After sitting for 2 days at room temperature, the Ru(OEP)Np2observed in Figure 4-1 disappeared and a new diamagnetic species identified as Ru(OEP)=CHC(CH3formed(see section 4.5.1). Integration reveals that the yield of the neopentylidene complexaccounts for approximately 50 % of the original Ru(OEP)Np2while the balance isconverted to Ru(OEP)Np. A change in the concentration of the organic species insolution was also noted. For example, there was a modest increase ( 11 %) in theconcentration of the 2, 2, 5, 5-tetramethylhexanes as judged by integration. Also, adistinct increase in the intensity of the neopentane peak found at 0.90 ppm was noted,although integration of this signal was not possible because of the proximity of the methylsignal of 2, 2, 5, 5-tetramethylhexane (0.89 ppm). The kinetic analysis for thedisappearance of the Ru(OEP)Np2(as monitored by 1H NMR spectroscopy) at severaltemperatures gave an excellent first-order dependence on the concentration ofRu(OEP)Np2(for 3 half-lives) as shown in Figure 4-2, where ln[Ru(OEP)Np2]varieslinearly with time; the slope of plot affording the experimental rate constant k accordingto the standard expression (ln[Ru(OEP)Np2]= kobst + ln[Ru(OEP)Np2]0)for first-orderreactions.The mechanism given in equations 4.10-4.12 is postulated for the decomposition ofRu(OEP)Np2. This is consistent with the reaction schemes proposed for the1285.002.50 Slope=-1.20E-04/sz2.001.501.000.500.00 I I I0 50 100 150 200 250 300Time (s)Figure 4-2: First-order plot for the thermal decomposition of Ru(OEP)Np2at38° C. *Ln Np-CH3= Ln (integration of the neopentyl methyl signal of theRu(OEP)Np2species, ö -2.42 ppm). Raw data in appendix B.k1Ru(OEP)Np2 Ru(OEP)Np + Np 4 10k1FLc.c(cH3)k iiRu(OEP)Np2+ Np• c::=KU=:: + C(CH3)4Np 4.11H. C(CH3) H. .C(CH3)ii k3 iicEJIZD UZ + 1/2 Np2Np 4.12— d[Ru(OEP)Np2]= k [Ru(OEP)Np2]I1÷k2[Ru(OEP)Np]—k1[Ru(OEP)Np]’4.13dt . 1[Ru(OEP)Np] +2[Ru(OEP)Np]129decomposition ofRu(OEP)Et26and Ru(OEP)Me2,Th’8both involving the rate-determininghomolysis of a Ru-R bond followed by hydrogen atom abstraction by the liberated radical.However, the corresponding rate law (equation 4.13) suggests that this mechanism is onlyconsistent with the observed kinetics (i.e. first-order) provided that the reaction of the freeneopentyl radical with Ru(OEP)Np2(reaction 4.11) is much faster than the reaction of thisradical with Ru(OEP)Np (the k4 process of reaction 4.10); that isk2[Ru(OEP)Np]>>k..1[Ru(OEP)Np)]. Further, reaction 4.12 must be faster than reaction 4.11 (i.e.3[Ru(OEP)(CHC(CH)Np]>k2[Ru(OEP)Np][Np ]). The fact that the initial[Ru(OEP)Np] is approximately 3-5 times the intitial [Ru(OEP)Np2]suggests that k2should be 100k4, in order for the reaction to appear first order for 3 half-lives. Underthis condition, the second term in brackets in equation 4.13 approaches unity, and thus therate expression is then reduced to the experimentally found first-order type,-d[Ru(OEP)Np2]=2k1[Ru(OEP)Np]where Lb = 2k1.The requirement that k2 500k4 presents some difficulty because the rate of therecombination process of reaction 4.10 is considered to be near difiuision controlled(i.e. k4 1 M1s’), 10 However, the observed first-order kinetics require that themaximum value of k..1 is M’s at the limit where the hydrogen abstraction reaction isdiffusion controlled (i.e. k2= M’s’). Therefore, the proposed mechanism may beconsidered to be somewhat tentative although it is difficult to imagine any other schemewhere the initial Ru-Np homolysis (equation 4.10) is not rate determining.Abstraction of the ct-hydrogen from the five-coordinate Ru(OEP)Np complex(reaction 4.14) was also considered because the concentration of this species remained130kRu(OEP)Np + Np• Ru(OEP)CHC(CH3)+ C(CH3)4 4.14significant throughout; however, reaction 4.14 was excluded as this would ultimatelyresult in a quantitative yield of the neopentylidene species, with no net change in theconcentration of Ru(OEP)Np. Similar arguments were invoked to exclude the analogousreaction from the mechanism for the decomposition of Ru(OEP)Et2.6Both electronic andsteno arguments can be invoked to explain the relative resistance of these five-coordinatespecies to hydrogen abstraction. For example, perhaps the Ru(III) center does notactivate the c- and/or (3-site(s) to the same extent as the Ru(IV) center of the dialkyls, andthus reaction 4.12 can not compete (i.e.k2>>k4). Also, the axial Ru-C bond distance inthe five-coordinate species is expected to be shorter and this might stenically hinder attackat the (1-position in these complexes. Although these bond lengths are unknown fordialkyl systems, the Ru-C bond is a full 0.09 1 A longer in Ru(OEP)Ph2than inRu(OEP)Ph (2.096 and 2.005 A, respectively).tm’8Table 4-1 lists the rate constants (k2= lç,i/2) measured at temperatures ranging from22 to 450 C, and the Eyring plot of the data (ln k1/T vs. l/T) is shown in Figure 4-3. Thisplot yields values of 16 ± 2 kcal mol’and -27 ± 9 e.u. for i.H1 and respectively.Given that the homolysis reaction 4.10 is rate-determining, the AH1 obtained in thisway represents the upper limit of the bond dissociation energy of the Ru-Np bond(BDERU..NP),1°because the BDERU..N is given by the difference between the activation131Table 4-1: Rate constants for the decomposition ofRu(OEP)Np2’at varioustemperatures.Initial Temperature L x i05 (s1) k2 x io (s1)[Ru(OEP)Np2]1’ (K)(mM)0.45 295.8 2.76 1.381.4 300.6 4.95 2.470.22 306.1 7.75 3.871.4 311.3 12.0 6.001.2 318.3 20.4 10.2a) This species was generated in situ by the reaction of Ru(OEP)C12withapproximately 2 equivalents ofNpLi. b) Initial concentrations of Ru(OEP)Np wereestimated as a fraction of the Ru(OEP)C12based on the ratio of Ru(OEP)Np2to totalruthenium products (i.e. Ru(OEP)Np/(Ru(OEP) + Ru(OEP)Np)} as determined byintegration. Raw data in appendix B..148-I2-I6444-168Figure 4-3: Eyring plot for the decomposition ofRu(OEP)Np2.Sqe=-7aBKIrtart=993QB1 B15Vf(1)132enthalpies of the forward (homolysis) and reverse (recombination) processes ofequilibrium 4.10 (i.e. H1 -t.H-i). This relationship is illustrated in Figure 4-4.Ru(OEP)Np + NpAH0=BDEFigure 4-4: Reaction profile for the decomposition of Ru(OEP)Np2,showing therelationship between the bond dissociation energy (BDE) and the enthalpies ofactivation (z\H).Although the activation enthalpy for the reaction between the two radicals (AFL1)isunknown, it is assumed to be small relative to \H1 and, in the extreme case where= 0 kcal moF’, z\H, would equal BDERU..NP. Hence, this parameter is consideredto be the upper limit of the BDERU..NP. In practice, LH.1 is usually approximated at 2kcal mol’ as this is the activation enthalpy of diffusion controlled reactions (i.e k..1=1 M’s’), such as the combination of radicals.’° With this assumption, the BDERU..NPis approximately 14 kcal mor’. In fact, this value is probably an over estimate of theBDERU..Np as the kinetic data require that the maximum value of lci is M1&’AH1tRu(OEP)Np2133which translates into a AH, of approximately 5 kcal mol4.t By these arguments, theupper limit of BDERUNP is estimated as 11 kcal mof’.The Ru(OEP)Et2is the only other Ru(OEP)(alkyl)2system to which this analysishas been applied, and in this case, the Ru-Et bond was found to be 8-11 kcal mof’stronger (BDERU..Et =21.7 kcal mof’)6 than the Ru-Np measured bond strength. Thisseems reasonable considering that the Co-Np bond was the weakest within a series ofRCo(saloph)pytt complexes” with bond strengths ranging from 18 to 25 kcal mof’.The authors attributed the weakness of the Co-Np bond to steric effects which areundoubtedly involved in the Ru system as well; steric interaction between theneopentyl ligand and the porphyrin causes considerable bending of the Ru-C bond inRu(OEP)Np (see section 4.5.3), although the expected longer bonds of thebis(neopentyl) complex probably reduce this stress somewhat. Probably of greaterimportance is the trans effect of the second neopentyl ligand. When the trans positionis vacant as in Ru(OEP)Np, no cleavage of the Ru-alkyl bond occurs in thetemperature range studied (22 -44° C) showing that the Ru-Np bond is much strongerin the absence of the trans axial ligand, in spite of the steric factor. The same transeffect was cited in the case of the Ru(OEP)Et2complex,6and Ru(OEP)Ph2where theBDERU.Th was measured at 29.6 kcal mofl.ThSThe value of AH1 was calculated for k iO7 M’&1 using transition state theory, given that zSH.1 = 2 kcals mol’when k1 = M1s’.’° As a first approximation, this calculation assumes that the change in rate is influenced onlyby changes inSaloph = N, N’-bis(salicylidene)-o-phenylenediamine1344.1.3 Reaction with three equivalents of neopentyllithiumThe reaction of Ru(OEP)C12with 3 equivalents ofNpLi results in the immediate andquantitative production of a single Ru(OEP) species as judged by 1H NMR (Figure 4-5).This was isolated and identified as [Ru(OEP)Np]2(p-Li) (see section 4.5.4). In thisspecies the two lithium atoms are sandwiched between the two metalloporphyrin moieties.Although this type of bridging structure has been observed in a number of aromaticorganic systems,’2it is unprecedented in metalloporphyrin chemistry. Again, traces ofneopentyl chloride and 2, 2, 5, 5-tetramethylhexane are observed as organic productshinting at the production of neopentyl radicals during the course of this reaction.As demonstrated in section 4.1.1, that Ru(OEP)Np and Ru(OEP)Np2are produceddirectly by the reaction of Ru(OEP)Cl2with 2 equivalents ofNpLi, the lithium-bridgeddimer might result from the reaction of the mono- and bis(neopentyl) species with NpLi.In fact, treatment of Ru(OEP)Np with one equivalent ofNpLi affords the[Ru(OEP)Np]2(t-Li) product in quantitative yield as shown below (reaction 4.15). The2Ru(OEP)Np + 2NpLi [Ru(OEP)Np]2Li+ Np2t 4.15only organic product is the 2, 2, 5, 5-tetramethyihexane, which was isolated andsubsequently identified from a reaction using 12.2 mg of Ru(OEP)Np and 1.4 NpLi. Thiswas accomplished by separating the organic fraction (including solvent) on thetNp2 =2, 2, 5, 5-tetramethythexane135SI IIIIIIII1II iil I0 8 6 4 2 0 —2 —4 -5 PPM -8Figure 4-5: 1H NMR spectrum (300 MHz) of the products of the reaction ofRu(OEP)C12 (2.1 mM after mixing) with 3 equivalents ofNpLi (4.2 mM aftermixing). S= solvent; 1 = [Ru(OEP)Np]2(p.-Li) (see Figure 4-19, (p 167) or Table 4-2, (p.179) for peak assignments); 2 = 2, 2, 5, 5-tetramethyihexane; 3 = anthracene(4.7 mM).-a-136vacuum line and analyzing by GC/MS, the 2, 2, 5, 5-tetramethylhexane beingcharacterized by the parent peak at 142 m/e. Although the mechanistic details of reaction4.14 are not known, this reaction probably begins with the outer-sphere reduction of theRu(OEP)Np species by NpLi (reaction 4.16) in a process analogous to the reduction ofRu(OEP)Np + NpLi ‘ [Ru(OEP)Np]Li + Np• 4.16Ru(OEP)Cl2(reaction 4.3). which also accounts for the production of neopentyl radicals.A coupling of two [Ru(OEP)Np]Li moieties would then produce the final product(reaction 4.17).2[Ru(OEP)NpJLi [Ru(OEP)Np]2Li 4.17The intermediacy ofRu(OEP)Np2in the reaction ofRu(OEP)C12with 3NpLi isalmost certain as the reaction of Ru(OEP)Np with Npis still considered to be rapid.Obtaining the lithium-bridged dimer from this species necessitates outer-sphere reductionfollowed by homolysis of one Ru-Np bond as shown in reactions 4.18 and 4.19.Ru(OEP)Np2+ NpLi [Ru(OEP)Np2JLi+ Np• 4.18[Ru(OEP)Np2]Li [Ru(OEP)Np]Li + Np• 4.19Although the Ru(IV)fRu(III) reduction potential ofRu(OEP)Np2is unknown, it isprobably similar to that measured for the closely related Ru(OEP)Me2species (-1.39 V vs.AgIAgCl). 13 This means that the oxidation potential for NpLi would have to be greaterthan 1.39 V in order for reaction 4.18 to be thermodynamically favourable. In the eventthat Ru(OEP)Np2is reduced, the decomposition of the resulting [Ru(OEP)Np2fanion137according to reaction 4.18 is almost certain as the corresponding [Ru(OEP)Me2fspeciesdecomposes to [Ru(OEP)Mef and Me• within 500 j.ts, as determined by fast scan cyclicvoltammetry.13The lithium-bridged dimer is also quantitatively produced from the reaction of[Ru(OEP)12with two equivalents ofNpLi with no organic co-products (reaction 4.20).[Ru(OEP)]2+ 2NpLi [Ru(OEP)Np]2Li 4.20Although an oxidized form of the [Ru(OEP)]2dimer has been utilized for formation ofmetal alky1s,5’6this is the first case that a cs-bonded organometallic species has beenprepared from the reaction of an organolithium reagent with the neutral dimer species.With the discovery of this chemistry (eqs. 4.15 and 4.20) came new ideas about thepossible course of the reaction of NpLi with the dichioro species. The [Ru(OEP)]2speciesor perhaps its monomeric associate Ru(OEP) could play a significant role in the overallprocess as the latter species would most likely result from the reduction of Ru(OEP)C12by2 equivalents ofNpLi.In section 4.1.1, it was proposed that the overall reaction was initiated (at least inpart) by the outer-sphere reduction of Ru(OEP)C12by NpLi to yield [Ru(OEP)Cl2]Li(reaction 4.3). Heterolytic cleavage of one of the Ru-Cl bonds of this product could thengenerate Ru(OEP)Cl (reaction 4.4) which would ultimately lead to Ru(OEP)Np. That therate of such a reaction would be consistent with the rates observed here, however, isunclear as the [Ru(OEP)Cl2fanion was shown to have a lifetime on the order of minutesin CV experiments (see chapter 3). As the reducing strength of the NpLi is great enough138to effect a Ru(III)/Ru(II) reduction (eq.4. 15), another scenario is now proposed.Further reduction of [Ru(OEP)C12]Liwith a second equivalent of NpLi could generatethe bare Ru(OEP) monomer according to reactions 4.21 and 4.22 below. This[Ru(OEP)C12]Li+ NpLi [Ru(OEP)C12]Li+ Np• 4.21[Ru(OEP)C12]Li ‘ [Ru(OEP)] + 2LiC1 4.22reduction is at least as likely as the reduction of Ru(OEP)Np2proposed above(reaction 4.18) as the reduction potential of [Ru(OEP)C12is approximately -0.82 V(vs. AgIAgCl, see chapter 3). Furthermore, the [Ru(OEP)C12JLiproduct of thisreaction is expected to break down rapidly in accordance with reaction 4.22 as theanalogous anion produced electrochemically vanished within at most a second duringCV scans (see chapter 3). Once formed, the highly reactive bare Ru(OEP) product ofreaction 4.22 might then be expected to react rapidly with the excess NpLi to form[Ru(OEP)Np]Li and ultimately [Ru(OEP)Np]2(.t-Li) (reactions 4.17).Reactions 4.21 and 4.22 might also be involved in the mechanism of the reactionof Ru(OEP)C12with 2 equivalents of NpLi (section 4.1.1) as the attack of neopentylradicals on the highly reactive Ru(OEP) intermediate would yield Ru(OEP)Np. Sucha reaction is expected to be extremely rapid as the reaction rate of the Fe(OEP)analogue with alkyl radicals approaches diffusion-control.141394.1.4 Reaction with 4 equivalents of neopentyllithiumTwo distinct metalloporphyrin species are visible in the NMR spectrum uponreaction of Ru(OEP)C12with 4 equivalents of NpLi (Figure 4-6). One product isclearly [Ru(OEP)Np](.t-Li) (see section 4.5.4) which is produced along with asecond diamagnetic species. This new species is composed of 2 neopentyl groups perRu(OEP) moiety (as judged by integration) symmetrically positioned on each face ofthe porphyrin, as judged by the quartet centered at 3.55 ppm for the porphyrin methylsignals. Furthermore, the species seems to be a Ru(II) complex judging from therelative positions of the ct- and y- protons signals (-1.64 and -7.21 ppm, respectively)of the neopentyl ligand (cf. Figure 4-5) (note, the relative positions of these two peaksare reversed in the Ru(IV) bis(neopentyl) complex (Figure 4-1)). These observationslead to the conclusion that this new species is “Ru(OEP)Np2Li”;however, thesimultaneously coordination of both neopentyl ligands to the ruthenium metal seemsunlikely. As previously mentioned (see section 4.1.3), the one-electron reduction ofRu(OEP)Me2species (both chemically and electrochemically) results in the rapidcleavage (500 l.ts) of one Ru-alkyl bond to give the Ru(II) mono alkyl anion[Ru(OEP)Mef,13and that a Ru(II) complex could sustain both Ru-Np bonds seemsunlikely. The structure shown in Figure 4-7 is thus tentatively proposed to account forthe nature of”Ru(OEP)Np2Li.1401-CM3ZrNp-CM3__ _________ __LNP-CH2I IIIIIIII IIIIIIIIIIIlIII1IIIIIIIIIIIIIIIItII I IIIIIIIJIIIIII!IIj1JI IJIlI 11111 hIhhhhlThIjIIu 10 6 4 2 0 -2 -4 -6 -e PPMFigure 4-6: ‘H NMR spectrum (300 MHz) of the products of the reaction ofRu(OEP)C12 (5.1 mg, 4.8 mM after mixing) with 4 equivalents of neopentyllithium(2.2 mg, 19 mM after mixing). 1 = [Ru(OEP)Np]2(ji.-Li);2=2, 2, 5, 5-tetramethyihexane. Remaining peaks are assigned to Ru(OEP)NpLi.2141LiRuI.iNpFigure 4-7: Proposed structure for the co-product of the reaction ofRu(OEP)C12with four equivalents of NpLi.Such a proposal could also explain the relatively broad signal observed for the neopentylmethylene protons at -7.21 ppm as the proximity of the quadrupolar lithium atom wouldincrease the relaxation rate and thus broaden the signal. A similar broad signal wasobserved for these protons in the 1H NMR spectrum of free neopentyllithium.The formation of this “Ru(OEP)Np2Li”species competes with the formation of[Ru(OEP)Np]2(p-Li),as opposed to being the result of any further reaction of the dimericspecies with NpLi, because only a trace of”Ru(OEP)Np2Liwas observed in the NMRspectrum when [Ru(OEP)Np}2(j.i-Li) was treated with I equivalent ofNpLi. On theother hand, the reaction of Ru(OEP)Np with 2 equivalents ofNpLi afforded both productsin an approximate 1:1 ratio, as did the reaction of [Ru(OEP)]2with 4 equivalents ofNpLi.It therefore seems possible that the excess NpLi reacts with the [Ru(OEP)Np]Li (reaction4.23) produced in reaction 4.19 at a rate that is competitive with the coupling process ofreaction 4.17.[Ru(OEP)Np]Li + NpLi “Ru(OEP)Np2Li” 4.231424.2 Reaction of Ru(OEP)CI(NH3)with neopentyllithiumFigure 4-8 shows the 1H NIVIR spectrum of the products of the reaction ofRu(OEP)Cl(NH3)with one equivalent ofNpLi where two major metalloporphyrin speciesare observed in approximately equal yield after 1 h reaction time: the paramagneticRu(OEP)Np (24% of the original Ru(OEP)Cl(NH3)and a new diamagnetic species(26%). The spectrum of the latter species displayed peaks identical to those observedwhen a C6D solution of [Ru(OEP)]2was sealed under NH3 gas (Figure 4-9) and wastherefore assigned as Ru(OEP)(NH3)2.The third minor ruthenium porphyrin speciesproduced in approximately 6 % yield was [Ru(OEP)]2as judged by the distinct NIVIRspectrum of this species (ö(ppm), 22° C, C6D: 10.2 (s) Fl0; 25.9(m), 11.1(m) - CH2-;3.41 (t), -CH3). The combined yield of these three species only accounts for 60 % of theinitial Ru(OEP)Cl(NH and, there appears to a set of multiplets present beneath themethylene signal ofRu(OEP)(NH3)2at 3.90 ppm which is likely due to a fourthuncharacterized Ru(OEP) species, although the remaining peaks for this species were notapparent. The 2, 2, 5, 5-tetramethylhexane (6.3%) and neopentyl chloride species(13 %)are also present in this spectrum.In an analogous reaction, Ke had noted that equal proportions of Ru(OEP)Me2andRu(OEP)(P11Bu3)2were rapidly generated upon treatment of Ru(OEP)Br(PBu3)withMeLi.Th This reaction was considered to occur via two steps involving nucleophihicsubstitution followed by the disproportionation of the mixed methyl(phosphine)Ru(III)intermediate (reactions 4.24 and 4.25). The first step is the simple metathesis reaction1433IIPflhIIIIIIIIIIII,III282624i—iI•114121086420—2—4—6—8PPI.4Figure4-8:‘HNMRspectrum(C6D,300MHz)oftheproductsof thereactionof Ru(OEP)Cl(NH3)(9.5 mg,5.5mMaftermixing)withoneequivalentof NpLi(1.1mg,5.5mMaftermixing).S=solvent;1=Ru(OEP)Np;2=Ru(OEP)(NH3)2;3=[Ru(OEP)]2;4=2,2,5,5-tetramethyihexane;5=neopentylchloride;6=anthracene(5.8 mM)SI0))(.,-0)I;;;;)In I!,a,2I,)0)o.0)461632144-CH2-CH3- oHmeNH31IIIIIIIIIIIIIIIIIIIIIIIIIrIJ11tJTTIIIIIIIIIIIIIIIIIIIIIIIIIII1086420—2—4—6—8PPMFigure4-9:‘HNMRspectrum(300 MHz)of Ru(OEP)(NH3)2producedinsitubythereactionof [Ru(OEP)]2withanhydrousNH3.Ssolvent,1=freeNH3..145N 0 0Ru(OEP)Br(PnBu3)+ MeLi ‘ Ru(OEP)Me(P”Bu3)+ LiBr 4.24Ru(OEP)Me(P’Bu3) Ru(OEP)Me + Ru(OEP)(PnBu3)2 4.25while the disproportionation of reaction 4.25 was independently demonstrated by treatingRu(OEP)Me with PnBu3.Th A similar scheme was considered for the reaction ofRu(OEP)Cl(NH3)with NpLi; however, the experimental evidence tends to rule this out.For example, the analogues of reactions 4.24 and 4.25 would not account for theformation of the organic products which again suggest the involvement of neopentylradicals. Also, no Ru(OEP)Np2was produced which is the expected coproduct from thedisproportionation of Ru(OEP)Np(NH3).Furthermore, the Ru(OEP)Np(NH3)species isstable (at least in the presence of excess NH3) as shown by the 1H NMR spectrum ofRu(OEP)Np in C6D sealed under anhydrous NH3 (Figure 4-10): there is clearly only oneRu(III) species in solution which is new and must be Ru(OEP)Np(NH3),which wasrelatively stable, traces ofRu(OEP)(NH3)2appearing only after one month. Whether theRu(OEP)Np(NH3)solution species undergoes disproportionation in the absence of excessNH3 is unknown.The Ru(OEP)Cl(NH3)CIINpLi reaction is likely initiated by an outer-spherereduction (reaction 4.26), perhaps involving rapid decomposition of the putativeRu(OEP)Cl(NH3)+ NpLi Ru(OEP)(NH3)+ LiC1 + Np 4.26[Ru(OEP)Cl(NH3)JLiintermediate; this is not certain, however, as the anion generated146S-CH3-CH- -CH2b-Np-CH3I4 i2 10 8 4 2 0 —2PP!4—4p.’ LII10.3 11.0 37.7 I1.0Figure 4-10: 1H NMR spectrum (300 MHz) ofRu(OEP)Np(NH3produced insitu by the reaction of Ru(OEP)Np with anhydrous NH3. S = solvent; 1 = free NH3.147during cyclic voltammetry ofRu(OEP)Cl(NH3)had a lifetime on the order of minutes asdemonstrated by the reversibility of the reduction at scan rates as slow as 20 mV/s (seechapter 3). Nevertheless, it is difficult to imagine a different fate for this[Ru(OEP)Cl(N}13)fspecies as there is no indication that a second reduction (i.e. Ru(II) toRu(I) ) can be effected by the NpLi. The same discussion was presented earlierconcerning the fate of the proposed [Ru(OEP)C12]Lispecies (reaction 4.4).It is not difficult to imagine a series of simple bimolecular reactions involving theunsaturated Ru(II) species and the neopentyl radical to account for the products, forexample, reactions 4.27 to 4.31 below.Ru(OEP)(NH3) Ru(OEP) + NH3 4.27Ru(OEP)(NH3)+ NH3 . Ru(OEP)(NH3)2 4.282Ru(OEP) ‘ [Ru(OEP)]2 4.29Ru(OEP)(NH3)Cl+ Np• Ru(OEP)(NH3)+ NpC1 4.30Ru(OEP) + Np• Ru(OEP)Np 4.314.3 Reaction of Ru(OEP)C12with (neophyl)2MgThe purity of the (neophyl)2Mgprepared in this work was suspect, and therefore aseries of in situ experiments, where the ratio of the starting materials was varied (i.e.Ru(OEP)C12:(neophyl)Mg ,was difficult to interpret. The only conclusion that could bedrawn from these studies was that the yield of the Ru(OEP)(neophyl) product decreased148as the relative amount of (neophyl)2Mgwas increasd as judged by the loss of the distinctpeaks of this Ru(III) species (see section 4.5.2) leaving only diamagnetic products. Thissuggests that (neophyl)2Mgmight also act as a reducing agent, reducing any Ru(III)products to Ru(II) species in a manner similar to the NpLi.4.4 Reaction of Ru(OEP)C12with benzylpotassiumAn attempt to prepare Ru(OEP)(CH26H5and/or Ru(OEP)(CH2C6H5)by reactingRu(OEP)C12(57 mg, 80 i.imol) with approximately 2 equivalents of benzylpotassium (23mg, 177 .tmol) proved unsuccessful, Benzene suspensions of the two reagents weremixed together in the glove-box and then allowed to react for 1/2 an hour at RT. Thereaction solution was then charged onto an anaerobic alumina column which wassuccessively eluted with deoxygenated toluene, chloroform and methylene chloride;however, no metalloporphyrin species could be isolated.In an attempt to understand the reasons for the synthetic failure, a suspension of 2equivalents of benzylpotassium (2.9 mg (22 j.tmol) in 0.5 mL ofC6D,)was added to andthoroughly mixed with, a suspension of Ru(OEP)C12(7.6 mg (10.8 p.mol) in 1.0 mL ofC(,D6). The mixture was then sealed in an NMR tube under nitrogen and the reaction wasfollowed by NMR. Figure 4-ha shows the spectrum taken after 30 minutes; twoproducts are visible, one diamagnetic complex of D4h symmetry (ö (ppm): OEP 9.65(s),Hmeso; 3.78(q), CH2; 1.85(t), CH3; probable benzyl peaks -0.82(s) CH2; 3.10(d), o-H;5.62(t), rn-H; 6.0(t), p-H), and a second paramagnetic Ru(III) species (6(ppm): OEP12.24, 6.78, CH2; 0.35, H0;-1.65, CH3; probable benzyl peaks 15.52). The products149S________________1iiLJLIIII11111111111iiiill1IIIITIIII1111111111IllillIfliii11111111I,,i,ifjiiI’IJIII!IIIFVJ1614121086420—2PPM—4Figure4-1la:1HNMRspectrum(300MHz)oftheproductsof reactionofRu(OEP)C12(7.2mMaftermixing)with2equivalentofbenzylpotassiumafter30mm.s=solvent;1=Ru(OEP)(CH2C6H5)?;2=Ru(OEP)(CH2C6H5)?(tentativeassignmentsarelistedinTable4-2,p.179).150CH3Bz-CH2?HmesoCf’CH2bI ‘ I I I I j I I I I I I I I I I I I 1 I10 8 4 2PPM 0Figure 4-1 ib: ‘H NMR spectrum (300 MHz) of the products of reaction of Ru(OEP)C12(7.2 mM after mixing) with 2 equivalent ofben.zylpotassium after 3 months.151are presumably the target complexes (i.e. Ru(OEP)(CH2C6H5)and Ru(OEP)(CH2C6H5));however, these species account for only a small fraction of the starting material as therewas still a significant amount of unreacted benzylpotassium as judged by the distinctorange colour of the undissolved material in the NMR tube.After 24 hours, the diamagnetic species (tentatively Ru(OEP)(CH2C6H5)disappeared leaving the paramagnetic species (tentatively Ru(OEP)(CH) and[Ru(OEP)]2(with Ru(OEP)(CH2C6H5):[Ru(OEP)] 2) and a significant amount ofundissolved (benzyl)K. Both the dimer and the paramagnetic species graduallydisappeared over a period of 2-3 months leaving one major diamagnetic species insolution. This species appears to be dimeric judging from the well resolved set ofmultiplets (centered at 3.98 and 4.35 ppm) for the porphyrin methylene signals (see Figure4-1 lb). 7b,15,16 The remainder of the OEP protons are observed at their characteristicchemical shifts positions (ö(ppm): 9.3 8(s), Hmeso; 1.859(t), CH3), while the small signal at-9.42 ppm could be characteristic of the methylene signal of coordinated benzyl ligandalthough the corresponding aryl signals are not located. Given the results of the reactionwith NpLi, this species could be analogous to the lithium-bridged dimer, i.e.[Ru(OEP)(CH2C6H5)](j.i-K) However, this is considered unlikely for two reasons.First, the meso peak is found at 9.38 ppm which is somewhat downfield of the shiftsobserved for other [Ru(OEP)R] anions (see section 4.5.4); and secondly, the species wasnot observed when Ru(OEP)Cl2was reacted with 3 equivalents of benzylpotassium, when[Ru(OEP)]2was the only apparent Ru(OEP) species in solution for the 3 months thereaction was monitored. The identity of the supposed dimer remains to be established.152Although the synthesis of the benzyl species was not pursued, the NMR studies suggestthat in any future attempts, a minimum reaction time of 24 hours is needed to form fullythe paramagnetic intermediate, while 2 to 3 months are needed to produce the diamagneticdimer. In any case, the formation of [Ru(OEP)]2in these experiments shows that thereducing ability of benzylpotassium plays an important role in this chemistry.4.5 Characterization of isolated complexes4.5.1 Preparation and isolation of Ru(OEP)CHC(CH3),Ru(OEP)Np andRu(OEP)(neophyl)As described in section 4.1.1, the reaction of Ru(OEP)Cl2with two equivalents ofNpLi yields a mixture of Ru(OEP)Np and Ru(OEP)Np2.The latter product decomposesin solution over a period of 2 d at RT, to give a 50:50 mixture ofRu(OEP)Np andRu(OEP)CHC(CH3),which can be partially separated on an anaerobic alumina column,although the conditions for complete separation have not been worked out. A system ofneutral alumina (activity 1) with deoxygenated toluene as the eluant was first attempted;however, this was abandoned after 1 h as very little movement of the porphyrin productswas detected. Addition of benzene at this point did result in the movement of both specieswith the neopentylidene having the longer retention time. However, both products had atendency to “spread out” as they moved down the column and complete separation of thetwo species could not be achieved. The first red material collected from the column underthese conditions was pure Ru(OEP)Np, although this had to be collected in fractionsbecause eventually a mixture of both species eluted from the column. After 2-3 h, the153eluant took on a rose colour which was due to the presence of mostlyRu(OEP)CHC(CH3),as judged by NIVIR spectroscopy (see Figure 4-12); nevertheless, asignificant amount of a rose-coloured material (which may or may not be theneopentylidene complex) could not be removed from the column even after elution for 12h with ‘PrOHlbenzene (2 % v/v). Clearly the conditions were not ideal for separatingthese two complexes as only a trace amount of Ru(OEP)CHC(CH3)could be isolated.Future attempts using combinations of different solvents with perhaps differentchromatographic matrices seem warranted.Although the reaction of Ru(OEP)C12with 2 equivalents ofNpLi yieldedRu(OEP)Np in excess of 80% as determined in the NMR experiments, the separationprocedure described above was cumbersome and only about 30 % of this material couldbe isolated. The preferred synthesis involved the reaction of the dichioro species with 3equivalents ofNpLi, when the only material isolated from the column (neutral alumina andbenzene) was Ru(OEP)Np in approximately the same 30% yield. The isolation of thisspecies might seem surprising as the N1VIR studies clearly show that the sole product ofthis reaction was [Ru(OEP)Np]2(i-Li) (section 4.1.3). However, it was laterdemonstrated (section 4.6.2) that the mononeopentyl species results from the reaction ofthis u-Li dimer with H20.The degree of purity of the (neophyl)2Mgreagent used in this work was uncertain;however, the yield of Ru(OEP)(neophyl) was maximized when the supposed ratio of(neophyl)2Mgto Ru(OEP)Cl2was 1.5 in in situ NMR experiments. Therefore, this was154the ratio of reagents used in the synthesis work, where the Ru(OEP)(neophyl) was isolatedin 18 % yield (see chapter 2 for details).4.5.2 Spectral characteristicsFigure 4-12 shows the NMR spectrum of a trace amount of Ru(OEP)CHC(CH3)isolated as described above. The multiplet centered at 3.9 ppm for the anisochronousporphyrin methylene protons reveals the magnetic inequivalence of the two faces of theporphyrin in this diamagnetic monomer. The meso signals appear as a singlet at 9.94 ppmand the porphyrin methyl signals appear as a triplet at 1.95 ppm. The nine methyl protonsof the axial neopentylidene give rise to the singlet at -2.10 ppm while the carbene proton isseen as a singlet at 12.35 ppm, this low field shift being characteristic of carbenecomplexes (typically 7.07 to 18.85 ppm);b for example, the analogous peak of the closelyrelated Ru(OEP)CHCH3appears at 13.03 ppm. 5a As well, metal-carbene carbonsnormally appear at relatively low fields in the 13C NMR spectra.’7 For example, theacetylene bridging ligand of [Ru(TMP)]2(p,-CH)was assigned a carbene structure (seechapter 1) based on the appearance of a signal at 264 ppm downfield from TMS in theNMR spectrum.’8 Unfortunately the analogous signal was not observed in thespectrum of the neopentylidene complex isolated here presumably because the sample wastoo dilute.Figure 4-13 and Figure 4-14 show the ‘H NMR spectra (C6D)of Ru(OEP)Np (at22° C) and Ru(OEP)(neophyl) (50 C), respectively. As discussed in chapter 3, thesespectra are characteristic of five-coordinate paramagnetic Ru(ffl) complexes. The ‘H155S-CH3=CH2(CCII3)Hmeia1J-=CHC(CH3)I-IIIjIITIIIIII1IIIII1iIIIIIIIIIIIIIIIIIIIIIIIIIIIJIIIIIIII(1II1JIIIIIIII12108420—2I’Pk4Figure4-12:‘HNMRspectrum(C(,D6,300MHz)ofRu(OEP)CHC(CFI3)isolatedfromthereactionofRu(OEP)C12with2equivalentsofneopentyllithium.156S-CFI3Np-CH3 -____[I I I I I I I I I I I I I II I I I I I I II liii I I I I I I I I I I I III I I I II I I II I I I I I I I I II I I I I II II I I14 12 10 8 4 2 QPPM —2Figure 4-13: ‘H NMR spectrum (CoD6,300 MHz) of Ru(OEP)Np (T=22° C).S = solvent.1570*SFigure 4-14: ‘H NMR spectrum (C6D,300 MHz) of Ru(OEP)(neophyl) (T50°C). S = solvent, o-, m-, p- respectively refer to the ortho-, meta- and para-signals(tentatively) of the axial neophyl ligand.-CH30--C(CH3)216 14 12 10 8 6 4 2 0 —2 PPM158NMR spectrum of Ru(OEP)Np is typical of a Ru(llI) octaethylporphyrinato complex ofC4 symmetry with broad signals spanning the region from -2 to 14 ppm. The porphyrinmethylene protons give rise to two broad signals (13.48 and 6.09 ppm), downfield fromtheir normal diamagnetic positions, while the porphyrin methyl and meso signals appearsomewhat upfield from their diamagnetic positions (-1.40 and 2.15 ppm, respectively).Integration of the signal at 5.78 ppm indicates 9 protons corresponding to the methylgroups of the axial neopentyl. As with Ru(OEP)MeTh’8and Ru(OEP)Et,6the cL-protons ofthe axial ligand are not visible, presumably because of their proximity to the paramagneticmetal center.When the NMR spectrum of Ru(OEP)(neophyl) is obtained at 22° C, thefrequencies of the porphyrin signals (ö (ppm), C6D:2.45 meso; 14.1, 6.0 -CH2; -1.1-CH3)are similar to those reported for the neopentyl analogue. At this temperature,however, the signals of the axial neophyl ligand are obscured by the overlapping porphyrinmethylene signals, and thus the spectrum was collected at 50° C (Figure 4-14), when 4 ofthe 5 different proton types of the axial neophyl signals are also visible. The signal at 5.1ppm integrates for 6 protons and is therefore assigned to the methyl protons, while thephenyl signals appear at 5.95, 6.5 and 12.9 ppm and are tentatively assigned thep-, m- and0-protons, respectively; the peak at 5.95 integrates for 1 proton while the signal at 12.9integrates for two (an accurate integration could not be obtained for the peak at 6.50ppm). The m- and 0-protons are assigned based on the assumption that the shift of thelatter proton (relative to its diamagnetic position, i.e 7 ppm) will be greater because it iscloser to the paramagnetic metal center. Again the cL-protons are not visible.159As discussed in chapter 3, the shift in signals of groups bonded to the pyrrole andmeso sites in paramagnetic metalloporphyrins (in relation to their diamagnetic positions) issometimes cited as evidence for the direction of charge transfer in these systems.20”However, as also noted in chapter 3, application of these arguments to Ru(III) systemsleads to contradictory conclusions. This is true also for the neopentyl and neophylsystems where, for example, the upfield shift in the meso signal indicates a metal toporphyrin charge transfer while the downfield shift of the methylene signals indicatestransfer of charge in the opposite direction. These predictions, based upon the molecularorbitals derived by iterative extend Huckel calculations, are clearly too simplistic for thesesystems.The effective magnetic moments of 2.4. and 2.2 B.M. (as determined by Evan’smethod’9)for the Ru(OEP)Np and Ru(OEP)(neophyl), respectively, are somewhat higherthan the spin-only value of 1.73 B.M. predicted for 1 unpaired electron, possibly indicatinga significant degree of spin-orbit coupling in these complexes. The Curie-type plots(Figure 4-15 and Figure 4-16) might be cited to support this conclusion as the interceptsfor the meso and methylene isotropic shifts differ significantly from the theoretical value ofzero. Of note, however, the Curie plots for both Ru(OEP)Ph and Ru(OEP)Me also givesignificant non-zero intercepts while the magnetic moments are much closer to theexpected spin only value (1.84 and 1.96 B.M., respectively).tm’8The source of this nonCurie behavior, which is commonly observed in paramagnetic metalloporphyrins,T’82°isunclear.160CH2CH2bCH312100. -2CC-8-100 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.004511f(K’)Figure 4-15: Isotropic chemical shifts (calculated relative to Ru(OEP)Np2)vs.lIT for Ru(OEP)(neopentyl) in CDCI3.1510E.—C -5-..C— -10-15neophyl-CH3CH2bCH30 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.0045111’ (IC’)Figure 4-16: Isotropic chemical shifts (calculated relative to Ru(OEP)Np2)vs.lIT for Ru(OEP)(neophyl) ind8toluene.t,Only the isotropic shifts of the porphyrin and the neophyl methyl signals are plotted.1614.5.3 Crystal structures of Ru(OEP)Np and Ru(OEP)(neophyl)The structure of Ru(OEP)Np (Figure 4-17) is approximately square pyramidalwith the Ru atom displaced 0.11 A out of the mean plane of the porphyrin toward theneopentyl ligand. This is similar to the displacement of 0.12 A reported forRu(OEP)Ph.Th’8All of the bond lengths and angles of the metalloporphyrin moiety andthe disorder observed for an ethyl group are consistent with previously reportedRu(OEP) structures.7a.s2oalThe axial neopentyl ligand is also disordered, exhibitingtwo orientations with the C(38) and the C(39) carbons being common to both. Thustwo Ru-C bond lengths (37 and 37a) are listed (2.069 and 2.12 A), both beingconsiderably longer than the 2.005 A reported for Ru(OEP)Ph.8 This is consistentwith the typically weaker Ru-C3 bond (vs. Ru-C2 bond),22 although steric effectslikely contribute to the elongation of this bond as a significant amount of stress isinduced by the interaction of the porphyrin ring with y-hydrogens of the neopentylligand. As such, the Ru-C(Np) bonds are, for example, longer than those ofhexakis(neopentyl)diruthenium(III) where there is no steric interaction (2.023-2.051A).23 Thus the minimum N-Ru-C(Np) bond angle in either conformation is reduced toconsiderably less than 900 (81.1 and 78.1 A) to alleviate this stress. Indeed, this stericinteraction causes considerable distortion in the neopentyl ligand itself where the RuC(37 and 37a)-C(38) bond angles (128.2 and 126.2°) are much larger than theexpected 109°.162C24cza C23C25C? Cs C3 C21CZCZ8A CZ?p C6 C4C8 HIC28 C4142 ciC3? C38 C4OAClO Rul C39C3? C40H3C30 C12 C41A44C14 CI 6C29C13CIS Cl? C35 C36C31C33C32 C34Figure 4-17: ORTEP diagram of Ru(OEP)Np; thermal ellipsiod 33%.163Distortions (but no disorder) are also apparent in the structure ofRu(OEP)(neophyl) (Figure 4-18) although these are “expressed” in different ways.For example in this square pyramidal complex the Ru atom is displaced by 0.20 A outof the mean plane of the porphyrin which is considerable more than the distances listedfor Ru(OEP)Np and Ru(OEP)Ph above. Furthermore, while the Ru-C(neophyl) bondlength is slightly shorter (2.053 A) than the Ru-C(Np) bond, the minimumN-Ru-C(neophyl) bond angle (85.6°) is considerably closer to 90° in this case. On theother hand, the Ru-C(37)-C(38) bond angle exhibits distortion (126.8°) similar to theanalogous angle in Ru(OEP)Np. The source of the steric effect is slightly different forthis species as the “offending” ‘y-methyl group (of Ru(OEP)Np) has been replaced by aphenyl ring which is parallel to the porphyrin ring. As such, there is no stericinteraction of this group with the porphyrin core. However, the phenyl ring clasheswith the methylene hydrogens of an OEP ethyl group thus producing the observeddistortions. Indeed, this effect can be seen in the neophyl phenyl group itselfwherethe C(43) and C(44) atoms are found -0.0134 and 0.0137 A out of the mean plane ofthe phenyl ring. In addition, the neophyl C(37)-C(38) bond is somewhat elongated(1 .513 A) and the C(3 7)-C(3 8)-C(4 1) bond angle is somewhat strained in this structure(116.4°).164C34Figure 4-18: ORTEP diagram of Ru(OEP)(neophyl); thermal ellipsoids 33%.C32C33C36C35C30ciec2ocioC39c28 CeC40C42C43C441654.5.4 Preparation and characterization of IRu(OEP)Np12(I.L-Li)Preparation of this complex is demanding in that it requires exact proportions ofanalytically pure starting materials as no clear method has been developed to separate thisspecies from the byproducts or impurities. There are three approaches to the preparation;1) reaction ofRu(OEP)C12with 3 equivalents ofNpLi, 2) reaction of Ru(OEP)Np with 1equivalent ofNpLi and 3) reaction of [Ru(OEP)]2with 2 equivalents ofNpLi. The lastmethod is the least labour intensive, and the analytically pure product can be isolated inapproximately 45 % yield (see chapter 2 for details).The complex, prior to the diffIaction study, was initially formulated as[Ru(OEP)Np]Li; however, the X-ray crystal structure (see section 4.5.5) clearlyestablished that this species has a dimeric structure with two Li atoms sandwichedbetween two staggered {Ru(OEP)Npf moieties.. Examination of the solution ‘H NMRspectrum of this material (Figure 4-19) indicates that this species maintains the sameconfiguration in solution, at least in benzene.Although more or less typical of a diamagnetic Ru(OEP) system ofC4, symmetry,the ‘H NMR of [Ru(OEP)Np]2(-Li)displays a number of distinct features. Forexample, the meso protons resonate at 8.00 ppm which is about 1 to 2 ppm upfleld of suchsignals in neutral Ru(OEP) systems, and this reveals the anionic nature of the[Ru(OEP)Npf moiety. The closely related [Ru(OEP)Ph]Na24and [Ru(OEP)Me]Na’3species similary display meso signals upfield of 9.00 ppm (8.96 and 8.55, respectively).The relative positions of the axial neopentyl signals are consistent with a Ru(II) rather166-CH3Figure4-19:‘HNMRspectrum(C6D,300MHz)of[Ru(OEP)Np]2(t-Li).Ssolvent.Np-CH3HesoCH2aNp-CH2i.iiii.uiiiiiiiiiiiriii.viui,,,II,Iii,i,iiI,,IlIlIlvIl1086420—2--4—6PPM—8167than a Ru(IV) system as the methylene signals (-7.45 ppm) are found at 5.2 ppm upfield ofthe methyl protons (-2.28 ppm)(with a Ru(IV) system, the relative positions are reversed).The dimeric nature of the solution structure is apparent in the extent of separationbetween the diastereotopic porphyrin methylene signals (3.53 and 3.37 ppm, multiplets at300 MHz). Separations of this magnitude have been reported only for dimeric systemssuch as [RuV1(OEP)]2and [Ru(OEP)L]2Q.t-O) (L= halide, hydroxy, alkoxy, phenyl),where the proximity of the two porphyrin rings results in sufficient shielding to resolvecompletely the anisotropic magnetic”56In contrast, these protons appearas a single multiplet in monomeric species such as [Ru(OEP)R]Na (R = Ph and Me)’3’24(3.7 and 3.6 ppm, respectively). The7Li{’H} NlvIR spectrum displays one broad singlet(-14.85 ppm vs. LiBr), shifted significantly upfield because of the porphyrin ring current,and is similar to that recently reported forLi2(THF)4OEP species.254.5.5 Crystal Structure of [Ru(OEP)Npj2(ji.