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Reactions of acetylene and allene with amidodiphosphine iridium complexes Forde, Cameron Edward 1992

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REACTIONS OF ACETYLENE AND ALLENE WITHAMIDODIPHOSPHINE IRIDIUM COMPLEXESbyCAMERON EDWARD FORDEB. Sc., Trinity Western University, 1990A THESIS SUBMITTED IN PARTIAL FULFiLLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEinTHE FACULTY OF GRADUATE STUDIESDepartment of ChemistryWe accept this thesis as conformingto the required standardTHE UNIVERSiTY OF BRITISH COLUMBIAAUGUST 1992© Cameron Edward Forde, 1992In presenting this thesis in partial fulfillment of the requirements for an advanced degree at theUniversity of British Columbia, I agree that the Library shall make it freely available forreference and study. I further agree that permission for extensive copying of this thesis forscholarly purposes may be granted by the head of my department or by his or her representatives.It is understood that copying or publication of this thesis for financial gain shall not be allowedwith out my written permission.Cameron E. FordeDepartment of ChemistryThe University of British ColumbiaVancouver, CanadaSeptember 3, 1992IIAbstractThe reaction of the alkyl halide complexes Ir[N(SiMe2CHPPh)1(CHR)X(2; R = H, X= I: 3; R = H, = Br: 4; R = Ph, X = Br) with one equivalent of acetylene produces thecorresponding allyl (or phenylallyl) complexes fr[N(SiMeCHPPh](r13-CH4R)X(6; R = H,X = I: 7; R = H, X = I: 8; R = Ph, X = Br). A deuterium labeling study indicates that the allylcomplexes form by vinylidene migratory insertion into the iridium-alkyl bonds. Using excessacetylene produces the isoprenyl complexes Ir[N(SiMe2CH2PPh2)21(C57)X(10; X = I: 11; X =Br) from the methyl derivatives 2 and 3. The reactivity of these complexes is blocked by anagostic interaction of a methyl group with the metal. Complex 10 reacts with trimethyiphosphineto generate a new compound, Ir[N(SiMeCHPPh)](PMe3)(C5H7I,in which the tridentateligand has changed from meridional to facial coordination. The addition of excess acetylene to thebenzyl bromide complex, 4, results in elimination of the benzyl ligand as toluene and a dualvinylidene insertion process to produce fr[C(CH2)N(SiMeCHPPh](C(CH2) CH). An X-raystrucmre determination shows that one vinylidene unit has inserted into the iridium-amide linkageand the other vinylidene unit has inserted into an in situ iridium acetylide bond.The12-allene complex Ir[N(SiMe2CHPPh)](r1-C3H4previously reported from thislaboratory was found to exist in a dynamic equilibrium with a new complex which has twoincorporated molecules of allene. This new complex is proposed to be the iridacyclopentanecomplex, fr[N(SiMe2CH2PPh)1 C6H8,based on NMR evidence and literature precedent. Thisiridacyclopentane complex is stable only in the presence of allene. Attempts to stabilize thiscomplex by coordinative saturation with the potent Lewis base thmethylphosphine produced thetrimethylphosphine iridacyclopropane complex, Ir{N(SiMe2CH2PPh2)](PMe3) (C3H4). Thiscomplex could also be prepared directly from the iridacyclopropane complex,Ir{N(SiMe2CHPPh)1(r1-C3H4.The introduction of allene to the ailcyl halide complexes 2-4was found to result in the reductive elimination of the alkyl halide and to form an equilibriummixture of the iridacyclopropane and iridacyclopentane complexes. The kinetics of the reductiveinelimination of benzyl bromide from complex 4 was studied by phosphorus-3 1 NMR spectroscopy.The reaction was found to have a pseudo-first order dependence upon metal complex concentrationwhen excess allene was employed. The activation parameters were found to be AH = 67 (9) Umol-1 and EIS1 = —260 (30) 3 mol1 K-1. The rate-determining step of this process is proposed tobe the associative step.ivTable of ContentsAbstract.iiTable of contents ivList of tables viiList of figures viiiList of abbreviations ixAcknowledgments xDedication xiChapter 1: Introduction1. Phosphine and mixed-donor ligands in organometallic chemistry 12. The oxidative addition reaction 43. The reductive elimination reaction 64. Migratory insertion 65. Scope of this Thesis 76. References 7Chapter 2: Reactions of Acetylene With Iridium(III) Alkyl Halide Complexes1. General introduction and background 102. Literature survey 123. Reactions with one equivalent of acetylene 154. Reactions with excess acetylene 20A. Methyl derivatives 21B. Benzyl derivative 25V5. General observations and mechanistic considerations 306. Summary 317. Future work 328. References 32Chapter 3: Reactions of Allene with Amidodiphosphine Iridium Complexes1. Introduction 352. Literature survey 353. Previous work on amidodiphosphine iridium complexes 384. Allene coupling and decoupling at amidodiphosphine iridium centres 395. Reactions with trimethyiphosphine 416. Allene reactivity with alkyl halide amidodiphosphine iridium complexes 477. Summary 518. Future work 529. References 52Chapter 4: Experimental1. General 552. Solvents 553. Reagents 564. Syntheses of metal complexes 565. NMR measurements 576. Syntheses of new compounds 57mer-Ir[N(SiMe2CHPPh)](rj3-CH5)X 57mer-Ir[N(SiMe2CHPPh2)2](113-C3H5) ,658mer-Ir[N(SiMeCHPPh](r3-CH5)Br, 7 58mer-fr[N(SiMePPhj-CH41-Ph)Br, 8 58mer-fr[N(SiMe2CHPPh)](r3-CH2D1 -Ph)Br, 8-d2 59mer-trans-fr[N(SiMeCHPPh(Me)I(PMe3), 9A-C 60mer-lr[N(SiMe2CHPPh)21[11-C(CH2) H3jX 62mer-Ir[N(SiMe2CH2PPh2)2] [Ii-C(CH) HI,10 62mer-Ir[N(S1Me2CH2PPh2)21[ri-C(CH) H3jBr,11 63fac-Ir[N(SiMeCHPPh)j(PMe3)[C(CH2) H]I,12 63mer-Ir[C(CH2)N(SiMeCH2PPh2)][11‘,i-C(CH) CHIBr, 13 64mer-Ir[N(SiMeCH2PPh2)2](112-C3H4), 14 65mer-Ir[N(SiMeCH2PPh) ](C6H8), 15 66fac-Ir[N(SiMe2CH2PPh2)2](PMe3)(fl2-C3H4), 16 677. References 68Appendix A: X-Ray Crystallographic Analysis1. Experimental details 70A. Crystal data 70B. Intensity measurements 71C. Structure solution and refmement 712. Tabulated data 72Appendix B: Kinetic Data 77viiList of TablesTable 2.1. Selected bond lengths (A) for Ir[C(CH2)N(SiMe2CH2PPh2)2]-(C(CH) CH), 13 29Table 2.11. Selected bond angles (degrees) for fr[C(CH)N(SiMeCHPPh]-(C(CH) CH), 13 30Table 3.1. Kinetic data for the reductive elimination of benzyl bromide 48Table A.Ia. Final atomic coordinates (fractional) and Beq (A2) 72Table A.Ib. Hydrogen atom coordinates (fractional) and B10 (A2) 73Table A.II. Selected bond lengths (A) with standard deviations 75Table A.Ill. Selected bond angles (degrees) with standard deviations 75Table B.I. Run 1: Kinetic data at T = 35.0 ± 0.1 °C 77Table B.II. Run 2: Kinetic data at T 35.3 ± 0.2 °C 78Table B.llI. Run 3: Kinetic data at T = 35.3 ± 0.1 °C 79Table B.IV. Run 4: Kinetic data at T = 45.2 ± 0.1 °C 80TableB.V. Run 5: Kinetic data at Temp = 45.2 ± 0.1 °C 81Table B.VI. Run 6: Kinetic data at T = 55.2 ± 0.2 °C 82Table B.Vfl. Run 7: Kinetic data at T = 55.1 ± 0.2 °C 82Table B.VIll. Run 8: Kinetic data at T = 55.2 ± 0.2 °C with added 1,4-cyclohexadiene 83Table B.IX. Run 9: Kinetic data at T = 55.0 ± 0.2 °C with added 1.4-cyclohexadiene 84Table B.X. Kinetic data summarized 85List of FiguresFigure 1.1. Some representative multidentate phosphine 1igds 2Figure 1.2. Chiral (f3-aminoalkyl)phosphine ligands 3Figure 1.3. Free, A, and coordinated, B, —N(SiMe2CHPPh) 4Figure 1.4. The trimethylenemethane, methylidene and vinylidene aniidodiphosphine iridiumcomplexes 4Figure 2.1. Free, A, and metal-coordinated, B, vinylidene 10Figure 2.2. The 300 MHz 1H NMR spectrum of Ir[N(SiMe2CHPPh)J(C5H7Br,11 22Figure 2.3. Two possible geometric isomers of Ir[N(SiMePPhj()(PMe3I,12. 24Figure 2.4. The 300 MHz 1H NMR spectrum of lr{C(CH2)N(SiMe2CH2PPh2))-[C(CH2)CCHJBr, 13 26Figure 2.5. The molecular structure ofIr[C(CH)N(SiMeCHPPh](C(C ),13 27Figure 3.1. Cyclic oligomers of allene 37Figure 3.2. The 3,4-dimethylenemetallacyclopentane moiety 37Figure 3.3. Rh(acac)(C6H8)py2 and Ir(acac)(C6H8)(12-C3H4 py 37Figure 3.4. r2-t, A, andi2-cy, B, modes of allene coordination 38Figure 3.5. The 300 MHz 1H NMR spectrum of Ir[N(SiMe2CHPPh)](C6H8,15 40Figure 3.6. Five possible structures of Ir[N(SiMeCPPhJ( Me3)(4,16 43Figure 3.7. The 300 MHz 1H NMR spectrum ofIr[N(SiMeCH2PPh)2](P(C,15 44Figure 3.8. The Eyring plot of the kinetic data for the reaction of fr[N(SiMeCHPPh)]-(CH2Ph)Br, 4, with excess allene 49ixList of AbbreviationsAside from the standard IUPAC and SI abbreviations the following abbreviations are usedin this Thesis.acac acetylacetonatoBDH British Drug Housebr broadBut tert-butyl —C(CH3)cis cisoidal coordination geometryA heatAS * change in entropy of activationAH3 change in enthalpy of activation6 chemical shiftd doubletfac facial coordination geometiygem geminal dispositionJ coupling constantm- metam multipletMe methylmer meridional coordination geometryMSD Merck-Sharp-DohrneNMR nuclear magnetic resonanceorthop- paraPh phenylPr1 isopropyl —CH(CH3)2py pyridineS singlett tripletirans transoidal coordination geometryvt virtual tripletxAcknowledgmentsFirst and foremost I would like to thank Dr. Michael Fryzuk for instilling in me a sense ofthe scope and importance of organometallic chemistry. It has been a pleasure to work under hissupervision and I have learned much from him in the course of our daily interaction, only a fractionof which could be presented in this Thesis.I would lilce to thank Dr. Steve Rettig for his excellent work on the X-ray crystal structureanalysis, especially in that he went Out of his way to have the results ready for the Edmonton CICconference.The onerous and time-consuming task of proof-reading this Thesis was borne by manyindividuals and I would like thank each one for their unique contributions: Dr. Craig Montgomery,Dr. Lucio Gelmini, Dr. Martin Ehiert, Mr. Richard Schutte, Mr. Kevin Ross, Ms. LisaRosenberg, Mr. Myl Mylvaganam, Mr. Jeff Debad, Mr. Guy Clentsmith, and Mr. Eric Brouwer.In addition I would like to thank Eric Brouwer and Pauline Chow for our many helpfuldiscussions, both chemistry related and otherwise. I wish you both success in your respectiveendeavours and look forward to our continued friendship.xA thumbnail sketch, a jewelers stoneI need an idea to call my own.Old man don’t lay so stillYou’re not yet young there’s time to teach.Point to point, point observationChildren carry reservations.Standing on the shoulders of giantsLeaves me cold, leaves me cold.I need an idea to call my ownA hundred million birds fly away.-M. Stipe1CHAPTER 1INTRODUCTION1. Phosphine and mixed-donor ligands in organometallic chemistry.The formation of metal-carbon bonds and the transformations that can be wrought toorganic fragments at a metal centre comprise much of the subject matter of organometallicchemistry.1 Formally, only those complexes containing a metal-carbon bond can be consideredorganometallic complexes, but many ligands in organometallic chemistry involve coordination to ametal through elements other than carbon. These ancillary ligands are only rarely involved in thereactivity of the complex and are used to manipulate the steric and electronic properties of thecomplex. The phosphine family of ligands is quite commonly used as ancillary ligands since thedesired steric and electronic properties can be adjusted by appropriate choice of the phosphine.One way in which phosphine ligands can be modified is by altering the size of thesubstituents. The cone angle2has been introduced as a measure of the steric bulk of a phosphineligand, and phosphine ligands of a wide range of cone angles have been prepared. Phosphineligands with large cone angles (eg. tri-t-butylphosphine and tricyclohexyiphosphine) have beenused to stabilize coordinatively unsaturated complexes.The electron-donating ability of the substituents on phosphorus changes the Lewis basicityof the ligand. For example, ailcyl substituents are better electron donors and produce more Lewis-References p. 7Chapter 1 2basic phosphines than the corresponding aryl analogues. Thus the electron density at a metalcentre can be controlled to some extent by the choice of substituent on the phosphine.The ubiquitary presence of phosphine ligands in organometallic chemistry is due in part tothe NMR activity of the phosphorus nucleus. The 31p nucleus is has a nuclear spin of one halfand is 100 % abundant and has adequate sensitivity for NMR measurement (about one one-thousandth that of proton). The magnitude of two-bond phosphorus-phosphorus couplingconstants across a metal(2Jpp)3 as well as the one-bond metal-phosphorus coupling constants(1Jivp, where M is a spin-half nucleus)4are useful stereochemical probes. The chemical shift canalso be used to determine the oxidation state of the phosphorus nucleus; however, there are anumber of parameters involved and such assignments should be made carefully.Phosphine ligands with more than one phosphorus atom available for coordination to ametal have also found much use in organometallic chemistry. Such ligands that coordinatethrough more than one atom are called chelating ligands (from the Greek chtë, claw). The donoratoms