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Synthesis characterization, and reactivity of ruthenium maltolato complexes Jonker, Michael J. 1993

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SYNTHESIS, CHARACTERIZATION, AND REACTIVITYOF RUTHENIUM MALTOLATO COMPLEXESbyMICHAEL JEFFREY JONICERB.Sc., Trinity Western University, 1991A 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 COLUMBIASeptember 1993© Michael Jeffrey Jonker, 1993In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.(Signature)Department of  CV/Vil .11,t—ryThe University of British ColumbiaVancouver, CanadaDate  5^/(t 3DE-6 (2/88)ABSTRACTThe goal of this project was to synthesize and analyze some new ruthenium maltolatocomplexes as well as to explore their viability as homogeneous catalysts, particularly inaqueous media.The compounds Ru(ma)2(PPh3)2 (1), Ru(ma)2(DMS0)2 (2), Ru(ma)2(COD) (3) andRuH(ma)(C0)(PPh3)2 (4) (where Hma is maltol) were prepared by the interaction ofpotassium maltolate with RuC12(PPh3)4, RuC12(DMS0)4, [RuC12(COD)ln, andRuHC1(C0)(PPh3)3, respectively. All of these complexes were analyzed by 1H, OH } 13Cand, where appropriate, (1H} 31P NMR spectroscopy. In addition, compounds 2 and 3yielded crystals suitable for study by X-ray crystallography. Comparisons are made betweenthe compounds prepared in this project and other previously synthesized maltolatocomplexes.The ambidentate nature of dimethyl sulfoxide (DMSO), where it has the ability tocoordinate via the sulfur or the oxygen moiety, is also discussed. The DMSO complex, 2,was found to contain two sulfur-bound DMSO ligands, which is the coordination modeexpected for a Ru(II) compound. The structure of the DMSO fragment of compound 2 isdiscussed with respect to structures reported for other DMSO derivatives.The triphenylphosphine compound, 1, has been found to have the ability to catalyzethe dimerization of phenylacetylene to a 1:1 mixture of E- and Z-1,4-diphenylbutenyne.Possible reactions of terminal acetylenes with transition metal complexes are discussed and amechanism for the dimerization reaction is proposed.Table of ContentsPageAbstract^Table of Contents^List of Figures viList of Tables^ viiAbbreviations viiiAcknowledgements^Dedication^ xiChapter 1: PHYSICAL STUDIES ON MALTOL AND MALTOLATO COMPOUNDS1.1 General Introduction^ 11.2 Nuclear Magnetic Resonance Properties of Maltolato Complexes^41.3 Elucidation of Stereochemistry via NMR Data^ 81.3.1 Elucidation of the Stereochemistry of Ru(ma)2(PPh3)2^ 81.3.2 Elucidation of the Stereochemistry of Ru(ma)2(DMS0)2 131.3.3 Elucidation of the Stereochemistry of RuH(ma)(CO)(PPh3)2^ 151.4 X-Ray Crystal Structure Data^ 181.5 Discussion of Results 221.6 References^ 22Chapter 2: CHEMISTRY OF SULFOXIDES2.1 Introduction  ^242.2 Structural Characteristics of DMSO^ 252.2.1 Structure of Free DMSO 252.2.2 Structure of Coordinated DMSO^ 262.3 Valence Bond Model^ 292.4 Exceptions to the HSAB Theory^ 322.5 Methods of Analysis of the Mode of DMSO Bonding^ 342.5.1 X-Ray Crystallography^ 342.5.2 Infrared Spectroscopy 352.5.3 1H and 13C NMR Studies^ 362.6 References^ 37Chapter 3 REACTIONS BETWEEN TERMINAL ALKYNES AND METAL COMPLEXES3.1 General Survey^ 393.1.1 Organic Products of Allcynes with Transition Metal Complexes^403.1.1.1 Alkyne Metathesis and Disproportionation^403.1.1.2 Dimerization of Alkynes^ 413.1.1.3 Trimerization of 1-Alkynes 423.1.1.4 Polymerization of 1-Alkynes^ 443.1.2 Organometallic Products of Alkynes with Transition Metal Complexes^443.1.2.1 n-Complexes^ 443.1.2.2 Acetylide Complexes 453.1.2.3 Vinylidene Complexes^ 463.1.2.4 Alkenyl Complexes 463.1.2.5 Enynyl Complexes^ 473.1.2.6 Metallacyclopentadienes 503.2 Reaction of Terminal Allcynes with Maltolato Complexes of Ruthenium^ 503.2.1 Reactions with Acetylene^ 523.2.2 Reaction of Ru(ma)2(PPh3)2 with Substituted Acetylenes^ 523.2.3 Attempted Reactions of Ru(ma)2(DMS0)2, Ru(ma)2(COD) andRuH(ma)(C0)(PPh3)2 with Substituted Acetylenes^ 523.3 Proposed Mechanism for the Dimerization of Terminal Alkynes^543.4 References^ 60ivChapter 4 EXPERIMENTAL PROCEDURES4.1 General Procedures^ 644.2 Reagents and Starting Materials^ 644.3 Analytical Methods 654.4 X-Ray Crystal Structures^ 654.5 Syntheses^ 664.5.1 Ru(ma)2(PPh3)2^ 664.5.2 Ru(ma)2(DMS0)2 664.5.3 Ru(ma)2(d6-DMS0)2^ 674.5.4 Ru(ma)2(COD)2 674.5.5 RuH(ma)(C0)(PPh3)2^ 684.6 Reactions with Alkynes 684.6.1 Reaction of Ru(ma)2(PPh3)2 with Phenylacetylene ^ 684.6.2 Reactions with Acetylene^ 694.7 References^ 69SUMMARY AND FUTURE PROSPECTS^ 70APPENDICESA.1 X-Ray Crystallographic Analysis of Ru(ma)2(DMS0)2^ 71A.2 X-Ray Crystallographic Analysis of Ru(ma)2(COD) 81VList of FiguresFig. 1.1: Structure of Maltol ^ 1Fig. 1.2a: 1H NMR of Ru(ma)2(PPh3)2^ 9Fig. 1.2b: 31P NMR of Ru(ma)2(PPh3)2 10Fig. 1.3a: 1H NMR of Ru(ma)2(PPh3)2 (single isomer)^ 11Fig. 1.3b: 31P NMR of Ru(ma)2(PPh3)2 (single isomer) 11Fig. 1.4: 1H NMR of Ru(ma)2(DMS0)2^ 14Fig. 1.5a: 1H NMR of RuH(ma)(C0)(PPh3)2 16Fig. 1.5b: 31P NMR of RuH(ma)(C0)(PPh3)2^ 17Fig. 2.1: Structure of DMSO^ 25Fig. 2.2: General Structures of Coordinated DMSO^ 27Fig. 2.3: Canonical Forms of DMSO^ 30Fig. 2.4: Valence Bond Diagram for Free DMSO^ 31Fig. 2.5: Electronic Factors Determining S- or 0-Coordination^ 32Fig. 2.6: 0-Coordination to a "Soft" Metal Due to Steric Factors 33Fig. 3.1: 1H NMR of E- and Z-diphenylbutenyne^ 53viList of TablesTable 1.1: 1H NMR Data for Maltol and Some Maltolato Complexes^6Table 1.2: 13C NMR Data for Maltol and Some Maltolato Complexes 7Table 1.3: NMR Data for Some Acetylacetonato Complexes^ 19Table 1.4: MO2C2 Bond Lengths and Angles versus Ligated Atom Size^20Table 1.5: Carbon-Carbon Bond Lengths in the Maltolato C50 Ring 21Table 2.1: Structural Data for Free DMSO^ 26Table 2.2: Selected Bond Angles for Some DMSO Compounds^27Table 2.3: Selected Bond Lengths for Some DMSO Compounds 28Table 2.4: Sulfoxide Stretching Frequencies^ 35Table 3.1: Dimerization of Phenylacetylene 43VIIAbbreviations%^per centA Angstrom (10-10 in)acac^acetylacetonateanal. analysisatm^atmosphereBun butylBut^tertiary butylcalcd calculatedCOD^1,5-cyclooctadieneCP* pentamethylcyclopentadienyl substituent8^chemical shift (NMR)d doubletDMSO^dimethyl sulfoxidedppe 1,2-bis(diphenylphosphino)ethanedppm^1,2-bis(diphenylphosphino)methaneEl electron ionization (mass spectroscopy)eqn^equationEt ethylfig.^figureGC gas chromatographyHSAB^Hard-Soft-Acid-Base [Theory]Hz hertzIR^infraredJ scalar nuclear spin-spin coupling constant (NMR)Kma^potassium maltolatem^multipletma maltolate anionMe^methylMHz megahertzmmol^millimolemol moleMS^mass spectroscopyNMR nuclear magnetic resonancePh^phenylpKa negative log of the acid dissociation constantppm^parts per millionpy pyridines^singlett tripletTHF^tetrahydrofurantmen N,N,N',N-tetramethylethylenediamine0^degree°C degree CelsiusAcknowledgementsI would like to sincerely thank Dr. Michael D. Fryzuk, firstly, for supporting my research,and secondly, for his guidance throughout the course of this project. I would also like to thankall those members of the chemistry department, past and present, who gave me good counsel, beit with this project or on the basketball court: Mr. Murugesapellai Mylvaganam, Mr. GuyClentsmith, Mr. James Ravensbergen, Mr. Andrew Tovie, Mr. Shane Mao, Mr. Danny Leznoff,Mr. Paul Duval, Ms. Lisa Rosenberg, Mr. Xiaolang Gao, Ms. Pauline Chow, and Mr. CameronForde. Also to be thanked is Mr. Peter Borda for performing the microanalyses, and Dr. SteveRettig for determining the crystal structures.Furthermore, I would like to thank my undergraduate professors, Dr. J. VanDyke, Dr. C.Montgomery, and Dr. C. Cross, with whom I worked closely. You always showed suchenthusiasm in what you were teaching that I decided to make chemistry my field of study.Finally, and most importantly, I would like to express my gratitude to my family, dad,mom, Rob, Darryl, Chantal, and above all, Eileen, to whom I dedicate this thesis.M.J.J.To my wife,EileenxiChapter 1Physical Studies on Maltol and Maltolato Compounds1.1 General IntroductionThe heterocyclic compound 3-hydroxy-2-methyl-4-pyrone (maltol) is foundnaturally in a variety of locations including in the vapors of roasting malt, in the branchesof the larch tree, and in needles of the silver fir. It can also be prepared via the distillationof cellulose, from the acid hydrolysates of soybeans, and as a product of the alkalinehydrolysis of streptomycin chloride.1 It is virtually non-toxic and is often added to foodsas a sweetener. Maltol contains a ketonic oxygen and a hydroxyl group attached to adjacentcarbons (Fig. 1.1). The hydroxyl group is easilydeprotonated in basic media, with a plCa value reportedto be 8.672 to 8.683,4 at 25 °C in water. When^OHdeprotonated, maltol is capable of forming anI0,0'-chelating ligand, coordinating through the^60^n 3ketonic and hydroxyl oxygens.Figure 1.1Structure of MaltolAlthough maltol has been known since the late1800's, its coordination chemistry has developed relatively recently. One of the first metalmaltolato complexes synthesized was the neutral tris-chelate complex of iron,5 which alsohappens to be one of the few maltolato compounds to be fully characterized by X-raycrystallography.3 The syntheses of a number of other divalent2 and trivalent6 first rowtransition metal maltolato complexes were subsequently described, in addition to those ofthe lanthanides,7 and many of the p-block metals and metalloids.8-10 A number of1maltolato complexes that have been reported in the literature are presented in Scheme 1.1:1,11 11,12 iii,' iva,6 ivb,14 v,15 v1,14 vii,14 vm,14 and ix.16 Although this isnot an extensive review of all maltolato compounds, it does illustrate the majority of thosethat are known. The abbreviations Hma and ma will be used throughout this work formaltol and the maltolato ligand, respectively.Maltol has found a variety of in vivo uses as a chelating ligand for a number ofmetals. For example, the compound A1(ma)3 has been used in studies attempting to relatethe presence of aluminum in the brain to neurological disorders such as Alzheimer's diseaseand dialysis encephalopathy.17 Moreover, Fe(ma)3 has been found to have potential forthe treatment of iron-deficiency anaemia.3 Maltol has found uses in such complexes due tothe facile deprotonation of its hydroxyl group in basic media, its high affinity for metals, itslow toxicity, and its ability to produce water-soluble complexes which are stable tohydrolysis.3.17 Also important is that neutral complexes of the type M(ma) n can beprepared, where n is equal to the valency of the metal atom, M. It is necessary for neutralcomplexes to be used for in vivo studies in order to allow for their facile membranediffusion. In addition, the study of Al passage to the brain demands an aluminumcompound with a molecular mass of 400 dalton or less in order for the complex to be ableto pass the blood-brain barrier.17Studies on maltolato compounds of second and third row transition elements arerelatively few and much more recent. Only one ruthenium maltolato complex has beenreported to date, that being the tris-chelate Ru(ma)3 complex.14 For this reason, a study ofruthenium maltolato complexes was undertaken. In addition, with maltol providing water-soluble complexes of aluminum17 and iron,3 it was anticipated that water-solubleruthenium compounds could similarly be prepared in order to provide a homogeneouscatalyst for an aqueous medium.2,f PPh3M ''I ■0^PPh30„„NPhJle**.oC)^I^PPh3I= Co, Ni, ZnN N = dipyridylII(0„,„ivi())M = Cu, Mn, Co, Ni, ZnIIINi^N)1 mai 2M = Mn, Cr, Fe^M = Rh, RuIVa^IVbN N = ethylenediaminetrimethylenediamineN,N-dimethylenediamine M = Os, UVIM = Pd, PtVII^VIII0 0 =IX[Scheme 1.13In this chapter, the chemistry of some maltolato compounds will be discussed,ultimately focusing on the new ruthenium maltolato complexes: Ru(ma)2(PPh3)2 (1),Ru(ma)2(DMS0)2 (2), Ru(ma)2(COD) (3), and RuH(ma)(C0)(PPh3)2 (4). Theruthenium maltolato complexes discussed in this work were all prepared by interaction ofpotassium maltolate (Kma) with an appropriate ruthenium chloride. Metathesis of thechloride, together with displacement of a neutral ligand, yields the correspondingruthenium maltolato compounds (Scheme 1.2). These compounds were analyzed by 1H,13C ( 1H) and, where appropriate, 31P( 1H) NMR and IR spectroscopy. In addition, 2and 3 yielded crystals suitable for single-crystal X-ray analysis and all four of thesecompounds gave suitable elemental analyses.1.2 Nuclear Magnetic Resonance Properties of Maltolato ComplexesProton and carbon NMR assignments have been made for maltol as well as for anumber of maltolato complexes. Proton NMR assignments are relatively straightforward,while carbon NMR spectra require a little more interpretation. Data from the 1H NMRspectra of maltol and a number of its complexes are recorded in Table 1.1. The protonNMR spectrum of uncoordinated maltol consists of a singlet due to the hydroxyl proton,two doublets corresponding to the ring protons, H(5) and H(6), and a singlet arising fromthe methyl protons, H(7). (Refer to Fig. 1.1 for molecular numbering scheme; hydrogenatoms are numbered according to the associated carbon atoms.) Upon complexation, thesinglet due to the hydroxyl proton is absent, while the remainder of the resonancesgenerally shift downfield, with H(5) being deshielded the most and the methyl protons theleast. This deshielding is a natural consequence of electron donation from the maltolatoligand to the meta1.184oThPh3P,„,... I .......Ph3P 0^}1PPh3Ph3R-,.. I^.....