-Li)The structure of [Ru(OEP)Np]2Q.t-Li) (Figure 4-20) reveals a centrosymmetricdimer in which two Ru(OEP)Np units are bridged via two lithium ions. Each Li issandwiched between two six membered rings on each metalloporphyrin moiety for a totalof twelve bonds. Among these, the Ru and N(4) atoms are common to both Li ions withthe C(19), C(20), C(1) and N(1) rounding out one ring while C(16), C(20), C(l) and N(3)complete the other. The net result of this is that the two metaliporphyrin units are stackedin a somewhat staggered rather than eclipsed manner. Although this interaction has no168C30 C29C32C3 1C12C13CIIC14 C28Cls LV N3C27C4 I-C16• C9 C8• C333’ N’ C38C7 C37C181/’1C26 3’ C6C25 C39•N4N C404L. 1C19LiC4C3ClC36 C3C2c C23C21C24C22Figure 4-20: ORTEP Diagram of [Ru(OEP)NpJ2(i,-Li);thermal ellipsoids33%.169dramatic effect on the metalloporphyrin core, the N(4) atom is displaced 0.165 A outof the mean plane of the metalloporphyrin towards the two Li ions, while the Ru atomsare pulled toward the porphyrin so that they now lie only 0.0135 A out of the meanplane of the porphyrin toward the neopentyl ligand. No disorder is found in theneopentyl ligand in this system, although the steric constraints discussed forRu(OEP)Np (section 4.5.3) are still evident as the Ru-C(37) distance is 2.100 A, theminimum N-Ru-C(37) angle is 79.75°, and the Ru-C(37)-C(38) angle is 124.2°.The Li-C bond distances (2.309- 2.408 A) lie well within the range of 2.26- 2.66A reported for it-bonded Li atoms in analogous sandwich compounds of aromatic andnonaromatic hydrocarbon residues.’2 On the other hand the Li-N bond distances(2.3 59- 2.44 1 A) are considerably longer than the 2.10-2-25 A reported for Li-Nbonds,12 reflecting the weaker nature of the Li-N it-bond. Recently, the structure ofNa2(THF)4OEP was reported25 where two Na(THF)2moieties were bonded to allfour nitrogens on each face of the porphyrin. The longer Na-N distance ranged from2.452-2.508 A which is consistent with the larger Na atoms. Finally, the Ru-Li bondsof [Ru(OEP)Np](j.t-Li) (2.777-2.83 7 A) fall at the higher end of the range of Litransition metal bonds (2.3 8-2.92 A) reported for a variety of mixed-metalorganolithium compounds.’21704.6 Reactivity of jRu(0EP)Np12(-Li)4.6.1 Reaction with 02The [Ru(OEP)NpJ2(.t-Li) species in solution is extremely sensitive to air reactingrapidly (within minutes) upon exposure to produce a mixture of [Ru(OEP)0H12(p-O)6and Ru(OEP)Np, as judged by NIVIR spectroscopy. Peaks due to the Ru(OEP)Npdisappear within an hour under normal fluorescent light, the complex presumablybecoming oxidized to the i-oxo dimer. These results contrast those obtainedpreviouslytm”6for the photo-induced air oxidation of the Ru(porp)Ar complexes (porp =OEP, Ar = Ph, m-MeC6H4p-MeC6H4,p-MeOC6H4,p-FC6H4;porp = TPP, Ar = Ph)which generated the corresponding [Ru(porp)Ar]2(p.-O) complexes where the axial Ru-Arbonds remain intact. The loss of the Np ligand in this case is presumably due to therelative weakness of the Ru-Np bond.Quite surprisingly, a j-oxo dimer was apparently also produced when[Ru(OEP)Np]2(p.-Li) was sealed in an NtVIR tube under dried 02. Figure 4-21a showsthe 1H NMR spectrum obtained within 5 minutes of exposure to 02, where 3 majordiamagnetic Ru(OEP) complexes are visible as judged by the 3 meso signals observedbetween 9.2 and 9.5 ppm. The two well resolved multiplets at 3.95 and 2.42 ppm for the171CH2a- .CH2frIL1Tlllll1TTTJllTl liii JhThTjhTTl1Tn-2 —4-e -ioFigure 4-21: ‘H NMR spectrum (C6D,300 MHz) of the products of thereaction of [Ru(OEP)NpJ(j.i-Li) with 02. Spectra were collected: a) within 5minutes; b) after 2 days. S = solvent.S-CH3meaoNp-CH3Np-Cl-I2lT1TTllflrITrllil.lTIliltTrr,,1rrr‘‘‘fIllIp’lTT I TI‘Trill lIj II 1r71 T111111111T jTI TIlII IITTI rh8 6 4 2 0172porphyrin methylene protons signify that the major product is a t-oxo dimer although theformation of such a species was unexpected under these conditions. This is because wateris necessary to effect the oxidation of [Ru(OEP)]2to the Il-oxo dimer2o and it wasassumed that water would play a role in this oxidation as well. The source of water (ifinvolved) is unclear as a significant effort was made to dry the apparatus and reagents (seechapter 2 for details for drying gases). At least one and perhaps both of the minorproducts have coordinated neopentyl, judging by the peak found at -3.85 ppm and the twopeaks found at -8.63 and -9.45 ppm which are presumably due to the neopentyl methyland methylene signals of two different species. The relative position of these signalsimplicate Ru(ll) rather than Ru(IV) (see section 4.5.4). The remaining porphyrin signalsof this/these species are shrouded by the signals of the major Ru(TV) p-oxo dimer product.In the spectrum taken after 2 days (Figure 4-21b), two of the three meso peaksobserved earlier have virtually disappeared along with the peaks assigned to the neopentylligands, essentially leaving only the major product, tentatively assigned as a[Ru(OEP)OR]2(- )complex, although the axial ligands are not evident. The absence ofthis(these) signal(s) implies that these ligands are deuterated, although this is somewhatunexepected as it requires cleavage of the relatively strong C-D bonds (i.e. sp3) ofC6D.Furthermore, the fate of the neopentyl ligands is uncertain although presumably they arelost to reactions with 02; the singlets observed at 0.70 and 0.99 ppm are likely due tooxidized organic products. Clearly this system is quite complicated and more work isneeded to elucidate the the mode of reactivity.1734.6.2 Reaction with 1120As described previously (section 4.5.1), the Ru(OEP)Np complex could be isolated fromsolutions of the j.i-Li dimer by column chromatography (alumina). Oxygen was excludedfrom the process by bubbling argon gas through the system; however, no attempt wasmade to exclude water and therefore H20 was suspected to be the oxidant. In an attemptto test this hypothesis, wet degassed C6Dtwas condensed onto a sample of[Ru(OEP)Np]2(p.-Li),the tube was sealed, and the changes in the NMR were thenmonitored over time (Figure 4-22). The results suggest that H20 does indeed oxidize thisspecies to yield the Ru(III) mono(neopentyl) complex in what appears to be a two-stepprocess. The first step is quite rapid judging from the spectrum taken within 8 minutes asnone of the characteristic peaks of [Ru(OEP)NpJ2(t-Li)are present. Four relativelybroad peaks appear between 0 - 6 ppm, which slowly shift over a period of several hoursto positions characteristic of Ru(OEP)Np. This type of behaviour might be interpreted interms of a rapid equilibrium involving the Ru(ffl) mono(neopentyl) species where theequilibrium is slowly shifting in favour of this species (i.e. the relative concentration ofRu(OEP)Np is increasing).Reactions 4.32-4.34 below show a possible reaction scheme, where initially[Ru(OEP)NpJ2(jt-Li) is rapidly reduced by one equivalent ofH20 to produce a Ru(II, III)dimeric species perhaps bridged by a single lithium ion. In this scenario, the spectralThe C6D underwent 6 freeze-pump-thaw cycles but no attempt was made to dry the solvent.174S H10I week - — —__________355 — — —________________—___22611327$ DI I I I I I I I I Ij I I4 2 C —2PP4Figure 4-22: ‘H NMR (300 MHz) spectral changes observed over time for thereaction of [Ru(OEP)Npj(.i-Li)( 3mM) in water-saturated ( 30 mM)27C6D5.S = solvent.175Ak A14 12 1C S[Ru’(OEP)Np]2Li+ H20 [Ru”(OEP)Np]2Li+ LiOH + 1/2H2 fast 4.32[Ru”(OEP)Np]2Li Ru(OEP)Np + [Ru11(OEP)Np]Li fast 4.33[Ru”(OEP)Np]Li + H20 Ru”(OEP)Np + LiOH + l/2H0 siow 4.34changes being monitored in Figure 4-22 are represented by reactions 4.33 and 4.34. Thesubsequent dissociation equilibrium (reaction 4.33) is reasonable for a structure stabilizedby only a single Li atom. According to this mechanism, the reaction rate would beretarded as the concentration of the Ru(OEP)Np product increases as the equilibrium ofreaction 4.33 is forced to the left. The data in Figure 4-22 reveal that the magnitude ofthe shift in the peaks does indeed decrease over time, suggesting achievement of a limitingrate. Hydrogen gas should also be produced according to this mechanism but is notdetected at these concentrations.4.6.3 Reaction with NI!3Figure 4-23 shows the NMR spectrum of a C6D solution of [Ru(OEP)Np12(p.-Li)sealed under anhydrous NH3. Judging from the single porphyrin methylene signal (3.07ppm multiplet), the dimeric structure of this complex has been disrupted. Indeed, theabsence of a second metalloporphyrin unit is also apparent in the general downfield shift ofthe remaining porphyrin (8 8.60, Hmeso; 1.82(t), CH3) and neopentyl protons (6 -1. 17,-CH3; -6.023, -CH2) relative to those of the original complex. Futhermore, the 7Li signalshifts 9 ppm downfield from that of the original dimer to -5.8 ppm (relative to LiBr in1762Figure 4-23: ‘H NMR spectrum (C6D,300 MHz) of [Ru(OEP)Np]2(.L-Li)(7mM) under anhydrous NH3. [Ru(OEP)Np]2(j.t-Li) was generated in situ from thereaction of Ru(OEP)Np( 10.1mg, 7mM after mixing) with I equivalent ofNpLi(1.lmg, 7mM after mxing). Ssolvent. 1 = free NH3;2 = 2, 2, 5, 5-tetramethyihexane. 3 = internal anthracene reference(5.5 mM).Np-CH3Hmeso SI I-CH3211111111 ‘I TI I I 111111 IIIT[I 111 IIIIII II 11111111 IJ10 B 5 4 0Np-C142I I II I I I I TI—2• I,,•.I••,•I,,•• I-4 -s PPM177H20) clearly reflecting the loss of the second Ru(OEP)Np moiety. However, this signalappears sufficiently upfield of LiBr to conclude that the Li is still shielded to a greatextent by the porphyrin ring. Noticeably absent from this ‘H spectrum is a peak assignableto coordinated ammine although the broad singlet at -0.3 ppm assigned to free NH3. couldpossibly result from a rapid exchange equilibrium. The species present is most likely[Ru(OEP)(NH3)Np]Li, although to account for the 7Li shift, the cation must be moreclosely associated with the porphyrin moiety than illustrated.178Table 4-2: ‘H NIVIR spectra of the discussed Ru(OEP) complexes.’Complex Porphyrin Axial LigandsHmeso -CH2 CH3Ru(OEP)Np2 9.76(s) 3.65(a) 1.77 -2.42(s, -CH3),-1.25(s, -CH2)Ru(OEP)Np’ 2.15 13.48, 6.09 -1.40 5.78(CH3)Ru(OEP)Np(NH3)1’ -2.80 9.20, 5.37 -2.30 12.74(Np-CHRu(OEP)CH2C(CH 9.94(s) 3.90(m) 1.95(t) -2. 10(s, -CH3),12.35(s, =CH-)[Ru(OEP)Np]2Q.t-Li) 8.00(s) 3.53(m), 3.37(m) 1.65(t) -2.28(s, -CH3),-7.45(s, -CH2)Ru(OEP)(NH3)2 9.34(s) 3.90(q) 1.97(t) -8.06(NH3)Ru(OEP)NpLi 8.70(s) 3.55(q) 1.76(t) -1. 64(s, -CH3)-7.2 1(s, -CH2)Ru(OEP)(neophy1) 3.69 13.59, 6.30 -0.80 5.95, 6.5, 12.9 (o-,m-, p-H), 5.1 (-CH3)Ru(OEP)(CH2Ph)’ 9.65(s) 3.78(q) 1.85(t) 6.08(t,p-H), 5.62(t,rn-H), 3.1 0(d, o-H),-0.82(s, CH2-)Ru(OEP)(CH2Ph)M 0.35 12.24, 6.78 -1.65 15.52ea) All spectra were obtained in C6D at RT unless otherwise noted. b) All signals werebroad singlets. c) Spectrum obtained in C6D at 500 C. d) Structural assignments aretentative. e) Proton assignment unknown.1794.7 References for Chapter 41lron Porphyrins, Lever, A.B.P.; Gray, H.B. Eds., Addison-Wesley, Massachussetts,(1983), Parts 1-2.2 Vitamin B12, Dolphin, D. Ed., John Wiley, New York, (1982), Vols 1-2.3a) Brothers, P.J.; Collman, J.P. Ace. Chem. Res. 19, 209 (1986).b) Guilard, R.; Kadish, K,M. Chem. Rev. 88, 1121 (1988).4Fleischer, C.B.; Thorp, R.; Venerable, D. J. Chem. Soc., Chem. Commun. 475 (1969).a) Coilman, J.P.; Brothers, P.J.; McElwee-White, L.; Rose, E J. Am. Chem. Soc. 107,6100 (1985).b) Venburg, G.D. Ph.D. Dissertation Stanford University, 1990.c) Coilman, J.P.; Rose, E.; Venburg, G.D. I Chem. Soc., Chem. Commun. 11(1994).6 Coilman, J.P.; McElweeWhite, L.; Brothers, P.J.; Rose, E. J. Am. Chem. Soc. 108,1332 (1986).‘ a) Sishta, C.; Ke, M.; James, B.R.; Dolphin, D. J. Chem. Soc., Chem. Commun., 7871986.b) Ke, M. Ph.D. Thesis, University of British Columbia, 1988.c) Seyler, J.W.; Leidner, C.R. Inorg. Chem. 29, 3636 (1990).d) Seyler, J.W.; Safford, L.K.; Leidner, C.R. Inorg. Chem. 31, 4300 (1992).8 Ke, M.; Rettig, S.J.; James, B.R.; Dolphin, D. J. Chem. Soc., Chem. Commun., 1110(1987).9Kochi, J.K. in Free Radicals, Koehi J.K. Ed., John Wiley and Sons, New York, (1973),Vol I, Chapter 11, p. 668.10 Halpern, J. Ace. Chem. Res. 15, 238 (1982).‘ Tsou, T.-T; Loots M.; Halpern, J. J. Am. Chem. Soc., 104, 623 (1982).18012 Setzer, W.N.; Schleyer, P.von R.; Adv. Organomet. Chem., 24, 353 (1985).13 Seyler, J.W.; Safford, L.K.; Fanwick, P.E.; Leidner, C.R. Inorg. Chem. 31, 1547(1992).14 Song, B.; Goff, H.F. Inorg. C/urn. Acta 226, 231(1994).15 Coliman, J.P.; Barnes, C.E.; Brothers, P.J.; Collins, T.J.; Ozaswa, T.; Gallucci, J.C.;Ibers J. A. J. Am. Chem. Soc., 106, 5151(1984).16 Ke. M.; Sishta, C.; James, B.R. ; Dolphin, D.; Sparapany, J.W.; Ibers, J.A. Inorg.Chem., 30, 4766 (1991).17 Gallop, M.A.; Roper, W.R. Adv. Organomet. Chem. 25, 121 (1986).18 a) Rajapakse, N.; James, BR.; Dolphin, D. Can. J. Chem. 68, 2274 (1990).19 a)Evans, D.F. J. Chem. Soc., 2003 (1959).b) Deutsch, J.L.; Poling, SM., J. Chern. Ed, 46, 167 (1969).c) Sur, S.K. J. Mag. Res., 82, 169 (1989).d) Eaton, S.S.; Eaton, G.R. Inorg. Chern., 19, 1096 (1980).20a) Coliman, J.P.; Barnes, C.E.; Swepston, P.N.; Ibers, J.A. J. Am. Chem. Soc., 106,3500 (1984).b) Balch, A.L.; Renner, M.W. I Am. Chem. Soc., 99, 2603 (1986).c) Baich, A.L.; Chan, Y.-W.; La Mar, B.N.; Latos-Grazynski, L.; Renner, M.W. Inorg.Chem., 24, 1437 (1985).d) La Mar, G.N., Walker, F.A. in The Porphyrins, Dolphin, D. Ed., Academic Press,New York, N.Y., (1979), vol 4, chapter 2.e) Sishta, C. Ph.D. Thesis, University of British Columbia, 1990.21a) Seyler, J.W.; Fanwick, P.E.; Leidner, C.R. Inorg. Chem. 31, 3699 (1992).b) James, B.R.; Dolphin, D.; Leung, T.W.; Einstein, F.W.B.; Willis, A.C. Can. J. Chem.62, 1238 (1984).c) James, B.R.; Pacheco, A.; Rettig, S.J.; Ibers, J.A. Inorg. Chem. 27, 2414 (1988).d) Ariel, S.; Dolphin, D.; Domazetis, G.; James, B.R.; Leung, T.W.; Rettig, S.J.;181Trotter, J.; Williams, G.M. Can. J. Chem. 62, 755 (1983).e) Masuda, H.; Taga, T.; Osaki, K.; Sugimoto, H.; Mori, M.; Ogoshi, H. Bull. Chem.Soc. Jpn. 55, 3887 (1982).1) Masuda, H.; Taga, T.; Osaki, K.; Sugimoto, H.; Moñ, M.; Ogoshi, H. J. Am. Chem.Soc. 103, 2199 (1981).22 Skinner, H.A.; Connor, J.A. Pure Appi. Chem. 57, 79 (1985).23Tooze R.P.; Motevalli, M.; Hursthouse, M.B.; Wilkinson, G. J. Chem. Soc., Chem.Commun. 799 (1984).24Leidner C.R.; Seyler, J.W. .1 Chem. Soc. Chem. Commun. 1794 (1984).25 Arnold, J.; Dawson, K.Y.; HoiThian, C.G. J. Am. Chem. Soc., 115, 2707 (1993).26 a) Coliman, J.P.; Barnes, C.E., Collins, T.J.; Brothers, P.J. J. Am. Chem. Soc., 103,7030 (1981).b) Coilman, J.P.; Brothers, P.J., McElwee-White, L.; Rose, E; Wright, L.J. .1. Am.Chem. Soc., 107, 4570 (1985).27 Seidell, A. Solubilities ofInorganic andMetal Organic Compounds, 3” Ed., VanNorstrand, New York, 1940, vol I.182Chapter 55. Organometallic Complexes of (Tetramesitylporphyrinato)ruthenium5.1 IntroductionWhen this thesis work began, no organometallic complexes of (tetramesitylporphyrinato)ruthenium had been reported in the literature despite the promise of uniqueand interesting chemistry due to the steric constraints imposed by the 4 mesityl groups(see chapter 1). Since that time, a number of it complexes including olefin-’, acetylene-’and carbene-2species have been reported in addition to the Ru(TMP)Me2complex (withpurely a-bonded methyl groups) which was prepared according to reaction 5.1 (thissynthesis was noted in a Ph.D. thesis subsequent to the synthesis used in this currentthesis).2K2[Ru(TMP)] +2 Mel Ru(TMP)Me2+ “2 VJ” 5.1This chapter reports on the reactions ofRu(TMP)X2(X= Br, Cl) with PhLi, MeLiand NpLi. As part of these studies, two “a-bonded species” (Ru(TMP)Ph2andRu(TMP)Me2)were isolated and unambiguously identified by microanalysis, ‘H NMR andUV visible spectroscopy along with the crystal structure of Ru(TIvIP)Ph2.The reaction ofeach of the complexes with carbon monoxide was examined and the insertion productRu(TMP)(COPh)Ph was also isolated and characterized. The kinetics of the thermaldecomposition of all three isolated species were studied and the bond dissociation energies183of the Ru-Me, Ru-Ph and Ru-COPh bonds were thereby obtained. Finally, a brief accountof the photo-induced oxidation ofRu(TMP)Me2by 02 is included.5.2 Preparation and Characterization of Ru(TMP)R2complexes (R = Ph or Me)As described in chapter 4, several Ru(porp)R2complexes (porp= OEP, R= Me, Et,Ph, p-CH3C6H4m-CH3C6H4,p-CH3O64,p-FC6H4;porp= TPP, R Ph) havepreviously been prepared in these laboratories by treating Ru(porp)X2(porp= OEP, TPP;X= Br, Cl) with a 5-fold excess of the appropriate organolithium or Grignard reagent.The products were isolated in approximately 30 % yield by column chromatography(aluminalbenzene).In this thesis work, Ru(TMP)Me2and Ru(TMP)Ph2were prepared by treating thedihalo (Br or Cl) precursor with MeLi and PhLi in a procedure analogous to thatdescribed for the OEP derivatives3(see also chapter 2 for details). However, thepurification procedures were modified somewhat with, for example, CC14 beingsubstituted as the eluting solvent when running columns containing Ru(TMP)Ph2,as noseparation could be achieved with the earlier reported benzene or toluene. In contrast,analytically pure Ru(TMP)Me2could be isolated from an alumina column using any of theabove solvents provided that the procedure was performed in the dark. Thus, the dimethyland diphenyl derivatives were isolated in approximately 30% yield and the respectiveelemental analyses are consistent with the assigned formulations (see chapter 2).The ‘H NMR spectra of bis(phenyl) and dimethyl complexes are shown in Figures5- L and 5-2, respectively. Both spectra are typical of diamagnetic Ru(TMP) complexes1’2184with well resolved peaks falling in the range of-2 to 9 ppm. The appearance of thesespectra also shows the effective D4h symmetry of these complexes on the N]\4R time-scale.The single peak observed for both the o-Me and rn-H of the mesityl fhnctions reveals themirror symmetry of the porphyrin plane, while the equivalence of all 8 pyrrole protonsdemonstrates the C4 symmetry of each complex. The proton assignments shown are easilymade from relative integrations and/or the spin-spin coupling patterns; the frequenciesobserved for Ru(TMP)Me2are virtually identical to those given in the 1990 thesis.2The upfield shifts of the axial ligands result from the shielding influence of thearomatic porphyrin ring.5 The phenyl signals of Ru(TMP)Ph2are shifted for exampleupfield to frequencies similar to those observed for Ru(OEP)Ph2,3Ge(TPP)Ph26and otherdiamagnetic mono-phenyl metalloporphyrins.7The decreasing magnitude of this effectwith increasing distance from the porphyrin plane can be observed as the o-, m- andpsignals of the phenyl group in Figure 5-1 appear consecutively closer to the frequency offree benzene (ö= 7.16 ppm).The X-ray crystal structure of Ru(TMP)Ph2is shown in Figure 5-3 and selecteddimensions are listed in Table 5-1 along with corresponding data of some relatedstructures. Full details are given in appendix F. Notably common among all the TIVIPstructures is the near 90° angle formed between the planes of the metalloporphyrin moietyand the four mesityl groups. This feature is believed to be imposed by a steric interaction185oCH,IIli.,.iIiI.PiIliIiIII.I.,lii!IllltJrlr1TlJ Till.. lIlilII II uijTlI9 8 7 C’ 5 4 3 2 P4Figure 5-1: ‘H NMR spectrum (CJ)o 300 MHz) of Ru(TMP)Ph2.S= solvent;o, m, andp refer to the protons of the coordinated phenyl groups.pyrl. p-CH,rn-HI-186o-CH3i.’’