can be separated by any number of atoms, although two and three member backbones havebeen the most common since the resulting ring systems are five- and six-membered. With thismethod chelating phosphorus ligands can be constrained to certain geometries about a metal (eg.R2PPR R2PPR R2, PR2R2PPPR2R2P/ThPR2Figure 1.1. Some representative multidentate phosphine ligands.References p. 7Chapter 1 3cis or facial). Some representative examples of multidentate phosphine ligands are shown inFigure 1.1.Chelating ligands which have the ability to coordinate to metal atoms through disparatenuclei have also been prepared. This class of ligands is known as mixed-donor ligands and theycan have some advantages over multidentate ligands of the same donor type. The mixed-donorligands used in the preparation of the catalysts for the catalytic asymmetric cross-coupling reactionprovide a good example of some of the advantages. The chiral (f3-aminoalkyl)phosphine ligands5have been prepared from optically active amino acids (Figure 1.2). Nickel and palladiumcomplexes with these ligands have been used in the catalytic asymmetric Grignard cross-couplingof secondary alkyl magnesium reagents with alkyl and aryl halide compounds.6 The nitrogendonor of these ligands aids in the orientation of the attack of the Grignard reagent and results inthe formation of optically active products.R>Me2N PPh2Amino acid R Lipar,d Amino acid R LipandS-alanine Me S-Aiapbos S-phenylalanine CI4Ph S-PhephosS-Ieucine Bu’ R-Leuphos R-phenylgtycino Ph R-PhGlyptiosS-vane Pr’ S-Valphos R-cyclohexyiglycine C6H11 R-ChGiyphosS-isoleucine Bu6 S-iiephos R-t-4eudne But Rt-LeuphosFigure 1.2. Chiral ()3-aminoalkyl)phosphine ligands.A thdentate amidodiphosphine family of mixed-donor ligands has been prepared in theselaboratories (Figure 1.3). This family of ligands has been used to make many exceptionalcompounds; examples are amide complexes of the later transition elements7 and phosphinecomplexes of the early transition series and lanthanide group.8 Some unusual organic fragmentshave been stabilized at an iridium complex with this ligand. Three examples are shown in Figure1.4; the trimethylenemethane,9methylidene,’0and vinylidene’1”2complexes. The startingReferences p. 7Chapter 1 4Me2 Me2R2P(’NPRAMe2 Me2R2P—M—PRLBFigure 1.3. Free, A, and coordinated, B, N(SiMe2CHPPh).material for the formation of these complexes is the iridium amidodiphosphine cyclooctenecomplex, 1, the preparation of which is shown in Reaction i.i.’’,/NPh2 H2Me2SI\T’—Me2S1” I %%\.P..-PPh2 H2Figure 1.4. The trimethylenemethane, methylidene and vinylidene amidodiphosphine iridiumcomplexes.2. The oxidative addition reaction.[(rCI(C8H14)2]+ 2 L1N(S1MeCH?Ph)—(2L1CI, 2C8H14)(1.1)Me2Si’”F’\I: N—Ir=CH2Me2Si(,.pPh2Me2SK”rN—Ir=C=CH2.1 IMe2Si,pPh2The oxidative addition reaction is important in many catalytic and stoichiometric reactionsin organometallic chemistry.16 The reaction involves the addition of the two parts of a molecule,A-B, to a metal. The A-B bond breaks and new bonds between the metal and A and B form. Themetal complex needs to have available an oxidation state that is two higher than before the additionand also have available sites for coordination. The reagents which oxidatively add to metalcomplexes can be separated into three categories:’7nonpolar reagents, electrophilic reagents andReferences p. 7Chapter 1 5Ph3PCl—Jr—COPPh3Scheme 1.102Ph3PI .1ciH lr—COHIPPh3Ph3PI0— lr—C0OfPPh3Ph3PCl Jr—C0MePPh.,.-, Pe2 I\ 1,CH2R: N—lr—X.1 IMe2Si,p‘%,.*‘ Ph22: R = H, X = Br3: R=H, X=I4: R=Ph,X=Brreagents where a bond remains between the two added parts. The reactivity of the iridiumcomplex, trans-Ir(PPh3)2(CO)C1, with each of these classes of compounds is summarized inScheme 1.1. The amidodiphosphine iridium complex, 1, mentioned above is quite similar to thisiridium complex; there are two phosphine donors trans to one another and a uninegative ligand.The oxidative addition of alkyl halides to the iridium cyclooctene complex, 1, was found toproduce coordinatively unsaturated complexes, 2,15,18 315 and 419 (Reaction 1.2).RCH2X—(C8H14)(1.2)References p. 7Chapter 1 63. The reductive elimination reaction.The re :rse of the oxidative addition reaction is the reductive elimination reaction.Reductive elimination is important in organometallic chemistry since carbon-carbon bonds can beformed and many catalytic cycles include reductive elimination steps.’6 In order for reductiveelimination to occur two substituents need to be cis to each other in the coordination sphere of ametal. Reductive elimination of ailcyl halides is observed in the reactivity studies presented inChapter 3.4. Migratory insertion.Another mode of reactivity that is of importance to organometallic chemistry is migratoryinsertion.20 The migratory insertion reaction is vital to many catalytic cycles and to stoichiometricformation of organic molecules. In order for migratory insertion to occur the two substituentsneed to be cis to each other in the coordination sphere of the metal and the process is usually aidedScheme 1.2H2CCH H2 H2(I). I /C_C\LM—R LM FIII(ii). cI LMRL,)M—RH2C ‘‘2I, C(iii). IIN LMRLM—RReferences p. 7Chapter 1 7by the addition of some ligand to stabilize the resulting complex. Many olefin polymerizationreactions are proposed to proceed by olefin insertion into metal-alkyl bonds (Scheme 1.2i).21Carbon monoxide is a ligand which quite commonly undergoes migratory insertion into metal-carbon bonds (Scheme L2ii). The migratory insertion of the vinylidene moiety (Scheme 1.2iii) isobserved in the acetylene reactions reported in Chapter 2.5. Scope of this Thesis.The study of the reactivity of d6, amidodiphosphine iridium ailcyl halide complexes ispresented in this Thesis. The addition of unsaturated hydrocarbons, acetylene and allene, to theseiridium complexes results in the formation of carbon-carbon bonds and thus transformations oforganic molecules at the metal centre. The addition of acetylene to the amido diphosphinecomplexes is reported in Chapter 2. The rearrangement of acetylene to vinylidene and subsequentmigratory insertion of the vinylidene moiety into iriclium-alkyl bonds is observed. Chapter 3extends this reactivity to the three carbon diene, allene. The reductive elimination of alkyl halidecompounds from the iridium(Ill) alkyl halide complexes occurs when allene is introduced. Theexperimental details of the work are reported in Chapter 4. Some ideas for future work arepresented at the ends of Chapters 2 and 3.6. References.(1) Coliman, 3. P.; Hegedus, L. S.; Norton, 3. R.; Finke, R. G. Principles and Applicationsof Organotransition Metal Chemistry; University Science Books: Mill Valley, CA, 1987,pp 1-2.(2) Tolman, C. A. Chem. Rev. 1977, 77, 313.(3) Finer, E. G.; Harris, R. K. Prog. NMR Spectroscopy 1970, 6, 61.References p. 7Chapter 1 8(4) Pregosin, P. S.; Kunz, R. W. NMR Basic Principles and Progress; Springer-Verlag:Heidelberg, 1979; Vol. 16, pp 55ff.(5) Hayashi, T.; Fukushima, M.; Konishi, M.; Kumada, M. Tetrahedron Lett. 1980,21, 79.(6) Hayashi, T.; Konishi, M.; Fukushima, M.; Kanehira, K.; Hioki, T.; Kumada, M. J. Org.Chem. 1983, 48, 2195.(7) Fryzuk, M. D.; Montgomery, C. D. Coord. Chem. Rev. 1989, 95, 1.(8) Fryzuk, M. D.; Haddad, T. S.; Berg, D. I. Coord. Chem. Rev. 1990, 99, 137.(9) Fryzuk, M. D.; Joshi, K.; Rettig, S. J. Organometallics 1991, 10, 1642.(10) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. J. J. Am. Chem. Soc. 1985, 107, 6708.(11) Fryzuk, M. D.; McManus, N. T.; Rettig, S. J.; White, 0. S. Angew. Chem., mt. Ed.Engl. 1990, 29, 73.(12) Fryzuk, M. D.; Huang, L.; McManus, N. T.; Paglia, P.; Rettig, S. J.; White, 0. S.Organometallics 1992, 11, in press.(13) Fryzuk, M. D.; MacNeil, P. A. Organometallics 1983, 2, 355.(14) Fryzuk, M. D.; MacNeil, P. A. Organometallics 1983,2, 682.(15) Fryzuk, M. D.; MacNeil, P. A.; Rettig, 5. 3. Organometallics 1986,5, 2469.(16) reference 1, pp 279-343.(17) reference 1, pp 28 1-284.(18) Fryzuk, M.D.; MacNeil, P. A.; Rettig, S. J. Organometallics 1985,4, 1145.(19) Fryzuk, M. D.; MacNeil, P. A.; Massey, R. L.; Ball, R. 0. .1. Organomet. Chem. 1989,368, 231.(20) reference 1, pp 355-394.• References p. 7Chapter 1 9(21) reference 1, pp 383-393.References p. 710CHAPTER 2REACTIONS OF ACETYLENE WITH IRIDIUM(Ill) ALKYL HALIDE COMPLEXES1. General introduction and background.One of the key features of organometallic chemistry is the stabilization of reactiveorganic molecules at a transition-metal centre.’ Many molecules are unstable at normaltemperatures and pressures, requiring special conditions to stabilize them or special conditionsto produce them. One reactive molecule that has been stabilized by coordination to transitionmetals is vinylidene, the tautomer of acetylene (Figure 2.1). While free vinylidene has beengenerated thermally by modulated beam dynamic mass spectroscopy at 820 K2 and has anestimated life-time of 10 ps,3 many examples of stable transition-metal vinylidene complexesand their methods of preparation are reported in the literature.4’5:C CH2 LM C CH2A BFigure 2.1. Free, A, and metal-coordinated, B, vinylidene.The most conmion route of vinylidene formation within the coordination sphere of ametal is the rearrangement of coordinated terminal ailcynes. This rearrangement can proceedvia two distinct pathways: (i) a concerted route which involves a Tj2- to r .. slip of the alkyneReferences p. 32Chapter 2 11Scheme 2.1LAM--C- -LM-HII LflM=C=C\LM—CC—Hwith concomitant a, proton shift (Scheme 2.IA); or, (ii) an allcynyl(hydrido) route whichinvolves the oxidative addition of the alkyne C-H bond followed by a 1,3-hydrogen shift(Scheme 2.IB). Even though theoretical studies6 have shown that the alkynyl(hydrido) route isenergetically disfavoured, iridium (Scheme 2.H) and rhodium (Scheme 2.111)8 systems havebeen reported that proceed by this route. After a brief literature survey of rhodium and iridiumsystems in which vinylidene intermediates are invoked, the reactions of d6 iridium ailcyl halidecomplexes with acetylene will be presented and the evidence for vinylidene intermediates in thissystem of complexes will be discussed.Scheme 2.11Pr Pr’3 Pr’3P P PI RCCH —_____ICI—Ir - CI—fr—CCR CI—Ir=C=C_n. A‘ 2)P P PPr Pr’3 Pr’3R = S1Me3,COOMeReferences p. 32Chapter 2 12Pr’3 PhPIcCl—Rh-—IllIcPr HiiPr’3I,Cl—RhC%PhCPh3 Ph3P PI PhCCH ICI—Rh=C=CHPhCI—Rh—PPh3—(PPh3) IP P—(HCI)Ph3 Ph3OHScheme 2.111Pr’Pr’3PI PhCl—Rh=C=C(Pr’spy 1/Cl—Rh—CC—PhP NaCpPr13—(py, PPrPr’3P%CPhH2. Literature survey.A rhodium vinylidene intermediate is proposed in the reaction of phenylacetylene withchlorotris(triphenylphosphine)rhodium(I) (Scheme 2.IV). The reaction with excessScheme 2.IVPh‘Ph3References p. 32Chapter 2 13Ph4PMe3Me3P7Ir—HMe3Pphenylacetylene produces the substituted rhodacyclobutene, while the addition of 3-butenoicacid generates the bicyclic compound shown.9 The insertion step in each case involves theinsertion of either the alkyne or the alkene into the rhodium-vinylidene unit.The reaction of mer-trans-Ir(PMe3)3(Ph)(Cl)H with phenylacetylene involves migratoryinsertion of a vinylidene unit (Scheme 2.V). While it has not been shown that the vinylintermediate formed is produced by vinylidene insertion into the iridium-hydride bond, the finalproduct is formed by vinylidene migratory insertion into the iridium-vinyl group.’