•Ru*** ..^+ 2 KmaPh3lp" I '`CIPPh3+ KmaCIPh3P„,„ I ...„,PPh3.1%.*Ph3PrCO(-00„„^...oPPh3'RdPh3P# ICO0S„,*Rd.^+ 2 KmaS/S = sulfur-bound DMSO0= oxygen-bound DMSO4Scheme 1.25The hydride-carbonyl derivative, 4, is formed as a mixture of two isomers, in a15:1 ratio; the data recorded in Table 1.1 correspond to the major isomer. The 1H NMRspectra of the dimethyl sulfoxide (1) and viphenylphosphine (2) compounds are complexdue to the presence of a number of isomers and thus their NMR data were not recordedhere.Table 1.1 1H NMR Data For Maltol and Some Maltolato CompoundsaChemical Shift 8 (ppm).156Compound^H(5)^H(6)^H(7)^(Hz)^Ref. Maltol 6.39^7.63^2.37^3.6^14[Re(ma)2(NPh)(PPh3)]+^6.40; 6.60 b^2.00; 2.60 e^16Rh(ma)3^6.73^7.67^2.54^5.0^14Pd(ma)2 6.57^7.70^2.43^5.2^15[Pd(PPh3)2(ma)]+^6.50^b^2.50^5.1^14[POPPh3)2(ma)]+^6.57^b^2.51^4.8^14Zn(na)2(PY)d 6.49^7.68^2.42^5.2^19Zn(ma)2(tmen)e^6.38^7.53^2.37^c^20Cd(ma)2(trnen)e^6.37^7.53^2.38^5.2^12In(ma)3^6.62^7.79^2.48^c^20Sn(ma)2 6.67^7.73^2.36^c^20Ru(ma)2(COD)^6.34; 6.63 7.53; 7.57 2.28; 2.46 5.4^this workRuH(ma)(C0)(PPh3)2f^5.78^6.97^1.86^5.2^this workRu(ma)2(DMS0)2 interpretation complicated by^this workRu(ma)2(PPh3)2^presence of three isomers^this worka. in CDC13 b. obscured by phenyl resonances c. data not given d. py = pyridinee. tmen = N,N,M,N1-tetsamethylethylenediamine f. values quoted for major isomer6The broad-band decoupled 13C NMR spectrum of maltol has been assignedn andis similar to the spectra of its metallic complexes.14," The methyl carbon, C(7), appearsnear 15 ppm for both maltol and its complexes and is far removed from the other carbonresonances, thus being readily assigned. The ketonic carbon, C(4), is found at the lowestfield of all the resonances and undergoes a significant downfield shift upon complexation.The signals for the other four ring carbons are found within the range of 110-160 ppm.Again, data have been tabulated for a variety of maltolato compounds, including thecyclooctadiene (3) and hydride-carbonyl (4) complexes (Table 1.2).Table 1.2 13C NMR Data for Maltol and Some Maltolato Complexesa,bCompound C(2) C(3) C(4) C(5) C(6) C(7) Ref.Maltol 148.9 142.6 172.1 113.2 154.3 13.8 21Rh(ma)3 160.6 155.8 186.9 111.9 151.2 14.8 14155.5 186.8 111.8Pd(ma)2 159.7 155.6 185.6 111.5 151.7 14.1 14155.4 185.2 111.4[Pd(ma)(PPh3)2]+ 164 158.3 c 112.1 153.2 14.6 14[Pt(ma)(I)Ph3)2l+ 164 158.7 c 112.7 153.9 13.9 14Zn(ma)2(tmen) 153.3 149.8 178.2 110.3 150.5 14.8 20Cd(ma)2(tmen) 153.7 151.9 178.4 111.3 149.9 15.1 20Sn(ma)2 154.3 151.8 177.7 111.8 152.7 15.0 20In(ma)3 154.3 150.6 176.5 110.8 152.3 15.5 20Ru(ma)2(COD) 157.9 154.1 182.5 111.9 150.2 14.6 this work159.7 154.3 185.1 112.0 150.9 15.0RuH(ma)(C0)(PPh3)2 156.6 152.5 180.5 111.1 149.0 14.1 this workRu(ma)2(DMS0)2 interpretation complicated by this workRu(ma)2(PPh3)2 presence of three isomers this worka. all spectra recorded in CDC13^b. refer to Fig. 1.1 for molecular numbering schemec. not located71.3 Elucidation of Stereochemistry via NMR DataThe data from the 1H, 13C{1H) and 3113(1H) NMR spectra can be utilized in orderto determine the number of isomers present as well as the orientation of the ligands aroundthe ruthenium core in the triphenylphosphine, 1, DMSO, 2, and hydride-carbonyl, 4,compounds, particularly regarding their cis/trans stereochemistry. Compound 3 wasformed as a single isomer. It contains a bidentate cyclooctadiene moiety which naturallyoccupies two cis positions, as well as two maltolato ligands, the orientations of which weredetermined by single-crystal X-ray crystallography (Appendix A.2).1.3.1 Elucidation of the Stereochemistry of Ru(ma)2(PPh3)2 (1)Compound 1 contains a number of isomers, as illustrated by its 1H and 31P {1H)NMR spectra (Figs. 1.2a and 1.2b). By gathering spectra on samples with a variety ofisomer ratios, it was determined that three isomers were present. Two of these isomers (iand ii) contain chemically equivalent maltolato and triphenylphosphine ligands while thethird isomer (iii) contains two inequivalent maltolato and two inequivalenttriphenylphosphine ligands. Thus the maltolato region of the 1H NMR spectrum consistsof four singlets due to the methyl protons and two sets of four doublets due to the twoolefinic protons (Fig. 1.2a). The 31P {1H) NMR spectrum consists of a doublet ofdoublets for isomer iii due to coupling of the two inequivalent phosphorus nuclei as wellas a singlet for each of the other two isomers, i and ii, which each contain equivalentphosphorus nuclei (Fig. 1.2b). It was possible to isolate isomer i of this compoundalthough it could not be done reproducibly. This isomer is one of the two containingequivalent maltolato and triphenylphosphine ligands. Its 1H and 3113( 1H) NMR spectraare shown in Fig. 1.3a and Fig. 1.3b.8I8.0^7.5^7.0^6.5^6.0^5.5^5.0^4.5^4.0^3.5^3.0^2.5^2.0PPMFig. 1.2a 1H NMR spectrum of Ru(ma)2(PPh3)2 (1) in C6D6Fig. 1.2b 3' P NMR spectrum of Ru(ma)2(PPh3)2 (1) in Csps BO^60^40PPMFig. 1.3b 31P NMR spectrumof Ru(ma)2(PPh3)2(single isomer) in C6D6r 12.5ti^0^6. 5^6. 0 5.5^5.0^4.5^4.0^3.5^3.0rrmFig. 1.3a 1H NMR spectrum of Ru(ma)2(PPh3)2 (single isomer) in C6060 0' = maltolato P = triphenylphosphineTheoretically, there are five possible geometric isomers of this compound: twotrans and three cis isomers. The two trans isomers, A and B, as well as two of the cisisomers, C and D, all contain chemically equivalent maltolato and triphenylphosphineligands. The other cis isomer, E, contains chemically inequivalent maltolato andtriphenylphosphine ligands. Thus, of the three isomers observed by NMR at least one, ifnot all three, contain cis triphenylphosphine ligands. Since there is at least one cis isomer,it might be assumed that the cis geometry is the more stable of the two and that all threeisomers are of the cis form. That all three isomers are cis would concur with resultsreported for the analogous 13-diketonate compounds of triphenylphosphine.22,23 Forexample, by coordinating acetylacetonate in lieu of maltolate, one obtains a compoundwhose 1H NMR spectrum displays two methyl resonances of equal intensity and onemethine resonance, indicating the presence of two equivalent but asymmetrically boundacetylacetonate ligands.22 These data unequivocally establish a cis stereochemistry.12Likewise, when an asymmetric 13-diketonate such as trifluoroacetylacetonate is coordinated,three isomers are observed, F, G and H, all of which contain cis phosphine groups.23 Itwould seem a valid assumption that the maltolato complexes would exhibit a behaviorsimilar to that observed for their P-diketonate analogues.CH31.3.2 Elucidation of the Stereochemistry of Ru(ma)2(DMS0)2 (2)The DMSO compound, 2, is analogous to the triphenylphosphine derivative, 1, inthat it contains two maltolato ligands in addition to two other unidentate ligands. Themaltolato portion of the 1H NMR spectrum appears to exhibit similar features as well,consisting of four singlets and two sets of four doublets (Fig. 1.4). However, althoughthere are clearly four singlets, the doublets are not as distinct as in the spectrum of thetriphenylphosphine derivative, making certain assignments difficult. Furthermore, thereare a large number of DMSO methyl resonances (8 singlets), seemingly more than would13III,.2. 5III2.0DMSOmethylmatte!r H(6)7.maltolr H(5)iL.^1^. I^•^I^1^I^IF^7^TE7^IIIIrt6.5 6.0 5.5 5.0 4.5^4.0^3. 5^3.0PPMFig. 1.4 1H NMR spectrum of Ru(ma)2(DMS0)2 (2) in C6D6be required by the presence of three isomers. However, the large number of peaks couldsimply be due to the inequivalence of the methyl groups of each DMSO upon coordinationbecause of hindered rotation around the MS bond. It is difficult to assign thestereochemistry of this compound by NMR spectroscopy alone, although cis coordinationseems to once again be the case. This is further supported by a single-crystal X-ray studywhich confirmed the cis orientation of one of the isomers (Appendix A.1). However, noanalogous 0,0-chelate compounds of ruthenium, such as 13-diketonates with DMSOligands, have yet been reported in the literature, making comparisons impossible.1.3.3 Elucidation of the Stereochemistry of RuH(ma)(C0)(PPh3)2 (4)The 1H and 31P( 1H) NMR spectra of 4 both indicate the presence of two isomers,one major and one minor isomer, in a ratio of 15:1. For each isomer, the 1H NMRspectrum exhibits two doublets and a singlet, corresponding to the maltolato olefinic andmethyl protons, respectively, in addition to the resonances of the phosphine phenyl protonsand a binomial triplet arising from each of the hydrides coupled to two equivalentphosphorus nuclei (Fig. 1.5a). The coupling constant, Jp_H = 21.0 Hz is indicative of a cisorientation of the hydride with respect to the phosphines. This value is very close to thevalue of 20.5 reported for the analogous compound, RuH(acac)(C0)(PPh3)2. 24 The31P{ 1H) NMR spectrum contains a singlet near -5 ppm, arising from the presence oftriphenylphosphine displaced during the reaction with maltolate. Also apparent are twosinglets, one for each of the two isomers of 4 (Fig. 1.5b). The knowledge that the twophosphorus nuclei are equivalent allows an unequivocal trans assignment of thetriphenylphosphine ligands. With the maltolato ligand occupying cis positions, the hydrideand carbonyl ligands must also occupy cis positions. Therefore, the two isomers, I and J,must arise from the orientation of the maltolato group, where the oxygen trans to thehydride can be either the ketonic or hydroxyl oxygen. Again, this structure is in accord151 ^1-13.50PPM^Logo...fil................—A-11.--...^^t " " 1 Ul I CI1 I^^I^r^r8.0^7.5^7.0^6.5^6.0^5.5^5.0^4.5^4.0^3.5^3.0^2.5^2.0PPMFig. 1.5a 1H NMR spectrum of RuH(ma)(C0)(PPh3)2 (4) in C6D6 I^.0••.0^-with previous reports on analogous P-diketonate complexes where the phosphines are alsofound to assume trans positions.22,240 0' = maltolateP = triphenylphosphineAs can be seen from Table 1.1, the maltolato resonance values for the rutheniumhydride compound, 4, are far upfield from those observed for all of the other maltolatocompounds listed. This is most likely due to diamagnetic anisotropy; this shielding via aring current effect occurs when a proton is positioned directly above or below an aromaticring. This is certainly very feasible for this system, where the maltolato ligand issandwiched between the phenyl groups of the two trans phosphines. Similar observationscan be made regarding acetylacetonato complexes where the resonances of the methyl andmethine protons are shifted far upfield for the complex RuH(acac)(C0)(PPh3)2, relative toother acetylacetonato complexes (Table 1.3).1.4 X-Ray Crystal Structure DataA single-crystal X-ray structure of maltol has not yet been determined; however,structures for a number of maltolato complexes have been reported. This section will bedevoted to discussing pertinent features of these structures, as well as pointing outcorrelations and drawing conclusions from the structural data. The data are derived fromthe compounds [Re(ma)2(NPh)(PPh3)11/31)1141,16 A1(ma)3,17 Ph2B(ma),10 Fe(ma)3,3Cd(ma)2(tmen),2° as well as from the new compounds Ru(ma)2(DMS 0)2 and18Ru(ma)2(COD). If the compounds contain two or more rnaltolato ligands any data, such asbond lengths or bond angles, will be given as the mean of all the maltolato ligands. Theonly exception is in the case of Al(ma)3, where one of the three maltolato ligands isdisordered so that only the data from the two ordered ligands will be used.Table 1.3 NMR Data for Some Acetylacetonato ComplexesaChemical Shift 8 (ppm)Compound CH3 -CH= Ref.Hacacb 2.04 5.51 25Zr(acac)4 1.92 5.48 25Hf(acac)4 1.92 5.46 25Ce(acac)4 1.91 5.31 25Th(acac)4 1.93 5.44 25Pt(acac)2 2.08 5.53 26Ru(acac)2(PPh3)2 1.62/1.77 5.05 23RuH(acac)(C0)(PPh3)2 1.06/1.30 4.36 24a. all spectra