. .F I I F I F [I F I F I F F I F F I10 2 0—2 PP1Figure 5-2: ‘H NMR spectrum (C6D,300 Mz) of Ru(TMP)Me2.S solvent.p-CH3ni-H8 6 4187C27CZ3$C20doC9 C3 C3iaCa)-— C2Q° C3aB c d34,C34‘ C4Ciic4 CuCsC13C14cii\Ci4 c7C22CLS C7 Ci C26 C3Ciz ciiC7 Cii Ci Cit42 cc C2*CsciaC4 c3i.CIc C33b)CsRt ‘C: cx• Cs.Ci C34C33a‘SFigure 5-3: a) ORTEP diagram of Ru(TMP)Ph2.b) Proposed structure;thermal ellipsoids 33%.188Table 5-1: Selected dimensions for some ruthenium porphyrin complexes.Ru-L” (A) L-Ru-LComplexa Ref. Ru-N” (A) porphyrin/mesityl°angle“Ru”Ph2 d 2.040 90.5° 2.069e 157.8°“Ru”(CH3CN) 8 2.043 not available 2.7 180°“Ru”(OCH(CH)2 9 2.034 85.8 1g92 180°“Ru”(S(CHCH1) 10 2.049 88.0° 2372’s 180°Ru(OEP)Ph2 3 2.047 not applicable 2.096e 160°a) “Ru”= Ru(TMP). b) average bond lengths c) average dihedral angle between theporphyrin and mesityl groups. a) this work. e)Ru-C. f)Ru-N. g) Ru-O. h)Ru-Sbetween the porphyrin and the o-Me groups of the mesityl rings. The same interaction hasbeen cited to explain the limited range of angles (64-90°)’ 1,12 observed between theporphyrin and the phenyl rings in the structures of TPP complexes. Not surprisingly, thisinteraction appears to be greater when the ortho-sites of the 4 phenyl rings are occupiedby Me groups as the corresponding angles do not deviate very far from 90° in the TIvIPcomplexes of Table 5-1. The metalloporphyrin moiety is essentially square planar with theRu atom centered approximately within the porphyrin core. All the other bond lengthsand angles within the macrocycle correlate well with those of the other TMP species inTable 5-1. The average Ru-C(Ph) bond length of Ru(TMP)Ph2is 0.027 A shorter thanthe analogous bond length in Ru(OEP)Ph2;however, both lengths are within the range of1.997-2.187 A observed for other Ru-C(sp2,aryl) bonded systems.’3Figure 5-3a shows the disorder of the axial phenyl groups in the Ru(TMP)Ph2structure. Each orientation is statistically equivalent and thus the angle of the Ph-Ru-Phbond is uncertain as two possible structures account for this disorder: that involving the189phenyl rings labeled A and C in Figure 5-3a or alternatively the structure involving the Aand D phenyl rings. This corresponds to Ph-Ru-Ph bond angles of 157.8° and 1800respectively. Although the data do not allow for a choice between the two structures, theformer is favored as similar structures have been reported for other metalloporphyrinsystems. Of note, the C-Ru-C bond angle in Ru(OEP)Ph2was about 159°, while theC-Ge-C angle in Ge(porp)Me214was approximately 173°.The exact cause of the severe bending in these six-coordinate organometallicporphyrin systems is unclear although both steric and crystal packing effects have beenconsidered and rejected.3 This leaves electronic effects; however, the nature of thisinteraction is not known. Furthermore, these effects seem to be limited to the six-coordinate species as the metal-carbon bond in five-coordinate metalloporphyrin species isapproximately perpendicular to the porphyrin plane,’5 except in cases where obvious stericinteractions are observed (see chapter 4).5.3 Reaction of Ru(TMP)X2(X= Cl or Br) with NpLiAttempts to prepare Ru(TMP)Np2using the procedure described in section 5.2 forthe bis(phenyl) and dimethyl derivatives gave ambiguous results. Typically, a benzenesoution of Ru(TMP)Br2was treated with a large excess (5-9 equivalents) of NpLi (inbenzene) and the product solution was then charged onto an alumina column. Only oneband eluted from the column using benzene or toluene; however, this material contained amixture of Ru(TMP) species as judged by ‘H NMR spectroscopy. One was aparamagnetic Ru(llI) species as indicated by the broad signal at -32.9 ppm for the pyrrole190protons, and at least two diamagnetic species were evident judging by the sharp singlets at8.46 and 9.04 ppm, also characteristic of the pyrrole protons. Attempts to use chlorinatedsolvents (CH2C1 or Cd4)to separate these species only resulted in the isolation of a smallamount of Ru(TMP)C12.In light of the reactivity of Ru(OEP)Cl2with NpLi (see chapter 4), a series of in situexperiments reacting Ru(TMP)X2(X= Br and Cl) with 2, 3 or more equivalents ofNpLiwas performed (in C6D)to determine if the chemistry was comparable to that of the OEPsystems. Although the results are somewhat more complicated, they do suggest that thechemistry is to some extent similar.Figure 5.4 shows the ‘H NMR spectrum of the products of the reaction ofRu(TMP)Cl2with two equivalents ofNpLi. One paramagnetic (compound A) and twodiamagnetic (compounds B and C) Ru(TMP) species can be observed, and Table 5-2 liststhe tentative assignments for each compound. It should be noted that a large amount ofundissolved product was visible in the NMR tube and thus the combined integration of allthree products account for only 20 % of the Ru(TMP)Cl2added ( as determined relativeto the anthracene reference).The spectrum of compound A is typical of a Ru(III)(TMP) species and thus most ofthe distinct signals of this complex were relatively easy to assign. In contrast, the signalsof compounds B and C can not be distinguished from Figure 5-4 alone and a comparisonof the results from subsequent experiments was necessary to make the given assignments.191SFigure 5-4: 1H NMR spectrum (C6D,300 MHz) of the products of the reactionof Ru(TMP)C12(10,1 mg, 5.3 mM after mixing) with 2 equivalents NpLi (1.7 mg,10.9 mM after mixing). S = Solvent, An = internal anthracene reference (2.1 mg,11.8 i.tmol) 1 = neopentyl chloride, 2 = 2, 2, 5, 5-tetramethylhexane, 3 =neopentane. Tentative assignments; A= Ru(TMP)Np, B= Ru(TMP)Np2,C=[Ru(TIVIP)Np]Li.192C23A2 A BA—3a PI2 6 2 6 2 4 2 2 2 0 P6AnAnAnC,8 6 4 2 C —2 -4 PPh,4 6Table 5-2: 1H NIVIR (C6D,300 MHz) signals observed following the reactionofRu(TMP)Cl2(10.6 pmol) with 2 equivalents of neopentyllithium (21.8 .tmol).Compound pyrrole o-Me and p-Me meta-H Axial neopentyl -C(CH3)/-CH2A -32.4 0.30’, 710 4.00, 4.31 4.OcY’B 8.20 2.136’ d -1.841-0.74C 7.93 2.44, 2.35, 2.28 d -0.85/ -5.34Proposed structures; A= Ru(TMP)Np, B= Ru(TMP)Np2,C [Ru(TMP)NpJLia) The second o-Me signal is hidden among the peaks in region 2.1 to 2.5 ppm. b) Theseprotons are tentatively assigned to the broad peak at the base of the rn-proton signal.c) This signal is probably the o-Me peak, the p-Me peak being hidden among the peaks inregion 2.1 to 2.5 ppm. d) These peaks were obscured by the solvent peak at 7.16 ppm.For example, the relative yield of these species would change from one experiment to thenext and thus one could assign the signals comparing the relative intensity of the peaksfrom two or more experiments. Furthermore, these two complexes are essentially the onlyproducts observed upon the reaction of Ru(TMP)X2(X= Br or Cl) with three equivalentsof neopentyllithium (Figure 5.5).Compounds A, B, and C in table 4.2 are tentatively assigned as Ru(TIvIP)Np,Ru(TMP)Np2and [Ru(TMP)Np]Li, respectively. These assignments are based on certainfeatures in Figure 5-4 and Figure 5-5 that compare favourably with those of the OEPanalogues (see chapter 4). For example, as previously mentioned, compound A is clearlya Ru(III) species and thus is assigned as Ru(TMP)Np, all but two of proton environmentsbeing easily assigned in Table 5-2. The subsequent co-isolation of this material (with193ICftFigure5-5:1HNfVIRspectrum(C6D,300M1-Iz)of theproductsofthereactionof Ru(TMP)C12(8.2mg,4.3mMaftermixing)with3equivalentsof NpLi(2.0mg,13mMaftermixing).S=solvent,An=internalanthracenereference(1.4 mg,7.8.tmol),1=neopentylchloride,2=2,2,5,5-tetramethylhexane,3=neopentane.TentativeassignmentsB=Ru(TMP)Np2,C=[Ru(TMP)Np]Li.I 2-:..:.-:.1.4dILJ•:..:..:.-14ppw194compound B) (vide infra) indicates that the absent o-Me peak is hidden in the region of2.1-2.5. The neopentyl methyl might be assigned to the broad signal beneath the peak at4.00 ppm, albeit this is somewhat upfield of the analogous protons of Ru(OEP)Np (5.78ppm).Compound B has been assigned as Ru(TMP)Np2for two reasons. First, thereappear to be two neopentyl ligands per metalloporphyrin unit as judged by the relativeintegration of the neopentyl methyl (-1.84 ppm) and the porphyrin pyrrole (8.23 ppm)signals. In addition, the relative positions of the axial neopentyl signals are characteristicof a Ru(IV) species. The y-methyl protons (-1.84 ppm) appear upfield of the x-methylenesignal (-0.72 ppm) as was the case for the Ru(OEP)Np2(-2.42 and -1.25 ppm for themethyl and methylene protons, respectively; see chapter 4). Presumably the a.-protonsexperience considerable desbielding relative to the y-methyl protons due to the proximityof the highly oxidized metal center in these Ru(IV) complexes. It is notable that NIVIRsolutions of compound B (in mixtures with C, or A and C) were stable for periods of up toa week at room temperature, in contrast to the Ru(OEP)Np2species which underwentcomplete homolysis of one Ru-Np bond within 2 days under the same conditions (seechapter 4). This implies that the analogous bond in the TMP complex is much stronger ifin fact compound B is Ru(TMP)Np2.This is somewhat unexpected as the bond strengthsof the corresponding phenyl analogues (i.e. Ru(OEP)Ph2vs. Ru(TMP)Ph2)are almostidentical (see section 5.5.4).Compound C is believed to be [Ru(TMP)Np]Li. This is the monomeric analogue ofthe {Ru(OEP)Np]2(p.-Li) dimer produced by the reaction of Ru(OEP)C12with three195equivalents of NpLi (see chapter 4). The dimeric structure is assumed to be precluded bythe bulky TMP macrocycle in this case. The proton designations in Table 5-2 were allunambiguous and strongly support the proposed formulation. For example, theintegrations indicate one neopentyl ligand per Ru(TMP) moiety and the 2 signals observedfor the ortho-Me protons indicate C4, symmetry. Furthermore, the relative positions ofthe neopentyl y-methyl (-0.85 ppm) and the x-methylene (-5.34 ppm) signals suggest aRu(II) product, as the relative positions of the corresponding signals of[Ru(OEP)NpJ2(p-Li)were the same (-2.28 and -7.45 ppm, respectively).Only one metalloporphyrin product is visible in the ‘H NMR spectrum (Figure 5.6)when Ru(TMP)Br2was treated with approximately 7 equivalents ofNpLi. Integrationsindicate that this species is composed of two neopentyl ligands per Ru(TMP) moiety andthe single peak observed for each of the o-Me (2.28 ppm) and rn-protons (7.09 ppm) ofthe mesityl groups, indicate these ligands are situated symmetrically on each side of themetalloporphyrin ring (i.e.D4h). Furthermore, the neopentyl c-methylene protons (-6.31ppm) appear upfield of the y-methyl signal (-0.98 ppm) suggesting that this is a Ru(II)species (cf. Table 5-2). These features coupled with the results of the results of ananalogous OEP experiment (see chapter 4) imply that the metalloporphyrin product of thisreaction is Ru(TMP)Np2Li.As discussed for the OEP analogue, it is considered unlikely that both neopentylligands are simultaneously bonded to the metal center in this Ru(II) species (see chapter 4)and therefore the structure shown in Figure 5-6 is proposed to account for this spectrum.There is no precedent for such a species other than the OEP analogue described196v-Cl-I10Figure5-6:‘HNMRspectrum(C6D,300MHz)of theproductsof thereactionof Ru(TMP)Br2(5.88mg,5.6mMaftermixing)with7equivalentsofneopentyllithium(3mg,38mMaftermixing).Ssolvent,1=excessNpLi,2=neopentylbromide,3=2,2,5,5-tetramethylhexane.‘Pt P3pyrENp-CHi8I 4irrNp-CH24197in chapter 4, as far as the author is aware; however, the proximity of the lithium atomswould account for the broadening of the methylene signals of the axial neopentyl ligands.Broad signals were also observed for the corresponding protons of [Ru(OEP)Np2]Liandof free neopentyllitbium.In view of these in situ results, the reaction was again attempted on a preparatoryscale. In this effort, Ru(TMP)Br2(72 mg(69 tmol), in 8 mL dry degassed toluene) wastreated at room temperature with two equivalents ofNpLi (10.8 mg( 138 pmol), in 5 mLdry degassed toluene) and the column purification (aluminalbenzene) was performed underanaerobic conditions (see chapter 2 for details). Only one band was isolated from thecolumn which was a mixture of mainly (unidentified impurities were also present)Ru(TMP)Np (compound A) and Ru(TTvIP)Np2(compound B) ([B]: [A] 9 as judged by‘H NMR spectroscopy), the chemical shifts ind8-toluene being almost identical to thosereported in Table 5-2 (in C6D). For example, the pyrrole-, o-Me, and p-Me signals,corresponding to those listed in Table 5-2 for compound A, were found at -32.3, 0.35 and0.73 ppm, respectively, while the rn-protons appeared at 4.10 and 4.34 ppm. A new broadpeak at 2.33 ppm is tentatively assigned to the second o-Me group, although, an accurateintegration could not be obtained as this peak overlaped with another signal (vide infra).In addition, a second broad signal at 3.72 ppm, integrating for 9H, is tentatively assignedto the Np-Me protons.Many of the signals of compound B (Ru(TMP)Np2)also appear in the spectrum ofthe isolated material (ö(ppm) 8.10, pyrr; -1.93, Np-CH;-0.87, Np-CH2). Unfortunately,the o-Me signal at 2.14 ppm was hidden beneath the solvent peak (2.19(m) ppm);198however, a new singlet at 2.36 ppm (atop the broad singlet described above for the o-Meprotons ofRu(TMP)Np), could be attributed to the p-Me signal (not seen in Figure 5-5).This is certainly consistent with the chemical shift of the corresponding signal ofRu(TMP)Me2(2.41 ppm) ind8-toluene.The microanalysis suggests that the isolated material is made up of mostly theRu(III) species as it is consistent with the formulation Ru(TMP)Np.H20(Anal. calcd.:C, 75.43; H, 6.75; N, 5.77. Found: C, 75.09; H, 6.75; N, 5.18). In addition, the massspectrum (El) displayed peaks at 952 and 822 mle for the Ru(TIVIP)Np and Ru(TMP)moieties respectively, both fragments being characteristic of Ru(TMP)Np2andRu(TMP)Np species. Of note, a very weak signal was detected at 1033 mlecorresponding to Ru(TMP)(Np)Br, but this appears to be a minor rather than a majorcoproduct as this formulation is not consistent with the elemental analysis (Anal. calcd.:C, 70.91;H, 6.15;N, 5.42).As noted above, the assignments for the products of the in situ reactions ofRu(TMP)X2(X= Br and Cl) with NpLi depend heavily upon the products identified forthe analogous reactions of Ru(OEP)C12(see chapter 4). This comparison seemsreasonable as the presence of 2, 2, 5, 5-tetramethylhexane (0.89 and 1.17 ppm in Figures5.4 and 5.5) suggests the involvement ofNp radicals in the present reaction. This organicproduct was also cited as evidence for the participation of these radicals in the reactions ofRu(OEP)C12(see chapter 4) and presumably results from the coupling of two of thesehighly reactive intermediates.199The reducing strength of the NpLi figured prominently in the chemistry withRu(OEP)C12,and an initial outer-sphere reduction of the dichloro species was proposed asone source of neopentyl radicals. The analogous reduction ofRu(TMP)C12proposed inreaction 5.2 below is as least as favourable as the OEP system as the reductionRu(TMP)C12+ NpLi [Ru(TMP)C12]Li+ Np• 5.2potentials of Ru(OEP)C12and Ru(TMP)C12are identical (see chapter 3). Of course,reaction 5.2 can be generalized to include Ru(TMP)Br2as the metalloporphyrin productsof the reaction of this species with NpLi are the same. Several other reactions involvingradical attacks and/or further reductions by NpLi were proposed in chapter 4 to accountfor all of the products observed for the OEP system, and these proposals can be applied tothe present case as well. The reader is referred to chapter 4 for a frill discussion of thesereactions.One notable difference between the reactions ofNpLi with Ru(OEP)Cl2andRu(TMP)C12was the degree of reduction observed for the various ratios of startingmaterials. For example, reaction of Ru(OEP)Cl2with three equivalents ofNpLi results inone Ru(II) product ([Ru(OEP)Np]2.i-Li)),whereas the same treatment ofRu(TMP)C12seems to yield a Ru(II) and a Ru(IV) product (tentatively [Ru(TMP)Np]Li andRu(TMP)Np2). This difference is possibly due to competition from the standardmetathesis reaction in the TIVIP system. Normally such lithium reagents react according tothe simple substitution equilibria (metathesis reactions) shown in equations 5.3 and 5.4.This type of chemistry was generally rejected in the OEP system as it does not200Ru(TMP)C12+ NpLi .. Ru(TMP)(Np)Cl + LiC1Ru(TMP)(Np)Cl + NpLi - Ru(TMP)Np2+ LiC1 5.4account for the majority of the products observed. However, reactions 5.3 and 5.4 mightbe expected to exhaust the supply ofNpLi, thus reducing the amount available to effectthe reduction reactions and thus a good portion of the products remain unreduced. On theother hand, the Ru(TMP)Np2product might simply be resistant to reduction. In any case,further experiments are warranted for the TMP system as a significant amount ofundissolved product was observed in the NIvIR tubes during the measurement of each ofthe spectra in Figures 5-4 and 5-5, and the identity of this material has not beendetermined. Furthermore, none of the proposed products of this reaction have been fullyisolated and characterized and therefore further discussion is not warrented.5.4 Reactions of Ru(TMP)R2(R= Me, Ph) complexes with COMigratory insertion processes represent one of the major classes of reactivity oforganometallic complexes and these reactions generally involve the migration of anorganic fragment to an appropriate cis ligand (for example CO). Metalloporphyrincomplexes are, at first sight, not good candidates for this type of chemistry because of thelack of available cis sites, yet insertion reactions have been observed for a variety of thesecomplexes including those of iron’6 and ruthenium.3aThese “direct insertion” reactionsappear to proceed without prior cis-coordination of the inserting species and are generallyattributed to caged radical processes.201In earlier studies in these laboratories,3Ke found that C6D solutions ofRu(OEP)Ph2react very slowly (> 1 month at room temperature and under standardlaboratory lighting) with 1 atm CO to produce Ru(OEP)(CO)2.During the course ofthe reaction, a single diamagnetic intermediate ofC4 symmetry was observed in the ‘HNIvIR spectrum and this was tentatively assigned as Ru(OEP)(COPh)(Ph). The results ofthis present thesis work (vide infra) tend to support this assignment and thus Ke’s workrepresents the first direct insertion of CO reported for an organoruthenium porphyrincomplex.In an experiment similar to that performed by Ke, a C6D solution ofRu(TMP)Ph2reacted in a completely analogous way; that is, treatment of this complex with 1 atm COunder normal laboratory lighting, resulted in the quantitative conversion toRu(TMP)(CO)2with one diamagnetic intermediate observed en route. In this case,however, the intermediate was isolated and fully characterized as Ru(TMP)(COPh)Ph.This was made possible by the fact that the rate of decomposition of benzoyl complex wasslowed considerably in the absence of light. Indeed, after the Ru(TMP)Ph2/COreactionwas left for one month in the dark at room temperature, Ru(TMP)(COPh)Ph constituted95 % of the product mixture with the balance observed as Ru(TMP)(CO)2.Similar resultscould be achieved within 10 days at 350 C, and thus this was the procedure adopted forrepetitive preparations (see chapter 2 for details).The Ru(TMP)(COPh)Ph was air-stable for at least 24 h in solutions at roomtemperature and under fluorescent laboratory lighting; however, attempts to isolate thismaterial on an alumina column (benzene eluant) resulted in the production of a significant202amount ( 30 %) of Ru(TMP)Ph, which was clearly derived from the aroyl complex as theonly other metalloporphyrin observed in the ‘H NMR spectrum prior to the purificationwas Ru(TMP)(CO)2.The carbonyl complex was ultimately removed by washing theproduct mixture with pentane. Unfortunately this reduced the yield ofRu(TMP)(COPh)Ph to just 24%. It should be noted, however, that no attempt was madeduring chromatographic procedures to exclude light and thus the overall yields might beimproved by running columns in the dark.The elemental analysis and spectral data (see chapter 2) are consistent with theformulation Ru(TMP)(COPh)Ph. For example, the appearance of a new band (relative toRu(TMP)Ph2)in the infrared spectrum is characteristic of the benzoyl Co (Vco 1752cm’). Figure 5-7 shows the ‘H NMR and the 2-D COSY spectra of the isolated complex.The C4 symmetry is evidenced by the singlet observed at 8.57 ppm for the 8 pyrroleprotons, which reveals the major C4 axis of symmetry, while the two signals observed foreach of the o-Me (2.39 and 1.57 ppm) and rn-protons (7.18 and 7.01 ppm) of the mesitylgroup reveal the absence of an orthogonal cyh mirror plane. The axial ligands give rise totwo sets of signals which were grouped together with the aid of the cosy spectrum (Figure5-7b). The peaks of the Ru-COPh fragment are tentatively assigned downfield of those ofthe Ru-Ph ligand as the shielding effect of the porphyrin ring is expected to be reducedwith increasing distance from the porphyrin plane.The Ru(TMP)Me2complex also undergoes the CO insertion reaction prior tocomplete conversion to the dicarbonyl species. Figure 5-8 shows the ‘H NIVIR spectrum ofthe reaction solution taken 5 days after the introduction of CO. In addition to the203Spyrro-CH3°p-CH1in-HIrn-HrIrpfl’m0pj-T‘‘i‘.TflTTTrliTrJTrflhlJllItjt1flFr11TFTTT1111111rrrlTrrrITrrrrprrTrrT-rr-r1--rrrrrn-9987654321PPM0Figure5-7:a)‘HNMRspectrum(C6D,300MHz)of Ru(TMP)(COPh)Ph.Ssolvent.Notethato,mandprespectivelyrefertotheortho-,meta-andpara-protonsoftheaxialphenylligand.o’,m’andp’refertothecorrespondingprotonsoftheaxialbenzoylligand.204—II Lp 6S00Cl 0:: ? § 4.0 2.0Figure 5-7: b) COSY spectrum of the region between 0 and 7 ppm.205I1[JIT i U I I • I I I I I I I I I I8 2 0-2 -4PPMFigure 5-8: ‘NMR spectrum (C6D,300 MHz) of Ru(TMP)Me2under CO(1 atm) for 5 days. S = solvent, I = Ru(TMP)Me22 = Ru(TMP)(CO).Thelabeled peaks are assigned to Ru(TMP)(COMe)Me.126 2.4 2.2 2.