°The vinylidene complex 5 has been prepared in our laboratories11 by the addition ofacetylene to the cyclooctene complex, 1; the reaction proceeds via an unstable2-acetyleneintermediate, which undergoes an acetylene to vinylidene rearrangement (Scheme 2.VI). Thereactivity of this complex with Group 13 ailcyl compounds”2and with alkyl halides12 hasrecently been reported. Relevant to this Thesis is the reaction of 5 with methyl iodide whichScheme 2.VBUtCCHTIPF6—(TICI)+ PF6Me3P-ButCCHH PF6Ph Me3 II PhCH_________/3Me3P—1r-—C Me3P—rCCBUtMeP’ \\H CH Me3P: /c—c CHH2 Me2 IBut+ PF6References p. 32Chapter 2 14Scheme 2.VIMe2SI’ P HHCCH \ I C: N—Ir—III—(C8H14).1 I cMe2SL P HPh2/NPh2Me2Si\I: N—lr=C=CH2Me2Si..._— Ph25produces the3-allyl complex 6; the progress of this transformation was studied by phosphorus-31 NMR spectroscopy and the proposed mechanism is summarized in Scheme 2.Vll. The firststep of the proposed mechanism involves the trans-oxidative addition of methyl iodide13’4 tothe vinylidene complex 5. Migratory insertion of the vinylidene unit into the iridium-methylbond generates an isopropenyl ligand which produces ther3-allyl complex, 6, by a 1,2-hydrogen shift.The intermediate A in Scheme 2.VII might be accessible by reaction of acetylene withthe alkyl halide complex Ir[N(SiMe2CH2PPh2)2](Me)I, 2. The potential for the in situformation of the vinylidene unit and subsequent migratory insertion invited further study. Thisroute would also make multiple insertions of the vinylidene moiety possible, and could lead tonew oligomerization or polymerization products. With this goal in mind a study of the reactionof acetylene with three suitable alkyl halide complexes, which had already been prepared andcharacterized in our laboratories, fr[N(SiMe2CHPPh)j(Me)I,’5’62, Jr[N(SiMeCHPPh)]-1References p. 32Chapter 2 15Scheme 2.VllMe2SiPh\ I CH3I:N—IrCCHMe2Si(lPh25Me2S(’”2Me2S\\Ph2 H2-PIf:N71r=C=CH2Me2SiPh2 APh2Me2S(”P: NMe2Si( I CH2PPh2(Me)Br’63, and fr[N(SiMe2CHPPhj(CHh)Br,’74 , was undertaken.3. Reactions with one equivalent of acetylene.The introduction of one equivalent of acetylene into solutions of the ailcyl halidecomplexes 2-4 produces the allyl complexes, 6-8 (Reaction 2.1). The phosphorus-31 NMRspectra of these complexes exhibit two signals, each of which is a doublet. It has been observedthat the magnitude of phosphorus-phosphorus coupling constants is dependant on the cis or6References p. 32Chapter 2 16Ph2 Ph2Me2Si(?HR+ 1 HCCH_______(2.1)Me2SI I Me2Si,, X“—PPh2 Ph22: R=H,X=I 6: R=H,X=I3: R=H,X=Br 7: R=H,X=Br4:R=Ph,X=Br 8:R=Ph,X=Brtrans orientation of the phosphine donors;’8cis-phosphine ligands produce coupling constantsless than 100 Hz, while trans-phosphine donors have coupling constants greater than 100 Hz.The magnitude of the phosphorus-phosphorus coupling constants for the allyi complexes 6-8 arebetween 400 and 500 Hz and this strongly indicates a trans-orientation of the phosphorusnuclei, which then requires meridional coordination of the tridentate ligand. This is alsoevidenced in the proton NMR spectra where the separation of the ortho- from the meta- andpara-phenyl resonances is greater than 0.5 ppm in each case (a separation of less than 0.5 ppmwould suggest cis-diphenylphosphines).19 The allyl complexes 6-8 exhibit the expectedresonances for allyl ligands in the proton NMR spectra20’(or phenylallyl resonances22’3for8). The phenylallyl complex could not be formed by the reaction of benzyl bromide with thevinylidene complex 512Two possible mechanisms can be proposed for the formation of the allyl ligand: (i)direct acetylene insertion, and (ii) acetylene to vinylidene rearrangement, followed byvinylidene insertion. In the first mechanism the direct insertion of the acetylene into theiridium-alkyl bond generates a propenyl ligand which then requires a 1,3-hydrogen shift togenerate the allyl ligand (Scheme 2.VIIIA). The alternative mechanism proceeds byReferences p. 32Chapter 2 17Scheme 2.VfflLM—CH2RAl B H2LM—CH2RLAM’ CH2RLM—CH2RH________H2C=CH H2C\LM—CHR - L,M— )CH LM ‘CH2IRH HC”rearrangement of2-coordinated acetylene to a vinylidene ligand which then requires migratoryinsertion of the vinylidene unit into the iridium-alkyl bond and a 1,2-hydrogen shift to producethe allyl ligand (Scheme 2.VIIIB).In order to discern the applicable mechanism a labeling study was undertaken. Doublydeuterium-labeled acetylene, DCECD, was employed as the position of the labels in the finalproduct would differentiate the two mechanisms. Scheme 2.IX delineates the two mechanismsand the product that would be produced by each pathway. The acetylene insertion route(Scheme 2.IXA) results in the central position of the allyl being deuterium-labeled while thevinylidene mechanism (Scheme 2.IXB) leaves this position unaffected. The benzyl bromidecomplex, 4, was reacted with one equivalent of acetylene-d2 and the proton NMR spectrum ofReferences p. 32Chapter 2 18Scheme 2.IXMe2Si\ I DCCD:N—ir—Br•‘PhCH2 IMe2 pPh24/%Ph2MO2S\ I Br /CD2CD2 N—Ir—CMe2Si’ !, CH2\4%__ Ph2the product, Ir[N(SiMe2CHPPh)]3-CHDh)Br,8-d2, exhibits the resonance of thecentral proton. This evidence supports the proposal of a vinylidene intermediate in the reactionpathway.The proposed mechanism for the reaction of one equivalent of acetylene with the ailcylhalide complexes, 2-4, is shown in Scheme 2.IXB. The first step is the2-coordination of theacetylene. The coordinated acetylene rearranges to a vinylidene moiety, which then inserts intothe iridium-ailcyl bond. The resultant isopropenyl ligand undergoes a 1,2-hydrogen shift toyield the observed allyl product.PhCH2AjReferences p. 32Chapter 2 19With this mechanism the initial coordination of the acetylene must be cis to the alkylgroup in order for the subsequent migratory insertion to be viable. Alternatively, coordinationof the alkyne trans to the alicyl group followed by a rearrangement at the metal centre such thatthe acetylene (or vinylidene) ligand ends up cis to the alkyl group is possible. Thisrearrangement could potentially occur by phosphine or alkyne dissociation and rearrangementof the resulting five-coordinate complex. The assignment of the structure of five-coordinate d6complexes as square-based pyramids is based both on NMR spectroscopic,’6”7’26X-raycrystallographic,’6”7’25-7and theoretical28-30studies. In order to determine if these fivecoordinate, d6 alkyl halide complexes, 2-4, are fiuxional in solution, thus allowing forcoordination of the acetylene cis to the alkyl group to occur, the reaction of the methyl iodidecomplex, 2, with a strong Lewis base was performed.Introducing trimethyiphosphine into a solution of Ir[N(SiMe2CHPPh)](Me)I, 2,results in immediate coordination of the phosphine as evidenced by the colour change from/Ph2Me2St p\>N7jr_I9A+Ph2 /S..Ph2• p PMe2S M Me2S p\ , e PMe3 \ ,N—fr—i : N—fr—Me (2.2).1 I .11/IMe2Si p Me2St pPh2 2 \.—‘Ph2 9B+9CReferences p. 32Chapter 2 20green (five-coordinate Ir(ffl)) to yellow (six-coordinate lr(llI)) (Reaction 2.2). The phosphorus-31 NMR spectrum indicates the presence of three compounds, 9A-C, which are shown inReaction 2.2. In each of these complexes the tridentate ligand has maintained a meridionalgeometry.One set of signals can be unambiguously assigned based on an independent synthesis ofthat compound. The complex with the trimethylphosphine trans to the amide, 9C, was preparedby the addition of trimethylphosphine to the cyclooctene adduct 1,16 which, followed by thetrans-oxidative addition of methyl iodide,’3”4generates complex 9C. The other two productscould not be unambiguously assigned. A mixture of the three products was found to convertquantitatively to complex 9C on warming to 65°C in benzene-d6 for two days. Thisrearrangement likely proceeds by dissociation of one ligand, rearrangement of the five-coordinate intermediate and then reassociation of the dissociated ligand.The presence of three complexes on addition of trimethyl phosphine and therearrangement of the six-coordinate complexes 9A-C all suggests that iridium complexes of thistype are fluxional in solution. Not only is there the possibility that the incoming acetyleneligand can coordinate cis to the alkyl group, there is also the possibility that the coordinativelysaturated complex can undergo some sort of rearrangement that results in the cis-orientation ofthese ligands which is required for migratory insertion.4. Reactions with excess acetylene.When excess acetylene is employed, more than one equivalent of acetylene isincorporated in the final products. The methyl and benzyl compounds were found to exhibitdifferent reactivities under these conditions and the results for each will be presented separately.In each case vinylidene intermediates are invoked based on product analysis. The products ofReferences p. 32Chapter 2 21the acetylene reactions with the methyl complexes will be discussed first, followed by aproposed mechanism for the formation of these complexes and then the results of somereactivity studies. The product of the reaction of acetylene with the benzyl analogue and theproposed mechanism for the formation of this compound will then be considered.A. Methyl derivatives.The addition of excess acetylene to the methyl halide complexes, Ir[N(SiMe2CH2..PPh2)](Me)X (2: X = I; 3: X = Br) results in the formation of two new complexes, 10 (X I)and 11 (X = Br), which have incorporated two equivalents of acetylene. Based on NMRspectroscopic evidence these complexes are proposed to have the structures indicated inReaction 2.3.Ph2 ,/%Ph22::::>7i222 (2.3)Ph2 \.Ph22:X=I 1O:X=I3:X=Br 11X=BrThe proton NMR spectra of these two complexes exhibit four olefinic proton resonancesin the region of 4.8 to 5.9 ppm (Figure 2.2). For the peaks in which couplings can bedistinguished, the magnitude of the coupling constants is small (ca. 0.5 Hz) and suggestsgeminal rather than vicinal disposition of the protons. This assignment is consistent with therearrangement of the acetylene ligands to vinylidene units prior to insertion into the iridiummethyl bond. The methyl resonance is observed at higher than usual field for methylresonances (—0.95 ppm for 10 and —0.86 for 11). The upfield shift of these methyl resonances isproposed to be due to an agostic interaction31 of the C-H bonds with the metal. The doublevinylidene insertion into the iridium-methyl bond produces the isoprenyl ligand depicted inReferences p. 32C C z N It’.)liii111111IjiliiiIIIIIIIIIIIIIIIIIIIIITIIIIIIIIIIIIII’IUTjII876543210—1PPMChapter 2 23Scheme 2.XMe2S CH__\ it.N7IrCCHMe2Si pPh2H2 P H2/%Ph2 // M /%Ph2 //HCCHe2S\C/ I c ./xIMe2Sç X H Me2Si p% Ph2 Ph2P/Ph2CH2.1-iMe2Si\—PhReaction 2.3.The proposed mechanism is based on the mechanism proposed for the formation of theallyl ligands. As shown in Scheme 2.X, the first step is the2-coordination of the acetylenewhich rearranges to a vinylidene ligand at the metal. The migratory insertion of the vinylideneunit into the iridium-methyl bond produces an isopropenyl intermediate. Before this ligandrearranges to an allyl ligand, another equivalent of acetylene coordinates to the metal andrearranges to a vinylidene ligand. Migratory insertion of this vinylidene unit into the iridium-2: X=I3: X=BrH210: X=I11: X=BrReferences p. 32Chapter 2 24isopropenyl ligand generates the observed final products with isoprenyl ligands, 10 and 11.The agostic interaction of the methyl C-H bonds with the metal apparently blocks muchof the anticipated reactivity of complexes 10 and 11. The introduction of small molecules(hydrogen, carbon monoxide, acetylene and allene) results in no reaction. Maleic anhydride, acommon dienophile, fails to react, possibly due to distortion of the planarity of the diene, or lossof conjugation. Another possibility is that the metal complex could act as a stericallydemanding protecting group. A low-temperature proton NMR spectroscopic study32 wasperformed to determine whether or not the exchange of the agostic methyl protons with themetal could be slowed down. However, even at —80 °C, no resolution of the two species, freeand agostic C-H, was observed.Trimethylphosphine does react with Jr[N(SiMe2CHPPh)](C5H7I,10. Addition ofexcess trimethyiphosphine to a solution of 10 in toluene resulted in an immediate reaction. Thephosphorus-3 1 NMR spectrum indicated that there was complete conversion to a single newcompound, 12, with three different phosphorus environments. The highest field resonance isattributed to the coordinated trimethyiphosphine ligand. The coupling pattern of this signal is adoublet of doublets. The two doublet couplings are indicative of coupling to a cis- (9 Hz) andto a trans-phosphine (388 Hz). One of the phosphines of the tridentate ligand is trans to thetrimethyiphosphine ligand while the other is cis to this ligand and the resonances of these twoPh2 Ph2P PMe2Si Me2SI\ 1/ \ I/PM>CHMe2S1r Me2Si_. r\Ph2 c Ph26 IIH2C I H2CCH3A BFigure 2.3. Two possible geometric isomers ofIr[N(SiMe2CHPPh)j(C57(PMeJ,12.References p. 32Chapter 2 25nuclei appear as two doublets of doublets. The pendant arms of the tridentateamidodiphosphine ligand are therefore cis to one another, which then requires this ligand toassume facial coordination. The two remaining sites of the octahedron are occupied by theisoprenyl and the iodo ligands. Two isomers are then possible: one isomer has the iodo grouptrans to the amido group (Figure 2.3 12A) while the other has the isoprenyl ligand trans to theamide (Figure 2.3 12B). These two isomers should be able to be distinguished by carbon-13NMR spectroscopy; the isomer with isoprenyl ligand trans to the amide should result in thepresence of a large, trans phosphorus-carbon coupling constant in the carbon-13 spectrum. Butdue to time constraints this experiment was not performed.B. Benzyl derivative.The reaction of excess acetylene with the benzyl bromide complex, Ir[N(SiMe2CH2-PPh2)1(CHh)Br, 7, produced a new compound, 13, with only a singlet in the phosphorus-3 1NMR spectrum. The two phosphine donors must therefore exist in magnetically equivalentenvironments. The proton NMR spectrum of this compound is quite complex (Figure 2.4). Thepresence of two silyl methyl resonances indicates the formation of a molecule with lowsymmetry, while the separation of the ortho- from the meta- and para-phenyl proton resonancesindicates that the diphenyiphosphino donors have maintained a trans coordination geometry,which implies a meridional coordination of the tridentate ligand. The set of olefinic resonancesin the region of 3.7 to 5.8 ppm suggests that a compound like 10 or 11 has not formed in thiscase and the resonances of the benzylic protons were