recorded in CDC13^b. acac = acetylac,etonateThere are a number of notable trends involving the five-membered MO2C2 ring(Table 1.4). One significant feature is the dependence of the bond lengths and angles ofthis ring on the size of the ligated atom, M. As M increases in size, the M-0 bondslengthen and the 0—M-0 bite angles decrease. Concomitantly, the M—O—C and 0—C—Cangles increase with the increase in size of the ligated atom. In addition, there are sometrends which are less adhered to, where the C-0 bond lengths decrease while the C—Cbond lengths increase, as M increases in size. Through this, it can be seen that themaltolato ligand has a remarkable facility to accommodate a variety of metals by internal19adjustment of both bond lengths and angles of the five-membered MO2C2 ring.20 when NIis small in size, it can get in close to the two oxygens, which is displayed by the short M-0bond lengths. This leads to a larger bite angle which is compensated for by increases in theM-0-C and 0-C-C angles. When M is larger, it is more distant from the oxygens,leading to a smaller bite angle and subsequent decreases in the M-O-C and 0-C-C angles.Table 1.4 MO2C2 Bond Lengths and Angles Versus Ligated Atom SizeB(1ll)a ^AlWip Fe(III)c Ru(II)d^Ru(11)e Re(W)f ccuDgCrystal IonicRadii (A)27 0.23 0.51 0.64 0.69^0.69 0.72 0.97M-Ok BondLength (A)h 1.595 1.928 2.065 2.098^2.106 2.117 2.329M-Oh BondLength (A)i 1.529 1.873 1.987 2.092^2.099 1.992 2.2180-M-0 BiteAngle (°) 99.49 84.9 80.5 80.82^79.5 78.4 74.2Angle (°)h 108.24 111.2 111.8 110.3^111.5 n/a 112.1M-Oh-CAngle (°)i 107.83 111.7 111.7 109.4^110.1 nia 113.9Ok-C-CAngle (°)h 112.1 117.0 117.7 119.7^119.2 n/a 120.1Oh_c_cAngle (°)i 112.1 115.1 118.1 119.1^119.3 n/a 119.8C-Ok BondLength (A)h 1.288 1.271 1.261 1.272^1.275 1.281 1.252C-Oh BondLength (A)i 1.343 1.330 1.330 1.313^1.321 1.331 1.310C-C BondLength (A) 1.394 1.423 1.407 1.448^1.419 1.407 1.466a. Ph2B(ma) b. Al(ma)3^c. Fe(ma)3 d. Ru(ma)2(DMS0)2 e. Ru(ma)2(COD)f. [Re(ma)2(NPh)(PPh3)][BPh4] g. Cd(ma)2(tmen) h. Ok = keto oxygeni. Oh = hydroxyl oxygen20or'CH3In addition, it should be noted that the (C(2)—C(3)) and (C(5)—C(6)) bond lengths(the olefinic bond lengths) of the maltolato ligand for all the compounds discussed are inthe range of 1.31-1.39 A (Table 1.5), indicating that they possess significant double bondcharacter (cf. 1.34 A for ethylene and 1.53 A for ethane). This fact, together with thelonger C-0(hydroxyl) bond compared to the C-0(keto) bond, demonstrates that the metal-ring interaction involves a substantial contribution from structure, K, rather than thedelocalized structure, L.16Table 1.5 Carbon—Carbon Bond Lengths in the Maltolato C50 RingCompound (C(2)—C(3)) Bond Length (A) (C(5)—C(6)) Bond Length (A)Ph2B(ma) 1.358 1.340A1(ma)3 1.350 1.313Fe(ma)3 1.376, 1.372, 1.397 1.315, 1.345, 1.347Ru(ma)2(COD) 1.385, 1.38 1.34, 1.33Ru(ma)2(DMS0)2 1.360, 1.364 1.329, 1.324[Re(ma)2(NPh)(PPh3)]+ 1.377 1.330Cd(rna)2(tmen) 1.357, 1.355 1.318, 1.336K L211.5 Discussion of ResultsAs mentioned at the beginning of this chapter, one of the goals of this project wasto produce water soluble ruthenium maltolato complexes for use as homogeneous catalysts.Unfortunately, the triphenylphosphine complex, 1, the COD compound, 3, and thehydride derivative, 4, were all insoluble in water. The DMSO complex, 2, was the onlyone of the four that could be deployed in aqueous solution. However, due to timeconstraints, no attempts were made to determine any catalytic capabilities. Nevertheless, aninteresting catalytic reaction between 1 and phenylacetylene in benzene was observed andwill be discussed in Chapter 3. Meanwhile, Chapter 2 will focus on the properties ofDMSO and its complexes, ultimately focusing on the ruthenium DMSO complex, 2.1.6 References(1) Cavalieri, L. F. Chem. Rev. 1947, 41, 525-584, and references cited therein.(2) Gerard, C.; Hugel, H. P. J. Chem. Res. (M) 1978, 4875-4889.(3) Ahmet, M. T.; Frampton, C. S.; Silver, J. J. Chem. Soc., Dalton Trans. 1988,1159-1163.(4) Tan, S. F.; Ang, K. P.; Jayachandran, H. J. Chem. Soc., Perkin Trans. II 1983,471-473.(5) Stefanovic, A.; Havel, J.; Sommer, L. Coll. Czech. Chem. Comm. 1968, 33,4198-4201; abstracted from Chem. Abs. 1969, 70, 53676b.(6) Morita, H.; Hayashi, Y.; Shimomura, S.; Kawaguchi, S. Chem. Lett. 1975, 339-342.(7) Dutt, N. K.; Sarma, U. U. M. J. Inorg. Nucl. Chem. 1975, 37, 1801-1802.(8) Finnegan, M. M.; Lutz, T. G.; Nelson, W. 0.; Smith, A.; Orvig, C. Inorg. Chem.1987, 26, 2171 -2176.(9) Habeeb, J. J.; Tuck, D. G.; Walters, F. H. J. Coord. Chem. 1978, 8, 27-33.(10) Orvig, C.; Rettig, S. J.; Trotter, J. Can. J. Chem. 1987, 65, 590-594.(11) Stewart, C. P.; Porte, A. L. J. Chem. Soc., Dalton Trans. 1972, 1661-1666.22(12) Morita, H.; Shimomura, S.; Kawaguchi, S. Bull. Chem. Soc. Jap. 1976, 49,2461-2464.(13) Gerard, C. Bull. Chim. Soc. Fr. 1979, 1451-1456.(14) Greaves, S. J.; Griffith, W. P. Polyhedron 1988, 7, 1973-1979.(15) Morita, H.; Shimomura, S.; Kawaguchi, S. Bull. Chem. Soc. Jpn. 1979, 52,1838-1843.(16) Archer, C. M.; Dilworth, J. R.; Jobanputra, P.; Harman, M. E.; Hursthouse, M.B.; Karulov, A. Polyhedron 1991, 10, 1539-1543.(17) Finnegan, M. M.; Rettig, S. J.; Orvig, C. 1986, 108, 5033-5035.(18) Tuck, D. G.; Yang, M. K. J. Chem. Soc. (A) 1971, 3100-3102.(19) Morita, H.; Shimomura, S.; Kawaguchi, S. Bull. Chem. Soc. Jpn. 1978, 5/,3213-3217.(20) Annan, T. A.; Peppe, C.; Tuck, D. G. Can. J. Chem. 1990, 68, 1598-1605.(21) Kingsbury, C. A.; Cliffton, M.; Looker, J. H. J. Org . Chem. 1976,41, 2777-2780.(22) Queiros, M. A. M.; Robinson, S. D. Inorg. Chem. 1978, 17, 310-314.(23) Gilbert, J. D.; Wilkinson, G. J. Chem. Soc. (A) 1969, 1749-1753.(24) Critchlow, P. B.; Robinson, S. D. Inorg. Chem. 1978, 17, 1902-1908.(25) Pinnavaia, T. J.; Fay, R. C. Inorg. Chem. 1966, 5, 233-238.(26) Lewis, J.; Long, R. F.; Oldham, C. J. Chem. Soc. 1965, 6740-6747.(27) Weast, R. C. ed. CRC Handbook of Chemistry and Physics; 70th ed.; CRC Press,Inc.: Boca Raton, Fla., 1989.23Chapter 2Chemistry of Sulfoxides2.1 IntroductionThe chemistry of sulfoxides is quite diverse. As early as 1907 it was discoveredthat sulfoxides can act as Lewis bases.1 However, research into the coordination ofsulfoxides to Lewis acids did not start in earnest until the early 1960s.2-4 At that time, theambidentate nature of sulfoxides was recognized, showing that they have the capacity tocoordinate via the oxygen or the sulfur atom. Coordination via oxygen generally occurswith "hard" acids while sulfur coordination occurs with "soft" acids. This is found tohold true for the majority of sulfoxide complexes including the new ruthenium sulfoxidecomplex, Ru(ma)2(DMS0)2 (2) which contains two dimethyl sulfoxide ligands boundthrough the sulfur atoms to metal generally considered to be soft."Hardness" and "softness" are qualitative characteristics that deal with the orbitaldiffuseness of acids and bases. Acids and bases can each be assigned relative hard or softqualities and it has been shown that generally hard acids bind more strongly with hardbases with the same being true for soft acids and bases. For a more detailed discussion ofhard and soft acids and bases, see Ref. 5. This aspect of sulfoxides has been extensivelyreviewed and coordination by oxygen versus coordination by sulfur can largely berationalized by the Hard Soft Acid Base (HSAB) theory." Any exceptions to this trend24can usually be explained by steric and electronic factors which will be discussed inSection 2.4.Dimethyl sulfoxide (hereafter abbreviated as DMSO) is the simplest and mostimportant of the sulfoxides. Original interest in this compound stemmed from itsIIIexcellent solvent properties. Since then ithas found many applications includingmedical uses as a diuretic and penetrantcarrier in addition to its ability to act as aligand.82.2 Structural Characteristics of DMSOFigure 2.1 Structure of DMSOThe structural characteristics of free DMSO as well as a large variety of DMSOcompounds have been thoroughly investigated. This section will review this work andwill discuss how and why the structure of DMSO changes upon coordination.2.2.1 Structure of Free DMSOStructural data for DMSO has been determined by a number of researchers. Theirresults are summarized in Table 2.1. There are some discrepancies in these sets of data;however, the discrepancies between each set may be accounted for by problems due torefinement. The data collected at 5 °C are most reliable because they are obtained nearerto room temperature than the other data and their refinement is more complete.9Therefore, these values will be the ones used for comparison in this work.25The DMSO molecule is approximately pyramidal with the sulfur atom at the apex(Fig. 2.1). The base positions are occupied by the oxygen and two carbons. Thesulfur atom is sp3 hybridized but the 0—S—C and C—S—C bond angles are both less thanthe expected 109.50.14 The 0—S—C bond angles are approximately 106.8° and the C—S—Cbond angle is 97.40. The small bond angles are often ascribed in VSEPR terms as being aresult of a lone pair of electrons occupying more space than a bond pair of electrons.15Table 2.1 Structural Data for Free DMSOBond Lengths (A) Bond Angles (°)State S-0 C—S C—S—C C—S-0 ReferenceGas 1.47 1.82 100±5 107±5 10Gas 1.477 1.810 96.38 106.71 11Solid (5 °C) 1.531 1.821 97.4 106.8 121.775 106.7Solid (-60 °C) 1.471 1.812 97.86 107.04 131.801 107.432.2.2 Structure of Coordinated DMSOThe general structures of S- and 0-bound DMSO are shown in Fig. 2.2.Differences in the geometry and bond lengths of free versus coordinated DMSO havebeen observed via X-ray studies on a number of DMSO compounds. The majority ofstructural data until 1980 has been compiled in a review article.6 Tables 2.2 and 2.3summarize these data for some typical compounds. As can be seen from these tables, the26extent of the changes in bond lengths and bond angles depends largely on whether theDMSO coordinates through the sulfur or the oxygen atom.../^LMLM -w--:A.mwme \‘ MeMeFigure 2.2 General Structures of Coordinated DMSOTable 2.2 Selected Bond Angles for Some DMSO CompoundsCompoundL C-S-0 (°)S-bonded^0-bondedL C-S-C (°)S-bonded 0-bonded DMSO 106.8 / 106.7 97.4 12RhC13(py)(DMS0) 108.0/ 110.6 99.7 16cis-PtC12(DMS 0)2 110.3 / 108.5 99.5 17107.6/ 107.9 103.3trans-PdC12(DMS 0)2 109.2 / 109.1 100.9 9RuC12(DMS0)3(DMS0) 106.0/ 106.3 101.6/ 104.2 98.6 99.0 18107.7 / 106.9 97.5106.3 / 106.4 100.1trans-CuC12(DMSE2)2 104.7 / 103.9 100.4 19[trans-FeC12(DMSQ)4] 103.5 / 103.7 99.4 20Ru(ma)2(DMS0)2 (2) 106.2/105.7 100.7 this106.4/106.2 99.6 worko27Table 2.3 Selected Bond Lengths for Some DMSO CompoundsCompoundS-0 (A)S-bonded^0-bondedS-C (A)S-bonded^0-bonded DMSO 1.531 1.821 / 1.775 12RhC13(py)(DMS0) 1.48 1.78 / 1.78 16cis-PtC12(DMS0)2 1.469 1.786 / 1.767 171.454 1.783 / 1.790trans-PdC12(DMS0)2 1.476 1.780 / 1.776 9RuC12(DMS0)3(DMSQ) 1.483 1.557 1.808 / 1.779 1.783 / 1.793 181.485 1.795 / 1.7831.485 1.787 / 1.794trans-CuC12(DMS02 1.531 1.771 / 1.765 19[trans-FeC12(DMS OW 2+ 1.541 1.804 / 1.795 20Ru(ma)2(DM5.0)2 (2) 1.474 1.780/1.782 this1.470 1.786/1.769 workFor S-bonding one observes the following,6 relative to free DMSO:i. The C-S-0 bond angles increase slightly or remain constant (between 106and 111° from 106.8').ii. The C-S-C bond angle increases (between 99 and 103° from 97.4°).iii. The S-0 bond length decreases (between 1.45 and 1.49 A from 1.531 A).iv. The S-C bond length remains relatively unchanged.For DMSO coordinated via the oxygen, the following trends are observed, againrelative to free DMSO:i. The C-S-0 bond angle decreases (between 101 and 105° from 106.8°).28ii. The C—S—C bond angle increases by a small amount (between 98 and 101°from 97.4°).iii. The S-0 bond length remains constant or increases slightly (between 1.53 and1.56 A from 1.531 A).iv. The S—C bond length remains relatively unchanged.In general, the most notable effect upon coordination of DMSO is the change inlength of the S-0 bond: a decrease corresponds with sulfur coordination and an increasewith oxygen coordination. This, along with the other observations, can be rationalizedusing a valence bond description of DMSO.23 Valence Bond ModelThe following model is not meant to explain completely the bonding processes inDMSO. It is merely being used as a guide to aid in understanding and interpreting theavailable data. More complex models have been proposed but these are beyond the scopeof this work.6DMSO has been described as a resonance hybrid of three canonical forms (Fig.2.3), with II being the usual representation for free DMSO, while for 0-coordinatedDMSO, I is dominant and for S-coordinated DMSO, III is used. However, this is notexperimentally observed.6Through X-ray emission studies it has been determined that the number of valenceshell electrons on the sulfur of free DMS 0 works out to be 5.30±0.08 so that the sulfur29atom carries a formal positive charge.21,22 Therefore, canonical form I might be the bestrepresentation for free DMSO. Indeed, this is confirmed by bond angle data.6'14 Using H3C^H3C-^: S=0.