ô 1.8 PPMI6 4-206known frequencies for Ru(TMP)Me2(see Figure 5-2) and the Ru(TMP)(CO)2product,17Figure 5-8 displays signals a species identifiable as Ru(TMP)(COMe)Me. The singletobserved at 8.62 ppm for the 8 pyrrole protons and the two signals observed for the o-Meprotons of the mesityl groups (1.68 and 2.07 ppm) are again consistent with C4symmetry. The signals observed upfield at -2.32 and -3.85 ppm integrate for 3 protonseach, and are tentatively assigned to the axial Ru-Me and Ru-COMe ligands, respectively.The former is assigned ftirther downfield as it is closer to the Ru(IV) center.This reaction was not followed to completion; however, Ru(TMP)(CO)2comprised70 % of the products after two weeks with 25 % Ru(TMP)(COMe)(Me) and 5 %Ru(TMP)Me2remaining. These results contrast with those observed for the Ru(OEP)Me2species which was quantitatively converted to Ru(OEP)(C0)2within 10 h under similarconditions.3’Furthermore, the putative acyl intermediate (i.e. Ru(OEP)(COMe)Me) wasnot observed in that case.The first observed step in the reaction of the Ru(porp)R2complexes (porp = OEP,R= Ph; porp= TMP, R= Me, Ph) with CO is clearly its direct insertion into the Ru-Rbond. Carbon monoxide also inserts into the Fe-C bond of five-coordinate alkyliron(III)porphyrins to yield the corresponding acyliron(III) derivatives. 16a,b A mechanism involvingthe CO-assisted homolytic cleavage of the Fe-alkyl bond followed by the rapid attack ofthe Fe-CO intermediate by the caged alkyl radical was suggested. 16a,b A similar processseems likely in the ruthenium systems (reaction 5.5), or at least in the cases where thearoyl or acyl intermediates were observed or isolated. In any event, the CO clearlyfacilitates the scission of the Ru-C bond of the bis(phenyl) complexes as solutions207Ru(porp)R2+ CO I’[Ru(porp)(CO)R, R ] Ru(porp)(COR)R 5.5of these species are indefinitely stable at room temperature in the absence of the gas (evenin the presence of light). Carbon monoxide likely assists in the cleavage of the Ru-Mebonds as well, although this has not been clearly established as these bonds are susceptibleto cleavage by light (see section 5.6).Reactions 5.6 and 5.7 show a plausible mechanism for the further reaction of thearoyl/acyl intermediates with CO. By analogy, reaction 5.7 indicates that the CORu(porp)(COR’)R + CO Ru(porp)(CO)R + R’CO 5.6Ru(porp)(CO)R + CO Ru(porp)(CO)2+ R 5.7also assists in the cleavage of the Ru-COR bonds although this has not been clearlydemonstrated. The Ru-COPh bond is weaker than the Ru-Ph bond (see section 5.5.2) andis susceptible to both thermal- and photo-induced homolysis. To establish the mechanism,it is necessary to monitor solutions of the Ru(TMP)(COPh)Ph in both the light and dark todetermine if the rate of decomposition varies greatly from that observed in the presence ofCO. In any case, reaction 5.7 is expected to be relatively rapid due to the trans influenceof the carbonyl ligand. This is certainly suggested from the observation that Ru(OEP)Phwas quantitatively converted to Ru(OEP)(CO)2within 6 h after introducing 1 atm COwith no intermediates being observed.3aIt was suggested3that CO binds to the sixth siteof the five-coordinate species rather than inserting directly into the relatively robust Ru-Phbond; the Ru(porp)(CO)R intermediate presumably then breaks down via the homolysis of208the Ru-R bond. Once again the participation of CO in this bond scission has to beconfirmed.The fates of the radical species produced in reactions 5.6 and 5.7 are not known, asthe organic co-products were not observed in the ‘H NMR spectra. Clearly, gaschromatography or mass spectroscopy should be employed to identify these species. Forexample, the PhCO species is probably consumed in solvent reactions (possiblyproducing benzaldehyde or benzophenone) or alternatively via a coupling process(producing PhCOCOPh). The fate of the MeCO is even less clear as the stability of thisspecies under these condition (i.e. 1 atm CO) is not known. The possibilities becomesomewhat complicated by the fact that acyl radicals are known to decarbonylate accordingto reaction 5.8,18 the rate being dependent on the stability of the radical produced.RCO bR+CO 5.85.5 Kinetics of the decomposition of the Ru(TMP)R2complexes (R= Me, Ph, COPh)Earlier work with Ru(porp)R2complexes (porp = OEP, R= Me, Et, or aryl; porpTPP, R=Ph)3”5°”9(see also chapter 4, section 4.1.2 for related Ru(OEP)Np2work)established that anaerobic thermolysis of these species in solution results in the homolyticcleavage of one of the axial Ru-R bonds to give the Ru(porp)R species. In situ studies inthe present work reveal that the same is true for the dimethyl and bis(phenyl) complexes ofRu(TMP). Furthermore, anaerobic thermolysis of Ru(TMP)(COPh)Ph induces scission ofthe Ru-COPh bond. It should be noted that the RUCMe and Ru-Cs0ibonds are also209susceptible to light-induced cleavage because the anaerobic photolysis ofRu(TMP)Me2and Ru(TMP)(COPh)Ph with a mercury vapour lamp leads to the same ruthenium(III)products as does thermolysis. In contrast the photolysis of a solution ofRu(TMP)Ph2gave no discernible reaction.Figures 5.9 and 5.10 show the ‘H NMR spectra of the products resulting from thethermolysis ofRu(TMP)Me2and Ru(TMP)Ph2,respectively. A spectrum identical to thatshown in Figure 5-10 is also produced upon thermolysis of Ru(TMP)(COPh)Ph. Theoverall appearances of these spectra are consistent with the presence of low spinRu(TMP) systems (see chapter 3) where the porphyrin signals appear as broad singletssignificantly shifted from their diamagnetic positions. The effect is most pronounced forthe pyrrole protons in these complexes which typically appear at fields higher than -30ppm. The separation in chemical shifts of the anisochronous 0-methyl and rn-protons ofthe mesityl groups arises from the magnetic anisotropy of the two porphyrin faces.Clearly this reflects the loss of molecular symmetry (i.e. from D4h to C4) upon the loss ofone axial ligand from the reactant molecule.The axial phenyl protons of Ru(TMP)Ph (Figure 5-10) appear as three broadsinglets at -90.2, -58.3 and 52.9 ppm in Figure 5-10, corresponding to the 0-, p-, andrn-protons, respectively. These resonances are similar to those reported for theRu(OEP)Ph analogue (-83.1, -48.8, 48.8 ppm, respectively).3”5’These widely shiftedsignals suggest significant delocalization of the unpaired electron density to the axial21010Figure 5-9: ‘H NMR spectrum (d8- toluene, 300 MHz) of Ru(TMP)Meprepared via the anaerobic thermolysis of Ru(TMP)Me2at 1110 C for 24 h.S = solvent.p-CH3rn-HS.0 3. 5 3.0 2.5 2’G 1. 5 10 05 PPA 01)0 —10—20 —30 PPA —40pyrr211pyrrp-CH3•I••‘•I•IIII•••‘I•‘‘••‘‘•I‘‘•‘‘I•‘‘‘‘‘•IIIIIIIIIIIIIIIIIIIIIIIIIIIIJIIIIIIIII[liiiI87654321OPPk4—1Figure5-10: 1HNMRspectrum(d8-toluene,300MHz)of Ru(TMP)PhpreparedviatheanaerobicthermolysisofRu(TMP)Ph2at1110Cfor 24h.S=solvent.Thethato,m, prespectivelyrefer totheortho-, meta-andpara-protons oftheaxial phenyl ligand.0%SPhIhIhIhIII1.11IIIII•IlIplIIIII1111111:111111111111JIIIIIIIIJIIII(CI1)..30—40—50-40—10—80—90PI’Arn-HoH)212phenyl ligand. In contrast, the axial methyl protons of Ru(TIVIP)Me are not observed inFigure 5-9, which is not unusual because the axial cx-proton signals are “extinguished” byextreme line-broadening due to the proximity of the paramagnetic metal center in theseruthenium(III) systems.The homolytic cleavage of the metal-carbon bond (reaction 5.9) is the initial andRu(TMP)R2 Ru(TMP)R + R 5.9rate-determining step in these reactions, and a study of the thermal dependence of thekinetics allows for an estimation of the bond strength (see chapter 4, section 4.1.2 for theRu(OEP)Np2system).2° This experiment is somewhat more difficult than it sounds, aseach system exhibits some idiosyncrasies that require procedural adaptations. Forexample, UV/visible spectroscopy is the preferred method for following these reactions;however, this is impractical for the light-sensitive complexes and thus the kinetics have tobe monitored by ‘H NMR spectroscopy in these cases. In the earlier studies with the OEPand TPP complexes,3l5researchers found that the reaction was not first-order in[Ru(porp)R21beyond 1.5 half lives when the thermolysis experiment was performed inbenzene. This was because the back reaction of equation 5.9 became competitive as theconcentration of the five-coordinate product increased. This problem was overcome byadding an excess of the radical scavenger, TEMPO,t or alternatively by studying thereaction in toluene which in many cases behaves in the essentially the same way. Thet 2, 2, 6, 6-tetramethylpiperidine-1-oxyl213latter approach was applied to the kinetic studies of the TMP complexes in this thesiswork.5.5.1 Thermal decomposition of Ru(TMP)Ph2The thermal decomposition of Ru(TMP)Ph2was monitored by UV/visiblespectroscopy as shown in Figure 5-11 for data collected at 1110 C. The appearance ofthree isobestic points at 368, 419 and 518 nm is consistent with the production ofjust theone new absorbing species (i.e. Ru(TMP)Ph) and the first-order plot of the data(Figure 5-12) was linear for the 3.5 half-lives the reaction was monitored.a,Ua,0a,Figure 5-11: UV/visible absorbance changes (measured at 25° C) for thethermolysis ofRu(TMP)Ph2at 1110 C. Initial [Ru(TMP)Ph21= 1.2 x iO M. a) 0s; b) 4111 s; c) 9096 s; d) 14,614 s; e) 20,700 s; e) 27,835 s; g) 37,456 s; h)49,989 s; i) 48 h.300 340 380 420 460 500 540 580Wavelength (urn)2140-0.5i-iI-:-2.5Figure 5-12: First-order plot for the thermal decomposition ofRu(TMP)Ph2intoluene at 1110 C. Absorbance changes were monitored at 414 nm. Raw data aregiven in appendix B.The mechanism shown in reactions 5.9 and 5.10 and the corresponding rateexpression (reaction 5.11; based on the steady state assumption for Ph) are consistentwith the kinetic data provided that the rate of the reaction of the phenyl radical withk1Ru(TMP)Ph2-.. Ru(TMP)Ph + Ph• 59k1k,’A C6D + (PhCH2 1/2 PhCHCHh)Ph• + PhCH3k Ph, CH3-HPh- 5.10—d[Ru(TMP)Ph2j= k [Ru(TMP)Ph — k1{Ru(TMP)Ph] 5.11dt 2 k1[Ru(TMP)Ph]+(k +k2)[PhCH3]jtoluene is rapid enough to overcome the k4 process of reaction 5.9. In other words,45000 50000Slope = - 4.3 X i0 s’Thtie (s)215(k2’ +k2”){PhCH3J>> lci[Ru(TMP)Ph], or to be more precise, this requires that(k2’ +k2’)>> M”s given that [PhCH3] 9.4 M, [Ru(TMP)Ph] 105M andk..1 1 M1s’ (see chapter 4). Independent studies in fact have shown that reaction 5.10yields a combined rate constant (i.e. (k2’ + k2”)) of the order of 106 Jf11 at 25° c 21which clearly satisfies the required condition at 1110 C. Thus the rate law reduces to thesimple first-order expression -d[Ru(TMP)Ph2]/dt= ki[Ru(TMP)Ph2],and k1 is thereforeequal to the experimental rate constant k0b.The observed rate constants at various temperatures for this thermolysis reaction aresummarized in Table 5-3 and the activation parameters AH= 33 ± 1 kcal mor’ andtS1=6.9 ± 0.3 e.u. were obtained from the Eyring plot (i.e. ln(kobdT) vs. l/T) shown inFigure 5-13.Table 5-3: Observed rate constants for the decomposition of Ru(TMP)Ph2at various temperatures in toluene.’Temperature (° C) Lis X S100 1.20106 2.50111 4.30119 11.0a) Absorbance vs. time data are given in appendix B.216-15-15.5-16-16.5-17—17.5 I I I I I I I I0.00254 0.00256 0.00258 0.0026 0.00262 0.00264 0.00266 0.00268 0.002711f(K’)Figure 5-13: Eyring plot for the decomposition of Ru(TMP)Ph2.5.5.2 Thennal decomposition of Ru(TMP)(COPh)PhAs previously mentioned, Ru(TIVIP)Ph is produced quantitatively upon thermolysisof Ru(TMP)(COPh)Ph in solution. Because of the sensitivity of this material to light, thereaction was monitored by ‘H NIVIR spectroscopy in the darkness of the NMR-probe andthe changes in the Ru(TMP)(COPh)Ph ‘H signals were analyzed. The benzoyl complexdecomposed directly to the mono-phenyl species, and the reaction was first-order in thereactant as demonstrated by the linear plots of ln(int_pyrr)t vs. time (Figure 5-14).The NrvIR and kinetic data are consistent with the homolysis of the Ru-COPh bond(reaction 5.12) being the rate determining step for the thermolysis; however, the fateintegration of the pyrrole signal, = 8.58 ppmslope’-16,592Kintcept = 27221743.53a50.50Figure 5-14: First-order plot for the thermal decomposition ofRu(TMP)(COPh)(Ph) in8-toluene at 800 C. *Ln(jnt.pyff) = Ln(integration of thepyrrole peak of Ru(TMP)(COPh)Ph, ö = 8.58 ppm). Raw data are given inappendix B.Ru(TMP)(COPh)Ph - Ru(TMP)Ph + PhCO 5.12of the benzoyl radical has not been established. This species is likely lost to rapidreactions with the toluene solvent although there was no evidence for any of theconceivable organic derivatives (eg. benzaldehyde or methylated benzophenone) in the 1HNMR spectrum. In any case, the subsequent reactions of the benzoyl radical must berapid enough to negate the back reaction of equilibrium 5.12.Table 5-4 shows the first-order rate constants obtained at 60, 70 and 80° C for thethermolysis of Ru(TMP)(COPh)Ph. The Eyring plot of the data (Figure 5-15) yieldsvalues of 22 ± 2 kcal mo11 and -11± 4 e.u, for i.H1 and tS1, respectively.-4slope3.4x10 s0 1000 2000 3000 4000 5000 6000 7000 8000Time (s)218Table 5-4: Observed rate constants for the thermolysis of Ru(TMP)(COPh)Ph intoluene. aTemperature (°C) initial k x 1 s[Ru(TMP)(COPh)Ph]x i03, M60.1 3.1 4.770.1 1.3 13.080.0 2.5 34.0a) Raw data are given in appendix B.-13.8-14-142-144—-146.-14.8C §qe=-11,3WK-15 it=18.1-15.2-15.4-15.6—15.8 I I IOXX2 Qt284 O.IXQ O.ctQ QW29 O.IXQ92 OXQ9’1 O.IX% O.W2 QIXI3 Offl3QFigure 5-15: Eyring plot for the decomposition of Ru(TMP)(COPh)Ph.2195.5.3 Thermal decomposition of Ru(TMP)Me2The kinetics of the decomposition of the light-sensitive Ru(TMP)Me2were also monitoredby ‘H NN’IR spectroscopy. This reaction is first-order in the dimethyl species(Figure 5-16) and yields the lone five-coordinate product with no intermediate speciesobserved en route.43.531251.50.50Figure 5-16: First-order plot for the thermal decomposition ofRu(TMP)Me2intoluene at 700 C. *Ln(int...pyff) = Ln(integration of the pyrrole peak ofRu(TMP)Me2,ö = 8.39 ppm). Raw data in appendix B.The reaction likely proceeds via the mechanism shown in equations 5.13 to 5.15which is drawn by analogy to the suggested mechanism for the thermolysis ofRu(OEP)Me2.3In the OEP system, the identification of the methane and ethylene coproducts in a 2:1 stoichiometry led to this reaction scheme. It should be noted, however,that neither species was observed in the solution ‘H NIVIR spectrum of the TMP system.The rate equation for this process, assuming a steady-state concentration for Me, is givenslope -3.35x1050 10000 20000 30000 40000 50000 60000 70000Time (s)220in equation 5.16, and thus the observed first-order dependence on the dimethyl speciesk1Ru(TMP)(CH3)2 k Ru(TIVIP)(CH3)+ CH3 5 13—1CHk IRu(TMP)(CH3)2+ CH3 + CHCH2 5.14CH3 k32 ‘ 2Ru(TMP)Me + CH2CH2 5.15— d[Ru(TMP)Me2]= k [Ru(TMP)Me2]I1+k2[Ru(TMP)Me]_ku(TMP)Me]’1 5.16dt ‘ [Ru(TMP)Me]+ku(TMP)Me1requires thatk2[Ru(TMP)(CH3)J>> k..i[Ru(TMP)CH3J. In this event, the 2nd term inbrackets of equation 5.16 is effectively I (i.e.k2[Ru(TMP)Me]/k2[Ru(TMP)Me]),andthe overall rate expression is therefore reduced to -d[Ru(TMP)Me]/dt=2k1[Ru(TMP)Me],where 2k1 k.It is important to emphasize, however, that the required kinetic condition presentsthe same paradox encountered for the Ru(OEP)Np2(see chapter 4, section 4.1.2); that is,the rate of the hydrogen abstraction must be much greater than the supposedly diffusioncontrolled20k4 recombination process. For the mechanism to be correct, the kinetic datarequire that the k4 recombination process must be somewhat slower than previouslybelieved, at least in the case of methyl (and apparently neopentyl) radicals. For example,in the limiting case that the hydrogen abstraction reaction is difilision controlled (i.e. k2M4 sj, the maximum value of k..1 would have to be 108 Ms in order to produce221the observed first-order dependence on Ru(TMP)Me2,given that [Ru(TMP)Me2]+[Ru(TMP)Me] 1 0 M. Even then, simple calculations suggest that the first-orderdependence would break down after about 1.5 to 2 half-lives, whereas the empirical data(see Figure 5-16) revealed first order behaviour for up to 3 half-lives; the observed datarequire that k2 100k4 or, in the limiting case, k4 1 M1s. Clearly this is much slowerthan diffusion control.In light of this anomaly, a second mechanism was considered involving the reactionof the methyl radical with ds-toluene (reaction 5.17). By the same token, this scenariok2PhCD3 + CH3 organic products 5.17requires that k2’ [C7D8]>> lci[Ru(TMP)Me], which in turn demands thatk2>> M’s1given that [Ru(TMP)Me] = M, [C7D8]= 9.4 M and assuming k1 iüHowever, this seems inconsistent with the known rate constant for reaction 5.17 in the gasphase(i.e. k2 104 M1s’ at 65° C)22 and therefore this scheme was rejected.Accordingly, the reaction scheme outlined in equations 5.13 to 5.15 probably doesapply to the Ru(porp)Me2systems and, in light of the kinetic results, the rate constant forthe coordination of methyl radicals to the Ru(porp)Me species has a maximum value onthe order of 1 I4’f’s As discussed, this conclusion is in direct conflict withconventional wisdom.The experimental rate constants obtained at temperatures ranging from 70 - 90° Care listed in Table 5-5. Included are the corresponding k1 rate constants for the homolysis222of the Ru-Me bonds based on the previously derived relation 2k1 = k0b. A plot of ln(ki/T)vs. lIT (Figure 5-17) yields an activation enthalpy (AH1)of 22 ± 2 kcals moF1 and anactivation entropy (AS1)of-17 ± 4 e.u.Table 5-5: Observed rate constants for the thermolysis of Ru(TMP)Me2in d8-toluene at various temperatures.’Temperature (°C) initial [Ru(TMP)Me2] kobs X 1 S1 k1 X 1 5x M70.0 4.5 3.4 1.779.8 3.3 8.8 4.483.2 3.4 10.4 5.289.8 5.8 20.4 10.2a) Raw data are given in Appendix B.5.5.4 Determination of the strength of Ru-R bonds (R= Ph, PhCO and Me)As discussed in chapter 4, the difference in the activation enthalpies for the forwardand reverse processes of the general reaction 5.9 (i.e.AHiMLit) corresponds to thedifference in the enthalpies of the reactants and products and thus translates directly intothe solution bond dissociation energies (BDE values) of the Ru-R bonds. Therecombination processes are believed to be diffusion controlled20and therefore theactivation enthalpies (i.e. tH1)are expected to be on the order of 2 kcal mor’. Thus, thebond dissociation energies are roughly estimated by the expression BDE = t\H1-2 kcal223-I8-162QX274 QX2 QftQ€ OfXi7i WX ox oX xx Qa Oft21f)Figure 5-17:Eyring plot for the decomposition ofRu(TMP)Me2mof1. Table 5-6 shows the bond dissociation energies so calculated for the threeRu(TMP)R2complexes described above. Also included are the BDE values of somerelated complexes determined in earlier work.It should be noted that the BDE values calculated in this way should be consideredwith caution as the recombination of the various radical species with Ru(TMP)R (i.e. thek step) may not necessarily be diffusion controlled. Specifically, the kinetic results forthe thermolysis ofRu(TMP)Me2and Ru(OEP)Np2suggest a maximum rate constant of1 M’s’ for the attack of Ru(TMP)Me by a free methyl radical. This translates to a-142-144-146-148-15-I52-15.4qe=-1c841 1<u1utj1 =15.5224Table 5-6: Bond dissociation energies for the axial Ru-R bonds of someRu(porp)R2complexes.Complex Activation Enthalpya BDE (kcal mol’) Ref(\H kcal mot’)Ru(TMP)Me2 22 20 twRu(OEP)Np1’ 16 14 twRu(OEP)Et21’ 23.7 21.7 19Ru(TMP)(COPh)Ph 22.0 20.0c twRu(TMP)Ph2 33 30.9 twRu(OEP)Ph2 32.1 30.1 3a,15cRu(TPP)Ph2 34.2 32.2 3aa) All values were measured in toluene (or dg-toluene) unless otherwise noted.b) Measured ind6-benzene. c) Value refers to the Ru-COPh bond.zS.H of approximately 5 kcal mol4,t and thus the BDE of Ru-Me approximates tozH - 5 = 17 kcal mol’. Therefore the BDE of 20 kcal mol’ in Table 5-6 shouldprobably be considered as an upper limit for the Ru-Me bond.Several factors influence the strength of the Ru-R bonds in Table 5-6. For example,the values listed represent bonds that are somewhat weakened by the trans influence of thesecond axial ligand. The various Ru-R bonds are clearly more robust in the absence ofthis effect, as the second axial bond did not cleave under the conditions of the experiment.The effect of the porphyrin macrocycle can also be observed as the axial Ru-Ph bonds inthe OEP and the TPP systems, for example, become moderately weaker as the basicity ofThe value of AH.1 was calculated for k1 = M1&’ using transition state theoiy, given that AH1 2 kcals mol’when k-i = M’s’.2° As a first approximation, this calculation assumes that the change in rate is influencedonly by changes in AIL.225the porphyrin increases. This trend has been previously noted for iron (III) complexes.23Note that the BDE values for Ru(TMP)Ph2and Ru(OEP)Ph2suggest that TMP and OEPare equally strong bases; the same conclusion was reached earlier (see chapter 3) from thereduction potentials of the corresponding dichloro compounds. Finally, the nature of theR group has a large effect on the strength of the axial bond. For example, the RUCar3,ibonds are some 8-12 kcal mot’ stronger than the RuCaiicyi bonds, consistent with theusually accepted stronger M-C2bond.24 It is interesting to note that the Ru-Ph bond isapproximately 11 kcal mol’ stronger than the Ru-COPh bond of Ru(TMP)(COPh)Ph.The Ru-C bond of the benzoyl ligand is presumably destabilized by steric interactions ofthe axial ligand with the porphyrin ring.5.6 Photoreactions of Ru(TMP)Me2As previously mentioned (section 5.2), the column purification ofRu(TMP)Me2wascarried out in the dark as solutions of this material were somewhat light-sensitive. Forexample, N1\4R samples (1O- 102 M) appeared stable for up to a day under normallaboratory light; however, decomposition products would begin to appear after extendedperiods unless the solution was stored in the dark. The reaction(s) was(were) clearlyaccelerated on the alumina as these decomposition products were always present in thematerial isolated from columns that were exposed to light, even after periods as short as a30 mm.In an attempt to better understand this chemistry, some in situ experiments wereconducted using a mercury vapor lamp as the light source. These studies revealed that the226metalloporphyrin products differ when the photo-induced reactions were carried out in thepresence or absence of dioxygen. For example, Ru(TMP)Me was the solemetalloporphyrin product when the dimethyl species ( 6 mM in dg-toluene) wasphotolyzed under argon for 5 h. On the other hand, photolysis of a solution ofRu(TMP)Me2( 4 mM in dg-toluene) sealed under dry 02 resulted in the formation of aRu(TMP)CO species within 3’/2 h, as judged by the in situ NMR and UV spectra, and thesolid state JR spectrum of the isolated material. The ‘H NMR spectrum (Figure 5-18) isvirtually identical to that of Ru(TMP)(CO)(1PrOH),la while the CO stretching frequency(1936 cm’, KBr) and the electronic absorption spectrum (?.ax(nm), toluene: 528, 412)also match those reported for this species. laThe broad peak at -0.55 ppm in Figure 5-18 is likely due to an organic co-productof the reaction. The integration indicates that this peak represents 3-4 protons and thebreadth and frequency of the signal suggest that this species is rapidly exchanging at thesixth coordination site of Ru(TMP)CO. The general broadness of the porphyrin signalstends to support this. This ligand is tentatively assigned as methanol although the OHstretch was not observed in the JR spectrum; the JR data were obtained in the solid state(KBr), however, and the methanol was possibly during the isolation procedure.tThe production of Ru(TMP)CO and methanol alone during the photolysis reactionunder 02 does not give a balanced reaction, and therefore at least one more product isThis material was isolated from the NN’IR solution by removing the solvent on the Rotovap.227ep-CHFigure 5-18: ‘H NMR spectrum(d8-toluene, 300 mHz) ofRu(TMP)CO(MeOH) produced by the photolysis of Ru(TMP)Me2under 1 atm 02.S = solvent. 