not present.In order to elucidate the structure of the new compound an X-ray structure determinationwas undertaken. Complex 13 belongs to the triclinic space group PT (#2), with unit celldimensions, a = 11.044 (2) A, b = 19.520 (3) A, c = 10.062 (1) A, cx 89.99 (l)°, = 109.72(1)°, y= 76.50 (l)° (Z = 2; R = 0.028). The molecular structure of this compound, 13, isReferences p. 32n C) 1IIf64PPMChapter 2 27Figure 2.5. The molecular structure ofIr[C(CH2)N(SiMeCHPPh2)21(C(CH2)CCH), 13.C29 C28C30C27C6CaH39C34ClC3C12C9CliC17References p. 32Chapter 2 28Scheme 2.XIMe2SV”H2 H Me2Si”’’HCCH \ I c \ I:N_w_IlI :N—Ir——ccHBr1 I C —(PhCH3) BrMe2S\,,PPh H Me2S\,,PPhHCCH/%Ph2 CH2Me2Si__\1__- p :N7Ir—CCH -Me2Si4.,pphHCCHshown in Figure 2.5. Selected bond lengths and bond angles are listed in Tables 2.1 and 2.11respectively (see Appendix A). The structure determination revealed that three equivalents ofacetylene have been incorporated into the compound. The protons associated with theincorporated acetylene were all located and were refined with isotropic thermal parameters.The carbon-carbon bond lengths in the C4H3 ligand support the triple (1.174 (9) A) and double(1.265 (9) A) bond formalism of a vinylidene unit inserting into an iridium-acetylide moiety.The acetylenic unit is not linear; the angle about the C-C-H linkages is 144 (4)°. This deviationfrom linearity is due to interaction with the metal in the form of the donation of electron densityfrom a bonding ligand molecular orbital to unfilled orbitals on the metal and subsequent back-Me2SIReferences p. 32Chapter 2 29donation of electron density from filled metal-based orbitals into antibonding orbitals on theligand.Based on the aforementioned mechanisms, the proposed mechanism for the formation of13 is depicted in Scheme 2.XI. The first equivalent of acetylene oxidatively adds to the metalacross the C-H bond to form an alkynyl(hydrido) complex. The hydride ligand and the benzylligand reductively eliminate as a molecule of toluene. An equivalent of acetylene is thencoordinated to the vacant coordination site and rearranges to the vinylidene moiety. There aretwo possible insertion pathways now possible; insertion into the metal-alicynyl unit andinsertion into the metal-aniide linkage. The insertion into the metal-alkynyl moiety would blockthe second insertion needed to produce the product, so the vinylidene unit must insert into themetal-amide bond preferentially. In the formation of the allyl complexes it was seen that thevinylidene unit inserted into the metal alkyl bonds and not the metal-nitrogen bond.Table 2.1. Selected bond lengths (A) for fr[C(CH2)N(SiMe2CH2PPh2)2](C(CH2)CCH), 13.Atom Atom Distance Atom Atom DistanceIr(1) Br(1) 2.6401 (7) C(31) C(32) 1.330(7)Ir(1) P(1) 2.339(1) C(32) H(37) 1.19(6)Jr(1) P(2) 2.337 (1) C(32) H(38) 0.92(5)Jr(1) C(31) 2.053 (4) C(33) C(34) 1.174 (9)Ir(1) C(33) 2.389 (6) C(33) H(39) 0.83(4)Jr (1) C (34) 2.230 (6) C (34) C (35) 1.476 (8)Jr (1) C (35) 2.039 (5) C (35) C (36) 1.265 (9)C (36) H (41) 1.05 (6) C (36) H (40) 0.63 (5)References p. 32Chapter 2 30Table 2.11. Selected bond angles (degrees) for Jr[C(CH2)N(SiMeCHPPh2)](C(CH2) CH),13.Atom Atom Atom Angle Atom Atom Atom AngleP (1) Ir (1) P (2) 160.61 (4) Jr (1) C (35) C (34) 76.9 (3)C (31) Jr (1) C (33) 166.9 (2) C (31) C (32) H (37) 110 (3)C(31) Jr(1) C(34) 141.4(2) C(31) C(32) H(38) 119(3)C(31) Jr(1) C(35) 103.4(2) H(37) C(32) H(38) 130(4)C (33) Jr (1) C (34) 29.2 (2) Jr (1) C (33) C (34) 67.9 (4)C(33) Jr(1) C(35) 64.4(2) lr(1) C(33) H(39) 133(4)C (34) Jr (1) C (35) 40.1 (2) C (34) C (33) H (39) 144 (4)Jr(1) C(31) N(1) 117.3 (3) C(33) C(34) C(35) 127.2(8)Jr(1) C(31) C(32) 123.7 (4) C(34) C(35) C(36) 133.7 (6)N(1) C(31) C(32) 118.9 (4) C(35) C(36) H(40) 114(7)Jr(1) C(34) C(33) 82.9(5) C(35) C(36) H(41) 116(3)Jr (1) C (34) C (35) 62.9 (3) H (40) C (36) H (41) 127 (7)Jr (1) C (35) C (36) 149.3 (5)5. General observations and mechanistic considerations.The presence of an acetylenic unit and the elimination of toluene from complex 13,support the alkynyl(hydrido) mechanism of vinylidene formation in this system. The twoproposed mechanisms for the conversion of a metal-bound alkyne to a coordinated vinylideneare shown in Scheme 2.J.4 When only one equivalent of acetylene was employed there wasrearrangement to the vinylidene and then migratory insertion of the vinylidene into the iridiumbenzyl bond. In the methyl system, the reductive elimination of methane must proceed at aReferences p. 32Chapter 2 31Scheme 2.XllMe2Si Br\ I,: N—Ir—CCH.1 IMe2St p•‘%%_ Ph2slower rate than the rearrangement to the vinylidene.6. Summary.The reaction of the alkyl halide complexes 2-4 with one equivalent of acetyleneproduces the corresponding allyl (or phenylallyl) complexes 6-8. A deuterium labeling studyindicates that the allyl complexes form by vinylidene migratory insertion into the iridium-alkylbonds. Using excess acetylene produces the isoprenyl complexes 10 and 11 from the methylderivatives 2 and 3 respectively. The reactivity of these complexes is blocked by an agosticinteraction of a methyl group with the metal. Complex 10 reacts with trimethyiphosphine togenerate a new compound, 12, in which the tridentate ligand has changed from meridional tofacial coordination. The addition of excess acetylene to the benzyl bromide complex, 4, resultsin elimination of the benzyl ligand as toluene and a dual vinylidene insertion process to produce13. An X-ray structure determination shows that one vinylidene unit has inserted into theMe2SI.Ph2References p. 32Chapter 2 32iridium-amide linkage and the other vinylidene unit has inserted into the iridium acetylide bond.7. Future work.Though it has been shown that vinylidene intermediates are involved in the reactions ofacetylene with the ailcyl halide amidodiphosphine iridium complexes studied, more questionshave been raised from this study. The reactivity of the isobutenynyl complex, 13, has not yetbeen investigated. The mechanism of the formation of this molecule is another area thatrequires further study. The reason for the change in mechanism that results from the change ofthe stoichiometry, from one equivalent to excess acetylene, is not known. The extension of thischemistry to other alkyl groups and the investigation of the reactions of acetylene with the arylhalide analogues may clear up some of the confusion that persists. Dialkyl amidodiphosphineiridium complexes have also been prepared in our laboratories17 and the reactions of thesecomplexes with acetylene would also be instructive. In particular, the competition of insertionproducts that would arise from utilizing mixed ailcyl or alkyl-aryl complexes would lead to anunderstanding of the ranking of preference of insertion of the vinylidene ligand. The syntheticutility of the vinylidene insertion reaction is yet to be realized. The potential for multiple (morethan two) insertions still exists if the interference of the agostic interaction and the eliminationreaction can be avoided. It may be possible to form long chains of vinylidene units andpotentially to form poly(vinylidene).8. References.(1) Coilman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applicationsof Organotransition Metal Chemistry; University Science Books: Mill Valley, CA,1987, pp 57ff.(2) Durán, R. P.; Amorebieta, V. T.; Colussi, A. J. J. Am. Chem. Soc. 1987, 109, 3154.References p. 32Chapter 2 33(3) Schemer, A. C.; Schaefer, H. F. I. J. Am. Chem. Soc. 1985, 107, 4451.(4) Bruce, M. I. Chem. Rev. 1991, 91, 197.(5) Bruce, M. I.; Swincer, A. G. Adv. Organomet. Chem. 1983,22, 59.(6) Silvestre, 3.; Hoffmann, R. Helv. Chim. Acta. 1985, 68, 1461.(7) Höhn, A.; Otto, H.; Dziallas, M.; Werner, H. J. Chem. Soc., Chem. Commun. 1987, 852.(8) Alonso, F. 3. G.; Höhn, A.; Wolf, 3.; Otto, H.; Werner, H. Angew. Chem., mt. Ed. Engi.1985,24, 406.(9) Chiusoli, 0. P.; Salerno, 0.; Giroldini, W.; Pallini, L. J. Organomet. Chem. 1981,219,C16.(10) Selnau, H. E.; Merola, J. S. J. Am. Chem. Soc. 1991, 113, 4008.(11) Fryzuk, M. D.; McManus, N. T.; Rettig, S. 3.; White, G. S. Angew. Chem., mt. Ed. EngL1990, 29, 73.(12) Fryzuk, M. D.; Huang, L.; McManus, N. T.; Paglia, P.; Rettig, S. 3.; White, G. S.Organometallics. 1992, 11, in press.(13) Coliman, 3. P.; Sears, C. T. 3. Inorg. Chem. 1968, 7, 27.(14) Labinger, J. A.; Osborn, J. A. Inorg. Chem. 1980, 19, 3230.(15) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. 3. Organometallics 1985, 4, 1145.(16) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. J. Organometallics 1986,5, 2469.(17) Fryzuk, M. D.; MacNeil, P. A.; Massey, R. L.; Ball, R. G. J. Organomet. Chem. 1989,368,231.(18) Finer, E. G.; Harris, R. K. Prog. NMR Spectroscopy 1970, 6, 61.(19) Moore, D. S.; Robinson, S. D. Inorg. Chim. Acta. 1981,53, L 171.References p. 32Chapter 2 34(20) Wakefield, J. B.; Stryker, 3. M. Organometalllcs 1990, 9, 2428.(21) Tjaden, E. B.; Stryker, 3. M. Organomerallics 1992, 11, 16.(22) Tulip, T. H.; Ibers, 3. A. J. Am. Chem. Soc. 1979, 101, 4201.(23) Tulip, T. H.; Ibers, 3. A. J. Am. Chem. Soc. 1978, 100, 3252.(24) Ashworth, T. V.; Chalmers, A. A.; Singleton, E. Inorg. Chem. 1985,24, 2125.(25) Hoffman, P. R.; Caulton, K. G. J. Am. Chem. Soc. 1975, 97, 4221.(26) Fryzuk, M. D.; MacNeil, P. A.; Ball, R. G. J. Am. Chem. Soc. 1986, 108, 6414.(27) Troughton, P. G. H.; Skapski, A. C. J. Chem. Soc., Chem. Comniun. 1968, 575.(28) Rossi, A. R.; Hoffmann, R. Inorg. Chem. 1975, 14, 365.(29) Rachidi, I. E.; Eisenstein, 0.; Jean, Y. New J. Chem. 1990, 14, 671.(30) Dotz, K. H.; Fisher, H.; Hoffmann, P.; Kreissel, F. R.; Schubert, U.; Weiss, K.Transition Metal Carbene Complexes; Verlag Chemie: Weinheim, 1983.(31) Brookhart, M.; Green, M. L. H. J. Organomet. Chem. 1983,250, 395.(32) Cracknell, R. B.; Orpen, A. G.; Spencer, K. L. J. Chem. Soc., Chem. Commun. 1984,326.References p. 3235CHAPTER 3REACTIONS OF ALLENE WITH AMIDODIPHOSPHINE IRIDIUMCOMPLEXES1. Introduction.This chapter extends the chemistry presented in the previous chapter to allene (propadiene,H2C=C=CH). Allene has been reported to insert into metal-halide,’-3metal-hydride4and metal-carbon5 bonds to form3-allyl ligands. However, this method of forming fl3-allyl ligands wasnot found to be viable for the iridium aikyl complexes studied. The reaction of allene with alkylhalide amidodiphosphine iridium complexes was found to result in the reductive elimination of thealkyl halide and the incorporation of one or two equivalents of allene to produce an equilibriummixture of two complexes. After a brief survey of the literature, the investigation of these twoallene complexes, and the studies of the reductive elimination of alkyl halides will be reported.2. Literature survey.The insertion of allene into metal-carbon, metal hydride, and metal-halide bonds are routesby which allyl complexes have been formed. Allene is proposed to insert into palladium-arylbonds based on product analysis.5 The aryl group is transferred to the {3-carbon of the allene toform the allyl ligand in situ (Reaction 3.1).References p. 52Chapter 3 36A similar insertion of allene into palladium-chloride1’2and -bromide3bonds is shown in Reaction3.2.PhCN X2PhcV “xX= CI, BrH2CC=CH—(4 PhCN) “V(3.2)The insertion of allene into rhodium- and iridium-hydride bonds has also been reported and isshown in Reaction 3•3•4MH(PPh3)2(CO)LM = Rh; L = PPh3M=Ir;L=COH2C=C=CH 6—(L)%\—M(PPh3)2CO (3.3)The rearrangement of a a-butenyl ligand to a methylallyl ligand at an iridium centre has beenproposed to proceed by an intermediate allene hydride complex (Reaction 34)•6MeHPh3 CH II____I,C____QC—Ir—jIICp H2Ph3Stable allene complexes of the formula M(PPh3)2(allene) have been prepared for the nickeltriad (allene isH2C=C=CH as well as the substituted derivatives,H2C=C=CHMe,References p. 52P\/PhL../ \H2CMeCN+0IICHR] (3.1)MePh3pI CHI—OC—Ir—CP CHPh3*pPh3MeHQp OC—Ir-—CH(3.4)pPh3 H2Chapter 3 37AFigure 3.1. Cyclic oligomers of allene.H2C=C=CMe,Me2C=C=CMe and PhHC=C=CHPh).7 In the nickel case only substitutedallene complexes can be isolated. Reaction of unsubstituted allene with nickel(O) complexesresults in the catalytic coupling of allene units to form exo-methylene substituted cyclic trimers(A), tetramers (B) and pentamers (C, Figure 3.1)8.9 The analogous reactivity with platinum(O)H2 CH2LMH2 CH2Figure 3.2. The 3 ,4-dimethylenemetallacyclopentane moiety.species resulted in the formation of a platinacyclopentane moiety like that shown in Figure 3.2.10The oxidative coupling of two allene molecules on rhodium’144 and iridium1547 complexes hasalso been reported. The pyridine adducts were isolated and X-ray diffraction studies confirm theformation of metallacyclopentane moieties (Figure 3.3).H2CCCH‘—C”2 (oC.CCH2 OfrCCCH2\ \Figure 3.3. Rh(acac)(C6HS)py2and Ir(acac)(C6H8(TI2-C3H4)py.B CReferences p. 52Chapter 3 383. Previous work on amidodiphosphine iridium complexes.Previous work in our laboratories has shown that the cyclooctene iridiumamidodiphosphine complex, 1, is a versatile starting material