^S=0:Li 1^•ri3k."Figure 2.3 Canonical Forms of DMSOthe bond angle data available it has been proposed that the sulfur atom is sp3 hybridizedand the oxygen atom is sp2 hybridized. Constructing a valence bond model on thisstructure would require a negatively charged oxygen which would provide sevenelectrons and a positively charged sulfur which would provide five electrons (Fig. 2.4).The five electrons from the sulfur go into the sp3 orbitals as one lone pair plus threesingle electrons available for bonding (two for S—C bonds and one for the S-0 bond).The oxygen has five of its electrons in sp2 orbitals (two lone pairs and one singleelectron) plus a pair of electrons in a p-orbital. The two sp2 lone pairs on the oxygen andone sp3 lone pair on the sulfur are available for coordination to a Lewis acid. In addition,the filled p-orbital on the oxygen is available for ir-bonding with the low-energy emptyd-orbitals of the sulfur. We now have a S-0 a bond plus a variable amount of pit-diroverlap depending on the electronic distribution around the sulfur-oxygen moiety.However, we should also attempt to apply our valence bond model to coordinatedDMS O.30M-S bonding\ \^S-C a bond.^.S+ sp3 I^I^I: S-01---a bondS d-orbitals (empty)'--- prt-dx overlap0- sp2 1 i^1 1^Ii^I•L,M-0 banding0 p-orbitalqFigure 2.4 Valence Bond Diagram for Free DMSOIt has been shown by X-ray crystallography and IR studies (refer to Section 2.5)that the S-0 bond order increases upon S-coordination but decreases or remains constantupon 0-coordination. This can be accounted for using our valence bond model. Bondingof the oxygen atom to a weak Lewis acid would be expected to have little effect on thepit-dn overlap in the S-0 bond while coordination to a stronger Lewis acid would pullmore electron density away from the oxygen, thereby reducing this overlap, and loweringthe bond order. This is supported experimentally.6 On the other hand, S-coordinationwould remove electron density from the sulfur, causing an increase in it-donation fromthe oxygen, providing an increase in the S-0 bond order and a subsequent decrease in thebond length, again, in line with the experimental evidence.The Valence Bond Theory can also be used to explain why hard metals bond viathe oxygen atom while softer metals bond via the sulfur atom. Because the sulfur atombears a formal positive charge, one would expect 0-coordination to be the most favorablein any scenario. Although it is true that the vast majority of DMSO complexes display31,CH3IV\I „Sri ,,s0Me2(0)S—Rh/ I/•:::---Rli—S(0)Me20 (0H3Ccoordination through the oxygen atom there are still many cases where S-coordination isobserved.6 The reason for this is that soft acids provide better orbital overlap with thesofter, more diffuse orbitals of the sulfur atom while hard acids overlap better with theharder, less diffuse orbitals of the oxygen atom.2.4 Exceptions to the HSAB TheoryAlthough hard acids generally coordinate to DMSO through the oxygen atom andsofter acids through the sulfur atom, there are instances where this trend is broken andDMSO will coordinate to a soft acid via the oxygen. These anomalies can be explainedin terms of electronic and steric factors.0 OvCCF3I .1)/1Me2S0—RW---RIC—OSMe2(/ 1 0 IF CCH3^ CF3aFigure 2.5 Electronic Factors Determining S- or 0-Coordination of DMSOIf a metal atom, generally considered to be soft, contains strongly electronegativesubstituents in addition to DMSO, the withdrawal of electron density increases the Lewis32acidity of the metal and may force the DMSO moiety to coordinate via the oxygen,whereas it would normally be expected to coordinate through the sulfur. An example ofthis can be observed in the pair of rhodium complexes depicted in Figure 2.5.23 As canbe seen from this illustration, DMSO coordinates through the sulfur for the methylcarboxylate compound (2.5a) as expected because Rh(II) is a soft metal. However, forthe trifluoromethyl carboxylate analogue (2.5b), the strongly electronegative CF3 groupspull electron density away from the metal centers causing the metal to become harder sothat the DMSO's bond via the oxygen atom.—1 2+?SMe2^IPh2P—PId—OSMe2PPh2aOSMe2 --1 2+Me2(0)S—dd—OSMe2IS(0)Me2COSMe2I „CICI—Rd—S(0)Me2Me2(0)S^IS(0)Me2bFigure 2.6 0-Coordination to a "Soft" Metal Due to Steric FactorsSteric factors can also govern whether DMSO coordinates via its oxygen orsulfur. Some examples are illustrated in the compounds in Figure 2.6a,24 b,18 and C.25'26In these cases, the steric bulk around the metal center forces some, if not all of the DMSOligands to coordinate through their oxygen atoms which is a more sterically favored33arrangement.24 For example, DMSO would be expected to be S-coordinated to Pd incompound 2.6a, whereas it has been experimentally determined to be 0-coordinated.24This is due to the fact that the chelating phosphine has a cone angle of 1250.270-coordination makes the methyl groups more remote from the metal center and thusalleviates steric interaction with the bulky phosphine substituents. Likewise,coordination of all four DMSO ligands through the sulfur atom in both compounds 2.6band c would be too sterically demanding due to the close proximity of the oxygen andmethyl groups.2.5 Methods of Analysis of the Mode of DMSO BondingNow that we have discussed how DMSO coordinates to metals and have proposeda model for why this happens, we must look at methods for determining the mode ofDMSO coordination and discuss how to interpret the results. There are three fundamentaltechniques used for this, these being X-ray crystallography and IR and NMRspectroscopy. Each of these methods will be discussed in turn in the following sections.2.5.1 X-Ray CrystallographyX-ray crystallography is, of course, the best way of determining the structure ofDMSO complexes. In addition to determining unambiguously the mode of DMSOcoordination, the crystal structure data aid in the discussion of bonding within the DMSOmolecule and to the metal itself (i.e. amount of backbonding, steric effects, bond orders,etc.). Nevertheless, X-ray crystal structure experiments cannot reveal 0- versusS -coordination in solution.34Table 2.4 Sulfoxide Stretching FrequenciesSulfoxide Compound vso (cm-1)Av (cm-1)(Vcomplex-Wree DMSO)Referencefree DMSO 1055 6,29[Rh(COD)(PPh3)(DMSQ)]+ 947 -108 29trans-CuC12(DMS02 980 -75 29cis-RuC12(DME0)3(DMS12) 1120, 1090 +65, +35 28960 -140trans-PdC12(DM.S.0)2 1116 +61 30trans-RuC12(DM5.0)4 1086 +31 31Ru(ma)2(DM0)2 (2) 1111 +56 this workRu(ma)2(d6-DM5..0)2 1113 +58 this work2.5.2 Infrared SpectroscopyDetermination of 0- versus S-bonding is generally easy to detect via IRspectroscopy. The S-0 absorption appears at 1055 cm-1 for free DMS0 as a broad andintense band and so is generally easy to observe. As mentioned in Section 2.2.2,S-coordination results in a strengthening of the S-0 bond while upon 0-coordination theS-0 bond is unaffected or slightly weakened. Thus, by looking at vso, one will observea bathochromic or hypsochromic shift for coordination via oxygen or sulfur, respectively.This is demonstrated in all of the compounds listed in Table 2.4 including the ruthenium-DMS0 compound, 2. Although this method is very useful, precautions must be taken.The S-0 stretching band is sometimes difficult to assign due to the presence of strongbands such as the CHrocking and CHdeformation absorptions of coordinated DMS0 in the35same region. In order to be sure of assigning the vso band correctly, one should preparethe DMSO complex as well as the deuterated analog. 25 For example, the IR spectrum ofRu(DMS0)4C12, which contains one 0-bound and three S-bound DMSO ligands, showsa number of strong bands in the region 1282-915 cm-1.28 By comparing this spectrum tothat of the d6-DMS0 analog where the CH bands are shifted to lower frequencies, it wasdetermined that two bands at 1120 and 1090 cm-1 correspond to vso of the sulfur-boundDMSO's, and a band at 915 cm-1 corresponds to vso of the oxygen-bound DMSO, whilethe other bands can be attributed to CHrocking and CHdeformation modes.2.5.3 1H and 13C NMR StudiesNMR spectroscopy has also proven to be a useful tool for determining the modeof sulfoxide coordination. Free DMSO exhibits a singlet at 2.57 ppm in the 1H NMRspectrum (CDC13). Upon coordination, the resonance is shifted downfield with themagnitude of the shift depending on 0- or S-coordination. The proton resonance of0-coordinated DMSO shifts downfield by about 0.5 ppm or less relative to free DMSOwhile S-coordinated DMSO gives larger downfield shifts of approximately 0.7 ppm ormore. For example, in the molecule cis-RuC12(DMa0)3(DMS0), the resonance for themethyl protons of 0-bonded DMSO appears at 2.69 ppm while those of the S-bondedDMSO's are shifted further downfield and fall within the range of 3.27-3.48 ppm(CDC13). Furthermore, the compound Ru(ma)2(DM.a0)2 which contains two S-boundDMSO ligands, exhibits 1H methyl resonances in the range of 2.91-3.37 ppm (CDC13).Clearly, in the case of 0-coordination, the methyl protons are more remote from the metalcenter so that the effect on the electron density around the methyl protons is less dramaticthan in the case of S-coordination.36Similar arguments apply to 13C (1H) NMR spectroscopy. In S-bonded DMSO the13C resonance is shifted further downfield from the free DMSO resonance than is that ofthe 0-bonded DMSO resonance. Again, for the compounds RuC12(DMS.0)3(DMSQ)and Ru(ma)2(DMS0)2 we can observe these trends. In the 13C (1H) NMR spectrum freeDMSO methyl carbons resonate at 41.1 ppm while in RuC12(DMa0)3(DMSQ) theresonance of the 0-bonded DMSO shifts downfield to 42.2 ppm and those of theS-bonded DMSO resonances shift even further downfield within the range of 44.0-46.5ppm (CDC13). In the compound Ru(ma)2(DMS0)2, the 13C resonances appear in therange 43.6-46.2 ppm (CDC13), again indicative of S-coordination.2.6 References(1) Hofmann, K. A.; Ott, K. Chem. Ber. 1907, 40, 4930.(2) Cotton, F. A.; Francis, R. J. Am. Chem. Soc. 1960, 82, 2986.(3) Francis, R.; Cotton, F. A. J. Chem. Soc. 1961, 2078.(4) Meek, D. W.; Straub, D. K.; Drago, R. S. J. Am. Chem. Soc. 1960, 82, 6013.(5) Hard and Soft Acids and Bases; Pearson, R. G., Ed.; Dowden, Hutchinson & RossInc.: Stroudsburg, 1973.(6) Davies, J. A. Adv. Inorg. Chem. Radiochem. 1981, 24, 115.(7) Kagan, H. B.; Ronan, B. Rev. Heteroatom Chem. 1992, 7, 92.(8) Reynolds, W. L. Prog. Inorg. Chem. 1970, 12,1.(9) Bennett, M. J.; Cotton, F. A.; Weaver, D. L.; Williams, R. J.; Watson, W. H. ActaCryst. 1967, 23, 788.(10) Bastiansen, 0.; Viervoll, H. Acta Chem. Scand. 1948, 2, 702.(11) Dreizler, V. H.; Dendl, G. Z. Natwforschg. 1964, 19, Teil A, 512.(12) Thomas, R.; Shoemaker, C. B.; Eriks, K. Acta Cryst. 1966, 21, 12.37(13) Viswamitra, M. A.; Kannan, K. K. Nature 1966, 209, 1016.(14) Johnson, C. R. Quart. Rep. SuIf. Chem. 1968, 3, 91.(15) Gillespie, R. J.; Nyholm, R. S. Quart. Rev. 1957, 11, 339.(16) Colamarino, P.; Orioli, P. J. Chem. Soc., Dalton Trans. 1976, 845.(17) Melanson, R.; Rochon, F. D. Can. J. Chem. 1975, 53 , 2371.(18) Mercer, A.; Trotter, J. J. Chem. Soc., Dalton Trans. 1975, 2480.(19) Willett, R. D.; Chang, K. Inorg. Chim. Acta 1970, 4, 447.(20) Bennett, M. J.; Cotton, F. A.; Weaver, D. L. Acta Cryst. 1967, 23, 581.(21) Sato, T.; Takahashi, Y.; Yabe, K. Bull. Chem. Soc. Jpn. 1967, 40, 298.(22) Takahashi, Y.; Yabe, K.; Sato, T. Bull. Chem. Soc. Jpn. 1969, 42, 2707.(23) Cotton, F. A.; Felthouse, T. R. Inorg. Chem. 1980, 19, 2347.(24) Davies, J. A.; Hartley, F. R.; Murray, S. G. J. Chem. Soc., Dalton Trans. 1979,1705.(25) Wayland, B. B.; Schramm, R. F. Chem. Commun. 1968, 1465.(26) Wayland, B. B.; Schramm, R. F. Inorg. Chem. 1969, 8, 971.(27) Tolman, C. A. Chem. Rev. 1977, 77, 313.(28) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans. 1973, 204.(29) James, B. R.; Morris, R. H.; Reimer, K. J. Can. J. Chem. 1977, 55, 2353.(30) Rayner, D. R.; Miller, E. G.; Bickart, P.; Gordon, A. J.; Mislow, K. J. Am. Chem.Soc. 1966, 88, 3138.