1 = MeOH (tentatively, see text).228pyrrI I I I I I I ( I I I I I I I I I I [II 1T_I I1T I1I I I I I I I IEFIJ8 6 4 2 OPPMindicated. On paper, the co-production of one equivalent of water conveniently balancesthe equation (reaction 5.18); however, there is no evidence for this species in the in situ‘H NMR spectrum. Clearly a more complete product analysis is warranted.Ru(TMP)(CH3)2+ 1.5 02 ‘ Ru(TMP)(CO)(CH3OH)+ H20 5.18Both of the above processes (photolysis in the presence or absence of 02) arepresumably initiated by the photo-induced homolysis of one Ru-Me bond (reaction 5.19).Ru(TMP)(CH3)2_hv Ru(TIvIP)CH3+ CH3 5.19The fate of the methyl radical produced is then dependent on the presence or absence of02. In the latter event, this species would presumably attack Ru(TMP)Me2to yieldRu(TMP)Me and perhaps methane and ethylene in a process akin to the thermal reaction(see section 5.5.3). In contrast, reaction 5.20 almost certainly dominates the chemistry ofthe methyl radical in the presence of dioxygen, as the rate of reaction between 02 and alkylradicals is essentially diffusion controlled.25 The mechanistic course of the subsequentoxidation of CH3 to CO is unknown.CH3 +02 CH300 5.20One can imagine at least three possible fates for the methylperoxy radical producedin reaction 5.20. For example, this species could attack the vacant coordination site of theRu(TMP)Me to yield the peroxo complex shown in reaction 5.21. Peroxo analogues ofRu(TMP)Me + CH3OW ‘ Ru(TMP)(Me)OOCH3 5.21229iron (III) and cobalt(III) have been prepared by the direct insertion (thermal- and photo-chemical, respectively) of 02 into the M-R bond’626 and, in truth, reactions 5.19 to 5.21could occur within the confines of the solvent cage to produce Ru(TMP)(CH3)OOCH by“direct insertion” as well. In any case, this peroxo species would likely break down viareaction 5.22, as similar chemistry has been established forRu(TMP)(CH3)(OOCH Ru(TMP)(CH3)(OH) + CH2O 5.22the closely related iron species (i.e. Fe(TMP)OOCH3— Fe(Th4P)OH + CH2O).16e,dFurthermore, the remaining methyl ligand could conceivably experience the same fateproducing Ru(TMP)(OH)2and a second mole of formaldehyde as summarized in reaction5.23. This is an attractive possibility as preliminary experiments suggest thatRu(TMP)(CH)OH+02 Ru(TMP)(OH)2+ CH2O 5.23Ru(TMP)(OH)2can serve as an intermediate in the decarbonylation of aldehydes andketones.27 On the contrary, there is no evidence for the presence ofRu(TMP)(OH)2,Ru(TMP)(CH3)(OH) or formaldehyde in the in situ 1H NIVIR spectrum and the suggestedreactivity pattern does not account for the production of methanol.It should be noted that certain Fe(porp)OOR complexes thermally decompose viahomolysis of the 0-0 bond to yield Fe(porp)0 and the alkoxy radical species. Thisreaction has been observed in complexes with R groups that lack the necessary cchydrogen atoms required for a reaction such as 5.22 (i.e. when R = tBu adamantyl,4-camphyl or aryls), 16e,f and is promoted by the addition of strong bases such as pyridineand 1 -methylimidazole which presumably influence the chemistry via coordination at the230vacant site of the iron peroxo complexes. Although reactions such as 5.22 and 5.23 seemmore favourable based on the observations for the iron systems (i.e. there is an availablea-hydrogen), a possible thermal reaction such 5.24 can not be ruled out as the effectRu(TMP)(Me)OOCH3 Ru(TMP)(CH3) 0)+CH30 5.24of the trans-methyl group is not known. At the very least, this reaction could bepromoted by light as such photo-induced homolysis of organic peroxides is wellknown.25’8The Ru(V) mono-oxo product of reaction 5.24 is not expected to be stableand in the presence of excess 02 would probably yield Ru(TMP)(0)2.9 This too is anattractive route as the dioxo complex is a strong oxidizing agent and will oxygenate anumber of organic species29 (also see chapter 1). However, neither Ru(TMP)(0) orRu(TMP)(0)2were observed in the ‘H NMR spectrum during the course of the photolysiswith the mercury vapour lamp. On the other hand, a significant amount ofRu(TMP)(O)2was visible (along with Ru(TMP)C0 and unreacted Ru(TMP)Me2)in the ‘H NMRspectrum of a C6D Ru(TIVEP)Me2/airsolution after one week under normal laboratorylight. It is not clear, however, if this dioxo species is an intermediate en route toRu(TMP)C0 or the product of a competitive thermal reaction under the less intense light.It should also be noted that the intermediacy of Ru(TMP)(0)2species is not consistentwith the production of methanol, as the dioxo complex oxidizes this alcohol presumably toformaldehyde.27While the iron studies provide compelling precedent for the production of a peroxointermediate formed via reactions 5.19 to 5.21, several questions remain about theplausibility of this route. For example, a significant amount of Ru(TMP)CH3was231observed in the ‘H NIVIR spectrum throughout the course of the photolysis with themercury vapour lamp, suggesting the CH300 had been consumed in other reactions. Asmentioned, the failure to observe any of the intermediate Ru(TMP) species predicted inreactions 5.2 1-5.24 is of concern, although these species might be very short lived underthe conditions of the experiment. Finally, the production of MeOH is not consistent withany of the conceivable fates ofRu(TIvIP)(CH3)(OOCH albeit the production of MeOHrequires conformation.In an alternative scenario, the methylperoxy radical produced in reaction 5.20 mightabstract a hydrogen atom from the axial methyl group ofRu(TMP)(CH3)2(and/orRu(TMP)CH3)according to reaction 5.25. Peroxy radicals do abstract hydrogenRu(TMP)(CH3)2+ CH300 Ru(TMP)(CH3)CH2+ CH300 5.25atoms from a variety of organic molecules and thus reaction 5.25 seems credible. In thisevent, the methyl hydroperoxide produced could serve as a source of methoxy andhydroxy radicals (reaction 5.26), especially when illuminated by the mercury vapourhvCH300 CH30+0H 5.26lamp. The conceivable fate of these radical species is limited only by one’s imagination;possibilities include hydrogen atom abstractions, coordination to Ru(TMP)Me or attack ofthe methylene ligand ofRu(TMP)(CH3)CH2.Finally, the coupling of primary and secondary peroxy radicals can result in the rapidformation of products such as those shown in reaction 5.27 for the present case. Such232reactions are involved, for example, in the termination of radical-chain processes.252 CH300 ‘ CH0 + CH3O +02 5.27This notwithstanding, reaction 5.27 is not considered to be important in this chemistry asthe relative concentration ofCH300 is expected to be exceedingly small and, unlessreactions 5.21 and/or 5.25 are extremely unfavourable, the significance of this couplingreaction is likely to be negligible in the overall scheme.It is impossible to determine which of the possible fates outlined for themethylperoxy radical is most important in this Ru porphyrin chemistry. Moreover, it is notclear how any of these pathways would lead to the proposed products. As far as theauthor is aware, there is only a single precedent in the organometallic literature for theCH3 to CO oxidation: the thermal oxidation ofRu(OEP)CH3by excess TEMPO (with[TEMPO]:[Ruj 5)30 Although no mechanistic studies were noted in this report, onehypothesis involved a series of stepwise hydrogen abstractions from the axial methylligand coupled with an oxygen atom transfer. TEMPO was thought to play the dual rolesof hydrogen atom abstractor and oxygen atom donor, as this species is a commonlyemployed radical and the only source of oxygen in the system. Thecurrent case (Ru(TIvIP)Me2/0)is far more complicated and more data clearly are neededto elucidate the reaction pathways responsible for the CH3 to CO transformation.2335.7 References for Chapter 51a) Rajapakse, N. Ph.D. Thesis, University ofBritish Columbia, 1990.b) Rajapakse, N.; James, B.R.; Dolphin, D. Can. J. Chem., 68, 2274 (1990).2 Venburg, G.D. Ph.D. Thesis, Stanford University, 1990.a) Ke, M. Ph.D. Thesis, University of British Columbia, 1988.b) Ke, M.; Sishta, C.; James, B.R. ; Dolphin, D.; Sparapany, J.W.; Ibers, J.A. Inorg.Chem., 30, 4766 (1991).4a) Camenzind, M.J.; James, B.R.; Dolphin, D. J. Chem. Soc. Chem. Commun., 1137(1986).b) Sishta, C.; Camenzind, M.J.; James, B.R.; Dolphin, D. Inorg. Chem., 26, 1181(1987).c) Camenzind, M.J.; James, B.R.; Dolphin, D.; Sparapany, J.W.; Ibers, J.A. Inorg.Chem., 27, 3054 (1988).Jason, T.R.; Katz, J.J. in The Porphyrins, Dolphin, D Ed., Academic Press, New York,1978, vol. IV, chapter 1, p.1.6a) Maskasky, J.E.; Kenney, M.E. J. Am. Chem. Soc., 95,1433 (1973).b) Kadish, K.M.; Xu, Q.Y.; Barbe, J.M.; Anderson, J.E.; Wang, E.; Guilard, R.J. J. Am.Chem. Soc., 109, 7705 (1987).a) Ogoshi, H.; Setsune, J.; Omura, T.; Yoshida, Z. I Am. Chem. Soc., 97, 6461 (1975).b) Coutsolelos, A.; Guilard, R. I Organomet. Chem., 253, 273 (1983).c) Kadish, K.M.; Boisselier-Cocolios, B.; Coutsolelos, A.; Mitaine, P.; Guilard, R.Inorg. Chem., 24, 4521 (1987).234d) Kadish, K.M.; Tabard, A.; Zrineh, A; Ferhat, M.; Guilard, R. Inorg. Chem., 26, 2459(1987).8 Rajapakse, N.; James, B.R.; Dolphin, D Stud Surf SeE. Catal., 55, 109 (1990)Cheng, S.Y.S.; Rajapakse, N.; Rettig, S.J.; James, B.R. J. Chem. Soc., Chem.Commun., 2669 1994.10 James, B.R.; Rajapakse, N. unpublished results.‘a) Fleischer, Acc. Chem. Res., 3, 105 (1970).b) Collins, D.M.; Countryman, R.; Hoard, J.L. J. Am. Chem. Soc., 94, 2066 (1972).12 a) Eaton, S.S.; Eaton, G.R. J. Am. Chem. Soc., 97, 3660 (1975). and referencestherein.b) Little, R.G., Ibers, J.A. J. Am. Chem. Soc., 95, 8584 (1973).c) Hoard, J.L. Science, 174, 1295 (1971).d) Ball, R.G.; Lee, K.M.; Marshall, A.G.; Trotter, J. Inorg. Chem., 19, 1463 (1980).13 a) Gregory, U.A.; Ibekwe, S.D.; Kilbourn, B.T.; Russel, D.R. J. Chem. Soc., (A), 1118(1971).b) Reveco, R.; Schmehl, R.H.; Cherry, W.R.; Fronczek, F.R.; Selbin, T. Inorg. Chem.,24, 4078 (1985).c) Chakravarty, A.R.; Cotton, F.A.; Tocher, D.A. .J Am. Chem. Soc., 106, 6409(1984).d) Chawdhury, S.A.; Dauter, Z.; Mawby, R.J.; Reynolds, C.D.; Saunders, D.R.;Stephenson, M. Acta Crystallogr., Sect. C, 39, 985 (1983).e) Dauter, Z.; Mawby, R.J.; Reynolds, C.D.; Saunder, DR. Acta Crystaiogr., Sect. C,39, 1194 (1983).f) Hitchcock, P.B.; Lappert, M.F.; Pye, P.L.; Thomas, S. J. Chem. Soc., Dalton Trans.1929 (1979).t4Miyamoto, T.K.; Sugita, N.; Matsumoto, Y.; Sasaki, Y.; Konno, M. Chem. Lett., 1695(1983).23515 a) Fleischer, E.B.; Lavellee, D. J. Am. Chem. Soc., 89, 7132 (1967).b) Takenaka, A.; Syal, S.K.; Sasada, Y.; Omura, T.; Ogoshi, H.; Yoshido, Z. ActaCrystallogr., Sect. B, 32, 62 (1976).c) Ke, M.; Rettig, S.J.; James, B.R.; Dolphin, D. I Chem. Soc., Chem. Commun., 1110(1987).d) Matthews, R.W.; Tasker, P.A. Inorg. Chem., 16, 3293 (1977).e) Doppelt, P. Inorg. Chem., 23, 4009 (1984).16a) Arafa, I.M.; Shin, K.; Goff, H.M, J. Am. Chem. Soc., 110, 5228, (1988).b) Gueutin, C.; Lexa, D.; Momenteau, M.; Saveant, J.-M. J. Am. Chem. Soc., 112,1874 (1990).c) Arasasingham, R.D.; Baich, A.L.; and Latos-Grazynski L. J. Am. Chem. Soc., 109,5846 (1987).d) Arasasingham, R.D.; Baich, A.L.; Cornman, C.R.; Latos-Grazynski J. Am. Chem.Soc. 111, 4357 (1989).e) Baich, A.L.; Hart, R.L.; Latos-Grazynski, L.; Traylor, T.G. J. Am. Chem. Soc., 112,7382 (1990).f) Arasasingham, A.L.; Baich, A.L.; Hart, R.L.; Latos-Grazynski, L. .1. Am. Chem. Soc.,112, 7566 (1990),g) Cocolios, P.; Laviron, E.; Guilard, R. J. Organomet. Chem., C(39), 228 (1982).17 Camenzind, M.J.; James, B.R.; Dolphin, D. .1. Chem. Soc., Chem. Commun., 1137(1986).18 Abell, P.1. in Free Radicals, Kochi, J.K. Ed., John Wiley and Sons, New York, 1973,vol II, chapter 13, p. 63.19 Coilman, J.P.; McElwee-White, L.; Brothers, P.J.; Rose, E. I Am. Chem. Soc., 108,1332 (1986).20 Halpern, 3. Acc. Chem. Res. 15, 238 (1982).21 Scaiano, J.C.; Stewart, L.C. I Am. Chem. Soc., 105, 3609 (1983).23622 Ingold, K.U. in reference 18, vol I, chapter 2, p. 37.23 Guilard, R.; Kadish, K.M. Chem. Rev. 88, 1121(1988).24a) Skinner, H.A.; Conner, J.A. Pure Appi. Chem., 57, 79(1985).b) Jones, W.D.; Feher, F.J. J. Am. Chem. Soc., 106, 1650 (1984).c) Nolan, S.P.; Hoff, C.D., Stoutland, P.O.; Newman, L.J.; Buchanan, J.M.; Bergman,R.G.; Yang, O.K.; Peters, K.S. J. Am. Chem. Soc., 109, 3143 (1987).25 Howard, J.A. in reference 18, vol. II, chapter 12, p. 3.26 Perree-Fauvet, M. Gaudemer, A.; Boucly, P.; Devynck, J. J. Organomet. Chem., 120,439 (1976).27 James, B.R.; Cheng, S.Y.S. unpublished results.28 Kochi, J.K. in reference 18, vol II, chapter 23, p. 665.29odcka T; James, B.R. in Metaioporphyrin Catalyzed Oxidations, Montanan, F.and Casella, L. Ed., Kluwer Academic Publishers, 1994, p. 121,. and references therein.° Seyler, J.W.; Fanwick, P.E.; Leidner, C.R. Inorg. Chem., 31, 3699 (1987)31a) Hill, C.L.; Whitesides, G.M. J. Am. Chem. Soc., 96, 870 (1974).b) Nigam, S.; Asmus, K.D.; Wilison, R.L. J. Chem. Soc., Faraday, Trans., I, 72, 2324(1976).c) Finke, R.G.; Smith, B.L.; Mayer, B.J.; Molinero, A.A. Inorg. Chem., 22, 3677(1983).d) Finke, R.G.; Hay, B.P. Inorg. Chem., 23, 3041 (1984).e) Hay, B.P.; Finke, R.G. J Am. Chem. Soc., 108, 4820 (1986).237Chapter 66. General Conclusions and Recommendation for Future WorkIn this thesis, the Ru(porp)X2complexes (porp = OEP, X = Cl; porp = TMP, X =Cl, Br) were prepared via the anaerobic oxidation ofRu(porp)L2reagents (porp = OEP,L= py; porp TMP, X = CH3N) with the appropriate FIX acid. These reactions wereshown to proceed by at least two discrete steps to give first the correspondingRu(porp)X(L) species, which are then further oxidized to give the final Ru”(porp)X2products. The isolation of Ru(OEP)Cl(py), and the co-isolation of Ru(TMP)Br(CH3CN)from product mixtures of incomplete reactions, confirmed the intermediacy of the Ru(III)species. If simple isolation procedures can be found, these reactions might prove to beuseful routes to the Ru(ffl) derivatives as well.The times needed to effect complete oxidation (to the Ru(IV) species) were foundto be on the order of days in this work, much longer than previously reported (severalhours). These difference probably reflect unidentified differences in the reactionconditions from the earlier work, and the effects of these differences on the Ru(llI) —*Ru(IV) oxidation. This step should be examined independently to determine what effectfactors such as the identity of L, the concentration ofH20 and/or the intensity of lighthave on the reaction rate. Furthermore, the possible role of 02 in the Ru(llI)/Ru(IV)oxidation should be studied.238The new Ru(TMP)X(NH3)species (X = Br, Cl) were also prepared by reduction ofthe corresponding dihalo complexes with anhydrous ammonia, a method that hadpreviously been applied only to the OEP systems. A third route to such compounds wasdiscovered when an in situ reaction of Ru(OEP)C12with Ru(OEP)py2led toRu(OEP)Cl(py). A similar avenue might prove to be useful in preparing the elusive five-coordinate Ru(OEP)Cl species (i.e. [Ru(OEP)]2+ Ru(OEP)C12). This complex wasprepared previously by treating Ru(OEP)C1(NH3)with HF; however, this result could notbe reproduced in this present thesis work.The Ru(OEP)Cl2species was used as a reagent in reactions with neopentyllithium,bis(2-methyl-2-phenylpropane)magnesium [(neophyl)2Mg], and benzylpotassium (BzK), inattempts to prepare the corresponding Ru(OEP)R2complexes. However, the reducingpower of these alkylating agents dominated the chemistry. This was best demonstrated forthe NpLi systems, as the products of the reaction were shown to be extremely sensitive tothe ratio of the starting materials: Ru(OEP)Np and Ru(OEP)Np2resulted from thereaction ofRu(OEP)Cl2with 2 equivalents ofNpLi, [Ru(OEP)Np](p-Li) from thereaction with 3 equivalents and [Ru(OEP)Np]Q.t-Li),and Ru(OEP)Np2Lifrom thereaction with 4 equivalent ofNpLi. A series of reactions involving the neopentyl radicalwas proposed to account for these products. Of these complexes, Ru(OEP)Np, and[Ru(OEP)Np]2Qi-Li)were isolated as was Ru(OEP)(neophyl) from the reaction ofRu(OEP)C12with 1.5 equivalent (neophyl)2Mg. An attempt to synthesizeRu(OEP)(CHPh)(n = 1, 2) was unsuccessful; however, in situ experiments suggest that239the 5-coordinate species can be synthesized via the reaction of Ru(OEP)C12with no morethan 2 equivalents of BzKThe Ru(OEP)Np2produced from the reaction ofRu(OEP)C12with 2 NpLidecomposes over a period of about 2 days to produce a 50:50 mixture of Ru(OEP)Np anda species which was tentatively identified as the carbene species Ru(OEP)(CHC(CH3).The reaction also results in the production of neopentane and 2, 2, 5, 5-tetramethyihexane.Kinetic studies at several temperatures reveal that the reaction proceeds by the rate-determining homolysis of a Ru-Np bond, followed by the rapid abstraction of an chydrogen atom from Ru(OEP)Np2.This mechanism presents a problem, however, in thatthe kinetics demand that the rate of the hydrogen atom abstraction must be much greaterthan the rate of the reaction of the Np radical with Ru(OEP)Np, a reaction that is in aclass generally considered to be diffusion controlled. It would be highly desirable todetermine the absolute rate of the reaction ofNp with Ru(III) porphyrins.The [Ru(OEP)Np]2(.t-Li) species is unique among metalloporphyrin complexes inthat it is the first lithium-bridged species reported. The lithium bridge is quite robust asthe dimeric structure is also consistent with the solution ‘H- and7Li-NMR spectra.However, the complex is extremely sensitive to both air and water becoming oxidized to[Ru(OEP)OH12(t-O)and Ru(OEP)Np, respectively, by these reagents.The reactions of Ru(TMP)C12with 6 equivalents ofPhLi or MeLi resulted in theisolation of the corresponding Ru(TMP)R2species. Reactions of Ru(TMP)C12with NpLi,on the other hand, displayed a sensitivity to the ratio of the reagents similar to the OEP240system, the concentration of Ru(II) products ultimately increasing with the increasingNpLi:Ru(OEP)Cl2ratio. The Ru(TMP)Np2,Ru(TMP)Np, [Ru(TMP)Np]Li andRu(TMP)Np2Lispecies were observed during in situ experiments, but attempts toseparate and isolate these complexes met with limited or no success.Both the Ru(TMP)Me2and Ru(TMP)Ph2complexes react with CO (at 1 atm) intwo discrete steps, initially producing Ru(TMP)(COR)R, and then Ru(TMP)(CO)2.Therate of the second step was slowed in the case of the Ru(TIVIP)(COPh)Ph species byperforming the reaction in the dark, and thus the benzoyl complex was isolated andcharacterized. This may prove to be a useful synthetic route to acyl and/or aroylcomplexes if the optimum thermal- and photo-conditions for each system can beestablished.The Ru(TMP)Me2,Ru(TMP)Ph2and Ru(TMP)(COPh)Ph complexes are allthermally susceptible to the homolytic cleavage of an axial bond, yielding the five-coordinate Ru(TMP)Me species