for both low and high oxidationstate iridium chemistry.’8-26 For example, reaction of excess allene with 1 yields an allenecomplex, 14 (Reaction 3•5)•27/%Ph2Me2S1’ Me2S1’ P H2\ 1) excess C3H4 \ I C:N• - :N—Ir...1I 2) vacuum / C (3.5)Me2S\,, Me2S\,,p H214The coordination of the allene molecule in 14 can either be described as a 1,2-it (Figure3.4A) or r12-a (Figure 3.4B), depending on the degree of backbonding from the metal to theolefin. The iridium-bound cL-carbon gives rise to a resonance at —3.82 ppm in the carbon-13NMR spectrum which is diagnostic of the r12-a coordination mode.27 Compound 14 is thereforebest described as an iridacyclopropane complex.H2 H2LM—j LM III \\C CH2 H2A BFigure 3.4. r2-1c, A, andi2-a. B, modes of allene coordination.The possibility that an iridacyclopentane unit like that found for the platinum, rhodium andiridium systems mentioned above (Figure 3.2) could have formed was not considered. In an1References p. 52Chapter 3 3 9effort to compare the earlier work in our laboratory with the literature systems this reaction wasinvestigated further.4. Allene coupling and decoupling at amidodiphosphine iridium centres.When complex 1 was sealed in an NMR tube with excess allene (Reaction 3.6), completeconversion of 1 to a new species, different from 14, was evident from the proton andphosphorus-3 1 NMR spectra. This new species is proposed to be the iridacyclopentane complex15. The proton NMR spectrum (Figure 3.5) displays signals at 6.17, 5.79 and 1.25 ppm in aratio of 2:2:4. The high field resonance is attributable to the protons on the a-carbon. The patternof this signal is a triplet of triplets attributable to coupling to two magnetically equivalentphosphorus nuclei and to equivalent coupling to the two terminal exo-methylene protons. Thetwo low-field multiplets are assigned to the two terminal exo-methylene protons.Ph2 Ph2/ PMe2Si Me2Si\ ( excess allene \:N—Ir II sealed tube /Me2Si H2 (3.6)1 15The iridacyclopentane complex, 15, is unstable to loss of allene. Removal of solvent andexcess allene in vacuo results in complete conversion of complex 15 to the iridacyclopropanecomplex, 14 (Reaction 3.7). The previously reported formation of complex 14 from thecyclooctene complex 1 and excess allene must have gone through the in situ generation andsubsequent decomposition of the iridacyclopentane complex 15. This conversion of 14 to 15 isas facile as the reverse reaction. The addition of excess allene to the iridacyclopropane complex14 results in the complete conversion of 14 to 15 as monitored by proton and phosphorus-3 1References p. 52Chapter 3 4000-CoFigure 3.5. The 300 MHz 1H NMR spectrum of fr{N(SiMe2CHPPh)](C6H8),15.References p. 52Chapter 3 4 1Me Si H2 Me2Si H22 \ I .C:N—V I :N Ir I.1 I”2 -(C3H4) /Me2SI% H2 Me2Sç (3.7)NMR spectroscopy (Reaction 3.8). The coupling of two allene molecules at this iridium centre isreversible and the two complexes 14 and 15 exist in a dynamic equilibrium.Me2Si H2 Me2Si H2\ C3H4 \ I:N 1r I :N—1r IM Si” Me Si IH2 (3.8)e2H22Ph2H214 15The relationship between the cyclooctene complex 1 and the two allene derivatives 14 and15 is summarized in Scheme 3.1. The cyclooctene complex 1 can be converted to either 14 or 15by judicious setting of the stoichiometry. These reactions of 1 are irreversible; the cyclooctenecomplex 1 cannot be regenerated.5. Reactions with trimethyiphosphine.The ready conversion of the iridacyclopentane complex 15 to the iridacyclopropanecomplex 14 by allene elimination prevented the isolation of the iridacyclopentane complex. Thestabilization of the rhodium and iridium metallacyclopentane complexes by the introduction ofpyridine,11”26’7mentioned above, indicated that the metallacyclopentane moiety could beReferences p. 52Chapter 3 42Scheme 3.1C3H48H14)—(C3H4) C3H4(14)Me2SiPH2excess C3H4— I C.....cCH2/ CICCHMe2SI%.,H 2stabilized by coordinative saturation of the metal. It seemed possible that the iridacyclopentanecomplex 15 might be stabilized in a similar manner.One Lewis base that binds readily to complexes of this type is trimethylphosphine. Thisligand has the additional benefit of producing a signal in the phosphorus-3 1 NMR spectrum that,combined with the two phosphines of the amidodiphosphine ligand, aids in stereochemicalassignment. The trimethyiphosphine signal is sufficiently different (much higher field) from thesignals of the phosphine arms of the tridentate ligand that its position in the NMR spectrum isreadily assigned. The magnitude of the phosphorus-phosphorus coupling constants allows forthe cis - and trans-phosphines to be distinguished: trans-disposed phosphines typically produceH214Ph21References p. 52Chapter 3 43coupling constants greater than 100 Hz, while cis-disposed phosphines results in smaller couplingconstants; I 2JCjS <100 Hz < I 2Jtrans 1.28The addition of one equivalent of trimethyiphosphine to the iridacyclopentane complex,fr[N(SiMe2CHPPh)1(C6H8,15, generated in situ, results in the quantitative formation of atrimethyiphosphine adduct, 16. The phosphorus-31 NMR spectrum of the new compoundconsists of two doublets of doublets for the diphenylphosphino nuclei and a high field triplet forthe trimethyiphosphine. The fact that there are two signals for the diphenylphosphino nuclei rulesout the formation of the trimethyiphosphine adduct of the iridacyclopentane complex. Allcouplings are less than 20 Hz, which indicates the three phosphorus nuclei are in a mutually cisgeometry. The tridentate amidodiphosphine ligand has adopted a facial coordination with thetrimethyiphosphine ligand trans to the amide donor atom. Four of the six coordination sites havebeen accounted for, leaving the remaining two sites for the allene ligand. Five possible structuresof this compound are shown in Figure 3.6. Structures A and A’ have meridional coordinationgeometries of the tridentate ligand and are thus not applicable. Structures B and B’ are notMe2S Me2Si“‘Me2SiMe2Si Me3 I \........ I Ph2P Ph2 PMe3Ph2BMe2Si:b%N_J•Me:Me2Si /Ph2 Ph2 Ph2Me2SI\1jç Me2SI\1JçMeSi.CMe2S1 MePh2pMe3Figure 3.6. Five possible Structures of fr[N(SiMeCHPPh)](PMe(CH4,16.References p. 52r) CDCD54321OPPMChapter 3 45distinguishable by NMR spectroscopy, but in these structures the trimethyiphosphine is trans toone of the diphenyiphosphino donors, and this is not supported by the phosphorus-phosphoruscoupling constants. The structure represented by C in Figure 3.6 is thus the appropriate structureof this compound.The 1H NMR spectrum of this complex, shown in Figure 3.7, contains the expectedmultiplets for the protons on the x-carbon; one centred at 82.38 ppm and another at 6 1.48 ppm.The two vinylidene protons also give rise to multiplets. The expected coupling pattern for each ofthese would be a doublet of doublets of doublets. This would ideally be observed as an eight linepattern and the coupling constants easily distinguishable. In this case though the couplingconstants are too small to yield a distinct pattern.Complex 16 could also be synthesized from the iridacyclopropane complex, 14 (Reaction3.9). The addition of trirnethyiphosphine to a solution of 14 resulted in the formation of 16, asverified by proton and phosphorous-3 1 NMR spectroscopy.Ph2/P ,,Ph2Me2S\____PMe3Me2Si I:N lr I : N—lr-2—PMe3MeMeS/’(3.9)2Ph2H2Ph2cThe addition of allene to complex 16 does not generate an iridacyclopentane complex.Presumably the conversion of the iridacyclopropane complex, 14, to the iridacyclopentanecomplex, 15, involves a coordinatively saturated intermediate. Saturating the metal centre with asixth ligand (like trimethylphosphine) blocks this associative pathway. A proposed mechanism isgiven in Scheme 3.11. The metallacyclopropane complex, 14, coordinates an equivalent of alleneReferences p. 52Chapter 3 46Ph2Me2SI P H2\:Me2SI” CHPh214Scheme 3.11Scheme 3.111PMe314_(C3H4)11C3H4,,Ph2P H2Me2Si 4Ch.. CH2 PMe3:N—Ir/ 1c0tCH2Me2Si H2Ph215Ph2Me2Si(‘.LN—Ir——PMe3Me2S 1/Ph2CH216C3H4—(C3H)Ph2 H2Me2Si\.N—IrCCH2C—Me2S1H2Ph21I,%%% Ph2H2Me2SI\ C_CCH2Me2SI p H2Ph215Ph2References p. 52Chapter 3 47to produce a coordinatively saturated intermediate that contains two 112-allene molecules; oneboundq2-a while the incoming ligand is bound i12-7t. The two allene units couple at the metal toform the observed iridacyclopentane complex, 15.The relationship between the iridacyclopropane, 14, iridacyclopentane, 15, complexesand the trimethyiphosphine adduct, 16, is summarized in Scheme 3.ffl.6. AIlene reactivity with alkyl halide amidodiphosphine iridium complexes.The reactivity of the alkyl halide amidodiphosphine iridium complexes with allene wasinvestigated in an attempt to form allyl complexes by insertion of allene into metal-carbon ormetal-halide bonds in direct analogy with the palladium systems mentioned above. Despite theavailability of both iridium-carbon and iridium-halide bonds for potential allene insertion, no allylScheme 3.IVPh2Me2Si(7,CH2R H2C=C=CH2 Me2S(’72MeSi MeSi2 2Ph2 H2R=H;X=t,2 14R=H,X=Br,3R=Ph;X=Br,4—(C31-14) C3H4Ph2.7 P HMe2S,‘•N—Ir1 “c CH2Me2Sc\, H2Ph215References p. 52Chapter 3 48complexes were formed. The addition of allene to benzene solutions of 2-4 was found to resultin the reductive elimination of the aikyl halide and the formation of the allene complexes 14 and15 described above (Scheme 3.IV). As mentioned above the position of the equilibrium between14 and 15 depends on the amount of allene introduced.While oxidative addition of alkyl halide compounds to iridium complexes is welldocumented,29-32the reverse reaction, reductive elimination, is not as well studied. Hence, inorder to better understand this phenomenon a study of the kinetics of this transformation wereundertaken. The allene dependence was nulled by using greater than ten-fold excess of allene.The reactants and products give rise to well separated signals in the phosphorus-3l NMRspectrum and consequently this spectroscopic technique was chosen to monitor the reaction. Themethyl derivatives, 2 and 3, react too rapidly to be monitored by NMR spectroscopy, while thebenzyl-bromide complex, 4, reacted at a rate amenable to such a study. The reaction of thebenzyl-bromide complex, 4, with excess allene at three different temperatures (35, 45 and 55°C)has a pseudo-first order dependence upon metal complex concentration. The observed pseudo-first order rate constants, k, at the various temperatures are collected in Table 3.1 (see Chapter 4and Appendix B).Table 3.1. Kinetic data for the reductive elimination of benzyl bromide.Run T k ti!2(#) (°U, (rnin1) (mm)1 35.0 (1) 2.0 (1) x iO 937 (2)2 35.3 (2) 9.4 (1) x iO 737 (8)3 35.3 (1) 9.6 (3) x iO- 720 (20)4 45.2 (1) 2.34 (4) x l0- 296 (5)5 45.2(1) 2.40(l)x 1O 289(1)References p. 52Chapter 3 49-9.6-9.8-10.-10.2-10.4-10.6-10.86 55.2 (2) 3.57 (3) x 1O- 194 (2)7 55.1 (2) 4.87 (7) x iO- 142 (2)The activation parameters, AH* and ASt, were obtained from a plot of ln () versus(Figure 3.8). The enthalpy of activation, AH, calculated from the slope of this Eyring plot, wasfound to be 67 (9) kJ mol1,while the entropy of activation , calculated from the y-intercept,was found to be —263 (2) J mo11K1. The proposed mechanism of this reaction is shown inScheme 3.V.0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 0.032l/T (1/K)Figure 3.8. The Lyring plot of the kinetic data for the reaction of Jr[N(SiMe2CHPPh)j-(CH2Ph)Br, 4, with excess allene.The rate of change of concentration of 4 with respect to time can be expressedalgebraically,_41=kj [4] [C3H]—k1[A] (3.a)References p. 52Chapter 3 50Scheme 3.VPh2 ,Ph2Me2\ f k1 Me2SI\ I C=CH2:N Ir—Br + C3H4 :N Ir—BrMe2S<RC/I Me2S<RC/I4:R=Ph A—(RCH2Br) k2,/Ph2Me2Si H2:N IrçiMe2S1H22Applying the steady state approximation, that the concentration of A (Scheme 3.V) isinvariant with time, results in the following expression:d[Aj= k1 [4) [C3H4]— k1 [A] — k2 [A] = 0 (3.b)Rearrangement of equation 3.b and substitution into equation 3.a results in equation 3.c.