(31) Jaswal, J. S.; Rettig, S. J.; James, B. R. Can. J. Chem. 1990, 68, 1808.38Chapter 3Reactions Between Terminal Alkynes and Metal Complexes3.1 General SurveyThe reaction of 1-alkynes with transition metal complexes affords a wide variety oforganic and organometallic products. Such reactions can produce new alkynes," linear andbranched dimers,5-15 branched and aromatic trimers,16-19 and higher oligomers andpolymers.20-22 Some of the organometallic products of these reactions includen-complexes,1,23-25 a-bonded acetylide derivatives, resulting from an oxidative addition to themeta1,26-33 terminal or bridging vinylidenes,24.34-3 7 enynyl complexes,38-4° andmetallacyclopentadienes.41,42 Another possible product, resulting from the addition of an alkyneto a hydride compound, is an allcenyl complex resulting from a simple insertion of the allcyneinto the metal-hydride bond.9•18,43-47 The vast array of reactivities observed between 1-allcynesand transition metal complexes is derived in part from the bifunctionality of terminal allcynes,where metal-allcyne interactions can occur at either the alkyne's C—H bond or its CC bond.In the following sections, each of the reactions mentioned above will be discussed inmore detail, in addition to describing some reactions between a few ruthenium maltolatocompounds and some allcynes, including a reaction with phenylacetylene which produces bothcis and trans isomers of 1,4-diphenylbut-1-en-3-yne. Because of the vast number of allcynes inthe literature, this review will focus primarily on reactions involving phenylacetylene.393.1.1 Organic Products of Alkynes with Transition Metal Complexes. Alkyne Metathesis and Disproportionation.Metathesis and disproportionation are two terms that have been used interchangeably bymany, although they technically have different definitions.' Alkyne metathesis (Eqn 3.1)consists of scission and reconstitution of the C—C triple bonds of either two different alkynes toyield a single product with the substituent groups redistributed or the reverse reaction, an unsym-2 RCEECRcatalyst_ RCCR + 1:11CCR'^(3.1) metrical alkyne giving two symmetrical products. Alkyne metathesis reactions have frequentlybeen carried out using W03 as the catalyst, such as with pent-2-yne, which is quite easilymetathesized to but-2-yne and hex-3-yne (Eqn 3.2).42 CH3C1-=-CCH2CH3 WO3 CH3C=CCH3 CH3CH2CMCCH2CH3pent-2-yne but-2-yne hex-3-yne (3.2)Another example of the metathesis reaction is the conversion of p-tolylphenylacetylene intodiphenylacetylene and bis(p-tolyl)acetylene (Eqn 3•3).2 However, with 1-alkynes this procedureis much more complicated. For example, propyne, 1-butyne, and 1-pentyne can be metathesized,again with W03, but only at very high temperatures (250 - 500 °C) and even then the majorproducts are cyclotrimers, not metathesis products.32 PhCE--_-C(C6H4)CH3 Mo (C0)6 PhC-=-CPh + H3C(C6H4)CEC(C6H4)CH3p-tolylphenylacetylene^diphenylacetylene^bis(p-tolyl)acetylene(3.3)40Disproportionation of alkynes, on the other hand, involves one alkyne acting as both anoxidant and a reductant in a particular reaction. For example, using a rhodium catalyst,phenylacetylene can be utilized in a disproportionation reaction yielding styrene and 1,4-diphen-3 PhC^[Rh]aCH PhCH=CH2 + PhCFEC-CECPhphenylacetylene^ styrene^1,4-diphenylbutadiyne^(3.4)ylbutadiyne (Eqn 3•4).1 This reaction is very similar to Glaser coupling," a reaction establishedin 1869, where oxygen is used to oxidize phenylacetylene into 1,4-diphenylbutadiyne (Eqn 3.5).2 PhCF.--CH + 1/2 02 [Cu] PhCa,C-CCPh + H20 phenylacetylene^ 1,4-diphenylbutadiyne^(3.5) Dimerization of AlkynesDimerization reactions of 1-alkynes with transition metals can produce three differentisomers: E and Z isomers of a 1,4-disubstituted dimer, A and B, respectively, as well as abranched 2,4-disubstituted dimer, C. With phenylacetylene, one generally observes only theproduction of the linear 1,4-dimers, A and B, while the branched 2,4-dimer, C, if formed,decomposes rapidly at room temperature. It was observed that a rhodium catalyst dimerizedphenylacetylene to the trans isomer, A, in addition to producing oligomers.11 However, uponrepeating this reaction, it was found that two dimers, A and one other, were formed and that thelatter isomer was very unstable, decomposing to give oligomers.7 Keeping the unstable isomer ata temperature of -40 °C enabled an NMR spectrum to be obtained, which indicated that it was41the branched isomer, C, of diphenylbutenyne. Generally, the only 1-alkynes known to formstable branched dimers are those with an alkyl substituent rather than an aryl substituent.\C=C/^\C=<^\,C=<Rc C/^ C/^ CRC RCAIn most cases, dimerization of phenylacetylene yields only the E isomer, although insome cases both E and Z isomers (A and B, respectively) are formed. No reports have beenmade where only the Z isomer is formed. The formation of only the E isomer or both E and Zisomers has been suggested to be due to the availability of two different mechanisms for theformation of these butenynes, one of which forms only the E isomer, while the other produces amixture of the two isomers.14,49 These mechanisms will be discussed in Section 3.3. Table 3.1summarizes the results of some dimerization reactions of phenylacetylene with various transitionmetals.3.1.13 Trimerization of 1-AlkynesTrimerization of 1-alkynes yields both aromatic and branched-chain products. Forexample, reaction of phenylacetylene with Cp*2LnCH(SiMe3)2 (Ln = La, Ce) produces the non-cyclic trimers, D and E,1° while reaction with [(1,5-C61110)Rha]2 gives the aromatic trimers, Fand G,19 and reaction with Ni(C0)2(PPh3)2 yields both a non-cyclic and two aromatic trimers,D, F and G.17 Aromatic trimers of acetylenes are believed to be formed via addition of a thirdalkyne to a metallacyclopentadiene intermediate which in turn is formed from the coupling oftwo other alkynes and a metal complex.19 Metallacyclopentadienes will be discussed further inSection 3.1 Dimerization of Phenylacetylene to 1,4-DiphenylbutenyneRelative % of Dimer FormedCatalyst E-butenyne Z-butenyne ReferencesACP*2YCH(SiMe3)2 a 100 0 10RhC1(PPh3)3 100 0 7,14,15RuH(C6H5)I-4 b 95 5 8[RuH(C0)(13Y)2(PPh3)2r c 67 33 9RuH2(1)Bun3)4 62 38 13[Rh(C0)(dpPm)l2(11-CCHPh) d 50 50 1{RuH(H2)[P(CH2CH2PPh2)3]1+ 7 93 6Cu(CCPh) ?e ? 5a. Cp* = r5-(C5Me5)^b. L4 = P(CH2CH2CH2PMe2)3 c. py = pyridined. dppm = bis(diphenylphosphino)methane e. both isomers formed but ratios not givenPhCE-C-C(Ph)=CH-CH=CHPh PhCEC-CH(Ph)-CH2-CE.--CPhPh PhPhPh Ph Ph433.1.1.4 Polymerization of 1-AlkynesPolymerization of phenylacetylene appears to give best results with early transition metalcatalysts. Ti(0Bun)4/Et3A1, M0C15/Ph4Sn, and WC16/Ph4Sn have all been shown to be veryeffective catalyst systems.20,21 These polymerizations are believed to proceed via an olefinmetathesis mechanism (Scheme 3.1), similar to that observed for the polymerization of somealkenes. These olefin metathesis polymerizations are initiated by a metal carbene which coupleswith an alkyne to yield a metallacyclobutene. The metallacyclobutene can then open up andcouple with another allcyne..""PC=Mcc ^,^""C M^etc.II^C IIScheme Organometallic Products of Alkynes with Transition Metal ComplexesIn 1:1 reactions between terminal alkynes and transition metal compounds, there aregenerally three different organometallic products that can be formed: 71-complexes, a-bondedacetylides, and vinylidenes. In the case of transition metal hydrides, one can also prepare alkenylcomplexes by insertion of the allcyne into the metal-hydride bond. In addition, metal complexescan react with two equivalents of allcyne to yield enynyl or metallacyclopentadiene complexes.All of these reactions will be discussed in turn in the following sections. n-ComplexesIt is generally agreed that initial interactions between alkynes and metal compounds yieldn-complexes.28.29,33 These 7r-complexes may be isolable or they may degrade spontaneously to44yield other species. For example, complexes H1 and 123 are stable at room temperature, whilecomplex J is stable in solution only at temperatures of -40 °C or lower29. At higher temperaturesJ decomposes to a hydride-acetylide species. Complex K,24 on the other hand, is converted to avinylidene species upon heating in solution at 50°C.Ph . ,.H^I^I0C—Rh—RhP^PPh^CHCOIc—PPh3OC‘0A Ob%C0r P,CH-1nkT4CO2Etr^P x.N , PPhC CHI *C0CO3.1.2.2 Acetylide ComplexesA number of acetylide and hydride-acetylide species have been prepared by interaction ofacetylenes with transition metal complexes. Compound L contains an II Lacetylide moiety,29while M contains a more unusual bridging 12T2-acetylide.31 Compound N is also a uniquecomplex, containing both an acetylide and an enynyl functionality.3245r-7(p‘erthcoc,phx = N , PPhe"0C-19h—Rh CO11P\i/3^ ./F) p*RuI N* C PhPh3.1.2.3 Vinylidene ComplexesThe vinylidene functionality can be either terminal, 0,24 or bridging, P.1 As mentionedpreviously, there is general concurrence that vinylidenes are formed via n-complexes.29However, there are still doubts about the mechanism of the metal-alkyne degradation. Inparticular, it is not completely established whether hydride-acetylide complexes are necessaryprecursors to the vinylidene derivatives as some have claimed,28.33 or whether a vinylidenecomplex can be obtained directly from a it-complex via a formal 1,2-hydrogen shift as has beenproposed on theoretical grounds by Silvestre and Hoffmann." Mechanistic studies will bediscussed further in Section Alkenyl ComplexesThe addition of alkynes to metal hydride complexes often yields alkenyl derivatives via asimple insertion of the alkyne into the metal-hydride bond. This process virtually always460Cs^HI ‘C°LpI cl^-Ph0e""■P P = dppe0H\c/PhII/C\0C—Rh-Rh—0010\ ‘'..1^i• P /P P\•/\,/P P = dppmPinvolves a cis insertion of the alkyne into the complex (Scheme 3.2). However, there are somereactions which yield unusual products. One example is the trans insertion of an alkyne into ametal-hydride bond rather than the expected cis insertion (Eqn 3.6).5152 A second peculiarity isa double insertion reaction where one alkyne inserts into a metal-hydride bond followed byinsertion of another alkyne into the newly-formed metal-alkenyl bond (Scheme 3•3).45Generally, one only observes insertion of a single alkyne into a metal-hydride bond.0C,^I0--Fe—HIC0 HC.a..--. CCF3 _ c0CHHI^\Fe-C,I^C--1-1\C0^CF3 (3.6) Enynyl ComplexesComplexes containing an TO-enynyl ligand formed by head-to-head dimerization ofacetylenes have been reported only very recently. The first example to be characterized by X-raycrystallography, compound N,32 appeared in the literature in 1989. Since this time a number ofenynyl compounds have been reported, such as compounds Q,38 R,6 and S.53 An osmiumbutenynyl complex, T,54 was reported in 1985 but this compound was formed by the oxidation of47RC=CR'^RC=CR'Tm-H [m]—H ^R'C=CRI [m]--HRCE.--.CR'^T1^R^R'^[NA]^H1Fr\^IR,C=QNI]^-HScheme 3.2Ph3P\Rh/HXPPh3OCZ R^RPh3P ^'C=C'RCECR^\Rh/ \H\PPh3OCZRiCE.--CR'R = CF3R' = 02CMeR'\^/RIPh3P^C=C^H\ / C=CIRh^Fiz^‘13OCZ \PPh3Scheme 3.348Phoc- 18( P11„, u..00P phIC)HPhPi/4,k. I •.AP^—1Ru^ PhNp C-P C—CH-Ph^p phP(OEt)2p(oEt)30^= Nome)3PP3 = P(CH2CH2PPh2)3R SiMe3IDD+D^P(:)//44„,.-F64 Ph1^AP14"OeI PitCH- 1Ph p-P bis(dimethylphosphino)ethane49—1PhHPh^P PMe3Pt^Ph(C0)3Ru/PhPh \Ru(C0)3Va bis(acetylide) derivative with AgPF6, rather than by a coupling of two alkynes. It is believedthat butenynyl complexes are intermediates in the formation of butenynes via coupling ofalkynes but this will be further explored in Section MetallacyclopentadienesIn addition to enynyl complexes, the reaction of two allcynes with a metal complex canproduce metallacyclopentadienes. As mentioned in Section, these complexes arebelieved to be intermediates in the formation of aromatic trirners formed via alkyne coupling.Some metallacyclopentadiene complexes, such as U41 and V,42 have been isolated and it hasbeen shown that they can be converted into aromatic trimers by further reaction with allcyne.41,42(Me30)PCF300„^,C F3CF300 CF3(Me30)P3.2 Reaction of Terminal Alkynes with Maltolato Complexes of RutheniumReactions of a number of acetylenes, RC-=-CR' (R = R' = H or R = Ph and R' = H, Me, Ph),with Ru(ma)2(PPh3)2, Ru(ma)2(DMS0)2, Ru(ma)2(COD) and RuH(ma)(C0)(PPh3)2 wereattempted. The results of these reactions will be reviewed in this section and are illustrated inScheme 3.4.50L = PPh3= DMSOL-L = CODHC^[Ru]-a7CH ^ ---EHC=CHI-n[Ru]PhCCMe .