in the first case and Ru(TMP)Ph in the last two. Kineticstudies indicate that the reactions of all three complexes proceed by the rate-determininghomolysis of the bond in question, and mechanisms based in part on the similar reactivityof the Ru(OEP)R2analogues are presented for Ru(TMP)Me2and Ru(TMP)Ph2.Theproposal for the dimethyl system involves scission of the Ru-Me bond followed by cs.hydrogen abstraction, in a reaction sequence analogous to that described for theRu(OEP)Np2system. Unfortunately, this presents the same paradox in the kinetic analysisencountered for the bis(neopentyl) system (vide supra). Moreover, the organic productsof the thermal decomposition of Ru(TJVIP)Me2have not been identified, and thus the241mechanism remains tentative. Similarly, the study of the decomposition of the benzoylcomplex is incomplete as the organic products of this reaction have not been identifiedeither.The light-induced reaction ofRu(TMP)Me2with 02 produces a Ru(TMP)(CO)Lspecies, the sixth ligand being tentatively identified as MeOH. A more complete productanalysis in needed and the mechanism of this reaction should be examined. Studying thereaction at reduced temperature or perhaps using a less intense light source might result inthe observation of some of the proposed reaction intermediates.242Appendix A :Temperature Dependences of the Isotropic ProtonShifts (ppm)a) Ru(TMP)C12°Temperature lIT H1 o-Me p-Me rn-H°C (x 10) obs, iso’ obs, iso’ obs, i50b obs, iso1’18.0 3.43 -55.42, -64.07 3.83, 1.62 4.07, 1.53 12.50, 5.2312.3 3.50 -56.63, -65.28 3.86, 1.65 4.104, 1.56 12.60, 5.331.4 3.64 -59.35, -68.00 3.93, 1,72 4.188, 1.65 12.82, 5.55-9.3 3.79 -62.25, -70.90 4.00, 1.79 4.20, 1.66 13.04, 5.77-19.4 3.94 -65.33, -73.98 4.07, 1.86 4.21, 1.67 13.40, 6.13-29.5 4.10 -68.42, -77.07 4.12, 1.91 4.41, 1.87 13.71, 6.44-39.5 4.28 -71.78, -80.43 4.20, 1.99 4.49, 1.95 14.06, 6.79-49.6 4.47 -79.75,-84.44 4.41, 2.20 4.71, 2.17 14.44, 7.17a) Diamagnetic correction based on data for Ru(TMP)(CH3CN):C6D at 20°C, Hpoie8.65, o-Me = 2.21,p-Me = 2.54, rn-H = 7.27 ppm. b) obs, observed chemical shift; iso,observed shift -diamagnetic correction. c) Temperature deviation ± 0.5° C.b) Ru(TMP)Cl(NH3aTemverature lIT Hoie o-Me p-Me rn-Ha rn-Hb°C (x103) obs, iso1’ obs, iso1’ obs, iso1’ obs, iso1’ obs, iso1’52.2 3.07 -28.60, -37.25 -0.54, -2.75 0.69, -1.85 4.24, -3.03 4.19,-3.0842.3 3.17 -29.77, -38.42 -0.63, -2.84 0.62, -1.92 4.13, -3.14 4.08, -3.1932.4 3.27 -30.88, -39.53 -0.71, -2.92 0.54, -2.00 4.01, -3.26 3.95, -3.3221.4 3.40 -32.30, 40.95 -0.82-3.03 0.45, -2.09 3.88, -3.40 3.81, -3.4611.5 3.51 -33.84, 42.49 -0.94, -3.15 0.65, -2.19 3.72, -3.55 3.65, -3.621.0 3.65 -35.67, 44.32 -1.06, -3.27 0.23, -2.31 3.54, -3.73 3.47, -3.80-9.4 3.79 -37.56, -46.21 -1.22, -3.43 0.11, -2.43 3.35, -3.92 3.27, -4.00-19.7 3.95 -39.85, 48.50 -1.37, -3.58 0.03, -2.51 3.14, -4.13 3.05, -4.22-29.7 4.11 -41.91, -50.56 -1.53, -3.74 -0.17, -2.71 2.92, -4.35 2.83, -4.44a) Diamagnetic correction based on data for Ru(TMP)(CHCN)2:C6D at 20°C, H018.65, o-Me = 2.21,p-Me = 2.54, rn-H = 7.27. b) obs, observed chemical shift; iso,observed shift -diamagnetic correction. c) Temperature deviation ± 0.5° C.243c) Ru(OEP)Np’Temperature” lIT CH2a CH2b CH3 NpCH3°C (x103) obs, i50b obs, iso’ obs, iso’ obs, iso’ obs, iso’-29.9 4.11 14.93, 11.21 5.65, 1.93 -2.23, -4.00 6.56, 8.98-19.6 3.95 14.68, 10.96 5.85, 2.13 -2.05, -3.82 6.21, 8.63-9.3 3.79 14.44, 10.72 6.03, 2.31 -1.86, -3.63 6.03, 8.451.0 3.65 1.35, -8.42 14.20, 10.48 6.20, 2.48 -1.69, -3.46 5.56, 7.9811.4 3.52 14.02, 10.30 632, 2.60 -1.54, -3.31 5.24, 7.6621.8 3.39 2.37, -7.40 13.84, 10.12 6.44, 2.72 -1.42, -3.18 5.00, 7.4232.4 3.27 2.80, -6.97 13.68, 9.96 6.54, 2.82 -1.28, -3.05 4.71, 7.1342.2 3.17 2.23, -6.54 13.51, 9.79 6.64, 2.92 -1.15, -2.92 4.53, 6.8752.1 3.08 3.61, -6.16 13.38, 9.66 6.72, 3.00 -1.05, -2.82 4.24, 6.66a) Diamagnetic correction based on data for Ru(OEP)NP2in C6D at 20° C, , Hmeso =9.76, CH2 3.72, CH3 = 1.77, Np-CH3= -2.42 ppm. b) obs, observed chemical shift; iso,observed shift -diamagnetic correction. c) Temperature deviation ± 0.50 C.d) Ru(OEP)(neophy1)’Temperature” 1ff Hmeo CH2a CH2b CH3 Neophyl-CH3”°C° (x103) obs, iso’ obs, i50b obs, iso’ obs, iso’ obs, iso’-48.7 4.46 15.22, 11.50 3.99, 0.27 -2.45, -4.22 9.61, 12.03-38.8 4.27 14.99, 11.27 4.37, 0,65 -2.20, -3.97 9.01, 11.43-28.9 4.09 -1.08, -10.85 14.75, 11.03 4.68, 0.96 -2.02, -3.79 8.58, 11.00-18.9 3.93 -0.26, -10.03 14.53, 10.81 4.98, 1.26 -1.82, -3.59 8.00, 10.42-8.9 3.78 0.39, -9.38 14.34, 10.62 5.22, 1.50 -1.63, -3.401.4 3.64 1.22, -8.55 14.15, 10.43 5.45, 1.73 -1.46, -3.2311.5 3.51 1.75, -8.02 13.98, 10.26 5.63, 1.91 -1.33, -3.10 6.60, 9.0223.2 3.37 2.30, -7.47 13.82, 10.10 5.81, 2.09 -1.19, -2.96 6.26, 8.6832.5 3.27 2.72, -7.05 13.68, 9.96 5.95, 2.23 -1.07, -2.84 5.95, 8.3742.4 3.17 3.14, -6.63 13.55, 9.83 6.08, 2.36 -0.97, -2.74 5.51, 7.9352.5 3.07 3.53, -6.24 13.42, 9.70 6.19, 2.47 -0.86, -2.63 5.20, 7.62a) Diamagnetic correction based on data for Ru(OEP)Np2in C6D at 20° C, , Hmeso = 9.76,CH2 = 3.72, CH3 = 1.77, Np-CH3= -2.42 ppm. b) obs, observed chemical shift; iso,observed shift -diamagnetic correction. c) Temperature deviation ± 0.5° C. d) o-, m- andp-protons of the neophyl phenyl group are not tabulated.244Appendix B :Kinetic Data for the Anaerobic Thermolysis ofRu(porp)R2ComplexesRu(OEP)Np2in C6DTemperature = 22.60 C[Ru(OEP)Np2]0 0.45 mMTime Int-meso mt-Np(mm) CR346 45.9 232271 33.3 107421 20.39 92.9571 17.19 77.4721 13.3 58.6854 12.45 48.3999 8.06 37.81121 6.99 35.3Temperature =32.95° C[Ru(OEP)Np2]0= 0.22 mMTime int- mt-Np(mm) meso CH312 4.68 22.2072 2.758 13.57132 2.07 10.45192 1.86 8.19252 1.361 5.97312 1.17 4.85372 0.767 3.40432 0.671 3.05Temperature = 45.15° C{Ru(OEP)Np2]0= 1.2 mlviTime int- mt-Np(mm) meso CH313 33.10 143.8033 25.00 107.6053 18.94 81.3073 15.11 63.6093 11.40 49.20113 9.44 39.00133 7.16 30.60153 5.81 24.20173 4.68 19.40193 3.19 15.80Temperature 27.45° C[Ru(OEP)Np2]0 1.4 mMTime int- mt-Np(mm) meso CH39 20.17 92.5084 13.76 64.90159 10.72 51.30234 8.45 40.20309 7.16 34.10384 5.59 27.00459 4.62 22.00534 3.78 17.12609 2.89 13.23684 2.56 11.26798 2.18 8.56Temperature = 38.15° C[Ru(OEP)Np2]0= 1.4 mMTime int- mt-Np(mm) meso CH39 22.20 102.9029 18.81 85.2049 15.70 73.7069 13.49 62.3099 10.77 49.60129 8.48 40.10159 6.91 32.60189 5.44 27.40219 4.51 21.50249 3.94 17.28279 3.05 14.33309 2.76 11.4245Ru(TMP)Ph2in Toluene (12 tM)Temperature = 1000 CTime (s) Absorbance330nm, 414nm0 0.623, 1.74317,491 0.574, 1.81861,338 0.504, 1.98197,421 0.456, 2.065140,490 0.428, 2.120182,834 0.408, 2.144225,474 0.397, 2.164315,998 0.385, 2.194Temperature = 119° CTime (s) Absorbance330nm, 414nm0 0.435, 1.1821,209 0.415, 1.2542,677 0.385, 1.3284,008 0.365, 1.3945,674 0.341, 1.4558,365 0.323, 1.50711,620 0.308, 1.55986,,400 0.280, 1.653Temperature 106° CTime (s) Absorbance330 nm, 414 nm0 0.436, 1.1797,742 0.4 10, 1.24 115,733 0.388, 1.28526,314 0.363, 1.33835,924 0.344, 1.37751,841 0.326, 1.42375,834 0.303, 1.50298,264 0.292, 1.561172,000 0.280, 1.617Temperature = 111° CTime (s) Absorbance330 nm, 414 nm0 0.435, 1.1824,111 0.415, 1.2549,096 0.385, 1.32814,614 0.365, 1.39420,700 0.341, 1.45527,835 0.323, 1.50737,456 0.308, 1.55949,989 0.299, 1.599172,800 0.280, 1.653Ru(TMP)(COPh)Ph ind8-tolueneTemperature = 60.10 C[Ru(TMP)(COPh)Ph]0= 3.1mMTime Ifltllpyrroie(mm)7.4 22.3022.4 20.0937.4 19.6752.4 18.5382.4 16.99112.4 15.60142.4 14.86202.4 12.02262.4 10.22382.4 7.65502.4 4.03622.4 3.17Teperature = 70.1°C[Ru(TMP)(COPh)Ph]0 1.3mMTime IfltHproie(mm)6.9 26.421.9 26.036.9 25.851.9 23.566.9 21.596.9 17.99156.9 11.05216.9 7.07276.9 4.32336.9 2.518396.9 1.356Temperature = 80.0° C[Ru(TMP)(COPh)Ph]0 2.5mMTime LfltHpyrroie(mm)5.1 42.320.1 3135.1 19.7450.1 14.6865.1 10.6980.1 7.7595.1 6.34110.1 4.77125.1 3.53246Ru(TMP)Me2ind8-tolueneTemperature = 70.00 C[Ru(TMP)Me2]0= 4.5 mMTime Int-R1(mm)7.3 42.267.3 36127.3 32.2187.3 28.2247.3 25.2307.3 22.6367.3 19.97427.3 18.24487.3 15.84607.3 12.58727.3 10.26847.3 7.551027.3 5.11Temperature = 79.8° C[Ru(TIvIP)Me2]0 3.3 mMTime Iflt4lpyrrole(mm)7 41.537 36.967 29.9127 20.35187 15.24247 11.12307 7.98367 6.27427 4.71Temperature = 83.20 C[Ru(TMP)Me2]0= 3.4 mMTime IfltH.0i.(mm)7 28.437 22.367 18.31127 12.44187 8.76247 6.14307 4.22367 2.89Temperature = 89.8° C[Ru(TMP)Me2]0= 5.8 mMTime 1nt-H.(mm)7 26.327 19.347 14.667 11.7287 9.17107 6.78137 4.93167 3.74247Appendix CAppendix C: X-ray Crystallographic Analysis of Ru(OEP)NpFigure C-I: PLUTO Plot showing the numbering scheme of Ru(OEP)Np.39CC,C34248C24CR4Figure C-2: Stereoview of Ru(OEP)Np.249Table C-i: Experimental Details.Space GroupZ valueDcalcr000Diii ractometerRadiationTemperatureTake—off AngleA. Crystal DataC41H55NRu704.98deep red, prism0.250 z 0.300 x 0.400triclinic25 ( 29.6 — 38.5’)0.39I (12)21.256 9/ca37464.43 emB. Intensity ReasurementsRigaku ATC6SPIOKe (X • 0.71069 A)21 ‘C6.0’Empirical FormulaForu1a WeightCrystal Color, BabitCrystal Dimensions (mm)Crystal SystemNo. Reflections Used for UnitCell Determination (20 range)Omega Scan Peak Widthat Half—heightLattice Parameters:a—6—v—13.044 (2)A14.270 (2)A12.500 (2)A115.83 (1)’110.76 (1)’95.92 (1)’1864.2 (6)A3250Table C-i: Experimental Details continiued.Detector ApertureCrystal to Detector DistanceScan TypeScan RateScan Width2emaxNo. of Reflections ReasuredCor re eti onsC. Structure Solution andStructure SolutionRefinementrunction RinimizedLeast—squares Weightsp—factorAnomalous DispersionNo. Observations (I>3.00(1))No. VariablesReflection/Parseeter RatioResiduals: R;Goodness of Fit IndicatorRax Shift/Error in Final CyclePaximum Peak in Final Diff. apPinimum Peak in Final Diff. Rap6.0 n horizontal6.0 mm vertical285 mmw-2e32.0’/min (in omega)(8 rescans)(1.31 • 0.35 tan9)60.Ô1’otal: 11331Unique: 10848 int .040)Lorentz—polari zati onAbsorption(trans. factors: 0.95 — 1.00)Decay (—15.00% decline)Secondary Extinction(coefficient: 0.45(4) E—06)RefinementPatterson RethodFull—matrix least—squaresI w (irol — (Fc))24Fo2/c(Fo2)0.00All non—hydrogen atoms498045211.020.036; 0.0321.730.090.26 e,”A3—0.26 eiA3251TableC-2:AtomiccoordinatesandBeq.Ito3,DCC.Cl.It0xy0CC.Pu(1)0.35107(2)0.32660(2)0.40188(3)4.04(1)C(21)0.6407(3)0.6701(3)0.9253(3)6.1U)MU)0.4880(2)0.4264(2)0.5074)2)4.08(8)C(22)0.5779(4)0.6729(4)1.0045(4)9.0(2)M(2)0.4370(2)0.2137(2)0.3688(2)4.16(8)C(23)0.7800(3)0.4864(3)0.8788(4)6.6(1)MU)0.2254(2)0.2352(2)0.2187)2)4.5(1)C(24)0.7304(4)0.4230(4)0.9410(4)9.1(2)N(4)0.2757(2)0.4465(2)0.4396(3)4.5(1)C(25)0.6712(3)0.0908(3)0.4619(4)6.7(2)C(1)0.5014(3)0.5315(3)0.6799(3)4.4(1)C(26)0.6618(4)0.0585(4)0.3567(5)0.9(2)Ccl)0.6053(3)0.3705(3)0.8001(3)4.7(1)C(27)0.4683(4).0.0567(3)0.1629(4)6.8(2)C(3)0.6556(3)0.4899(3)0.7608(3)4.1(1)c(28)0.4033(7)—0.1443(6)0.1535(7)7.7(3)0.54C(4)0.5835(3)0.4011(3)0.6465(3)C(268)0.4980(8)—0.0580(7)0.0671(9)7.7(4)0.46C(S)0.6059(3)0.3041(3)0.5649(3)4.5(1)C(29)0.0791(3)—0.0083(3)—0.1273(3)6.5(1)C(6)0.5392(3)0.215(3)0.4565(3)4.4(1)C(30)0.1410(4)0.0068(4)—0.2039(4)9.2(2)C(7)0.5661(3)0.1165(3)0.3945)3)5.0)1)C(31)—0.0562(3)0.1660(3)—0.0632(4)7.1(1)C(8)0.4797(3)(..0530(3)0.2693(3)5.1(1)C(32)—0.0466(4)0.2323(4)—0.1294(5)10.2(2)CU)0.3991(3)0.1146(3)0.2S37(3)4.5(1)C(33)0.0276(3)0.5566(3)0.3641(4)6.8(2)C(10)0.2917(3)0.0790(3)0.1403(3)4.9(1)C(34)0.0251(3)0.6109(4)0.2632(4)0.1(2)C(11)0.2376(3).0.1339(3)0.1215(3)4.7(1)C(31)0.2442(3)0.7161(3)0.6490(4)6.2(1)C(12)0.1123(3)0.0944(3)0.0014(3)C(30)0.2121(4)0.7119(3)0.1528(3)9.0(2)C(13)0.0560(3)0.1705(3)0.0281(4)5.5)1)C(37)0.2377(6)0.2423(6)0.4395(7)4.9(2)0.61C(14)0.1267(3)•0.2563(3)0.1639(3)4.9(1)c3780.2947(9)0.2203(0)0.4151(11)4.8(4)0.39.C115)0.1001(3)0.3S20(3)0.2300(4)5.3(1)C(38)0.2441(4)0.2595(3)0.5670(4)6.3(1)C(16)0.1682(3)0.4404)3)0.3578(474.9(1)C(39)0.269S(3)0.3718(3)0.6740(4)7.1(3)C(17)0.1392(3)0.3378(3)0.4215(4)5.3(1)C(40)0.1534(13)0.1635(11)0.3375(34)7.1(4)0.61C(1ê)0.2305(3)0.6051(3)0.5413(4)S.7)1(C(40P.)0.196(2)0.164(2)0.576(3)8.3(9)0.39C(19)0.3166(3)0.5466(3)0.5S26(3)4.6(1)C(41)0.3643(5)0.2339(6)0.6394(6)7.0(3)0.61C(20(0.4223(330.3880(2)0.6612)3)4.7)13C(4:R)0.1059(8)0.2610(9)0.4659U07.0(4)0.396.q—(8/3IRZEZL)1a3(a6..)Table C-3: Bond Lengths (A).ate. ate. 4stang* atos atea dstane.Ru(1) N(1) 2.021(3’ C(11) C’12’ 1.449(4)Ru(1) 14(2) 2.033(2) C(12) C(13? 1.361(5)RuCi) 14(3) 2.029(3) C(12) C(29) 1.499(5)Ru(1) 14(4) 2.028(3) C(13) C(14) 1.449(5)Ru(1) C(37) 2.069(7) C(13) C(31’ 1.508(5)Ru(1) C(37A) 2.12(1) C(14) CC15 1.388(5)14(1) CU) 1.381(4) C(15) C(16) 1.393(4)14(1) C(4) 1.378(4) C(16) C’17) 1.438(4)14(2) C(6) 1.377(4) C(17) Cc18. 1.353(5)14(2) C(9) 1.376(4 Ct17) C33 1.500(S)14(3) C(11) 1.389(4) CUB) C19. 1.451(4)14(3) C(14) 1.377(4’ CUB) C35) 1.504(5)14(4) C(16) 1.378(4’ C(19) C’20 1.382(4)14(4) C(19) 1.384(4) C(21) C’22) 1.511(5)CU) C(2) 1.444(4 C(23) C 24) 1.516(6)CU) C(20) 1.391(4) C(25) C26’ 1.482(6)C(2) C(3) 1.335(4) C(27) C28) 1.371(8)C(2) C(21) 1.S02(4 C(27) C28A) 1.374(9)C(3) C(4) 1.446(4) C(29) C(30) 1.519(5)C(3) C(23) 1.498(5) C(31) C32) 1.506(5)C(4) C(S) 1.382(4) C(33) C(34) 1.498(5)C(S) C(6) 1.390(4) C(35) C(36) 1.516(5)C(6) C(7) 1.446(4) C(37) C(38) 1.483(8)C(7) C(S) 1.357(4) C(37k) C(38 1.46(1)C(7) C(25) 1.510(3) C(38) C(39) 1.472(5,C(S) C(9) 1.444(4) C(38) C’4C) 1.4S(2C(S) C(27) 1.S4(4. C(38) C4CA) 1.51(2C(9) C(10) 1.387(4) C(38) C(41) 1.674(7)C(10) C(11) 1.384(4) C(35) C(41A) 1.81(1)253TableC-4:BondAngles(0).atomato.ato.angleatomato,ato.angleatomato,atomangl.atomatomate,angle11)1)lull)11(2)19.041’£49)CIlO)Clii)327.4)))0141)£11)£120)124.4(3)Cl’C)IC22l112.4(1)11(1)lull)11(3)172.0111£19)CoO)((11)321.4(3)£12)Cli)C(20)125.4(3)CII’C(1)C34’l12.e13)01(1)lull)11(4)09.0(1).11(3)Clii)C(12)109.6)3)CII)C)2)CI))101.3(3)()C(!)C26’111.2(3)11(1)mull)CII?)106.2(2)CoO)Clii)C(12)126.1(3)CII)C42)£121)123.0(3)CII)C()C29’115.4(5)11(1)mull)C(37A)92.1(3)Clii)£112)£433)106.0)))CI))£42)C(21)128.7(3)£481C()C206’136.6(5)11(2)mull)11(3)09.9(l)£411)C(12)£429)124.1(4)£12)CIII£44)106.6(3)C(12’C(0)C30’112.2(3)11(2)mull)1144)114.0(1)Cli))C(12)c(29)129.4(4)£42)C(3)£42))120.2(3)Cli))CI3)C33)113.3(3)11(2)lull)CII?)95.6(2)C(l2)C(13)£414)101.4(3)£44)CII)C(23)12S.0(3)Cli?)£133)C347134.543)11(2)mull)ColA)70.1(3)£112)£413)£431)126.0(4)WIll£14)Cl))110.4(3)Clii)CII!)C36)113.2(1)14(31mull)11(4)09.0(1)£1141cUfl£131)124.6(4)11(11C(4)C(S)124.3(1)mull)C(1)CIS)121.1(41MIIImull)C(37)01.1(2)1143)£414)£111)109.7(3)CI))£44)C(S)125.3(3)mull’C(36)C30)126.246)11(3)mull)£4376)95.0(3)11)3)£114)£115)124.6(3)£44)C(S)C(6)127.4(3)Cl)?)CoO)C’39)110.444)0114)mull)CII?)90.3(2)£113)C(14)COlS)125.7(4)11(2)C46)C(S)124.143)C(3)CIII)C40)315.1(7)11(4)lull)C(31k)107.9(3)£414)C(lS)£416)327.3)3)01(2)£16)Cli,310.0(3)C(37p£430)C41)105.9(4)lull)1(11)C(1)321.3(2)1144)C(16)C)lS)123.643)C(S)£16)£47)12S.9(3)C(3’761Cli’)C39)125.1(5)mull)01(1)C(4)127.0(2’11(4)Cfl6)Clii)310.7)3)C(6)Cl?)£48)106.9(3)(3?6’CIII)C406112(1)CII)11(1)£44)105.6(3)C)IS)£116)CII?)125.143)£06)C(7)C(25)324.6(3)CIlIA’CIII)C41k’100.6(5)mull)11(2)CII)126.7)2’£416)Cli?)£411)101.043)C)9)Cli)Cl2)126.513)(39’CII))C40’l11.S(6)mull)1112)£19)321.0421£116)CII?)£133)125.6)4)dl)COO)£19’101.0(3):(79Clil)C40k120(1)£46)11(2)C(9)106.043)CIII)CII?)((33)127.243)Cl?)CII)£12;)126.0(3)(39’CII!)C41)96.9(41mull)04(1)Clii)32.i(2)CII?)Clii)C9)101.0(3)£491£10)C(2)325.0(3)C(39’C(3’.)C41k’91.0(4)mull)11(3)£414)126.7(2)£111)CIII)£115)120.9)3)1142)C19)£46)110.1(3)t((0)CIII)C41)104.2(5)CIII)01(3)C(14)106.443)C1l91((10)£135)324.3)3)0142)£19)CIII)124.4(3)£1406)C135)C416)96(1)mull)11(4).C(16)127.2(2)11)4)CIII)Clii)109.9)))CII)C(9)dIll)125.5(3)loll)11(4)£139)121.2(2)11)4)£119)£120)124.3’))£116)01(4)C(l9)30S.413CIII)£119)£1201125.3’301)1)Cli)C(2)110.0)7’CII)((20)((19)126.01Table C-5: Least Square Planes.Plane number 1Atoms Defining Plane Distance esdN(l) 0.0102 0.0024N(2)—0.0103 0.0024NC3) 0.0115 0.0025N(4)—0.0110 0.0024Additional Atoms DistanceRu(l)—0.1171C(37)—2.1346C(37A)—2.1635Mean deviation from plane is 0.0107 angstromsChi—squared: 77.8Plane number 2Atoms Defining Plane Distance cadN)1) 0.0187 0.0024N(2)—0.0051 0.0024N(3) 0.0125 0.0025N(4)—0.0067 0.0024-C(1) 0.0962 0.0030C(2) 0.0360 0.0031C(3)—0.0589 0.0032C(4)—0.0370 0.0030C(S)—0.0700 0.0031C(6)—0.0555 0.0030C(7)—0.0745 0.0033C(8)—0.0339 0.0033C(9) 0.0044 0.0031C(10) 0.0391 0.0032CU1) 0.0636 0.0032C(12) 0.1004 0.0034C)13) 0.0337 0.0034C)14)—0.0240 0.0031C(15)—0.1019 0.0033C(16(—0.0915 0.0032C(17)—0.1293 0.0033C)18)—0.0330 0.0032C)19) 0.0565 0.0030C(20) 0.1411 0.0031Additional Atoms DistanceRu(1)—0.1124CC21)—0.0204C(23) —0.2534C)25) —0.1423C(27) 0.0025C(29) 0.2600C(31) 0.0261C)33) —0.2713C(35)—0.0594C(37)—2-.1307C(37A)—2.1585Mean deviation from plane is 0.0552 angstromsCM—squared: 11732.2Dihedral angles between least—squares planesplane plane angle2 1 0.11255Appendix DAppendix D: X-ray Crystallographic Analysis of Ru(OEP)(neophyl)C 39C40Figure D-1: PLUTO Plot showing the numbering scheme for Ru(OEP)(neophyl).C38I C3SC’sC42256c34 c34Figure D-2: Stereoview of Ru(OEP)(neophyl).257Table D- 1: Experimental Details.A. Crystal DataLapirical £oru1a C46B57NuForule Weight 767.05Crystal Color, aabit Deep red, prismCrystal Dimensions (mm) 0.250 X 0.300 X 0.350Crystal System onoclinicNo. Peflections Used for UnitCell Determination (26 range) 25 29.6 — 37.3’)Omega Scan Peak Widthat Half—height 0.37L.attice Parameters:a — 10.214 (4)Ab — 25.490 (2)Ac — 15.199 (l)AS — 97.43 (l)V — 3924 (HA3Space Group P2i/c ($14)1 value 40calc 1.298 9/cm316204.26E. Intensity measurementsDiffrectometer Rigaku AC6SPadiation 8IOe (X • 0.71069 kTemperature 21’CTake—off Angle 6.0Detector Ap.rture 6.0 mm horizontal6.0 mm vertical258Table D- 1: Experimental Details continiued.Crystal to Detector DistanceScan TypeScan RateScan WidthmaxNo. of Reflections ReasuredCorrectionsC. Structure Solution andStructure SolutionRefinementFunction MinimizedLeast—squares Weightsp—factorAnomalous DispersionNo. Observations (I>3.00(I))No. VariablesReflection/Parameter RatioResiduals: R; RGoodness of Fit IndicatorMax Shift/Error in Final CycleMaximum Peak in Final Diff. RapMiniaum Peak in Final Diff. Map285 mm32.0’/min (in omega)(8 rescans)(0.91 + 0.35 tane)60.0Total: 12258Unique: 11701 (Rint — .037)Lorents—polarizationAbsorption(trans. factors: 0.97 — 1.00)Ref inementDirect MethodsFull—matrix least—squaresI w ((Fol— Pci)24pQ2/2 C Fo2)0.00All non—hydrogen atoms551146011.980.04l 0.0381.980.110.54 e,43—0.42259TableD-2:AtomiccoordinatesandBeq.Ito.K7SItOKK7aqSIIi)0.32022(3)0.441440(H)0.26007(2)3.03(1)C(20)0.0664(4)0.16111(15)0.4000(1)N(S)0.1054(1)0.17115(10)0.2471(2)3.2(1)C(21)—1.091214)0.2457(2)0.1160(3)1.0(2)11(a)0.2237(3)0.4500(10)0.1362(2)).ZU)C(22)0.0019(S)0.2212(2)0.1404(3)6.9(3)NH)0.3246(3)0.51154(101o.2116H)).3HC(23)—0.0752(4)0.2727(2)0.1071(3)5.0(2)11(4)0.2059(3)0.4)9)2(11)0.3991(2)3.4(1)C124)—0.2040(5)0.2915(2)0.0509(3)7.1(1)CI))0.03061))0.34913(14)0.3106(3)3.5(21c(25)0.11)4(4)0.41)4(2)—0.1029(3)4.7(2)Cu)—0.0252(3)0)0667(14)0.2617(3)1.0(2)C(261—0.007943)0.4290(2)—0.1119(3)7.1(3)Cl))—0.0110(4)0.10966(14)0.1602(3)4.0(2)CI)))0.3)48(4)0.5155(2)—0.0092(3)4.6(2)dl)0.0121(410.35316(1410.1457(3134(3(C(21)0.2207(5)0.5601(2)—1.0921(1)7.21))C(S)0.0923(4)0.17)60(14)0.0656(2)C(29)0.3012(4)0.6297(210.21691))4.9(3)CII)0.164711)0.11796(14)0.0695(2)3.4(2)CHO)0.1990(5)0.6600(3)0.1130(1)7.0(1)CII)0.100614)0.43603(15)—0.0)56(2)3.8(2)Cl)))0.4140(4)0.6229(2)0.12511))4.6(2)CII)0.2107(4)0.40019(14)—0.0015(2)1.0(2)CI)))0.3690(5)9.6672(2)04)3211)6.0(3)CII)0.2004(4)0.0066(14)0.0929(2)1.4(2)Cl)))0.2001(4)0.4973(2)0.1)30(3)4.7(2)Coo)0.3504(4)0.52973(14)0.1162(3)3.7(2)CI)4(0.1643(5)0.3100(2)0.6462(3)7.3(3)Clii)0.37)3(410.34174(1)10.2254(3)3.4(2)Cl)5l0.0909(4)0.1015(2)6.6036(3)5.3(2)C(12)0.4407(4)0.59009(14)0.2671(3)1.7(2)C(36)—0.0414(3)0.3962(2)0.6102(3)7.0(3)C))))0.4330(4)0.30331(14)0.3542(1)3.7(2)Cliii0.4120(4)0.4002(2)0.2019(1)4.112)Clii)0.3612(4)0.5)620(14)0.3600(3)3.4(2)CIII)0.4461(4)0.3513(2)0.2744(3)4.4(2)C(1S)0.3323(4)0.31712(14)0.4494(2)1.4(2)COil)0.3007(5?0.3)1)12)0.143541)6.90)?C116)0.2592(1)0.47)02(14)0.464912)1.3(2)C)40)0.5943(4)0.3423)2)0.1002(3)5.1(2)Cli?)0.2254(l)0.43011(35)0.5499(2)3.0(2)C14110.4071(4)0.329342)0.1029(3)4.5(3)CIII?0.1319(4)0.41)0(2)0.5)62(2)3.9(2)C(13)0.342715)0.2933(2)0.1674(4)0.4(3)CIHI0)192(4)0.40108(14)0.4427(2)3.5(2)Cli))0.3001(13)0.2303(4)0.0795(0)14.2(11C(41)6.3301(10)0.2072(4)0.0210(0)13.3(7)C(45)0.4163(7)0.3)61(1)9.0242(4)10.0(5)C(46)0.4432(5)0.3539(2)0.1)06(1)1.5(3)•0.q—Table D-3: Bond Lengths (A).atoui atom distanc. atop atom distaneeRu(1) N(1) 2.030(3) C(12) C(29) 1.509(5)u(1) N(2) 2.026(3) C(13) C(14) 1.445(5)Ru(1) N(3) 2.043(3) C(13) C(31) 1.513(5)Ru(1) N(4) .2.027(3) C(14) C(15) 1.381(5)Ru(1) C(37) 2.053(4) C(15) C(16) 1.382(5)Nd) Cdl) 1.390(4) C(16) C(17) 1.437(5)N(1( C(4) 1.394(4) C(17) C(18) 1.361(5)N(2) C(6) 1.392(4) C(17) C(33( 1.495(5)N(2) C(9) 1.380(4) CUB) C(19) 1.441(5)N)3) CUl) 1.373(4) C(18> C(35) 1.507(5)N(3) C(14) 1.379(4) C(19) C(20) 1.379(5)NH> C(16) 1.386(4) C(21) C(22> 1.509)5)NH) C(19) 1.388(4) C(23) C(24) 1.5006)CU) C(2> 1.451)5) C(25) C(26) 1.5086)C(1) C(20) 1.377(5) C(27) C(28> 1.503(6)C2) C(3) 1.346(5) C(29) C(30> 1.517(6)C(2) C(21) 1.499(5) C(31) C(32) 1.5066)CU> C(4) 1.450(5) C(33) C(34) 1.504(6)C(3) C23) 1.518)5) C(35) C(36) l.478(6C(4) C(S) 1.374(5) C(37) C(38) 1.513(5)C(S) C(6) 1.389(5) C(3S) C(39) 1.565(6)C(6) C(7) 1.436(5) C(38) C(40) 1.524(S)C(7) C(S) 1.353(5) C(38) C(41) 1.505(5)C(7) C(25) 1.503(5) C(41) C(42) 1.373(6)C(S) C(9) 1.439(5) C(41) C(46) 1.382(6)C(S) C(27) 1.497(5) C(42) C(43) 1.47(1)C(S) C(10) 1.385(5) C(43) C(44) 1.26(2)C(10) C(1l) 1.380(5) C(44) C(45) 1.42(1)C(11) C(12) 1.4(5(5) C(45) C(46) 1.397(7)C(12) C(13) 1.339(5)261Table D-4: Bond Angles (°).atom atom atom angle atom atom atom angleN(1) Ru(1) N(2) 89.9(1) N(3) C(11) C(12) 109.6(3)N(1) Ru(l) N(3) 170.7(1) C(10) C(11) C(12) 126.4(3)N(1) Ru(1) N(4) 89.6(1) C(11) C(12) C(13) 107.4(3)N(1) Ru(l) C(37). 