[4] [C3H4 (3.c)If the k1 step is much faster than the opposing step, k2, then the observed rate constantbecomes;= Kj k2 [C3H4] (3.d)References p. 52Chapter 3 5 1kjwhere, K1 =If the converse is true then,kobs = k1 [C3H4] (3.e)The negative value obtained for S1 suggests that the rate-determining step involves theassociative step. The first, reversible step, kj, is thus proposed to be rate determining and theappropriate observed pseudo-first order rate constant is, k0b5 = kj[C3H4](equation 3.e).7. Summary.Therj2-allene complex 14 previously reported from this laboratory was found to exist in adynamic equilibrium with a new complex which has two incorporated molecules of allene. Thisnew complex is proposed to be the iridacyclopentane complex, 15, based on NMR evidence andliterature precedent. The iridacyclopentane complex 15 is stable only in the presence of allene.Attempts to stabilize this complex by coordinative saturation with the potent Lewis basetrimethyiphosphine produced the trimethylphosphine iridacyclopropane complex, 16. Thiscomplex could also be prepared directly from the iridacyclopropane complex, 14. Theintroduction of allene to the alicyl halide complexes 2-4 was found to result in the reductiveelimination of the alkyl halide and to form an equilibrium mixture of the iridacyclopropane andiridacyclopentane complexes 14 and 15. The kinetics of the reductive elimination of benzylbromide from complex 4 was studied by phosphorus-3 1 NMR spectroscopy. The reaction wasfound to have a pseudo-first order dependence upon metal complex concentration when excessallene was employed. The activation parameters were found to be zH = 67 (9) kJ mo11 andAS = —263 (2) 3 mo11 K-1. The rate-determining step of this process is proposed to be theassociative step.References p. 52Chapter 3 528. Future work.The generality of the reductive elimination reaction still requires investigation. Theextension of this reaction to bis(allcyl), bis(aryl) or even mixed ailcyl, mixed aryl or alkyl-arylcomplexes could lead to the formation of carbon-carbon bonds. The study of the kinetics of thesereactions would make an interesting comparative study. The effect of light on this reaction is alsoin need of further investigation. Preliminary results suggest that in the presence of light the rate ofthe reaction is nearly doubled. Presumably the light induces a radical chain mechanism. Thecomparison of the kinetics of the reaction in the presence and absence of light would result inbetter understanding of the two mechanisms. The present mechanism could possess some radicalnature since two experiments in the presence of a radical trapping agent, 1 ,4-cyclohexadiene,resulted in lower pseudo-first order rate constants (see Appendix B, runs 8 and 9).9. References.(1) Schultz, R. G. Tetrahedron 1964,20, 2809.(2) Schultz, R. G. Tetrahedron Lett 1964, 6, 301.(3) Lupin, M. S.; Shaw, B. L. Tetrahedron Lett 1964, 883.(4) Brown, C. K.; Mowat, W.; Yagupsky, G.; Wilkinson, G. J. Chem. Soc. (A) 1971,850.(5) Shimizu, I.; Tsuji, 3. Chem Lett 1984, 233.(6) Schwartz, I.; Hart, D. W.; McGiffert, B. J. Am. Chem. Soc. 1974, 96, 5613.(7) Otsuka, S.; Nakamura, A. Adv. Organomet. Chem. 1976, 14, 245.(8) Otsuka, S.; Nakamura, A.; Tani, K.; Ueda, S. Tetrahedron Lett 1965,5, 297.(9) Otsuka, S.; Tani, K.; Yamagata, T. J. Chem. Soc., Dalton Trans. 1973, 2491.References p. 52Chapter 3 53(10) Barker, G. K.; Green, M.; Howard, 3. A. K.; Spencer, 3. L.; Stone, F. G. A. J. Chem.Soc., Dalton Trans. 1978, 1839.(11) Ingrosso, G.; Immirzi, A.; Porn, L. J. Organomet. Chem. 1973,60, C35.(12) Imniirzi, A. J. Organomet. Chem. 1974, 81, 217.(13) Ingrosso, G.; Porn, L. J. Organomet. Chem. 1975, 84, 75.(14) Borrini, A.; Ingrosso, G. .1. Organomet. Chem. 1977, 132, 275.(15) Diversi, P.; Ingrosso, G.; Immirzi, A.; Zocehi, M. J. Organomet. Chem. 1975, 102,C49.(16) Diversi, P.; Ingrosso, G.; Immirzi, A.; Zocchi, M. J. Organomet. Chem. 1976, 104,Cl.(17) Diversi, P.; Ingrosso, G.; Jinmirzi, A.; Porno, W.; Zocchi, M. J. Organomet. Chem.1977, 125, 253.(18) Fryzuk, M. D.; MacNeil, P. A. Organometallics 1983, 2, 355.(19) Fryzuk, M. D.; MacNeil, P. A. Organometallics 1983,2, 682.(20) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. 3. Organometallics 1985,4, 1145.(21) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. 3. Organometallics 1986,5, 2469.(22) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. 3. J. Am. Chem. Soc. 1987, 109, 2803.(23) Fryzuk, M. D.; MacNeil, P. A.; McManus, N. T. Organometallics 1987, 6, 882.(24) Fryzuk, M. D.; Bhangu, K. J. Am. Chem. Soc. 1988, 110, 961.(25) Fryzuk, M. D.; Joshi, K.; Chadha, R. K. J. Am. Chem. Soc. 1989, 111, 4498.(26) Fryzuk, M. D.; Joshi, K. 3. Organometallics 1989, 8, 722.(27) Joshi, K. Ph D Thesis, University of British Columbia, 1990.References p. 52Chapter 3 54(28) Finer, E. G.; Harris, R. K. Prog. NMR Spectroscopy 1970, 6, 61.(29) Vaska, L. Acc. Chem. Res. 1968, 1, 335.(30) Mondal, 3. U.; Blake, D. M. Coord. Chem. Rev. 1982,47, 205.(31) Labinger, 3. A.; Osborn, 3. A. Inorg. Chem. 1980, 19, 3230.(32) Coilman, 3. P.; Sears, C. T. 3. Inorg. Chem. 1968, 7, 27.References p. 5255CHAPTER 4EXPERIMENTAL1. General.Unless stated otherwise all manipulations were performed at room temperature under anatmosphere of air- and moisture-free dinitrogen. Standard glove box and Schienk techniqueswere employed in the handling of all compounds. The dinitrogen (Linde) was purified by eitherpassing it through a column of activated molecular sieves and manganese(IV) oxide1 forvacuum line use or through a MO—40—2H purifier for glove box use. The glove box used was aVacuum Atmospheres model HE—553---2 workstation equipped with a refrigerator kept at—40°C. The vacuum line used was all glass with Kontes teflon valve ports and mercurymanometers on both nitrogen and vacuum manifolds.2. Solvents.Solvents were dried and deoxygenated prior to use. Hexanes and tetrahydrofuran (BDH)were dried and deoxygenated by refluxing over calcium hydride for at least 24 hours, distillingonto a mixture of sodium and benzophenone, and then distilling into appropriate containersunder argon (Linde) when the purple colour of the diradical benzophenone ketyl was evident.Toluene (BDH) was predried by refluxing over calcium hydride for at least 24 hours, distillingonto sodium and then distilling from molten sodium into appropriate containers under argon.References p. 68Chapter 4 56Methylene chloride (BDH) was predried by refluxing over calcium hydride and dried overphosphorus pentoxide and vacuum transferred before use. Benzene (BDH) was predried overactivated 4 A molecular sieves, dried by distilling from sodium benzophenone ketyl andvacuum transferred into appropritate containers. Acetonitrile (Fisher), 1,4-cyclohexadiene(Aldrich), and deuterated solvents, benzene-d6 and toluene-d8 (both MSD Isotopes) were driedovernight over activated 4 A molecular sieves, degassed with three “freeze-pump-thaw” cyclesand vacuum transferred before use.3. Reagents.Cyclooctene (Aldrich) was distilled under a nitrogen atmosphere and freeze-pump-thawed three times to exclude oxygen. Alkyl halide reagents (methyl and benzyl bromide andmethyl iodide all from Aldrich) were purified of water by storing over 4 A molecular sieves andpurified of oxygen by three “freeze-pump-thaw” cycles. Cinnamyl alcohol (Aldrich) was usedas received in the preparation of cinnamyl bromide by the published method.2 The alkyl lithiumreagent, n-butyl lithium (1.6 M solution in hexanes, Aldrich) was used as received. Deuteriumoxide (MSD Isotopes) was used without purification in the preparation of acetylene-d2.3Acetylene and allene (both Matheson) were purified with an alumina column immediately priorto use. Carbon monoxide (Matheson) was used as received. Hydrogen (Linde) was passedthrough a column of activated molecular sieves and manganous oxide.1 Maleic anhydride(Fisher) was purified by sublimation.4. Syntheses of metal complexes.Iridium trichloride hydrate (IrCl3.xH2O; on loan from Johnson Matthey) was used asreceived in the preparation of [IrCl(C8H 14)2]2.’ Preparations of fr{N(SiMe2CHPPh)1-(C8H14), 1,6,7 Ir[N(SiMe2CHPPh)](Me)I, 2,8.9 Ir[N(SiMe2CHPPh)](Me)Br, 3,9 andReferences p. 68Chapter 4 57Jr[N(SiMe2HPPh2)1(CHh)Br,4,’ were performed according to the indicated publishedprocedures.5. NMR measurements.All nuclear magnetic resonance (NMR) spectra were recorded on either a Varian XL—300 instrument at ambient temperature (20°C) unless noted otherwise. Proton spectra wereobtained at 299.94 MHz and were referenced to the residual solvent proton peak (C6D5H at7.15 ppm orC6D5D2Hat 2.09 ppm). Phosphorus-31 spectra, 31P{1H}, were obtained at121.42 MHz on the Varian and these spectra were referenced externally to thmethylphosphite,P(OMe)3 set at 141.00 ppm realitive to 85% phosphoric acid. Carbon-13 spectra were recordedat 75.43 MHz and were referenced to the solvent peak (C6D)at 128.00 ppm. All chemicalshift values, 8, are given in ppm and all coupling constants, J, are listed in Hz.6. Syntheses of new compounds.The structural depictions given for each compound are the proposed solution structuresbased on the NMR spectroscopic evidence except for fr[C(CH2)N(SiMeCHPPh] rL’,i12-C(CH2)CCHJ, 13, for which a X—ray structure determination was performed.mer-Ir[N(SiMe2CHPPh)j(rj3-CH5)X/...Ph2 HMe2SI\:N—Ir- :IMe2SI Ha SPh2Solutions of Ir[N(SiMe2CH2PPh )](Me)X (2, X = I; 0.154 g, 0.178 mmol; 3, X = Br;0.162 g, 0.199 mmol) in toluene (10 mL) were degassed on the vacuum line. One equivalent ofReferences p. 68Chapter 4 58acetylene was added to the frozen reaction vessels (77 K) via a constant volume bulb (55 mmHg in 62.443 mL). The solutions were warmed to room temperature and stirred for 6—7 days.During this time the solutions changed from green to yellow, then to reddish orange and then toyellow. The solvent was then removed in vacuo and the resulting powder was washed withhexanes and then extracted with toluene. Insoluble impurities were filtered off and the solutionwas concentrated and let stand at room temperature, which resulted in the formation of yellowcrystals.mer-Ir[N(S1Me2CHPPh)1(ri3-CH5)I,6This compound was previously synthesized by reaction of the vinylidene complex withmethyl iodide,11 and analytical data consistent with that preparation were obtained.mer-Ir[N(SiMe2CHPPh)](i13-CH5)Br, 7Yield 136 mg (81%). 1H NMR (C6D,, ppm): 0.34 (s, SiCH3 3H), 0.40 (s, SiCH33H), 1.10 (s, SiCH3 3H), 0.62 (s, SiCH3 3H), 1.53 (dvt, PCH2Si, 2H, 2JH,H = 1.5,[2JH,P+4J ÷ 2 = 9.7), 2.72 (dvt, PCH2Si, 2H, 2JH,H = 1.5,[2J,p+4H,p] ÷ 2 = 11), 0.75, 1.6(m, Ha), 2.1, 3.35 (m, Ha), 3.90 (m, l-{), 6.9-7.2 (m, m,p-P(C6HS)2), 7.2-7.3, (m, o-PC6H5), 7.5-7.6 (m, o-PC6H5),8.2-8.3 (m, o-PC6H5). 31P{1H} NMR (C6D,, ppm): -3.57 (d, CH2PPh2Jp,p = 425), -9.86 (d, CH2PCHSi). Due to the tendency of this compound to fail to crystallizeaccurate analysis of this compound was not obtained.mer-Ir[N(S1Me2CHPPh)](113-CH41-Ph)B r, 8HMe2SI7 ‘H4- “—PhHaMe Si BrPh7References p. 68Chapter 4 59A solution of Ir[N(SiMe2CHPPh)j(CHh)Br, 4, (0.110 g; 0.123 mmol) in toluene(10 mL) was degassed on the vacuum line. One equivalent of acetylene was added to the frozenreaction vessel (77 K) via a constant volume bulb (36 mm Hg in 62.443 mL). The solutionswere thawed and stirred for eight days. During this time the colour of the solutions changedfrom green to yellow, then to reddish orange and then back to yellow. The solvent was thenremoved in vacuo and the resulting powder was washed with hexanes and then extracted withtoluene. Insoluble impurities were filtered off and the solution was concentrated and let stand atroom temperature. The product formed as yellow crystals.Yield 85 mg (75%). 1H NMR (C6D,6, ppm): -0.6, (s, SiCH33H), 0.1 (s, S1CH33H),0.6, (s, SiCH3 3H), 0.9 (s, SiCH3 3H), 1.70 (ddd, PCH2Si, 2H, 2JH.H = 14.5,2H,P = 16.8,4Jj,p = 1.7), 2.49 (ddd, PCH2Si, 2H, 2JH,P = 11.8,4JH,P = 4.5), 2.65 (br. s, Ha, 2H), 3.4 (ddd,1I, 1H, J = 4.7, J = 11.1, J = 13.0), 4.5 (ddd, H, J = 3.6, J = 7.4, J = 10.8) 6.6 (m, oC3H465),6.8 (m, m-C3H4C6H5),6.9 (m,p-C3H4C6H5), 7.0-7.3 (m, m,p-P(C6H5)2), 7.8-8.1,(m, o-PC6H5),8.3-8.4 (m, o-PC6H5). 31P{1H} NMR (C6D6,6, ppm): -8.3 (d, CH2PPh2Jp,p= 440); -13.7 (d; CH2PPh). As mentioned above, this compound could not be crystallized toenable accurate analysis of this compound.mer-Ir[N(S1Me2CHPPh)1(rj3-CH2D1-Ph)B r, 8-d2/2p HMe2SiPhMe Si/Br_ID Ha2\PhA solution of Ir[N(SiMe2CHPPh)](CH2Ph)Br, 4, (0.100 g; 0.112 mmol) in toluene(10 mL) was degassed on the vacuum line. One equivalent of acetylene-d2 was added to thefrozen reaction vessels (77 K) via a constant volume bulb (37 mm Hg in 62.443 mL). TheReferences p. 68Chapter 4 60solution was thawed and stirred for eight days. During this time the colour of the solutionchanged from green to yellow, then to reddish orange and then back to yellow. The solvent wasremoved in vac. o and the resulting powder was washed with hexanes and then extracted withbenzene-d6and the solution transferred to an NMR tube.1H NMR (C6D,6, ppm): -0.6, (s, SiC!-!3 3H), 0.1 (s, SiCH3, 3H), 0.6, (s, SiCK3 3H),0.9 (s, SiCH3 311), 1.70 (ddd, PCH2Si, 2H, 2JHH = 14.5,2H,P= 16.8,4jH,p = 1.7), 2.49 (ddd,PCH2Si, 2H, 2JH,P = 11.8, 4JH,P = 4.5), 2.65 (s, Ha, 1H), 4.5 (t, H, 3JHD = 4.5) 6.6 (m, oC3H465),6.8 (m, m-C3H4C65),6.9 (m,p-C3FLI I),7.0-7.3 (m, ,n,p-P(C65)2,7.8-8.1,(m, o-PC6H5),8.3-8.4 (m, o-PC6H5).31P{1H} NMR (C6D,6, ppm): -8.3 (d, CH2PPh2Jp,p= 440); -13.7 (d; CH2PPh).mer-trans-Ir[N(SiMeCHPPhj(Me)I(PMe3), 9A-CMe2Si(”PMe3 Me2Si”pMe3 Me2Si””Me:N—I(——Me :N—I(—.