^^no reaction[Ru]PhC-a-CPh  ^no reaction L = PPh3^PhCa-_-_-CHL = DMSO^PhC=_--=CHL-L = COD^PhCE_--CH[Ru]^linear dimers^50° 6h^(2 isomers)[Ru]^negligible reaction100° 6d^(trimers)[Ru]no reactionPPh31 "Co(O b—R —H/ 1 0PPh3PhCa-CHPhC=T-_CMePhCa-CPh[Ru][Ru] [Ru]reaction occurs(productsundetermined)Scheme 3.4513.2.1 Reactions with AcetyleneToluene solutions of Ru(ma)2(PPh3)2, Ru(ma)2(DMS0)2 and Ru(ma)2(COD) wereplaced under an atmosphere of acetylene and stirred. Within one hour, each of these compoundsproduced a black powder assumed to be polyacetylene because of its insolubility. In an effort toavoid this kind of reaction, reactions with builder acetylenes were attempted.3.2.2 Reaction of Ru(ma)2(PPh3)2 with Substituted AcetylenesPhenylacetylene and Ru(ma)2(PPh3)2 (ca. 1 mol %) were dissolved in deuterated benzenein a sealed NMR tube and the reaction was followed by NMR spectroscopy. No reaction wasobserved after several hours at room temperature; however, the reaction was complete within 24hours upon heating the solution at 50 °C. This reaction produced an approximate 1:1 mixture ofE- and Z-1,4-diphenylbutenyne as shown by both NMR (Fig. 3.1) and GCMS studies. Amechanism for this reaction will be proposed in Section 3.3. Reactions with PhCECMe andPhOECPh in toluene were also attempted at temperatures up to 100 °C but only starting materialwas recovered.3.2.3 Attempted Reactions of Ru(ma)2(DMS0)2, Ru(ma)2(COD) andRuH(ma)(C0)(PPh3)2 with Substituted AcetylenesReactions of Ru(ma)2(DMS0)2 and Ru(ma)2(COD) with PhCECH, Ph-CMe, andPhCE-CPh in toluene solutions were attempted. All of these reactions returned only startingmaterial even after extended reaction at temperatures of 100 °C except for that of Ph-CH withRu(ma)2(DMS0)2. However, in order for this reaction to occur, temperatures of 100 °C wereemployed for a period of 6 days and even then the amount of product was very minimal. GCMSshowed mostly starting material in addition to three trimers. However, there was an insufficient52rymFig. 3.1 1H NMR spectrum of E- and Z-1,4-diphenylbutenyne in Csps^.amount of this material to allow for an adequate analysis in order to determine the nature of theproducts.As was noted in the previous section, the reaction of phenylacetylene with thetriphenylphosphine derivative, 1, proceeded spontaneously at 50 °C, whereas with the DMSOand COD derivatives, 2 and 3, the reaction did not proceed at all. It was hypothesized that thereaction with 1 proceeded via dissociation of one of the phosphine groups and subsequentcoordination of the phenylacetylene. The phosphine is much bulkier than the DMSO or CODfunctionalities of complexes 2 and 3, and should therefore dissociate much easier. To testwhether this reaction was proceeding via a dissociative mechanism, a solution ofphenylacetylene and 1 in a molar ratio of 50:1 in C6D6 was prepared and divided into two NMRtubes. Triphenylphosphine was added to one of the NMR tubes to see if it would hinder theprogress of the reaction. Both NMR tubes were sealed and spectra were obtained periodicallywhile heating at 50 °C. It was found that the sample containing no free triphenylphosphinereacted quite rapidly relative to the one to which triphenylphosphine was addedMixtures of RuH(ma)(C0)(PPh3)2 with PheaCH, PhCMe, and PhCPh in toluenesolutions did react, but the identity of the products could not be determined. Reactions withPhCaCH occurred rapidly at room temperature, while those with Ph -CMe and PhCECPhneeded temperatures of -40 °C in order to proceed. However, both the 1H and 31P{ 1H} NMRspectra of these reactions were very complicated, indicating either decomposition or a variety ofproducts being formed. No products could be isolated from these reactions.3.3 Proposed Mechanisms for the Dimerization of Terminal AlkynesDetailed mechanistic studies on metal-catalyzed dimerization of 1-allcynes to butenyneshave not been published, and the factors that govern regio- and stereoselectivity are not yet fully54understood. As mentioned earlier, there are two possible mechanisms to consider, one of whichis capable of producing both isomers (Scheme 3.5), while the other produces only the E-butenyne(Scheme 3.6).The mechanism for the preparation of E-butenyne is fairly simple, relative to thatrequired to produce both isomers, which is a little more involved. In both cases, the first step isthe formation of a it-complex. After this, the two mechanisms differ. In order to produce bothisomers of the dimer, the reaction most likely proceeds via a vinylidene intermediate, althoughthere is not complete concurrence as to whether or not the vinylidene moiety must be precededby an acetylide-hydride intermediate (Scheme 3.5). Coupling of the vinylidene complex with amolecule of 1-allcyne gives a butenynyl ligand which can reductively eliminate together with thehydride to form the butenyne compound. In the production of E-butenyne, a vinylideneintermediate is not involved. Instead, a hydride acetylide compound is formed from the firstacetylene molecule and the second acetylene cis inserts into the metal-hydride bond. The alkenyland the acetylide groups then reductively eliminate to give the E-butenyne isomer. Thefollowing discussion will attempt to account for why these mechanisms have been proposed.Firstly, we will discuss the more complicated mechanism involving the vinylideneintermediate. There is general agreement that the initial interaction of a terminal alkyne with ametal complex involves formation of a n-complex.28.29,33,55 However, the it-intermediates arenot always detected because of the fast rate of the it-acetylene-vinylidene rearrangement.55 Theequilibrium between the it-complex and the vinylidene complex has been studied and thevinylidene complex has been shown to be the thermodynamically preferred isomer.1.24There are two reasons that an acetylide intermediate is proposed to be present betweenthe it-complex and the vinylidene complex. Firstly, there have been observations of an acetylide-vinylidene equilibrium,2831•33'56 and secondly, a number of acetylide complexes have been used55Scheme 3.556as precursors for the formation of vinylidenes, whether it be by electrophilic addition to a metalacetylide complex (Scheme 3.7a)57-59 or via a bimolecular type of reaction (Scheme 3.7b).6°However, using extended Hiickel calculations, it has been shown on a theoretical basis thatinterconverting of a It-alkyne into a vinylidene via a 1,2-hydrogen shift by slippage of the alkyneto an n1-geometry (Scheme 3.7c) would be of much lower energy than the alternative route via ahydride-acetylide species." Therefore, it cannot be conclusively determined whether thereaction must proceed via an acetylide intermediate in all cases, or whether this occurs in onlysome cases.,H^+x+21-nikkc,‘' PhHCECPhPh‘,C=C/,HPhC(E)-1 ,4-diphenylbutenyne Scheme 3.6We must now address the question of why a vinylidene intermediate need be proposed atall. It has been stated that if one is to synthesize both cis and trans isomers of 1,4-butenynes, onemust proceed via a vinylidene intermediate.49 A vinylidene type of intermediate is required inorder to allow an attack of the subsequent alkyne at either the cis or the trans position of the57[M]—CE-C—RE+ ^ A C eR[M]=C=C/E‘RScheme 3.7aPhPhC^L^c,4\Pt W/+ [HPtL2(acetone,C \^c //^LL= PEt3Ph\c/HIIL, Cs, / \ LPt—Ptf,C \^\Ph"^L^LScheme 3.7b_LrIM,--C^I-1 HCR^ C \ RLIIM—C < R-^_Scheme 3.7c58.41(^RR/ C0H\C CP:ICII—WI ":=C--CE-1vinylidene's cc-carbon, thus producing both isomers. Moreover, there are cases where vinylidenecomplexes have been used as precursors in the formation of butenynes,1A0 which could indicatethat these are necessary intermediates in their production. A multi-step reaction has beenperformed, transforming a bis-alkyne complex into an enynyl complex (Scheme 3.8).40 In thisreaction, the bis-alkyne complex was first transformed into an alkyne-acetylide and then analkyne-vinylidene complex, after which addition of CO caused a coupling of the alkyne andvinylidene ligands to form the enynyl complex. In this case, all of the proposed intermediateswere isolated, but the reaction was not carried out to a fmal enyne product. However, it has beenshown that it is possible to convert an enynyl ligand into both the E- and Z-enyne isomers.638-H+H\C CP, *III--W-CE.--_-C-RF ciIi R = GMe3 I [Me30][BF4]RScheme 3.8Basically, the same first two steps are proposed in the mechanism for the production ofonly the E-butenyne; however, the mechanism differs in that no vinylidene derivative isinvolved. Indeed, a vinylidene moiety is not required in this scenario, and the mechanism would59be expected to proceed via an acetylide complex as has been proposed.14 In this case, the secondalkyne would insert into a metal-acetylide bond rather than a metal-vinylidene bond.Returning to the dimerization reaction of the triphenylphosphine compound, 1, withphenylacetylene, a discussion is required as to why the ratio of the two butenyne isomers is 1:1.As discussed, the formation of the Z-butenyne would lead to the conclusion that a vinylideneintermediate is involved. Furthermore, the equivalent production of the two isomers wouldsuggest that attack of the second equivalent of alkyne on the vinylidene intermediate is equallyprobable at either the cis or the trans position.3.4 References(1) Berry, D. H.; Eisenberg, R. Organometallics 1987, 6, 1796-1805.(2) Mortreux, A.; Blanchard, M. J. Chem. Soc., Chem. Commun 1974, 786-787.(3) Moulijn, J. A.; Reitsma, H. J.; Boelhouwer, C. J. Catal. 1972, 25, 434-436.(4) PenneIla, F.; Banks, R. L.; Bailey, G. C. Chem. Commun. 1968, 1548-1549.(5) Akhtar, M.; Weedon, B. C. L. Chem. Soc. Proc. 1958, 303.(6) Bianchini, C.; Peruzzini, M.; Zanobini, F.; Frediani, P.; Albinati, A. J. Am. Chem. Soc.1991, 113, 5453-5454.(7) Carlton, L.; Read, G. J. Chem. Soc., Perkin Trans. 1 1978, 1631.(8) Dahlenburg, L.; Frosin, K. M.; Kerstan, S.; Werner, D. J. Organomet. Chem. 1991, 407,115-124.(9) Echavarren, A. M.; Lopez, J.; Santos, A.; Montoya, J. J. Organomet. Chem. 1991, 414,393-400.(10) Heeres, H. J.; Teuben, J. H. Organometallics 1991, 10, 1980-1986.(11) Kern, R. J. J. Chem. Soc., Chem. Commun 1968, 706.(12) Kovalev, I. P.; Yevdakov, K. V.; Strelenko, Y. A.; Vinogradov, M. G.; Nikishin, G. I. .1.Organomet. Chem. 1990, 386, 139- 146.(13) Mitsudo, T. A.; Nakagawa, Y.; Watanabe, H.; Watanabe, K.; Misawa, H.; Watanabe, Y.J. Chem. Soc., Chem. Commun 1981,496-497.60(14) Singer, H.; Wilkinson, G. J. Chem. Soc. (A) 1968, 849-853.(15) Yoshikawa, S.; Kiji, J.; Furukawa, J. Makromol. Chem. 1977, 178, 1077-1087.(16) Keim, W.; Behr, A.; Roper, M. In Pergamon Press: Oxford, 1982; Vol. 8; pp 371-462.(17) Meriwether, L. S.; Colthup, E. C.; Kennerly, G. W.; Reusch, R. N. J. Org . Chem. 1961,25, 5155-5163.(18) Otsuka, S.; Nakamura, A. Adv. Organometal. Chem. 1976, 14, 245-283.(19) Wendt, J.; Klinger, U.; Singer, H. Inorg. Chim. Acta 1991, 183, 133-143.(20) Katz, T. J.; Hacker, S. M.; Kendrick, R. D.; Yannoni, C. S. J. Am. Chem. Soc. 1985, /07,2182-2183.(21) Masuda, T.; Higashimura, T. Acc. Chem. Res. 1984, 17, 51-56.(22) Sitnionescu, C. I.; Percec, V. Prog. Polym. Sci. 1982, 8, 133.(23) Angoletta, M.; Bellon, P. L.; Demartin, F.; Sansoni, M. J. Organomet. Chem. 1981,208,C12-C14.(24) Birdwhistell, K. R.; Burgmayer, S. J. N.; Templeton, J. L. J. Am. Chem. Soc. 1983, 105,7789-7790.(25) Hoffman, D. M.; Hoffman, R.; Fisel, C. R. J. Am. Chem. Soc. 1982, 104, 3858-3875.(26) Alchtar, M.; Richards, T. A.; Weedon, B. C. L. J. Chem. Soc. 1959, 933.(27) Al-Obaidi, Y. N.; Green, M.; White, N. D.; Taylor, G. E. J. Chem. Soc., Dalton Trans.1982, 319-326.(28) Alonso, F. J. G.; Hohn, A.; Wolf, J.; Heiko, 0.; Werner, H. Angew. Chem., Int. Ed. Engl.1985, 24, 406-408.(29) Bianchini, C.; Masi, D.; Meli, A.; Peruzzini, M.; Ramirez, J. A.; Vacca, A.; Zanobini, F.Organometallics 1989, 8, 2179 -2189.(30) Calvin, F.; Coates, G. E. J. Chem. Soc. 1960, 2008.(31) Deraniyagala, S. P.; Grundy, K. R. Organometallics 1985, 4, 424-426.(32) Jia, G.; Rheingold, A. L.; Meek, D. W. Organometallics 1989, 8, 1378-1380.(33) Wolf, J.; Werner, H.; Serhadli, 0.; Ziegler, M. L. Angew. Chem., Int. Ed. Engl. 1983, 22,414-416.(34) Birdwhistell, K. R.; Tonker, T. L.; Templeton, J. L. J. Am. Chem. Soc. 1985, /07, 4474-4483.(35) Davies, D. L.; Dyke, A. F.; Endesfelder, A.; Knox, S. A. R.; Naish, P. J.; Orpen, A. G.;Plass, D.; Taylor, G. E. J. Org . Chem. 1980, 198, C43-C49.61(36) Doherty, N. M.; Eischenbroich, C.; ICneuper, H. J.; Knox, S. A. J. Chem. Soc., Chem.Commun 1985, 170-171.(37) Roland, E.; Vahrenkamp, H. J. Mol. Catal. 1983, 21, 233-237.(38) Albertin, G.; Amendola, P.; Antoniutti, S.; lanelli, S.; Pelizzi, G.; Bordignon, E.Organometallics 1991, 10, 2876-2883.(39) Jia, G.; Gallucci, J. C.; Rheingold, A. L.; Haggerty, B. S.; Meek, D. W. Organometallics1991, 10, 3459-3465.(40) McMullen, A. K.; Selegue, J. P.; Wang, J. G. Organometallics 1991,10, 3421-3423.(41) Burt, R.; Cooke, M.; Green, M. J. Chem. Soc. (A) 1970, 2981.(42) Sears, C. J. J.; Stone, F. G. A. J. Organomet. Chem. 1968,11, 644.(43) Deshpande, S. S.; Gopinathan, S.; Gopinathan, C../. Organomet. Chem. 1991, 415, 265-270.