103.6(1) C(11) C(12) C(29) 123.9(4)N(2) Ru(1) N(3) 89.5(1) C(13) C(12) C(29) 128.7(4)N(2) Ru(1) N(4) 171.3(1) C(12) C(13) C(14) 107.4(3)N(2) Ru(l) C(37) 94.6(1) C(12) C(13) C(31) 127.1(4)N(3) Ru(1) 14(4) 89.6(1) C(14) C(13) C(31) 125.4(4)N(3) Ru(1) C(37) 85.6(1) N(3) C(14) C(13) 109.3(3)N(4) Ru(l) C(37) 93.9(1) N(3) C(14) C(lS) 124.4(3)Ru(l) N(1) C(1) 126.9(2) C(13) C(14) C(15) 126.3(4)Ruti) N(l) C(4) 126.9(2) C(14) C(15) C(16) 127.5(3)C(l) N(1) C(4) 106.2(3) 14(4) C(16) C(15) 124.3(3).(l) N(2) C(6) 127.2(2) N(4) C(16) C(17) 110.5(3)Ru(1) N(2) C(9) 127.4(2) C(15) C(16) C(17) 125.2(3)C(6) N(2) C(9) 105.3(3) C(16) C(17) C(18) 106.7(3)Rul) N(3) C(11) 126.8(2) C(16) C(17) C(33) 125.6(4)Ru(l) N(3) C(14) 126.8(2) C(18) C(17) C(33) 127.6(4)C(11) N(3) C(14) 106.3(3) C(17) C(18) C(19) 107.5(3)Ru(1) 14(4) C(16) 127.0(2) C(17) C(18) C(S) 128.1(4)Ru(l) 14(4) C(19) 127.4(2) C(19) C(18) C(35) 124.4(4)C(l6) N(4) C(19) 105.5(3) N(4) C(19) C(18) 109.7(3)N(1) C(1) C(2) 109.3(3) 14(4) C(19) C(20) 123.7(3)14(1) C(1) C(20) 124.1(3) C(18) C(19) C(20) 126.6(4)C(2) C(1) C(20) 126.7(3) C(1) C(20) C(19) 128.1(4)C(1) C(2) C(3) 107.7(3) C(2) C(21) C(22) 112.2(3)C(1) C(2) C(21) 124.3(4) C(3) C(23) C(24) 113.2(4)262Table D-4: Bond Angles (A) continued.ator atom atom angle atom atom atom angleC(3) C(2) C(21) 128.0(4) C(7) C(25) C(26) 113.6(4)C(2) C(3) C(4) 107.6(3) C(8) C(27) C(28) 111.2(3)C(2) C(3) C(23) 128.2(4) C(12) C(29) C(30) 112.7(4)C(4) C(3) C(23) 124.1(4) C(13) C(31) C(32) 113.9(3)N(1) C(4) C(3) 109.2(3) C(17) C(33) C(34) 112.3(3)N(1) C(4) C(S) 123.8(3) C(18) C(35) C(36) 113.1(4)C(3) C(4) C(S) 126.9(4) Ru(1) C(37) C(38) 126.8(3)C(4) C(S) C(6) 128.3(3) C(37) C(38) C(39) 107.4(4)N(2) C(6) C(S) 123.5(3) C(37) C(38) C(40) 109.9(3)N(2) C(6) C(7) 109.9(3) C(37) C(38) C(41) 116.4(3)C(S) C(6) C(7) 126.6(4) C(39) C(38) C(40) 104.2(3)C(6) C(7) C(8) 107.5(3) C(39) C(38) C(41) 109.4(4)C(6) C(7) C(25) 124.5(4) C(40) C(38) C(41) 108.8(3)C(S) C(7) C(25) 127.9(4) C(38) C(41) C(42) 123.3(5)C(7) C(8) C(9) 107.0(3) C(38) C(41) C(46) 119.0(4)C(7) C(S) C(27) 128.0(4) C(42) C(41) C(46) 117.6(5)C(9) C(S) C(27) 125.0(4) C(41) C(42) C(43) 124.6(7)N(2) C(9) C(S) 110.4(3) C(42) C(43) C(44) 110(1)N(2) C(9) C(10) 123.4(3) C(43) C(44) C(45) 134(1)C(S) C(9) CUD) 126.2(3) C(44) C(4S) C46) 112.1(7)C(9) C(10) C(11) 128.2(3) C(41) C(46)C(45) 122.2(6)N(3) C(11) CUD) 124.0(3)263Table D-5: Least Square Planes.Planenuaber 1Atoms Defining Plane Distance ladN(1) —0.0057 0.0027N(2) 0.0057 0.002724(3)—0.0059 0.002724(4) 0.0061 0.0027Additional Atoms DistancePu(l) 0.1587C(37) 2.1863Mean deviation frog plane is 0.0059 angstraasChz—squared: 19.2——— Plane nuaber 2Atcs Defining Plane Distance •sd24(1) 0.0412 0.002724(2> 0.0456 0.002724(3) 0.0286 0.002724(4) 0.0479 0.0027CU) —0.0097 0.0034C(2)—0.0449 0.0035C(3) —0.0227 0.0036C(4) 0.0103 0.0036C(S) —0.0048 0.0036C(6) —0.0173 0.0034Cr7) —0.0681 0.0036C(S) —0.0342 0.0036C(9) 0.0349 0.0034C(10) 0.0505 0.0036C(ll) 0.0118 0.0035C(12) —0.0521 0.0035C(13) —0.0659 0.0035C(14) —0.0054 0.0035C(1S) 0.0152 0.0035C(16) 0.0261 0.0034C(17)—0.0440 0.0035C(lS) —0.0398 0.0036C(19) 0.0130 0.0034CUD)—0.0241 0.0037Adthtienal Atoms DzstanceRu(1) 0.1995C(37) 2.2261Mean deviation from plane is 0.0307 angitromsChi—sQ1.ereth 3033.3Dihedral angles between least—squares planesplane plane angle2 1 0.18Plane nuaber 3AtOLS Defining Plane Distance cadC(41) 0.0007 0.0036C(42) —0.0002 0.0048C(43) —0.0134 0.0116C(44) 0.0137 0.0100C(45) —0.0021 0.0055C(46) —0.0001 0.0047Additional Atoas DistanceC(38) 0.0853sean deviation froa plane is 0.0050 angstroasChi—equared: 2.1Dihedral angles between least—squares planesplane plane angle3 1 4.803 2 4.98264Appendix EAppendix E: X-ray Crystallographic Analysis of [Ru(OEP)Np2(p-Li)C22aC36 C22C35C18 C20 C2C33 C19 C24aCi C23LiiC3N4C34 NiC16 C4 C24C37Rul C5C15 C39 C40C14N3C38 C6C32N2C13C31 Cii C9 C8 C25 C26C12 cioC29 C27C30 C28Figure E-1: ORTEP plot of a monomeric unit of[Ru(OEP)Np]2(.t-Li)265Figure E-2: Stereoview of [Ru(OEP)Np]2(t-Li).266Table E-1: Experimental Details.A. cs, Data£piricaJ Fonnuia C:BuW4R jFormula Weight 711.92CT7ataJ COb,, Babit rad, imguiaCrystal Dimensions 0.25 X 0.30 X 0.40Crystal System triclinicLattice Type pNo. of Reflections Used for UnitCell Determination (26 range) 25 ( 35.9. 41.4’Omega Scan Peak Widthat Balf.beight 0.33’Lattice Parameters a 13.824(3) .4b = 14.025(2) Ac= 11.943(3)Aa = 106.80(2)’8 = 114.78(2)’= 99.53(2)’V = 1900.0(8) A3Space Group P1 (#2)Z value 21.244 g/cmFOOt 752(MeKo) 4.45 cm’B. lnteniitv MeasurementsDiffractometer Rigaku AFC6SRadiation MoXa (. • 0.71069 A)5267Table E- 1: Experimental Details continiued.Fiphite mocb,omstedTake-off Angie 6.0’Detector Aperture 6.0 mm boritontal6.0mm verticalCryital to Detector Diatance 28.5 mlTemperature 21.0CScan Type w-29Scan Rate 32.0/man (in omega) (8 rcanz)Scan Width (1.15+ 0.35 tan 9)’65.1’No of Reflections Measured Total: 14234Unique: 13721 (R., = 0.041)Corrections Lorentz-polarizationAbsorption(trans. factors: 0.97. 1.00)C. Structure Solution and RefinementStructure Solution Direct Methods (SEELXSSS)Refinement Full-matrix least-squaresFunction Miutmized w(lFoI — FeD2Least Squares Weights =p-factor 0.00Anomalous Dispersion All Don-hydrogen atomsNo. Observations (1>3.OOo(l)) 7455No. Variables 442Rdection/Parwieter Ratio 16.87R.iduals. R: Rw 0.038 0.039Goodnom a! Fit Indicator 1.82Max Shift/Error in Final Cycle 0.02MaxImum peak in Final Duff. Map 0.44 /45Minimum peak in Final Duff. Map -0.41 C/5268TableE-2:AtomiccoordinatesandBeq.•990.*..)I)0.15333(3)0.21074(2)044063(2)1077(4)q20)05372(2)01181(2)01001(3)4.44(7)54(I)0.1422(2)045)2(2)03924)2)173(5)C(23)03237(5)01407(4)6.4745(7)15.6(2)54(2)0.2176(2)0.22)7(2)0.3543(3)1.54(4)C(22)0.0076(7)0.0052(7)6.17*3(30)(3.4(5)0.67II)))04063(3)0.5766(2)04032(2)1)4)4)C(234)0111(2)0.731(3)1419(2)55.3(0)0.2254(4)0.4664(2)0.4764(2)00212(2)546(5)C(22)4.0343(3)0.4066(4)03773(1)1.1(1)C(l)0.2471(2)0.0273(3)04772(3)447)7)C(24)-0.5236(0)0.3970(9)01100(10)9.4(3)010C(2)0.1474(5)0.1528(3)04073)4)066(0)C424.)-0.0233(0)0.4600(0)9.013(1)30,5(3)0.00.C(S)0.0639(2)0.4723(3)0.2653)4)0.03)6)C(26)00004(2)0(046(2)4.0009(3)4.7947)C(4)0.3432(2)0.394)42)0.2742(3)442(7)C(26)0.0227(3)0.3507(2)4.1171(2)7.04(9)C(S)0.3040(2)0.3057(2)03636(3)437(7)C(27)0.3053(3)-0.0239(3)4.02)4(1)194(7)C(0)0.3576(2)02337)2)0.3133(3)3.73)6)C(28)02476(4)4034443)4.3031(4)06(3)C(7)0.3365(3)0.1206(2)00131(2)2.97)6)C(79)01779(2)0.0009(2)0.4)10(5)0.26(0)C(6)01010)2)00131(2)0.0616(3)2.92)6)C(30)06372(4)0.0500)3)0)352(4)7.743)C(0)02002)2)0.5462)2)0.2008)2)3.53)6)C(3I)07299(3)0.3377(2)0.7344(4)177(9)CoD)0.3739(2)0.1209)3)02733)3)176(6)C(32)07152)4)0.3094(4)0.9373(1)67(3)CII)04034(2)03003(2)0.4039(3)247(6)C(33)0.7029(2)0.6070(2)0.9743(3)1.35(7)C(S))0.5575(2)0.1310(7)0.4737(3)306(6)C(54)06620(2).0.3493(3)3.0153(3)1)9(30)C(l1)0.9239(2)0.2292(3)0.5969(3)409)6)C(35)0.129643)0.7164(2)1995743)4.9747)C(14)0.5460(2)01072(2)00067)3)1.14(6)C(26)04631(4)07294(3)0.0739(4)0.34))CII)0.6049(2)04027(2)0.7319(3)314(6)C(37)0.2022(3)0.1093(2)9.0039(3)499(7)Coo)01343(2)04037(2)0.7262(3)*03(5)q30)02977(2)0.2043(2)91364(2)443(7)C(37)0.0063(2)0.0792(2)09433(3).294)6)C(30)0.1612(4)0.3034(5)1.1379(4)7.7(5)C(lO)0.1242(2)0.0332(2)0.0301(3)1.92(6)C(40)00943(3)6.3065(3)0*943(4)71(3)CoO)04343)7)0.0072(2)00749(2)373(6)C(41)03427)3)0353042)94733(4)07(3)L,(I)0.4354(4)0.0375(4)0.4014(5)46(3)=‘(’e(‘n(W)’-e(‘(447)’ 42tfi,.Wc.i+D,5U,oto.)Table E-3: Bond Lengths (A).b cR(I) N(1) O.(3) m(1) N(2) 2013(2)L)1( N(S) 2.017(2) I(1) 91(4) 2*46)2)2u(1) C(37) 2.100(3) I.(l) La(1) 2.117(5)L(I) L(1r 2.$37(2)_. 91(1) C( 1004(3)91(1) C(4) 1386)3) N(1) La(l) 2.200(2)91)2) CC6( 0.095(3) 91(2) C(9( 0.282)3)91(3) CCII) 5.384(3) 91(3) C(14) 0415(3)91)3. L(I) 3.300(5( 91(4) C(16) 0494(3)91)4, CCII) 1.307)3) 91(4) L(I) 2.369)S,91)4) Li)fl 2441)5) CCI) CCI) 1453(4)C(() C)20) 1.3844) C(S) l.(I) 2364)6)C,2’ C)3) 1.343)4) C(2) C(2() 1.537)5)C)3: C(4) 1.439’4 C(3) CCII) 1422(4C14) C(S( 1.303)4) c(S) C(6) (.375,4CCi C)7) 145114) C)7) CCI) 1.30(4,C), C)25) 1.506)4) C)9) C)9) (462)3,C)8 C(2I l.5O6(4 CCI) C110 I 317)4)C110 C)))) 1307)3) CCII) CC.12) (449(3)C)12) C03) 1.358,4, C02, C(26) 1.507)4)C(12, C)I4) 1.444)3) C)(3) CCII) IOOS)4)C(14 C)I5) 1.315(4) C((4) 5.i)1) 2320)5)C(15, COO) 1.301)4) COO) L)1) 2.509)6)C((6 CCI?) 0.445(3) COO) Li(lr 2406)6)C((7 COO) 1.094(4) CO?) C(13) 1.50114,CCII, CCII) 0.442(4) CCII) C(35) 1008)4)COO) COO) 0316)4) CCII) U(I) 2081)6)COO) 1.1)1) 3323)0) CCII) CCII) 1.36)))CC2I) CCII.) 0.07(2) C(3S) CCII.) 132)1)C(23) C(24) 1.202)9) C)25) C(36) (.499)4)C(27) CCII) 1.502(5) C(29) COO) 1.511)5)COo CC32) 1.479)6) C(33) C(34) 6.515)5)C)35) C(36) 0.497(5) CCI?) C(S$( 1005)4)C)39) CCII, 1421)4) CCII) C(40) 1034)5)CCII) C(4() 1.492)4) I... 1.. ).i270Table E-4: Bond Angles (°).•-I•Nd) La(I) N(2) 60.36(I)W)i) R(1) N(4) 6044(5)N)I) k(I) U(I) 66.6(1)N(2) (1) N(S) 600(I)14(2) Ru(S) C(37) 507.06)10)11(2) Rufl.) Li(1) 007.4(l)14(3) Ru(S) CII?) 62.5(1)11(3) Ru)I) Li(I) 151(1)1114) Ru(I( Li(I) 66.4(1)C(I?) Ru)I) LII) 123.2(1)L;1) Ru)I) 1(1)’ 650(2)Ruli 11)1) C)4) 127.0)2)C(l) Nil) C4) 105.5)2)C44) N,1) L)I) 1200(2)R.I; 11)2; Ci9 127.1(2)RuI, 11)2, CIII) 127.1)2)RuII) 11)3’ L)I) 464)1,C)II) 14(3) L)Ir 125.2)2)R;;) 11)4) C)16) 127.1)2;Ru)1) 11(4) Li))) 77.5)1)C)16, 11)4; Liii) 123.5)2)11)1) C)i) C(2) 160.6(3)11)1) C)i) Liii) 72.5(1)C)2; Cli) Li)I) 121.613)C;I; C)2) C(S) 107.0)1)C)I) C(2 C(21) 116.0)3)C)2; C(S) C(22; 0216)3)11(1) C4) C(3) 100.0)3;C)3 C,4 C(S) 1265(2)11)2, ci), C(5) 1244)2CII, CII, Cr, 0256)2)C,L C)7; CI25, 1249)3)Cr C9, CIII 1067(2;CII.’ C(9. C(27} 3247)3)11)2’ CII, C(iO) 324.1(2;CII. C(lO) CIII) 127.1)2)11)2; CIII) C(i2) 310.5)2)CIII; CIII) CIII) 3074(2)C)13; C)12) C(26) 025.2)2)aic—mgi.IM(i) N(S) 17565(1)I(I) C(37) 61.1(0)Iu(I) L)lr 031.6(1)lull) 14(4) 073.16(6)La(I( Li(S) 1112(1)Null) 14(4) 06.06(6)Nu(I) Lu)1( 126.0)1)Lull) C(27) 7976(10)Null) 1.u(I( 57.2)))lu)I( Li(l) 122.4(I)14(1) C(i) 127.3)3111)1) L,(I) 70.0(1)14(1) L61) 726)2)11(2) C(6) 1265)2)11(2) Cdl) 1055)2;14(3) C(14) 127.0(2;11)3) C14) 105 0)2;N(S) Lilir 71.0)2)11)4) CIII) 137.5)2;11)4) CIII) 104.6)2)14(4) Li))) 73.5)2)C))) C(20( 024.2)2)Cdl) C(20) 136 1(2)CII) Lu(I( 71.2(2)Cdl) C(21) 122.7)3;C(S) C(4) 100 1)2;C(S) CI23) 534.1)3C(4) C(S) 122 7)3;C(S) CII) 127,7(3)CII) CI7) 100.1)2)C)?) C(S) 107.4)2)C)?) C)25) 177 7)3)C(S) C(21) 026 6)2)CII) Cdl) 112.2)2;CII) CIII) 125 7)2)CIII) CIII) 0224(2C(I1( C(12) 126 0)2)CIII) C(29) 1245)3)CIII) CI14 107.3)2)14(1)NIl)04(1)14(3)N(I)04(3)N(S)14(4)14(4)CIII)Ru(l)CII)Ru)I)CII)Ru)I)CIII)CI14)Ru)I)C116)CIII)11)1)CII)C(20)CII)C(2)C(4)N) I)C)14)2)CII)CII)C(7i04)2’C(S)N(S)CIII)CIII)CIII)271Table E-4: Bond Angles (A) continued.•_0(12’ CCII) C(S))(%)3 Coo CCII)t)3) C4)C()2 Coo) L(I)COO) CCII) Cue)C(16) 0(25) U(Ir11(4) CoO) CCI?)Coil) Coil) CCI?)Con) Coo) La(•CCII) CCI?) C(S))0(27) CCII) 0(26)COil) C(l6) 0(33)11)4) C4)l) 0(20)CoO) CuP) 0(50)0(20) COl) L.())C)i) 0(20, Li)))Co2 0(2), C)22)0(3, C)23) C)24.)0(7) C)21) C(26)0(12) 0(23) COlD)C)17 C)33 C)34)Ru)1) 0(37) CCII)C(37) 0(34) 0(40)COIl, C031 C)40)0(40, 0(31) C041).— —C(14) COIl) 0(11) 123.6)3,91)1) 0(14) COIl) 1235)2’CC))) 0(14) CCII) 136.5)2)CCII) 0(14) Li(i 72.0)2)C(14) COIl) Li(I) 72.9)2)91(4) CCII) 0(15) 123.1(2)11(4) 0(16) Lb(lr 14.6)2)COIl) CCII) 13(I) 0C2)0(16) 0017) CCII) 107.1(2)CCII) 0(1?) 0(33) 119.0(3)0(2?) CCII) 0(26) 127.7(3)91(4) 0(16) 0(16) 110.2)3)11)4) COIl) Li))) 72.2(3)CCII) 0(19) Lao) 111.1)3)CO) 0(20) CCII) 127.1)2)CCII) 0(20) Li))) 74.1)2)C(2) C421) 0(22.) 12)41)C)3) 0(23) 0(24) 114.3)5)CCI) 0(27) 0(20) 1)4.2)3)COIl) CCII) C032) 1)4.3)3)Coil) CCII) COle) 111.0)3)C)37) CCII) CCII) 1066)3)0(37) CCII) 0(4)) 114 0)3)COIl) CCII) 0(41) 5106(3)91)l) Lao)) L)i)• 1130)2)U6.3)3)1)00)2)740(2)131.2)2)1164(2)76.4(1)516.4(2)2194(2)121.0(2)116.1(1)2074(2)234.6(1)116.3(2)126.5)2)71.3(2)244(2)110.5)7)113 4(0)1)2 2(2)114 4)3)102.1)5)124.2)2)1097)3)1001)2)101.2)3)272Table E-5: Least Square Planes.Plane number 1 Plane number 2Atoms defining plane Distance Atoms defining plane DistanceRu(1) -0.0135(2) Ru(1)-0.0009(2)N(1) 0.063(2) N(1) 0.065(2)N(2) 0.050(2) N(4) 0.057(2)N(3) 0.053(2) C(1)-0.030(3)N(4) 0.165(2) C(19)-0.021(3)C(1) 0.037(3) C(20) .0.048(3)C(2) -0.006(4) -C(3) .0.026(4) Additional Atoms DistanceC(4) 0.039(3) Li(1) 1.839C(S) 0.063(3)C(6) 0.100(3)C(7) 0.148(3) Plane number 3C(8) 0.130(3)C(9) 0.084(3) Atoms defining plane DistanceC(10) 0.067(3) Ru(1)-0.0008(2)C(11) 0.059(3) N(3) 0.071(2)C(12) 0.019(3) N(4) 0.077(2)C(13) -0.001(3) C(14)-0.024(3)C(14) 0.011(3) C(15) .0.058(3)C(15) 0.044(3) C(16)-0.024(3)C(16) 0.104(3)C(17) 0.099(3) Additional Atoms DistanceC(18) 0.142(3) Li(1)-0.024C(19) 0.143(3)C(20) 0.094(3)SummaryAdditional Atoms DistanceC(21) -0.125C(23) -0.164 plane mean deviationC(25) 0.187C(27) 0.115C(29) .0.005 1 0.0705 31483.2C(31) .0.065 2 0.0370 2030.4C(33) 0.008 3 0.0423 3288.2C(35) 0.146C(37) -2.039Li(1) 1.918Dibedrai angle. between plane. ()plane 1 22 3.403 2.84 0.57273Appendix FAppendix F: X-ray Crystallographic Analysis of Ru(TMP)Ph2Figure F-i: PLUTO Plot showing the numbering scheme of Ru(TMP)Ph2.1*323 Hi?C24H8H28Cl SH29aHGH12H30aH30274Figure F-2: Stereoview of Ru(TMP)Ph2.275Table F-i: Experimental Details.A. Crystal DataEmpirical Formula CB62N4RuFormula Weight 1036.33Crystal Color, Habit red, prismCrystal Dimensions. 0.25 X 0.35 X 0.45 mmCrystal System tetragonalLattice Type . 1-centeredNo. of Reflections Used for UnitCell Determination (29 range) 25 ( 20.0- 28.1°Omega Scan Peak Vidthat Half-height 0.38°Lattice Parameters a = 29.493(3)c = 12.615(3) 4V = 10973(3) A3Space Group 14/a (#88)Z value 81.255 g/cm3F000 4336s(MoKa) 3.22 cm1B. Intensity MeasurementsDiffractometer Rigaku AFC6SRadiation MoKo (A = 0.71069 A)graphite monocbromatedTake-off Angle 6.0°276Table F- 1: Experimental Details continiued.Detector Aperture 6.0 mm horisontal6.0 mm vertcalCrystal to Detector Distance 285 mmTemperature 21.O’CScan Type w-29Scan Rate 160/min (in w) (up to 9 .cans)Scan Width (1.05 + 0.35 tan 9)°2Dm; 60.0’No. of Reflections Measured Total: 8647Unique; 8353 (R = 0.028)Corrections Lorenta-polarizationAbsorption(trans. factors: 0.969 - 1.000)C. Structure Solution and RefinementStructure Solution Patterson Methods (DIRDIF92 PATTY)Refinement Full-matrix least-squaresFunction Minim.ized Ew(IFoI— jFcI)2Least Squares Weights=p-factor 0.000Anomalous Dispersion All non-hydrogen atomsNo. Observations (I>3.OOo(1)) 3814No. Variables 385Reflection/Parameter Ratio 9.91Residuals: R; ftw 0.037 ; 0.034Goodness of Fit Indicator 1.87Max Shift/Error in Final Cycle 0.01Maximum peak in Final Duff. Map 0.34 e/AMinimum peak in Final Duff. Map-0.32 e_ /A277TableF-2:AtomiccoordinatesandBeq.IR.4l)9.35000390902500I))))020309(4)02910249)03009(2)1442)0.23439(4)021111(1)0.1190(2)£41)03112(1)0.2913(I)04041(2)£42)0.34*1)0.3313(I)04104(2)C(3)0.3355(I)0.30*1)0.3249(3)£44)030434(10)013111(10)02414(2)C($)02411(1)1.20427)10)0.1053(2)C(I)02910(l)0.33I2I(Il)01005(3)£47)92394(l)0.34124(09)09032(3)C”,)£411)C(14)£411)1.210241)13111(1)4.0307(2)0.3)03(I)0.2591(1)00S5i2)0.1049(1)0.73944))0.0225(2)0.3003(l)0.40403(10)01294(2)0.2740(I)04290(l)0.1400(2)0.2957(l)04909(I)0.1212(3)03215(1)0411411)00310(3)03404(I)04309(I)00220(2)£411)13311)1)040194))00542(3)£41?)02343(I)0.4325(l)02319(3)£411)0.33*1)053414))00104(3)£411)030344))0.3079(I)00239(2)C(20)01392)1)9.33504))-0.0799(2)£421)0.1141(1)0.2)10(1)-0.0474(2)0.,ott.2009(0)050204(0)287(0)3.39(1)4.27(9)4.23(9)£422)0.0942(I)£432)01104)2)C(24)01000(1)C(25)01120(1)£420)0.90944))C(27)00931(2)0.2009001009012(3)£4.)£4.)CoO)£411)0.2114(1)4104142)1.4(I)02344(l)4.2779(2)11(l)02213(1)0.2073(5)1.1(1)02200(l)-0.1740(3)4(449)0.2689(9).00071(5)9.74))0.2395(2)-9.291)45)0.44))02033(I)4.1039(3)1.1(1)02303(3)1.1744(7)1.0(2)1.201343)0)099(9)3.7(2)02039(4)00044))09(4)523(1)2)0(1)312(7)3.19(7)3.02(0)310(7)327(7)2.11(7)345(0)211(0)391(0)291(9)31440)4914)0)50(I)54(I)£428)£030)C(29.)£430)£030.)£431)£421.)C(32)£432.)£433)£435.)£434)02299(I)02009(3)02400(2)03003(4)02940(4)03374(9)03200(4)0275(2)0372(2)0305(I)03:76(0)03211(5)•1901(3)0094(I)01137410)0.049(3)01025(7)0.041(1)0.179(1)DIII)))Ill090III0900100.9014(3)11.1(7)(.3(4)02(0)016541)0,094(4)1941)02972(9)0)19(3)0.4(1)0.199919)0140(5)82(1)03334(3)03)141)99(4)£434.)0339645)02097(4)0.321(1)o(Uu(a+($,,(W)’+U,94t)’+W,,e.•Wi +SVii.ot10+2UWteot•)307(4)412(9)Table F-3: Bond Lengths (A) aom dit.aDce a*om .mRu(1) N(1) 2.052(2) Ru(1) 14(2) 2.028(2)Ru(1) C(29s) 2.076(9) Ru(1) C(29) 2.062(8)N(1) C(1) 1.379(4) 14(1) C(4) 1.381(3)N(2) C(6) 1.382(3) 14(2) C(9) 1.382(3)C(i) C(2) 1.439(4)- C(1) C(10)- 1.397(4)C(2) C(3) 1.354(4) C(3) C(4) 1.442(4)C(4) C(5) 1.392(4) C(S) C(6) 1.393(4)C(S) Clii) 1.500(4) C(6) C(7) 1431(4)C(7) C(S) 1.346(4) C(S) C(9) 1.437(4)C(9) C(10) 1.396(4) C(10) C(20) 1.511(4)C(1i) C(12) 1.398(4) C(ii) C(16) 1.399(4)C(12) Clii) 1.393(4) C(12) C(17) 1.S04(4)C(13) C(14) 1.385(4) C(14) C(15) 1.369(4)C(14) C(18) 1.514(4) C(15) C(15) 1391(4)C(16) C(19) 1.511(4) C(20) C(21) 1.387(4)C(20) C(25) 1.399(4) C(21) C(22) 1.413(5)C(2i) C(26) 1.501(5) C(22) C(23) 1.370(5)C(23) C(24) 1.371(5) C(23) C(27) 1.526(5)C(24) C(25) 1.390(5) C(25) C(28) 1.500(5)C(29a) C(30a) 1.36(2) C(29a) C(34a) 1.37(2)C(29) C(30) 1.38(2) C(29) C(34) 1.34(2)C(30e) C(31a) 1.36(2) C(30) C(31) 1.51(3)C(iia) C(32a) 1.47(5) C(31) C(32) 1.20(7)C(32a) C(33a) 128(7) C(32) C(33) 1.43(7)C(33a) C(34a) 1.44(4) C(33) C(34) 1.35(4)• Symmetry oprntio: if2.x, 1/2-y, 1/2.:.279TableF-4:BondAngles (°).C(4)123.0(7)c(s)12C1(2)C(S)IlLS)))C(l0175.1(3)C)))107.3(3)C(S)1017(1)C(S)1010)3)CU))tILl(S)C(S)1*0(3)C)?)175.1(3)C(s)IlLS)))CI’)121.7(3)c(s)1215(3)CIII’)111,1(3)CII)121.2(5)C(iS)1150(2)q17)1*0(3)Monnm..aSoanib((13)C(14)C(IS)IlL1(3)C(l3)C(I4)CQI)1211(5)CII)CIII’)CII))1150(3)Cl))CIII)C(Il)1511(S)07(10)C(S))C(s))115.1(3)C(S))C(2l)C()2)IlLS(S)C(fl)C)?))qs.)111.1(3)C27iC(s))CC(4)1111(3)C(24)C(S))C(s))Is.4(4)C(S))C)?))C(24)111.1(S)C(S))C)?))CIII)111.1(2)Ra(I)C)?9.)C(34.)Il44(l)Rn)))((29)CIII’)till(S)C(S))C(S))C(14)111(1)C(S))CUe)C(S))111(1)C(S))CIII)C(s))ItS(S)C(S))C))?)C(S))121(3)C(S))C(S))C(S))Ill(S)q29)C($4)C(S))121(1).nm.—afl)q14)07(11)130.2(3)C414)47(11)C4lI)152.5(3)C(II)C(Il)CoO)121.0(1)07(10)c(S))C(S))1210)5)WI)C(S))C(S3)1*1(1)a31)C($)121.1(3)(7(5))c(s))C(s))1250(4)C(s))C(S))CUT)12)0)4)C(S))CII)C(S))1320)4)C(20)C(21)c(20)121.2(3)Rn)))C(S).)q30.)1275(1)CII’.)Cob)CoIn)117(1)Rn)I)C(S))C054)121.1(1)C(S).)C(S).)C(S).)130(2)Qob)CI).)CoO.)121(2)C(S).)C(S).)C(S).)Ill(s)CS).)C(S).)W4.)ISO(S)C(S).)C(14.)C(s).)120(I).tomn.10..Io.nI.111))RoIl)1112)5057(9)W(t)IIooN)))5542(P)q5S.)•55.7(3)qs.rlLl(2)C(25.)II0)2)2S)11.5(2)CoO)03171(2)x14(1)14(I)‘((I)11(1)11(2)11(2)qSI.)Rn)))Rn)))C(S)?11I)C(S)11(1)C(S)C(S)11(5)C(S)07(7)11(2)cot).C(S)as)CII)C(I))Rn) I)Rn)!)(nfl)Rn(I)Kill)Ru(I)Ru(l)14(I)11(2)SI(?)C(I IC(S)CII)C(4)C(s) C(S)C(S)C(S)C(S)CDI)C(I0)coil)C(IS)C(I2)N)))KnIt)14(I)Kill)14(7)Rn)))14(2)Kill)N(S)Knit)Rn)))NI)Cl)NI)Kill)1117)7111)C)))C(S)((I)C(7)C)?)N)))C(4)H)C(S)C(S)C(S)11(2)C(S)C(S)C(7)14(2)C(S)C(S)C(S)C)))007(15)C(1)C))))C(12)CIII)qII)CI?)C(I2)CoilCob)s0.3U)C(S))507(2)14(7)1100C(S).)531(3)C(7S)51.3(5)((I)2770(2)((4)3072(2)C(S)127302)((7)lbSI(S)COlD)01255)3)C(4)507.7(3)C(S)1257(3)C(S)275.5(3)C(tI)5)05(3)((7)2000(3)C(S)III1(3)C(S)1012(3)CIa)IS)I(S)C(S))till(S)((I?)IllS)))dl)1197(3)C))?)121I(S)C(I4)32?0(3)Table F-5: Least Square bøA-0.006(2)14(2) 0014(2)CII) 4.029(3)C(2) 4,033(4)C(3) 0.016(4)C44) 0.023(3)C(S) . 0.010(3)C(6) 6.000(3)C(7) 4.029(3)C(8) 4.031(3)C(0) 0.003(3)C(10) 0.002(5)Add,t.ocii AtomsRu(1) 4.026CIII) 4.036C(20) 0.060C(29a) 1.994C(29, 2.007plaai desi.*ooo ‘P1... .ubm 7At dai.i plo..C(20( 0.010(3)C)21) 4.00913)C(22) 4.001)4)C(23( 0.005(4)C(24 4.001(4)CIII) 4.008(3)Add,LIo..J Atom. Dsso.coC(10( 0.163C(26) 0.0340.035C(5e) 0.0051 0.0170 537.42 0.0044 1143 0.0039 10.14 0.0096 90.1o 0.0068 07.1• 0.0028 6.67 0.0054 249$ 0.0388 34.4• 0.0263 19.2Du. be.,.. —plo.. 3 2 3 4 1 6 72 1.643 5.10 2.724 0.42 1.12 3.619 3.45 094 2.00 1.094 9110 66.60 9883 $7.63 $7.397 $303 99.19 92.43 93.21 94.19 77.07$ 81.39 62.54 60.38 61.73 $2.61 103.91 20769 69.45 90.54 90.41 99.73 00.62 103.37 24.70 6.09Pie.. ..mbt 6M LM pie..C(11) 0.000(3)C(12) 4.004(3)C(13) 0.004(5)C(14) 4103(3)CIII) 4.003(3)C(16) 0.003(3)Addisa...I M Dii....C(S) 4.060Cli?) 4.053C(I6) 4.009C(10) 0.004Pie.. owobe 2Atom. d.9sw8 pIe.. Dssoot.1(l) 0.0032)C(1) .0.001(3)CII .0.005(4)CCI; . 0.006141C(4) .0.006(3jAdd,Uotoi Atom. Dii....Roll) .0.049C(S) 4.040C(I0) 9.002 Atom. ddwsg pie..C(25,C(30)C(21)C(32)C(33(C(34)Additecal Atom.Ro(1)Pie.. iiZbtt S.0,037(9)0.06(2)4.09(3)0.00(4)4.01(4)9.03(1)4.560Pie., s., SAtom. d4.1. plo.. Die....C(29.r 4.010(8)C(30a) 6.03)1)C(2Ia) 4.04(2)C(32o)’ 0.03(4)C(13i)° 4.02)3)C(34a) 0.02(1) Atom. Dii....RoIl) 4.426281


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