--I :N—I(—pMe3M S’ ‘I M S” ‘I Me S’ ‘Ie2 I e2 i 2A B CMethod I: Trimethyiphosphine (12 mm Hg in 62.443 mL) was condensed onto a frozensolution of mer-Ir[N(SiMe2CH2PPh2)21(Me)I (0.03 1 g; 0.036 mmol) in toluene (10 mL).Removal of the solvent in vacuo and extraction with benzene-d6 allowed for the mixture to beanalyzed by NMR spectroscopy. The phosphorus-3 1 NMR spectrum indicated that the solutioncontained three phosphorus containing components, 9A-C. Heating a sealed tube of thismixture to 65°C in benzene-d6 over a two day period resulted in the quantitative conversion tothe most stable isomer, proposed to be the isomer with trimethyiphosphine trans to the amide,References p. 68Chapter 4 619C. The identity of this isomer is assigned based on the independent synthesis given below(Method II).1H NMR (C6D, 6, ppm): mer-trans-Jr[N(SiMe2CH2PPh2)2](Me)I(PMe3): 0.60 (s,SiCH3,6H), 0.65 (s, SiCH3 6H), 1.97 (dvt, PCH2Si, 2H,2JHH = 13.6,[2JH,P+4J ÷2=5.9),2.17 (dvt, PCH2Si, 2H,[2JH,P+4, ] ÷ 2 = 5.4), 0.9 (d, P(Cfl3)J = 9.7), 0.32 (qrt, TrCH3JH,P = 5.6), 7.0-7.2 (m, m,p-P(C65)2), 7.5-7.6, (m, o-PC6H5),8.3-8.4 (m, o-PC6H5). mertrans-Ir[N(SiMeCHPPh2)](Me)(PM3) :0.40, (s, SiCK3 6H), 0.45 (s, SiCH3 6H), 1.57(dvt, PCH2Si, 2H, 2JH.H = 13,[2JH,P+41 ÷ 2 = 6), 2.2 (obscured, PCK2Si), 1.13 (d,P(CH3),J = 8), 2.2 (obscured, IrCH3), 6.85-7.0 (m, m,p-P(CK5)2), 8.0-8.1, (m, o-PC6K5),8.4-8.5 (m, o-PC6H5). mer-trans-Ir{N(SiMeHPPh2)]( Me)I(Me): compound in too lowconcentration to measure resonances. 31P{1H} NMR (C6D, 6, ppm): mer-transJr[N(SiMe2CHPPh](Me)I(P3):-9.15 (d; CH2PPh2Jp,p = 17); -60.66 (t; PMe3); mertrans-Ir[N(SiMe2CHPPh2)1(P e)I(Me): -22.7 (d; CH2PPh2Jp,p = 19); -71.0 (t; PMe3);mer-rrans-lr[N(SiMe2CH2PPh2)2](Me)(PMe3)I: -19.0 (d; CH2PPh2Jp,p = 16-18); -50.0 (t;PMe3).Method II: Excess trimethyiphosphine was vacuum transferred onto a solution offr[N(SiMe2CH..PPh)](C8H14(0.070 g; 0.084 mmol) in toluene (10 mL). After stirring forone hour the excess trimethyiphosphine, toluene and liberated cyclooctene were removed invacuo. The resulting powder was taken up in toluene (10 mL) and excess methyl iodide”wasvacuum transferred onto the solution. The orange colour of the solution was immediately lostas the coordinatively saturated mer-trans-Ir[N(SiMe2CHPPh)2](Me)I(PM3,9C, formed. Themixture was stirred for one half hour and the solvent and excess methyl iodide are removed invacuo. The resulting oil was extracted with toluene and crystallization of yellow bricks ensued.References p. 68Chapter 4 62Yield 100% by NMR. 1H NMR (C6D,6, ppm) 0.60 (s, SiCH3 6H), 0.65 (s, SiCH36H), 1.97 (dvt, PCH2Si, 2H, 2JH,H = 13.6,[2JH,P+4R, i ÷ 2 = 5.9), 2.17 (dvt, PCH2Si, 2H,[2JH,P+41 ÷ 2 = 5.4), 0.9 (d, P(CH3)J = 9.7), 0.32 (qrt, IrCH3JH,P = 5.6), 7.0-7.2 (m,m,p-P(C(J-15)2), 7.5-7.6, (m, o-PC6H5),8.3-8.4 (m, o-PC6HS). 31P{1H} NMR (C6D6, 6, ppm):-9.15 (d; CH2PPh2Jp,p = 17); -60.66 (t; PMe3). Elemental analysis of this compound was notattempted.mer-Ir[N(SiMe2CHPPh)][1-C(CH2) H3]XHdHHbA solution of mer-Ir[N(SiMe2CHPPh)j(Me)X(2, X = I; 0.150 g, 0.173 mmol: 3, X =Br; 0.268 g, 0.328 mmol) in toluene (10 mL) was degassed and acetylene was added to apressure of 1 atm. The reaction mixture was stirred overnight, with the pressure of acetylenemaintained at 1 atm. The solvent was removed in vacuo and the product extracted with toluene.Insoluble polymeric residue was filtered off and the solution was concentrated and left to standat room temperature.mer-Ir[N(SiMe2CHPPh)1[fl1-C(CH2) 2)CH3]I, 10Yield 118 mg (75%). ‘H NMR (C6D,6, ppm) -0.95 (s, C(CH2)C(3-0.15 (s,SiCH3)0.30 (s, SiCH3) 1.01 (dvt, PCH2Si2Jgem = 12.9,[JHP4P] ÷ 2 = 5.3) 2.59 (dvt,PCH2Si,[2JH,p+4, j ÷ 2 = 6.6) 4.91 (td, H,4JpH = 2.4,2Jgem 0.5) 4.98-5.01 (m, Hj) 5.16and 5.74 (td, Ha and Hb, p,H = 2.6 and JP,H = 3.1, Jgem = 0.5), 6.85 (m, p-PC6115),6.95 (m, mPC6H5), 7.00 (m, p-PCH5), 7.13 (m, m-PC6H5),7.8-8.0 (m, o-PC6H5), 8.45-8.55 (m, oPh,References p. 68Chapter 4 63PC6H5). 31P{1H) NMR (C6D,, ppm) -3.06 (s, CH2PPh2). Accurate analysis of thiscompound was previously obtained.12Previous work from our laboratories12involved the preparation of the carbon-13 labelledproduct by reaction of Jr[N(SiMe2CHPPh)Q3Iwith acetylene. The proton NMR of theresulting complex displays three resonances that are coupled to the carbon- 13 nucleus; they are:-0.95 (d,l3Cff1JC,H = 169), 4.91 (d, H,3JC,H = 13), 4.99 (d,Hd,3JC,H = 6).mer-Ir[N(SiMe2CH2PPh)2][rj-C(CH2) H]Br,11Yield 205 mg (72%). 1H NMR (C6D,, ppm) -0.86 (s, C(CH2)C(3-0.18 (s,SiCH3)0.32 (s, SiCH3) 1.11 (dvt, PCH2Si2fgem 12.8,[JH,P+41 ÷ 2 = 5.4) 2.54 (dvt,PCH2Si,[2JH,P+41 + 2 = 6.6) 4.84 (t, C(CH)C(34JP,H = 2.4) 4.98-5.01 (m,C(CH)C(H3) 5.24 (t, C(CH)C(3Jp,H = 2.8) 5.90 (t, C(CH)C(H3,JP,H= 2.6), 6.83 (m, p-PCH5),6.92 (m, m-PC6H5), 7.00 (m, p-PC6H5),7.03 (m, m-PC6H5),7.86-9793 (m, o-PC6H5), 8.47-8.54 (m, o-PC6H5). 31P{H} NMR (C6D,ö, ppm) -3.66 (s,CH2PPh)fac-Ir[N(SiMeCHPPh1(PMe3)[C(CH2(CH2)CH3II, 12Ph2/PHH Me2Si4M82SI\ ‘..Ifl NIrt__l3Me2SI..p1I aorMeSi.,.pHTo a stirred, degassed solution of mer-Ir[N(SiMe2CHPPh2)][C(CH)C(3j ,10, (0.055 g; 0.060 mmol) in toluene (10 mL) was added trimethyiphosphine in excess. Thesolution immediately changed from peach to pale yellow. The solution was stirred for half anReferences p. 68Chapter 4 64hour and the solvent was removed in vacuo. The oil was extracted with benzene-d6 and thephosphorus-3 1 and proton NMR spectra were recorded.Yield 90% by 31P NMR. 1H NMR (C6D6, 6, ppm) -0.16 (s, SiCH3), 0.13 (s, SiCH3),0.27 (s, SiCH3), 0.64 (s, SiCH3), 0.37 (d, P(CH3),1.49 (m, PCH2Si), 1.17 (m, PCH2Si), 2.2(m, C4HH3), 5.08 (m, Ha), 5.95 (m, He), 6.06 (m, Hb), 6.51 (m, Hd), 6.5-7.2 (m, m,pP(C6H5)2,7.6-7.7 (m, o-P(C6H5)2,7.9-8.0 (m, o-P(C6H5)2,8.2-8.3 (m, o-P(C6H5)2,8.4-8.5(m, o-P(C6H5)2).3-P{1H} NMR (CD6, 6, ppm) -59.15 (dd, PMe3,2Jtran.s=387.5 Hz,2J_8.5 Hz); -50.54 (dd, CH2PPh trans to PMe3,2J=19.6 Hz) and -37.69 (dd, CH2PPh cisto both other phosphines).mer-Ir[C(CH2)N(S1MeHPPh1[Ti‘,2-C(CH) lB r, 13a S cHdMe2Si’P2/ Br”jsc9Me2SLp H eA solution of fr[N(SiMe2CHPPh)](CHh)Br, 4, (0.063 g; 0.07 1 mmol) in toluene(10 mL) was degassed and acetylene was added to a pressure of one atmosphere. The solutionwas stirred magnetically overnight and the pressure of acetylene was maintained at oneatmosphere. The solvent and excess acetylene were removed in vacuo and the resulting oil wasextracted with toluene. Insoluble polymeric residue was filtered off and the solution wasconcentrated and left to stand at room temperature and the product crystallized as orangeprisms.Yield 28 mg (43%). 1H NMR (C6D, 6, ppm): 0.20, (s, Si(CH3)26H), 0.40 (s,Si(CH3)2,6H), 1.50 (dvt, PCH2Si, 2H,[2JH,p+4, ] ÷2 = 5.5,2JH,H = 14), 2.50 (dvt, PCH2Si,References p. 68Chapter 4 652H,[2JH,P+4, ] + 2 = 7.0), 3.7 (br 5, He), 4.1 and 4.2 (br s and br s, Ha and Hb), 5.0 and 5.8(br s and br s, H and Hd) 7.0-7.2 (m, m,p-P(C6)2), 7.4-7.5 (m, o-P(D6H’S)2) 7.9-8.0 (m, oP(C6H5)2.31P{1H} NMR (C6D,8, ppm): -10.60 (s, CH2PPh). Despite repeated attempts,accurate analysis of this compound was not obtained. The failure of the elemental analysis islikely due to the presence of toluene in the crystal lattice. See Appendix A for details of the Xray crystallographic analysis.mer-Ir[N(SiMe2CHPPh)](fl2-C3H4), 14The preparation of this compound from the cyclooctene precursor, 1, has been reportedpreviously.’3 A second procedure is reported here.Ph2aMe2Si H2:N—lrZMe2Si,lH2The addition of excess allene to the alkyl halide complexes,Ir[N(SiMe2CHPPh)J(CHR)X (2, R = H, X = I; 3, R = H, X = Br; 4, R = Ph, X=Br. Atypical reaction used about 30 mg of the alkyl halide complex.), in benzene (5 mL) results inreductive elimination of the alkyl halide (within five minutes for the methyl derivatives, 2 and3, and longer for the benzyl analogue, 4) and coordination of the allene. Removal of the excessallene, alkyl halide and solvent in vacuo produces the desired adduct with one equivalent ofincorporated allene.Analytical data consistent with that obtained from the first preparation were obtained.13The earlier preparation reported the allene and tridentate ligand methylene resonances asmultiplets. Coupling patterns of these resonances could be determined and are reported here.References p. 68Chapter 4 66‘H NMR (C6D,8, ppm) 1.13 (ddvt, Ir-CH2-C= H2, JH,p = 5.8, JH,H = 2.3, JH,H =2.0), 1.73 (dvt, PCH2Si, JH,H = 13.1, JH,P = 5.0), 1.80 (dvt, PCH2Si, JH,W=13.1, JH,P = 5.1),5.20 and 5.39 (dvt and dvt, Hb and H, JH,H = 2.0, JH,P = 1.3 and J,p = 1.5). All otherresonances were as previously reported.mer-Ir[N(S1Me2CHPPhZ)1(C6H8),15Ph2Hb•...:NMe2Si,Ha HbThis compound is stable only in the presence of excess allene. There are three methodsby which this compound can be prepared.Method I: A solution of Ir[N(SiMe2CH2PPh)](C8H14), 1, (0.030 g; 0.036 mmol) inbenzened6 was sealed under excess allene in an NMR tube. The presence of the product wasverified by NMR spectroscopy, see below.Method II: A solution offr{N(SiMe2CHPPh)1(r1-C3 4), 14, (0.044 g; 0.058 mmol)in benzene-d6 was sealed under excess allene in an NMR tube. The presence of the product wasverified by NMR spectroscopy, see below.Method Ill: The ailcyl halide complexes [fr[N(SiMe2CHPPh)](CHR)X(2, R = H,X = I; 3, R = H, X = Br, 4, R = Ph, X = Br)] in benzene-d6 were sealed in NMR tubes underexcess allene. The formation of the desired product was determined by NMR spectroscopy, seebelow.References p. 68Chapter 4 67Yield 100% by 31P and 1H NMR by each method. ‘H NMR (C6D,8, ppm): 0.57, (s,Si(CH3)2, 12H), 1.25 (tt, Ha, 3JP,H = 5.7,4JH,H=4JH,H = 2.9), 1.84 (Vt, PCH2Si, 4H,[2JH,P+4, ] ÷ 2 = 5.7), 5.79 and 6.17 (t and t, Hj, and H,4JH,H = 2.9), 6.95-7.10 (m, m,pP(C6H5)2,7.55-7.65, (m, o-PC6H5).31P{1H} NMR (C6D,6, ppm): -6.71 (s, CH2PPh2).fac-Ir[N(SiMePPh](PMe3)(- ,16Me2 Me2çS,Si7Ph2\1,PPh2Ha/l\HbMe3HdMethod IAllene was condensed onto a solution of fr[N(SiMe2CHPPh)21(C8H14,1, (50 mg;0.060 mmol) in toluene (10 mL). After stirring for half an hour excess allene, liberatedcyclooctene and the solvent were removed in vacuo. The resulting oil was extracted withtoluene and trimethyiphosphine was condensed onto the solution. The mixture was stirred forone hour and the solvent and the excess trimethyiphosphine were removed in vacuo. Theresulting powder was extracted with benzene-d6 and the phosphorus-3 1 and proton NMRspectra were recorded.Method HAllene was condensed onto a solution of Ir[N(SiMe2CH2PPh2)1(fl-C3H4), 14, (0.031g; 0.04 1 mmol) in toluene (10 mL). After stirring for half an hour, trimethyiphosphine wascondensed onto the metallacyclopentane generated in situ. The mixture was stirred for one hourReferences p. 68Chapter 4 68and the solvent, the excess reagents, and the liberated cyclooctene were removed in vacuo. Theresulting powder was taken up in toluene and left to stand at room temperature to crystallize.‘H NMR (C6D,, ppm): -0.27, (s, SiCH3 3H), 0.29 (s, SiCH3 3H), 0.60, (s, SiCH3,3H), 0.70 (s, SiCH3 3H), 0.36 Cd, P(CH3)9H, 2JH,P = 9.7), 1.8-2.0 (m, PCH2Si), 2.25 (m,PCH2Si), 2.96 (m, PCH2Si), 1.5, 2.4 (m, Ha and Hb), 5.5 and 5.53 (m, H and Hd), 6.6-7.9 (m,o,1n,p-P(CH5)). 31P{1H} NMR (C6D6, 8, ppm): -49.82 (d, PMe3, 24S = 15, 2jCs = 14),-4.89 (d, CH2PPh2, 2jcjS 14, 24s= 11), 3.18 (d, CH2PPh2J= 15, 24s= 11)7. References.(1) Bafus, D. A.; Brown, T. L.; Dickerhoff, D. W.; Morgan, G. L. Rev. Sd. Instrurn. 1962,33,491.(2) Corey, E. J.; Kim, C. U.; Takeda, M. Tettrahedron Lett. 1972,42, 4339.(3) Inhoffen, H. H.; Pommer, H.; Meth, E.-G. Justus Liebigs Ann. Chem. 1949,565,45.(4) Herdé, J. L.; Senoff, C. V. Jnorg. Nuci. Chem. Lett. 1971, 7, 1029.(5) van der Ent, A.; Onderlinden, A. L. Inorg. Synth. 1973, 14, 92.(6) Fryzuk, M. D.; MacNeil, P. A. Organometallics 1983, 2, 355.(7) Fryzuk, M. 0.; MacNeil, P. A. Organometallics 1983,2., 682.(8) Fryzuk, M. D.; MacNeil, P. A.; Rettig, S. 3. Organometallics 1985, 4, 1145.(9) Fryzuk, M. 0.; MacNeil, P. A.; Rettig, S. J. Organometallics 1986,5, 2469.(10) Fryzuk, M. 0.; MacNeil, P. A.; Massey, R. L.; Ball, R. G. J. Organomet. Chem. 1989,368, 231.(11) Fryzuk, M. 0.; Huang, L.; McManus, N. T.; Paglia, P.; Rettig, S. 3.; White, G. S.Organometallics 1992, 11, in press.References p. 68Chapter 4 69(12) Fryzuk, M. D.; McManus, N. T., Unpublished results.(13) Joshi, K. Ph D Thesis, University of British Columbia, 1990.References p. 68701. Experimental details.APPENDIX AX-RAY CRYSTALLOGRAPHIC ANALYSISA. Crystal data.Empirical FormulaFormula WeightCrystal Colour, HabitCrystal Dimensions (mm)Crystal SystemNumber of Reflections Used forUnit Cell Determination (28 range)Omega Scan Peak Width at Half-heightLattice Parameters:Space GroupZ valueDcaicFoyJt (MoKa)C39.5H45BrJrNP2Si2924.04 g mo11orange, prism0.150 x 0.300 x 0.450triclinic25 (32.7 39.2°)0.42a= 11.044(2)Ab = 19.520 (3) Ac=10.062(1)Aa=89.99(1)Af3=109.72(1)A‘y=76.50(1)AV = 1978.1 (5) A3P 1 #2)21.551 gcm391845.29 cm1Appendix A 71B. Intensity measurements.Diffractometer Rigaku AFC6SRadiation MoKcx ( = 0.71069 A)Temperature 21°CTake-off Angle 6.0°Detector Aperture 6.0 mm horizontal6.0 mm verticalCrystal to Detector Distance 285 mmScanType co-28Scan Rate 32.0° miir’ (in o)(8 rescans)Scan Width (1.26 + 0.35 tane)°4. VflNumber of Reflections Measured Total: 12 097Unique: 11 538 (Rj = 0.037)Corrections Lorentz-polarization Absorption(trans. factors: 0.53 - 1.00)Secondary Extinction(coefficient: 143.85 x 10-9)C. Structure solution and refinement.Structure Solution Patterson MethodRefinement Full-matrix Least-squaresFunctionMinimized Zw(FoI-IFcI)24 F2Least-squares Weightsa2 F0p-factor 0.00Anomalous Dispersion All non-hydrogen atomsNo. Observations (I > 3.00 a(I)) 7070No. Variables 454Reflection / Parameter Ratio 15.57Residuals: R; R 0.033; 0.028Goodness of Fit Indicator 1.54Max Shift / Error in Final Cycle 0.27Appendix A 72Maximum Peak in Final Diff. Map 1.57 e A3Minimum Peak in Final Diff. Map —1.16 e A32. Tabulated data.Table A.Ia. Final atomic coordinates (fractional) and Beq (A2).Atom x y z BecIr(1) 0.39919 (2)b 0.20100 (1) 0.46200 (2) 2.636 (8)CBr(1) 0.22549 (5) 0.26836 (3) 0.22100 (5) 4.22 (3)P(1) 0.5473 (1) 0.26445(6) 0.4386(1) 2.86(6)P(2) 0.2194 (1) 0.17473 (6) 0.5055 (1) 2.78 (5)Si(1) 0.3370 (1) 0.40674 (7) 0.4692 (2) 4.09 (7)Si(2) 0.1181 (1) 0.34419 (7) 0.5332 (2) 3.92 (7)N(1) 0.2698 (3) 0.3457 (2) 0.5226 (4) 3.2 (2)C(1) 0.466 1 (5) 0.3582 (2) 0.3946 (5) 3.7 (2)C(2) 0.08 82 (4) 0.2542 (2) 0.4927 (5) 3.5 (2)C(3) 0.4083 (6) 0.4593 (3) 0.6173 (7) 6.7 (4)C(4) 0.2141 (6) 0.4715 (3) 0.3239 (8) 7.3 (4)C(5) 0. 