(44) Dobson, A.; Moore, D. S.; Robinson, S. D. J. Organomet. Chem. 1979, 177, C8-C12.(45) Eshtiagh-Hosseini, H.; Nixon, J. F.; Poland, J. S. J. Organomet. Chem. 1979, 164, 107-121.(46) Romero, A. R.; Santos, A.; Lopez, J.; Echavarren, A. M. J. Organomet. Chem. 1990,391, 219-223.(47) Torres, M. R.; Vegas, A.; Santos, A.; Ros, J. J. Organomet. Chem. 1986, 309, 169-177.(48) Glaser, C. Chem. Ber. 1869, 2, 422.(49) Dobson, A.; Moore, D. S.; Robinson, S. D. Polyhedron 1985, 4, 1119-1130.(50) Silvestre, J.; Hoffmann, R. Hely. Chim. Acta 1985, 68, 1461-1506.(51) Bruce, M. I.; Harbourne, D. A.; Waugh, F.; Stone, F. G. A. J. Chem. Soc. (A) 1968, 895.(52) Harbourne, D. A.; Stone, F. G. A. J. Chem. Soc. (A) 1968, 1765.(53) Hills, A.; Hughes, D. L.; Jimenez-Tenorio, M.; Leigh, G. J.; McGreary, C. A.; Rowley,A. T.; Bravo, M.; McKenna, C. E.; McKenna, M. C. J. Chem. Soc., Chem. Commun1991, 522-524.(54) Gotzig, J.; Otto, H.; Werner, H. 1985, 423.(55) Antonova, A. B.; Ioganson, A. A. Russ. Chem. Rev. 1989, 58, 693-710.(56) Bianchini, C.; Meli, A.; Peruzzini, M.; Zanobini, F. Organometallics 1990, 9, 241-250.(57) Adams, R. D.; Davison, A.; Selegue, J. P../. Am. Chem. Soc. 1979, 101, 7232-7238.(58) Davison, A.; Selegue, J. P. J. Am. Chem. Soc. 1978, 100, 7763-7765.62(59) Birdwhistell, K. R.; Templeton, J. L. Organometallics 1985, 4, 2062-2064.(60) Afzal, D.; Lenhert, P. G.; Lukehart, C. M. J. Am. Chem. Soc. 1984, 106, 3050-3052.63Chapter 4Experimental Procedures4.1 General Procedures.All manipulations were performed under prepurified nitrogen in a Vacuum AtmospheresHE-553-2 workstation equipped with a MO-40-2H purification system or in Schlenk-typeglassware. Tetrahydrofuran, benzene and hexanes were predried by refluxing over CaH2 andthen distilled from sodium-benzophenone ketyl under argon. Toluene was predried byrefluxing over CaH2 and then distilled from sodium under argon. Deuterated benzene (C6D6,99.6 atom % D), purchased from MSD Isotopes, was dried over activated 4 A molecularsieves, vacuum transferred, and taken through a freeze-pump-thaw cycle three times before use.Deuterated chloroform (CDC13, 99.8 atom % D), also purchased from MSD Isotopes, wasdried over activated 4 A molecular sieves before use. Deuterated water (D20, 99.8% D),purchased from Stohler Isotope Chemicals, was used as received. Diatomaceous earth (Celite545®), purchased from Fisher, was dried overnight at 170 °C before use. Basic alumina(Brockman Activity I, 80-200 mesh) was supplied by Fisher and used as received.4.2 Reagents and Starting MaterialsRuC13.xH20 was purchased from Johnson Matthey and used as received. Thecomplexes [Ru(COD)C12]x,1 Ru(PPh3)4C12,2 RuHC1(CO)(PPh3)3 93 and Ru(DMS0)4C124were prepared according to published procedures. 3-hydroxy-2-methyl-4-pyrone (maltol) waspurchased from Sigma and used as received. The potassium salt of the maltolato anion wasprepared by addition of an ether solution (100 mL) of potassium t-butoxide (1.78 g, 15.964mmol) to an ether solution (50 mL) of maltol (2.00 g, 15.9 mmol). The resultant precipitatewas washed with ether (3 x 15 mL) and dried in vacuo.4.3 Analytical MethodsThe 1H and 31P(1H) NMR spectra were recorded in C.6D6 or CDC13 on a Varian XL-300 or a Bruker AC 200 spectrometer. Proton spectra were referenced using the partiallydeuterated solvent peak as the internal reference (i.e. 7.15 ppm for C6D5H and 7.26 ppm forCHC13). The 31P (1H) NMR spectra were referenced to external P(OMe)3 set at +141.00 ppmrelative to 85% H3PO4 at 0.0 ppm. 13C{ 1H} NMR spectra were recorded in CDC13 and werereferenced using the solvent peak at 77 ppm as the internal reference. All NMR couplingconstants, J, are reported in hertz. Infrared studies were performed on a Bomem MB-1001- iIR Spectrometer using a low gain DTGS (deuterated triglycerine sulphide) detector and werereferenced to polystyrene film. Gas chromatographic-mass spectral studies were carried out ona Kratos MS 80 machine using an El source. Mr. M. Lapawa was responsible for acquiring theGCMS data. Carbon and hydrogen analyses were performed by Mr. P. Borda of thisdepartment.4.4 X-Ray Crystal StructuresThe X-ray crystal structures were determined at the UBC Crystallographic Services byDr. Steve Rettig. The crystals were mounted on glass fibers. Further details of the structuredeterminations are given in the appendices.654.5 Syntheses4.5.1 Ru(ma)2(PPh3)2 (1).A solution of RuC12(PP113)4 (0.497 g, 0.407 mmol) in tetrahydrofuran (20 mL) wasadded to a suspension of 1Cma (0.134 g, 0.815 mmol) in tetrahydrofuran (30 mL). The mixturewas stirred for 16 hours at 22°C during which time the solution took on a reddish-orange color.The tetrahydrofuran was removed in vacuo and the product, 1, was extracted with toluene (40mL) and filtered through a layer of Celite®. The solution was reduced to a volume of 15 mLand the product precipitated out upon addition of hexanes (1.5 mL) yielding an orange-redpowder (0.29 g, 81%). The product was a mixture of three isomers. 1H NMR (C6D6, 8):triphenylphosphine, 7.8-7.6 (m, 12H, ortho); 7.2-6.9 (m, 18H, metalpara); maltolate (isomerI), 6.50 (d, 2H, H(6), 3JH_H = 5.1); 5.81 (d, 2H, H(5), 3JH.H = 5.1); 2.27 (s, 6H, H(7));maltolate (isomer II), 6.49 (d, 1H, H(6), 3JH_H = 5.1); 6.48 (d, 1H, H(6), 3JH_H = 5.1); 5.96(d, 1H, H(5), 3JH_H = 5.1); 5.83 (d, 1H, H(5), 3JH_H = 5.1); 2.17 (s, 3H, H(7)); 2.04 (s, 3H,H(7)); maltolate (isomer III), 6.46 (d, 2H, H(6), 3JH_H = 5.1); 5.88 (d, 2H, H(5), 3JH..H=5.1); 2.05 (s, 6H, H(7)). 31P NMR (C6D6, 8): isomer I, 60.56 (s); isomer II, 60.38 (d, 1P,2J p_p = 35.3 Hz); 57.27 (d, 1P, 2Jp_p = 35.3 Hz); isomer III, 57.54 (s). Anal. Calcd forC4014006P2Ru-(C7118)0.38; C, 66.80%; H, 4.76%. Found: C, 66.78%; H, 4.98%. Themicroanalysis sample was dried in vacuo for five days, but still contained traces of toluene. Aportion of the sample was used to produce an NMR spectrum which showed, by integration,that the analyte contained 0.38 equivalents of toluene, which provided an acceptable analysis.4.5.2 Ru(ma)2(DMS0)2 (2).A suspension of RuC12(DMS 0)4 (0.300 g, 0.619 mmol) and Kma (0.203 g, 1.24mmol) was stirred in toluene (60 mL) for 16 hours at 90 °C during which time the solution66became red in color. The solution was filtered through Celite® and reduced to a volume of 30mL. Slow addition of hexanes resulted in precipitation of an orange solid which contained freeDMSO. Recrystallization from toluene/hexanes removed this impurity yielding 1.03 g (86%) ofproduct. Dissolution in a minimum amount of benzene yielded orange prisms suitable forsingle-crystal X-ray analysis. 1I-1 NMR (C6D6, 8): maltolate: 6.58, 6.58, 6.52, 6.49 (d, 2H,H(6), 3JH_H = 5.1); 6.11, 6.11, 6.07, 6.04 (d, 2H, H(5), 3.41-H = 5.1); 2.19, 2.14, 2.12,2.07 (s, 6H, H(7)); DMSO: 3.32, 3.28, 3.20, 3.18, 2.97, 2.87, 2.85, 2.77 (s, 12H, methyl).IR (KBr disc, cm-1): 1111 (SO stretch). Anal. Calcd for C16H2208RuS2: C, 37.86%; H,4.37%. Found: C, 37.80%; H, 4.46%.4.5.3 Ru(ma)2(d6-DMS0)2This compound was prepared in the same manner as 2, but starting from the deuteratedDMSO complex, RuC12(d6-DMS0)4. IR (ICBr disc, cm-1): 1113 (SO stretch).4.5.4 Ru(ma)2(COD) (3).A suspension of [(COD)RuClAn (2.72 g, 9.69 mmol) and Kma (3.18 g, 19.4 mmol) intetrahydrofuran (60 mL) was heated at 65 °C for 16 hours. The tetrahydrofuran was thenremoved in vacuo and toluene (50 mL) was used to extract the product. The solution wasfiltered through a layer of Celite®. Removal of the toluene and washing with hexanes affordedan orange-red solid (4.27 g, 96%) in high purity (>95% by NMR). Crystals suitable for X-rayanalysis were provided by slow evaporation of toluene at -5 °C. 1H NMR (C6D6, 8):maltolate, 6.58 (d, 1H, H(6), 3./H_H = 5.6 Hz); 6.51 (d, 1H, H(6), 3.4i-H = 5.6 Hz); 6.32 (d,1H, H(5), 3JH_H = 5.6 Hz); 5.95 (d, 1H, H(5), 3JH_H = 5.6 Hz); 2.26 (s, 3H, H(7)); 2.13 (s,3H, H(7)); COD, 5.10-4.85 (m, 2H, olefinic); 3.85-3.55 (m, 2H, olefinic); 2.85-2.05 (m, 8H,67methylene). Anal. Calcd. for C201-12206Ru: C, 52.28%; H, 4.84%. Found: C, 52.05%; H,4.88%.4.5.5 RuH(ma)(C0)(PPh3)2 (4).A suspension of RuHC1(C0)(PPh3)3 (0.261 g, 0.274 mmol) and Kma (0.045 g, 0.274mmol) in tetrahydrofuran (40 mL) was stirred for 16 hours at 22 °C resulting in a yellowsolution. The tetrahydrofuran was then removed in vacuo and the product was extracted withtoluene (25 mL) and filtered through a layer of Celite®. The solution was reduced to a volumeof 10 mL and a yellow solid was precipitated by slow addition of ether. The product wasfiltered and washed with ether (2 x 5 mL) yielding 0.19 g (90%) in high purity (>95% byNMR). Two isomers were formed in —15:1 ratio. 1H NMR (C6D6, 8): triphenylphosphine,8.0-7.8 (m, 12H, ortho); 7.2-6.9 (m, 18H, metalpara); maltolate (major isomer), 6.41 (d, 1H,H(6), 3JH_H = 5.1); 5.63 (d, 1H, H(5), 3./H_H = 5.1); 1.97 (s, 3H, H(7)); maltolate (minorisomer), 6.37 (d, 1H, H(6), 3fH_H = 5.1); 5.38 (d, 1H, H(5), 3JH.H = 5.1); 2.24 (s, 3H,H(7)); hydride (major isomer), -13.65 (t, 1H, 2fp_H = 21.04); hydride (minor isomer), -13.24(t, 1H, 2Jp_H = 21.01). 31P NMR (C6D6, 8): (major isomer), 40.58 (s); (minor isomer),40.90 (s). IR (ICBr disc, cm-1): 1915.1 (CO stretch). Anal. Calcd for C43H3604P2Ru:C, 66.23%; H, 4.65%. Found: C, 65.99%; H, 4.59%.4.6 Reactions with Alkynes4.6.1 Reaction of Ru(ma)2(PPh3)2 (1) with Phenylacetylene.Ru(ma)2(PPh3)2 (0.037 g, 0.042 mmol) was dissolved in C6D6 (0.5 mL). Anapproximately equimolar amount of phenylacetylene was added to this solution and the reactionwas followed by NMR spectroscopy. No reaction was observed after several hours at room68temperature so the reaction mixture was heated for three hours at 50°C, after which time all ofthe phenylacetylene had been consumed. However, the product resonances were obscured bythe olefinic resonances of the maltolato ligand. The reaction was repeated, but this time anexcess of phenylacetylene was added to the ruthenium complex (ca. 1 mol % 1) and the mixturewas heated at 50 °C for 24 hours. NMR spectra indicated the presence of a 1:1 mixture of cis-and trans-1,4-diphenylbut-1-en-3-yne in addition to the starting ruthenium material. Theproduct was run through two consecutive 0.5 X 6 cm columns of basic alumina to isolate theorganic components and a GCMS was run. 114 NMR (C6D6, 8): phenyl, 8.0-7.3 (ortho, 4H);7.3-6.7 (meta, para, 6H); trans isomer, --7.1 (d, 1H, H(1), 3JH.H = 16.2); 6.32 (d, 1H, H(2),3.1H-H = 16.2); cis isomer, 6.43 (d, 1H, H(1), 3JH_H = 12.6); 5.81 (d, 1H, H(2), 3-41-H =12.1). G.C.: 2 peaks. M.S.: = Reactions with AcetyleneThe compounds Ru(ma)2(PPh3)2 (1), Ru(ma)2(DMS0)2 (2), and Ru(rna)2(COD) (3)were dissolved in toluene solutions and taken through a freeze-pump-thaw cycle three times.The solutions were each put under 1 atm. of acetylene and left stirring at room temperature.Within 1 hour, each of these three solutions had produced a deep black powder which wasinsoluble in solution and decomposed spontaneously upon exposure to air. This insolublematerial was assumed to be polyacetylene although no further characterization was attempted.4.7 References(1) Bennett, M. A.; Wilkinson, G. Chem. Incl. 1959, 1516.(2) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth. 1970, 12, 237.(3) Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, F. Inorg. Synth. 1974, 15, 45.(4) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans. 1973,204.69Summary and Future ProspectsThe four complexes, Ru(ma)2(PPh3)2 (1), Ru(ma)2(DMS0)2 (2) Ru(ma)2(COD) (3), andRuH(ma)(C0)(PPh3)2 (4) have been synthesized and characterized. In addition, some catalyticreactions involving these compounds have been studied. However, further investigation of theircatalytic potential is definitely needed.. Compound 1 proved to be a useful catalyst for the dimerization of phenylacetylene viadissociation of the phosphine group. This dissociative mechanism of 1 could perhaps beexploited in other reactions requiring a vacant coordination site.Furthermore, compound 4 proved to be a successful catalyst for reactions involving anumber of alkynes, although the products could not be identified. A deeper study into what ishappening here is also needed.Finally, with compound 2 being soluble in an aqueous medium, a study of its viability asa homogeneous catalyst in such solutions could be undertaken. Due to time constraints this wasnot done although it was initially declared to be one of the primary goals of this project. It is notknown how labile the DMSO moieties are or how active this compound is but a study could becarried out. In addition, interest was expressed in doing tests on this compound in terms of acancer therapy drug. Several DMSO compounds have been studied for this purpose due to thepenetrating ability of DMSO. The presence of two DMSO ligands together with the non-toxicmaltolato ligands could prove to make this a useful compound in this capacity.70•H15C14H160H8 f>,H2•04arsib,C84' 4•H10•C12H9H12 H13^C70 07• H6Ru lC9•08C15C16 4/4H210' •H2202C3 H1C2 0 ClAt H3'Ai- AC6 •01H17°3C4H20H4 C5H5C13H1104111SiH14 H18S2CIO05H7•AppendicesA.1 X-Ray Crystallographic Analysis of Ru(ma)2(DMS0)2 (2)71Figure A.1.1 Ortep Stereoview of Ru(ma)2(DMS0)272A.1.1 Experimental Details for Ru(ma)2(DMS0)A.1.1.1 Crystal Data for Ru(ma)2(DMS0)2Empirical Formula C31113708RuS2Formula Weight 702.82Crystal Color, Habit Orange, prismCrystal Dimensions 0.30 X 0.35 X 0.45Crystal System TriclinicLattice Type PNo. of Reflections Used for UnitCell Determination (28 range) 25 ( 38.5 - 44.5°)Omega Scan Peak Widthat Half-Height 0.37°Lattice Parameters a = 12.015(2) Ab = 16.509(2) Ac = 8.7933(8) Aa = 99.853(9)°13 = 100.225(9)°y = 94.28(1)°V = 1681.2(4) Ä3Space Group^ P1 (#2)Z Value 2Dcak^ 1.388 g/cm3F000 7261.1(MoKa)^ 6.19 cm-1A.1.1.2 Intensity Measurements for Ru(ma)2(DMS0)2Diffractometer^ Rigaku AFC6SRadiation MoKcc (X. = 0.71069 A)graphite monochromatedTake-Off Angle^ 6.0°Detector Aperture 6.0 mm horizontal6.0 mm verticalCrystal to Detector Distance^28.5 cmTemperature^ 21.0°CScan Type co - 20Scan Rate^ 32.0°/min (in omega) (8 rescans)Scan Width (1.21 + 0.35 tan 0)°20max^ 55.0°No. of Reflections Measured^Total: 8104Unique: 7729 (Rint = 0.030)Corrections^ Lorentz-polarizationAbsorption(trans. factors: 0.69 - 1.00)Decay (32.3% decline)A.1.1.3 Structure Solution and Refinement for Ru(ma)2(DMS0)2Structure SolutionRefinementFunction MinimizedLeast Squares Weightsp-FactorAnomalous DispersionNo. Observations (I>3.00a(I))No. VariablesReflection/ Parameter RatioResiduals: R; RwGoodness of Fit IndicatorMax Shift/Error in Final CycleMaximum Peak in Final Diff. MapMinimum Peak in Final Diff. MapDirect MethodsFull-Matrix Least-SquaresZw(IFol - IFc1)211a2(Fo) = 4F o21a2(F o2)0.00All non-hydrogen atoms594637915.690.038 ; 0.0432.420.020.09e-A3-0.95 r/A3A.1.2 Tabulated Data for Ru(ma)2(DMS0)2Table A.1.1 Final atomic coordinates (fractional) and Beq (A2)* for Ru(ma)2(DMS0)2atom BeqRu(1) 0.09043(2) 0.23363(1) 0.21640(3) 2.938(5)S(1) 0.22095(7) 0.27382(5) 0.08925(9) 3.93(2)S(2) 0.19746(7) 0.26643(5) 0.45252(8) 3.57(2)0(1) -0.1296(2) -0.0313(1) 0.2937(3) 5.76(7)0(2) -0.0397(2) 0.1840(1) 0.3166(2) 3.76(5)0(3) 0.1229(2) 0.1098(1) 0.1835(2) 3.64(5)0(4) -0.1709(2) 0.4175(2) -0.0646(3) 5.68(7)0(5) 0.0288(2) 0.3484(1) 0.2295(2) 3.67(5)0(6) -0.0312(2) 0.2091(1) 0.0054(2) 4.00(5)0(7) 0.1881(2) 0.2607(2) -0.0835(3) 6.21(7)0(8) 0.3084(2) 0.3164(2) 0.4831(3) 6.59(7)C(1) -0.2148(4) 0.0820(3) 0.4136(6) 7.1(1)C(2) -0.1249(3) 0.0536(2) 0.3298(4) 4.77(8)C(3) -0.0440(3) 0.1031(2) 0.2888(3) 3.60(7)C(4) 0.0425(3) 0.0646(2) 0.2156(3) 3.47(6)C(5) 0.0345(3) -0.0230(2) 0.1850(4) 4.32(8)C(6) -0.0514(4) -0.0665(2) 0.2214(4) 5.36(9)C(7) -0.0735(3) 0.5001(2) 0.1777(5) 5.53(10)C(8) -0.0939(3) 0.4185(2) 0.0713(4) 4.33(8)C(9) -0.0449(3) 0.3493(2) 0.1002(3) 3.54(7)C(10) -0.0759(3) 0.2741(2) -0.0172(3) 3.80(7)C(11) -0.1552(3) 0.2784(2) -0.1557(4) 5.39(9)76atom x Y z BeqC(12) -0.1979(3) 0.3486(3) -0.1732(5) 6.1(1)C(13) 0.2780(3) 0.3795(2) 0.1523(5) 5.85(10)C(14) 0.3462(3) 0.2237(3) 0.1283(5) 6.7(1)C(15) 0.1158(4) 0.3188(2) 0.5790(4) 5.71(10)C(16) 0.2207(4) 0.1786(2) 0.5429(4) 5.86(10)C(17) 0.5873(3) 0.3574(3) 0.4680(5) 6.8(1)C(18) 0.6467(4) 0.2963(3) 0.4019(6) 7.2(1)C(19) 0.7560(4) 0.3142(3) 0.3872(5) 6.4(1)C(20) 0.8076(4) 0.3918(3) 0.4378(5) 6.1(1)C(21) 0.7497(4) 0.4534(3) 0.5032(5) 6.3(1)C(22) 0.6408(4) 0.4368(3) 0.5180(5) 6.1(1)C(23) 0.5316(9) 0.1519(7) 0.809(2) 15.3(4)C(24) 0.511(1) 0.082(1) 0.727(2) 27.5(7)C(25) 0.563(1) 0.0168(10) 0.770(3) 29.8(9)C(26) 0.655(1) 0.0330(8) 0.871(3) 21.7(7)C(27) 0.6795(8) 0.110(1) 0.974(1) 15.8(4)C(28) 0.6136(9) 0.1700(6) 0.934(1) 13.8(3)C(29) 0.4429(5) 0.4679(5) 0.8497(5) 8.4(2)C(30) 0.5211(6) 0.4255(4) 0.9258(8) 8.9(2)C(31) 0.5771(4) 0.4583(5) 1.0770(8) 8.5(2)*Beq =7c2(U11(aa*)2 + U22(bb*)2 + U33(cc*)2 + 2U12aebb*cosy + 2U13aa*cc*cosp + 2U23bb*cc*cosa77Table A.1.2 Bond lengths (A) with estimated standard deviations for Ru(ma)2(DMS0)2atom atom distance atom atom distanceRu(1) S(1) 2.2068(8) Ru(1) S(2) 2.1957(8)Ru(1) 0(2) 2.106(2) Ru(1) 0(3) 2.090(2)Ru(1) 0(5) 2.078(2) Ru(1) 0(6) 2.105(2)S(1) 0(7) 1.474(2) S(1) C(13) 1.782(4)S(1) C(14) 1.780(4) S(2) 0(8) 1.470(2)S(2) C(15) 1.769(4) S(2) C(16) 1.786(3)0(1) C(2) 1.378(4) 0(1) C(6) 1.339(4)0(2) C(3) 1.311(3) 0(3) C(4) 1.277(3)0(4) C(8) 1.373(4) 0(4) C(12) 1.332(5)0(5) C(9) 1.314(3) 0(6) C(10) 1.266(4)C(1) C(2) 1.473(5) C(2) C(3) 1.360(4)C(3) C(4) 1.447(4) C(4) C(5) 1.419(4)C(5) C(6) 1.329(5) C(7) C(8) 1.480(5)C(8) C(9) 1.364(4) C(9) C(10) 1.449(4)C(10) C(11) 1.423(4) C(11) C(12) 1.324(5)C(17) C(18) 1.384(6) C(17) C(22) 1.379(6)C(18) C(19) 1.358(6) C(19) C(20) 1.345(6)C(20) C(21) 1.378(6) C(21) C(22) 1.350(6)C(23) C(24) 1.23(1) C(23) C(28) 1.31(1)C(24) C(25) 1.36(2) C(25) C(26) 1.26(2)C(26) C(27) 1.40(2) C(27) C(28) 1.37(1)C(29) C(30) 1.362(7) C(29) C(31)* 1.337(8)C(30) C(31) 1.377(8)*Symmetry operation: 1-x, 1-y, 2-z78Table A.1.3 Bond Angles (°) with standard deviations for Ru(ma)2(DMS0)2atom atom atom angle atom atom atom angleS(1) Ru(1) S(2) 96.25(3) S(1) Ru(1) 0(2) 173.58(6)S(1) Ru(1) 0(3) 94.99(6) S(1) Ru(1) 0(5) 90.61(6)S(1) Ru(1) 0(6) 90.09(6) S(2) Ru(1) 0(2) 88.74(6)S(2) Ru(1) 0(3) 94.38(6) S(2) Ru(1) 0(5) 93.47(6)S(2) Ru(1) 0(6) 171.70(6) 0(2) Ru(1) 0(3) 80.56(7)0(2) Ru(1) 0(5) 93.12(8) 0(2) Ru(1) 0(6) 85.33(8)0(3) Ru(1) 0(5) 169.81(8) 0(3) Ru(1) 0(6) 90.39(8)0(5) Ru(1) 0(6) 81.07(8) Ru(1) S(1) 0(7) 116.6(1)Ru(1) S(1) C(13) 114.4(1) Ru(1) S(1) C(14) 111.8(1)0(7) S(1) C(13) 106.2(2) 0(7) S(1) C(14) 105.7(2)C(13) S(1) C(14) 100.7(2) Ru(1) S(2) 0(8) 122.1(1)Ru(1) S(2) C(15) 107.5(1) Ru(1) S(2) C(16) 112.6(1)0(8) S(2) C(15) 106.4(2) 0(8) S(2) C(16) 106.2(2)C(15) S(2) C(16) 99.6(2) C(2) 0(1) C(6) 120.3(3)Ru(1) 0(2) C(3) 109.2(2) Ru(1) 0(3) C(4) 110.5(2)C(8) 0(4) C(12) 120.2(3) Ru(1) 0(5) C(9) 109.6(2)Ru(1) 0(6) C(10) 110.1(2) 0(1) C(2) C(1) 113.0(3)0(1) C(2) C(3) 121.2(3) C(1) C(2) C(3) 125.8(3)0(2) C(3) C(2) 122.7(3) 0(2) C(3) C(4) 119.0(3)C(2) C(3) C(4) 118.3(3) 0(3) C(4) C(3) 119.6(2)0(3) C(4) C(5) 122.8(3) C(3) C(4) C(5) 117.6(3)0(4) C(5) C(6) 119.8(3) 0(1) C(6) C(5) 122.9(3)0(4) C(8) C(7) 112.8(3) 0(4) C(8) C(9) 121.4(3)C(7) C(8) C(9) 125.8(3) 0(5) C(9) C(8) 122.6(3)79atom atom atom angle atom atom atom angle0(5) C(9) C(10) 119.1(3) C(8) C(9) C(10) 118.3(3)0(6) C(10) C(9) 119.8(3) 0(6) C(10) C(11) 123.2(3)C(9) C(10) C(11) 117.0(3) C(10) C(11) C(12) 120.4(3)0(4) C(12) C(11) 122.8(3) C(18) C(17) C(22) 118.9(4)C(17) C(18) C(19) 120.6(4) C(18) C(19) C(20) 119.9(4)C(19) C(20) C(21) 120.3(4) C(20) C(21) C(22) 120.5(4)C(17) C(22) C(21) 119.7(4) C(24) C(23) C(28) 122(1)C(23) C(24) C(25) 121(1) C(24) C(25) C(26) 117(1)C(26) C(26) C(27) 120(1) C(26) C(27) C(28) 115(1)C(23) C(28) C(27) 119(1) C(30) C(29) C(31)* 119.1(6)C(29) C(30) C(31) 120.0(6) C(29)* C(31) C(30) 120.9(5)80A.2 X-Ray Crystallographic Analysis of Ru(ma)2(COD) (3)04^C'0104 C7 04 C701 01OS I* 119 A lark;VISCZOdo-AN■C19Figure A.2.1 Ortep Stereoview of Ru(ma)2(COD)82A.2.1 Experimental Details for Ru(ma)2(COD)A.2.1.1 Crystal Data for Ru(ina)2(COD)Empirical Formula^C31H3708RuS2Formula Weight 459.46Crystal Color, Habit^Orange, prismCrystal Dimensions 0.100 X 0.100 X 0.154Crystal System^ OrthorhombicNo. of Reflections Used for UnitCell Determination (20 range)^25 ( 16.0 - 23.00)Omega Scan Peak Widthat Half-Height^ 0.38°Lattice Parameters a = 16.542(2) Ab = 9.684(2) Ac = 11.480(8) AV = 1839.2(6) A3Space Group^ Pna21 (#33)Z Value 4Dca/c^ 1.659 g/cm3F000 936p.(MoKa)^ 8.68 cm-1A.2.1.2 Intensity Measurements for Ru(ma)2(COD)Rigaku AFC6SMoKa (?.. 0.71069 A)6.0°6.0 mm horizontal6.0 mm vertical28.5 cm21.0°Cw-20216.0°/min (in omega) (8 rescans)(1.05 + 0.35 tan 0)°65.0°Total: 3755Lorentz-polarizationAbsorption(trans. factors: 0.96 - 1.00)Secondary Extinction(coefficient: 0.39(2) E-06)DiffractometerRadiationTake-Off AngleDetector ApertureCrystal to Detector DistanceTemperatureScan TypeScan RateScan Width20maxNo. of Reflections MeasuredCorrectionsA.2.1.3 Structure Solution and Refinement for Ru(ma)2(COD)Structure Solution^ Patterson MethodsRefinement Full-Matrix Least-SquaresFunction Minimized^Zw(IFol - IFc1)2Least Squares Weights 4F02/a2(F02)p-Factor^ 0.00Anomalous Dispersion^All non-hydrogen atomsNo. Observations (I>3.00a(I))^1775No. Variables^ 244Reflection/ Parameter Ratio^7.27Residuals: R; Rw^ 0.034; 0.029Goodness of Fit Indicator^1.44Max Shift/Error in Final Cycle^0.02Maximum Peak in Final Diff. Map^0.42e1A3Minimum Peak in Final Diff. Map^-0.73 r/A3A.2.2 Tabulated Data for Ru(ma)2(COD)Table A.2.1 Final atomic coordinates (fractional) and Beq (A2)* for Ru(ma)2(COD)2atom x Y z BeqRu(1) 0.17886(3) 0.23147(4) 0.50000(5) 2.50(1)0(1) 0.0089(3) 0.6358(5) 0.6663(5) 4.4(3)0(2) 0.1297(3) 0.4313(4) 0.4705(4) 2.8(2)0(3) 0.1114(3) 0.2584(4) 0.6531(4) 3.4(2)0(4) 0.0838(3) 0.0650(5) 0.0952(5) 3.8(2)0(5) 0.1992(3) 0.2308(5) 0.3219(4) 3.5(2)0(6) 0.0727(3) 0.1320(5) 0.4410(4) 3.4(2)C(1) 0.0751(4) 0.7218(6) 0.502(2) 4.6(3)C(2) 0.0578(4) 0.6030(7) 0.5746(6) 3.3(3)C(3) 0.0873(4) 0.4703(7) 0.5606(6) 2.8(3)C(4) 0.0747(4) 0.3757(7) 0.6543(7) 3.0(3)C(5) 0.0219(6) 0.4134(10) 0.7462(9) 4.1(4)C(6) -0.0097(5) 0.5408(9) 0.7465(8) 4.1(5)C(7) 0.2044(5) 0.1956(7) 0.0683(7) 4.6(4)C(8) 0.1430(4) 0.1400(6) 0.1484(7) 3.4(3)C(9) 0.1413(4) 0.1592(6) 0.2679(6) 2.9(3)C(10) 0.0767(4) 0.1054(7) 0.3335(8) 3.2(4)C(11) 0.0167(5) 0.0242(8) 0.2728(7) 3.6(4)C(12) 0.0245(5) 0.0063(7) 0.1587(7) 4.1(4)C(13) 0.2982(3) 0.3161(6) 0.498(2) 4.0(3)C(14) 0.2716(4) 0.3224(7) 0.6076(7) 3.7(3)C(15) 0.2990(5) 0.2266(8) 0.7011(8) 5.5(4)86atom x Y z BeqC(16) 0.2598(6) 0.0882(9) 0.7031(9) 7.3(6)C(17) 0.2141(5) 0.0502(7) 0.5959(8) 4.0(4)C(18) 0.2459(4) 0.0407(6) 0.4868(10) 3.9(4)C(19) 0.3349(5) 0.0665(8) 0.4618(12) 8.2(8)C(20) 0.3577(4) 0.2144(9) 0.4494(8) 5.4(4)*Beq=17c20.111(aa*)2 + U22(bb*)2 + U33(cc*)2 + 2U12aa*bb*cosy + 2143aa*cc*cos0 + 2U23bb*cc*cosa87Table A.2.2 Bond lengths (A) with estimated standard deviations for Ru(ma)2(COD)atom atom distance atom atom distanceRu(1) 0(2) 2.126(4) C(2) C(3) 1.385(9)Ru(1) 0(3) 2.098(5) C(3) C(4) 1.43(1)Ru(1) 0(5) 2.072(5) C(4) C(5) 1.42(1)Ru(1) 0(6) 2.114(4) C(5) C(6) 1.34(1)Ru(1) C(13) 2.138(5) C(7) C(8) 1.47(1)Ru(1) C(14) 2.157(7) C(8) C(9) 1.38(1)Ru(1) C(17) 2.153(7) C(9) C(10) 1.407(9)Ru(1) C(18) 2.161(6) C(10) C(11) 1.445(9)0(1) C(2) 1.365(8) C(11) C(12) 1.33(1)0(1) C(6) 1.34(1) C(13) C(14) 1.34(2)0(2) C(3) 1.306(7) C(13) C(20) 1.50(1)0(3) C(4) 1.288(7) C(14) C(15) 1.49(1)0(4) C(8) 1.363(8) C(15) C(16) 1.49(1)0(4) C(12) 1.347(9) C(16) C(17) 1.49(1)0(5) C(9) 1.335(7) C(17) C(18) 1.36(1)0(6) C(10) 1.262(9) C(18) C(19) 1.520(9)C(1) C(2) 1.45(1) C(19) C(20) 1.49(1)88Table A.2.3 Bond Angles (*) with standard deviations for Ru(ma)2(COD)atom atom atom angle atom atom atom angle0(2) Ru(1) 0(3) 79.5(2) Ru(1) 0(5) C(9) 110.1(4)0(2) Ru(1) 0(5) 84.7(2) Ru(1) 0(6) C(10) 111.3(5)0(2) Ru(1) 0(6) 92.7(2) 0(1) C(2) C(1) 112.2(7)0(2) Ru(1) C(13) 90.1(2) 0(1) C(2) C(3) 120.9(7)0(2) Ru(1) C(14) 89.5(2) C(1) C(2) C(3) 126.9(8)0(2) Ru(1) C(17) 158.0(3) 0(2) C(3) C(2) 123.3(7)0(2) Ru(1) C(18) 164.5(3) 0(2) C(3) C(4) 119.3(6)0(3) Ru(1) 0(5) 156.0(2) C(2) C(3) C(4) 117.2(7)0(3) Ru(1) 0(6) 83.3(2) 0(3) C(4) C(3) 119.3(7)0(3) Ru(1) C(13) 117.0(5) 0(3) C(4) C(5) 121.7(7)0(3) Ru(1) C(14) 81.2(3) C(3) C(4) C(5) 119.0(7)0(3) Ru(1) C(17) 79.5(3) C(4) C(5) C(6) 118.6(9)0(3) Ru(1) C(18) 116.0(3) 0(1) C(6) C(5) 122.8(8)0(5) Ru(1) 0(6) 79.5(2) 0(4) C(8) C(7) 114.3(7)0(5) Ru(1) C(13) 80.7(5) 0(4) C(8) C(9) 120.0(7)0(5) Ru(1) C(14) 116.8(3) C(7) C(8) C(9) 125.7(7)0(5) Ru(1) C(17) 117.3(3) 0(5) C(9) C(8) 121.0(7)0(5) Ru(1) C(18) 81.1(3) 0(5) C(9) C(10) 119.2(7)0(6) Ru(1) C(13) 159.6(5) C(8) C(9) C(10) 119.8(7)0(6) Ru(1) C(14) 163.7(3) 0(6) C(10) C(9) 119.1(7)0(6) Ru(1) C(17) 91.0(2) 0(6) C(10) C(11) 123.2(7)0(6) Ru(1) C(18) 90.8(2) C(9) C(10) C(11) 117.7(8)C(13) Ru(1) C(14) 36.3(5) C(10) C(11) C(12) 118.7(8)C(13) Ru(1) C(17) 94.0(3) 0(4) C(12) C(11) 123.3(7)89atom atom atom angle atom atom atom angleC(13) Ru(1) C(18) 81.5(2) C(14) C(13) C(20) 126(1)C(14) Ru(1) C(17) 81.2(3) C(13) C(14) C(15) 123.4(7)C(14) Ru(1) C(18) 91.4(3) C(14) C(15) C(16) 116.0(7)C(17) Ru(1) C(18) 36.8(4) C(15) C(16) C(17) 115.5(7)C(2) 0(1) C(6) 120.5(6) C(16) C(17) C(18) 125.5(8)Ru(1) 0(2) C(3) 110.0(4) C(17) C(18) C(19) 122(1)Ru(1) 0(3) C(4) 111.7(5) C(18) C(19) C(20) 115.0(6)C(8) 0(4) C(12) 120.3(6) C(13) C(20) C(19) 115.6(6)90


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