1079 (6) 0.3659 (3) 0.7094 (7) 6.1 (4)C(6) - 0.0219 (5) 0.4067 (3) 0.3963 (7) 6.7 (4)C(7) 0.6964 (4) 0.2577 (3) 0.5953 (5) 3.3 (2)C(8) 0.7933 (5) 0.1950 (3) 0.6338 (5) 4.5 (3)C(9) 0.9053 (5) 0.1870 (3) 0.7554 (6) 5.7 (3)C(10) 0.9205 (6) 0.2424 (4) 0.8390 (6) 6.2 (4)C(11) 0.8251 (6) 0.3046 (4) 0.8015 (6) 6.6(4)C(12) 0.7 152 (5) 0.3 124 (3) 0.6798 (6) 5.2 (3)C(13) 0.617 1 (4) 0.2428 (2) 0.2980 (4) 3.1 (2)C(14) 0.5526 (5) 0.2092 (3) 0.1849 (5) 4.8 (3)C(15) 0.6001 (6) 0.1935 (3) 0.0753 (5) 5.5 (4)C(16) 0.7110 (5) 0.2129 (3) 0.0751 (5) 5.3 (3)C(17) 0.7747 (5) 0.2472 (3) 0.1844 (6) 5.4 (3)C(18) 0.7298 (5) 0.2617 (3) 0.2968 (5) 4.4 (3)C(19) 0.2586 (4) 0.1293 (2) 0.6782 (4) 2.8 (2)Appendix A 73C(20) 0.3071 (5) 0.0571 (3) 0.7007 (5) 3.7 (3)C(21) 0.3385 (5) 0.0210 (3) 0.8322 (5) 4.2 (3)C(22) 0.3235 (5) 0.0579 (3) 0.9430 (5) 4.3 (3)C(23) 0.2784 (5) 0.1303 (3) 0.9256 (5) 4.6 (3)C(24) 0.2463 (4) 0.1660 (3) 0.7946 (5) 3.7 (2)C(25) 0.1234 (4) 0.1195 (2) 0.3866 (5) 3.1 (2)C(26) 0.1301 (5) 0.1090 (3) 0.2540 (5) 4.6 (3)C(27) 0.0490 (6) 0.0709 (3) 0.1619 (6) 6.1 (4)C(28) -0.038 1 (6) 0.0446 (3) 0.2037 (6) 5.9 (4)C(29) -0.0466 (6) 0.0557 (3) 0.3333 (6) 5.6 (3)C(30) 0.0328 (5) 0.0927 (3) 0.4254 (5) 4.5 (3)C(31) 0.3705 (4) 0.2808 (2) 0.5894 (5) 3.1 (2)C(32) 0.4405 (6) 0.2770 (3) 0.7270 (6) 4.3 (3)C(33) 0.45 16 (8) 0.0914 (4) 0.3635 (7) 7.2 (4)C(34) 0.5415 (8) 0.0993 (3) 0.4602 (8) 8.7 (5)C(35) 0.5394 (5) 0.12 15 (3) 0.5998 (5) 3.6 (2)C(36) 0.6069 (8) 0.0964 (5) 0.7260 (8) 5.8 (4)C(37) 0.543 (3) 0.480 (5) 0.011 (3) 16 (4)C(38) 0.49 (1) 0.433 (2) 0.030 (3) 25 (3)C(39) 0.346 (6) 0.444 (3) 0.003 (3) 13 (3)C(40) 0.313 (7) 0.494 (3) -0.014 (4) 18 (3)C(41) 0.334 (6) 0.549 (2) -0.035 (2) 26 (3)Table A.Ib. Hydrogen atom coordinates (fractional) and Bi0 (A2).Atomx____________Z BjcnH(1) 0.5375 0.3829 0.4223 4.4H(2) 0.4228 0.3642 0.29 14 4.4H(3) 0.0268 0.2598 0.3945 4.2H(4) 0.0437 0.2432 0.5565 4.2H(S) 0.4783 0.4275 0.6949 8.1H(6) 0.4460 0.4935 0.5835 8.1H(7) 0.3382 0.4845 0.6514 8.1H(8) 0.25 83 0.5042 0.2963 8.8Appendix A 74H(9) 0.1751 0.4464 0.2423 8.8H(10) 0.1439 0.4981 0.3564 8.8H(11) 0.1755 0.3308 0.7827 7.4H(12) 0.1233 0.4130 0.7284 7.4H(13) 0.0196 0.3654 0.7101 7.4H(14) -0.0123 0.4551 0.4102 8.0H(15) -0.0212 0.3949 0.3019 8.0H(16) -0.1061 0.4031 0.4048 8.0H(17) 0.7832 0.1553 0.5747 5.3H(18) 0.9732 0.1421 0.7813 6.9H(19) 0.9990 0.2371 0.9248 7.5H(20) 0.8347 0.3440 0.8612 7.9H(21) 0.6490 0.3579 0.6530 6.2H(22) 0.4714 0.1963 0.1823 5.8H(23) 0.5541 0.1684 -0.0026 6.6H(24) 0.7446 0.2022 -0.0032 6.4H(25) 0.8536 0.2617 0.1837 6.5H(26) 0.7780 0.2856 0.3757 5.3H(27) 0.3198 0.0302 0.6222 4.5H(28) 0.3711 -0.0306 0.8449 5.0H(29) 0.3450 0.0327 1.0354 5.2H(30) 0.2690 0.1567 1.0059 5.5H(31) 0.2144 0.2176 0.7830 4.4H(32) 0.1919 0.1282 0.2237 5.5H(33) 0.0547 0.063 1 0.0677 7.3H(34) -0.0945 0.0177 0.1397 7.0H(35) -0.1100 0.0371 0.3621 6.7H(36) 0.0253 0.1003 0.5189 5.4H(37) 0.4 16 (5) 0.333 (3) 0.772 (6) 9 (2)H(38) 0.505 (5) 0.237 (3) 0.768 (5) 5 (1)H(39) 0.430 (5) 0.079 (3) 0.282 (5) 5 (1)H(40) 0.608 (7) 0.119 (3) 0.772 (6) 4(2)H(41) 0.676 (6) 0.048 (3) 0.738 (6) 9 (2)Appendix A 75H(42) 0.5483 0.3860 0.068 1 30.5H(43) 0.2973 0.4078 0.0016 15.4H(44) 0.2209 0.5046 -0.0149 20.5H(45) 0.2796 0.5973 -0.0608 31.0aBeq2ZEUijai*aj*(aj.aj)b numbers in parentheses indicate the estimated standard deviation in the least significant digitC all atoms are assigned an occupancy of 1 except those associated with the lattice toluene, C(37) - C(41)Table A.ll. Selected bond lengths (A) with standard deviations.Atom Atom Distance Atom Atom DistanceJr (1) Br (1) 2.6401 (7) Si (2) N (1) 1.720 (4)Jr(1) P(1) 2.339 (1) Si(2) C(2) 1.883 (5)Jr(1) P(2) 2.337 (1) Si(2) C(5) 1.857 (6)Jr(1) C(31) 2.053 (4) Si(2) C(6) 1.860 (6)Jr(1) C(33) 2.389(6) N(1) C(31) 1.460(5)Jr (1) C (34) 2.230 (6) C (31) C (32) 1.330 (7)Jr (1) C (35) 2.039 (5) C (32) H (37) 1.19 (6)P(1) C(1) 1.820 (5) C(32) H(38) 0.92(5)P(1) C(7) 1.834 (4) C(33) C(34) 1.174 (9)P (2) C (13) 1.833 (4) C (33) H (39) 0.83 (4)P (2) C (2) 1.829 (5) C (34) C (35) 1.476 (8)Si(1) N(1) 1.716 (4) C(35) C(36) 1.265 (9)Si(1) C(1) 1.893 (5) C(36) H(40) 0.63(5)Si(1) C(3) 1.866 (6) C(36) H(41) 1.05(6)Si(1) C(4) 1.853 (6)Table A.llI. Selected bond angles (degrees) with standard deviations.Atom Atom Atom Angle Atom Atom Atom AngleBr(1) Jr(1) P(1) 88.20(3) N(1) Si(1) C(3) 111.5(2)Br(1) Jr(1) P(2) 86.73(3) N(1) Si(1) C(4) 113.0(2)Br(1) Ir(1) C(31) 97.2(1) C(1) Si(1) C(3) 111.9 (2)Br(1) Jr (1) C (33) 95.0 (2) C (1) Si (1) C (4) 105.8 (3)Appendix A 76Br(1) Jr(1) C(34) 119.9 (2) C(3) Si(1) C(4) 106.3(3)Br(1) Jr(1) C(35) 159.4(1) N(1) Si(2) C(2) 108.6(2)P(1) b(1) P(2) 160.61 (4) N(1) Si(2) C(5) 112.2(2)P(1) Ir(1) C(31) 79.4(1) N(1) Si(2) C(6) 112.4 (2)P(1) Jr(1) C(33) 105.9 (2) C(2) Si(2) C(5) 110.7 (2)P(1) Jr(1) C(34) 90.6(2) C(2) Si(2) C(6) 104.9 (2)P(1) fr(1) C(35) 96.0(1) C(S) Si(2) C(6) 107.9 (3)P(2) fr(1) C(31) 82.6(1) Si(1) N(1) Si(2) 136.4(2)P(2) Jr(1) C(33) 93.2(2) Si(1) N(1) C(31) 111.6(3)P(2) Jr(1) C(34) 108.2(2) Si(2) N(1) C(31) 111.7 (3)P(2) Jr(1) C(35) 95.3(1) P(1) C(1) Si(1) 123.2(2)C (31) Jr (1) C (33) 166.9 (2) P (2) C (2) Si (2) 124.1 (2)C(31) Jr(1) C(34) 141.4(2) Jr(1) C(31) N(1) 117.3 (3)C(31) Jr(1) C(35) 103.4(2) Jr(1) C(31) C(32) 123.7 (4)C(33) Jr(1) C(34) 29.2(2) N(1) C(31) C(32) 118.9 (4)C (33) Jr (1) C (35) 64.4 (2) C (31) C (32) H (37) 110 (3)C(34) Jr(1) C(35) 40.1(2) C(31) C(32) H(38) 119(3)Jr(1) P(1) C(1) 110.9 (2) H(37) C(32) H(38) 130(4)Jr(1) P(1) C(7) 115.5(1) Jr(1) C(33) C(34) 67.9(4)Ir(1) P(1) C(13) 117.4(1) Jr(1) C(33) H(39) 133(4)C(1) P(1) C(7) 106.7 (2) C(34) C(33) H(39) 144(4)C(1) P(1) C(13) 102.7 (2) Jr(1) C(34) C(33) 82.9(5)C(7) P(1) C(13) 102.3 (2) Jr(1) C(34) C(35) 62.9(3)Jr(1) P(2) C(2) 112.1 (1) C(33) C(34) C(35) 127.2(8)Jr(1) P(2) C(19) 115.3 (1) Ir(1) C(35) C(34) 76.9(3)Jr(1) P(2) C(25) 119.4(1) Jr(1) C(35) C(36) 149.3 (5)C (2) P (2) C (19) 105.7 (2) C (34) C (35) C (36) 133.7 (6)C (2) P (2) C (25) 100.8 (2) C (35) C (35) H (40) 114 (7)C(19) P(2) C(25) 101.7 (2) C(35) C(36) H(41) 116(3)N(1) Si(1) C(1) 108.1(2) H(40) C(36) H(41) 127(7)77APPENDIX BKINETIC DATAEach kinetic run was performed using a solution of Ir[N(SiMe2CH2PPh2)2}(CH2Ph)Br,4, (29 mg; 0.034 mmol) in benzene-d6in NMR tubes. Allene (218 mm Hg in 62.443 mL;0.740 mmol; 22 equivalents) was condensed onto the frozen solutions (77 K) in the NMR tubesand the tubes were sealed and kept frozen until the kinetic experiments were ready to be started.The decrease of the signal due to the starting material in the phosphorus-31 NMR spectrum(singlet at 0.01 ppm) was monitored as a function of time. The time for each run wasrecorded after 128 of 256 transients were collected. A delay of one second between pulses wasused to allow time for relaxation of the phosphorus nuclei and therefore allow for accurateintegrations. The integrations were converted to percentages and the percentages are listed inthe tables below. The k values were obtained from slopes of the lines obtained from the plots ofir’°°] (where T, T0 and T are the percentage of the starting material at time t, timenaught and at infinite time, respectively) versus time shown after each data table. The values ofk are the observed pseudo-first order rate constants and thus have the units of min1.Table B.I. Run 1: Kinetic data at T = 35.0 ± 0.1 °C.z t [Ir(PNP)(CH2Ph)BrJ in[(mm)____(%) ()6 99.1 -0.00924 99.1 -0.00951 97.3 -0.02872 95.4 -0.047Appendix B 78103 92.9 -0.074134 91.1 -0.093164 89.3 -0.113191 87.2 -0.137231 85.0 -0.163261 83.1 -0.185293 80.9 -0.211321 79.5 -0.229352 78.0 -0.248425 74.1 -0.299491 70.4 -0.35 1602 64.6 -0.436662 61.2 -0.490722 58.5 -0.53600 0.0slope = - 7.40 (6) x 10 min1y-intercept = 6 (2) xcorr = -0.9995k = 7.40 (6) x iO miw1tl/2 937 (2) mmTable B.II. Run 2: Kinetic data at T = 35.3 ± 0.2 °C.r(Tt-Tc,o)L t [Ir(PNP)(CH2Ph)Br] Ifl[(T0 - T00)(mm)____(%) ()7 100.0 0.00072 94.9 -0.05 3132 89.0 -0.117192 84.7 -0.167252 79.8 -0.226312 78.7 -0.240Appendix B 79372 73.1 -0.314432 67.7 -0.389492 64.8 -0.434552 60.5 -0.503612 57.7 -0.550665 54.6 -0.6061450 23.3 -1.4562830 7.5 -2.59300 0.0 -00slope = - 9.4 (1) x 10 mm.1y-intercept = 2 (1) x 102corr = -0.9986k = 9.4(1)x10min14/2 = 737 (8) mmTable B.Ill. Run 3: Kinetic data at T = 35.3 ± 0.1 °C.r(Tt-T)L t [Ir(PNP)(CH2Ph)Br]- T)(mm)____(%) ()7 100.0 0.00096 91.0 -0.094186 83.4 -0.182276 76.2 -0.272366 67.9 -0.388456 61.9 -0.480546 56.0 -0.580636 51.1 -0.672726 46.0 -0.776816 41.6 -0.878906 39.6 -0.926996 37.9 -0.97 1Appendix B 801176 32.1 -1.1371416 26.7 -1.31900 0.0slope = - 9.6 (3) x 10 min1y-intercept = 3 (2) x 10corr = -0.9957k = 9.6 (3) x iO- niin1= 7.2 (2) x 102 mmTable B.IV. Run 4: Kinetic data at T = 45.2 ± 0.1 °C.r(Tt-T)[Ir(PNP)(CH2Ph)Br]‘[(TO - T,)(mm) (%) ()9 100.0 0.00066 85.7 -0.154126 75.3 -0.284186 65.1 -0.429246 57.6 -0.552306 49.0 -0.7 13366 43.2 -0.839426 38.7 -0.949486 32.2 -1.133546 28.9 -1.241606 25.1 -1.382666 22.1 -1.510726 19.0 -1.661786 16.8 -1.784846 12.6 -2.07 100 0.0 —00slope = - 2.34 (4) x iO min1y-intercept = 0.02 (2)Appendix B 81corr = -0.9984k = 2.34(4)xlOmin1= 296 (5) mmTable B.V. Run 5: Kinetic data at Temp =45.2±0.1 °C.A t [Ir(PNP)(CH2Ph)Br] ifl[t.(mm) (%) ()7 100 0.00067 85.3 -0.159127 74.5 -0.294187 64.2 -0.443247 55.6 -0.587307 48.7 -0.7 19367 41.9 -0.870427 36.7 -1.002487 31.2 -1.165547 27.2 -1.302607 23.1 -1.465667 20.4 -1.590727 17.2 -1.760787 15.3 -1.877847 13.6 -1.99500 0.0 —00slope = - 2.40 (1) x iO min1y-intercept = 0.009 (6)corr = -0.9998k = 2.40(1)xlO3min1= 289(1)minAppendix B 82Table B.VI. Run 6: Kinetic data at T = 55.2 ± 0.2 °C.r(Tt-Tc,o)t [Ir(PNP)(CH2Ph)Br]- T00)(mm) (%) ()13 96.8 -0.03348 85.7 -0.15581 76.2 -0.271122 65.8 -0.418165 57.2 -0.558192 51.1 -0.671225 46.3 -0.771260 40.5 -0.904290 37.3 -0.987319 33.7 -1.087600 11.7 -2.144slope- 3.57 (3) x iO min1y-intercept 2.5 (8) x 102corr -0.9996k 3.57 (3) x i03 min1= 194(2)minTable B.VIL Run 7: Kinetic data at T = 55.1 ± 0.2 °C.r(Tt- T)A t [Ir(PNP)(CH2Ph)BrJ- Too)(mm)____(%) ()8 97.7 -0.02342 85.1 -0.16172 71.9-0.330102 63.3 -0.458132 54.9 -0.599162 47.7 -0.740Appendix B 83192 41.7 -0.874222 35.5 -1.034252 31.7 -1.150282 25.7 -1.359312 22.8 -1.478342 20.5 -1.586372 17.3 -1.755402 14.3 -1.947432 13.8 -1.982462 9.7 -2.33 1492 9.6 -2.34200 0.0 -00slope = - 4.87 (7) x 10 mm-1y-intercept 4 (2) x 102corr = -0.9984k = 4.87 (7) x 10 min’= 142 (2) ruinTable B.Vffl. Run 8: Kinetic data at T = 55.2 ± 0.2 °C with added 1 ,4-cyclohexadiene.r(Tt-Tcc,)A t [Ir(PNP)(CH2Ph)Brj- T)(mm)____(%) ()10 100.0 0.00055 89.6 -0.110100 82.8 -0.189145 82.8 -0.189190 75.4 -0.283235 70.6 -0.348280 61.2 -0.490325 54.9 -0.599370 50.1 -0.69 1Appendix B 84415 43.3 -0.837460 32.1 -1.138505 31.3 -1.161550 29.6 -1.21800 0.0 -00slope = - 2.4 (1) x 10 min1y-intercept = 0.10(5)corr = -0.98 12k = 2.4(1)x103m n= 2.9 (1) x 102Table B.IX. Run 9: Kinetic data at T = 55.0 ± 0.2 °C with added 1.4-cyclohexadiene.r(Tt-Tc,o)A t [Ir(PNP)(CH2Ph)Br] lfl[(T0 - T)(mm)______(%) ()9 100.0 000054 91.0 -0.09499 88.2 -0.125144 82.4 -0.194189 76.7 -0.265234 73.5 -0.308279 68.8 -0.374324 62.0 -0.478369 59.0 -0.527414 55.1 -0.596459 4.8 -0.718504 46.2 -0.773549 44.1 -0.819594 39.1 -0.939639 35.5 -1.036684 35.4 -1.038Appendix B 85-1.188-0030.50.072900slope = - 2.08 (4) x l0 min1y-intercept = 4 (1) x 10-2corr = -0.9969k = 2.08 (4) x iO- mm-1= 334 (7) mmTable B.X. Kinetic data summarized.Run Temp. slope y-intercept correl’n k t12(#) (°C) (min1) () () (mm4) (mm)1 35.0 (1) -7.40 (6) x io- 0.006 (2) -0.9995 7.40 (6) x iO- 937 (2)2 35.3 (2) -9.4 (1) x io- 0.02 (1) -0.9986 9.4 (1) x iO-4 737 (8)3 35.3 (1) -9.6 (3) x iO- 0.03 (2) -0.9957 9.6 (3) x io- 720 (20)4 45.2 (1) -2.34 (4) x i0 0.04 (2) -0.9969 2.34 (4) x iO- 296 (5)5 45.2 (1) 2.40 (1) x iO-3 0.03 (1) -0.9989 2.40 (1) x i0 289 (1)6 55.2 (2) -3.57 (3) x 10-s 0.025 (8) -0.9996 3.57 (3) x io- 194 (2)7 55.1 (2) -4.87 (7) x io- 0.04 (2) -0.9984 4.87 (7) x 103 142 (2)8 55.2 (2) -2.4 (1) x 10-s 0.10 (5) -0.9812 2.4 (1) x 10-s 290 (10)9 55.0 (2) -2.08 (4) x 10 0.04 (1) -0.9969 2.08 (4) x 10 334 (7)

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