- OXYGEN ATOM TRANSFER REACTIONS TO METAL CARBONYLS. KINETICS AND MECHANISM OF CO SUBSTITUTION REACTIONS OF M3(CO)12 (M equals Fe, Ru, Os) IN THE PRESENCE OF (CH3)3NO.
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Reported are the rates of reaction and activation parameters for CO substitution reactions of M//3(CO)//1//2 (M equals Fe, Ru, Os) with L (L equals PPh//3, P(OPh)//3, AsPh//3) in the presence of (CH//3)//3NO. In aprotic solvents the reactions are too fast
- Shen,Shi,Gao,Shi,Basolo
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- Electron-transfer catalysed substitution of dodecacarbonyltriruthenium mediated by dibenzoylethylene: A factorial design experiment
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The electron-transfer catalysed substitution of PPh3 for CO on Ru3(CO)12 mediated by dibenzoylethylene was studied using a factorial design experiment. Within the range of conditions investigated, the efficiency of the reaction was affected exclusively by a two-factor interaction between the Ru3(CO)12 and PPh3 concentrations. Maximum turnover numbers were achieved only when both of these concentrations were at their high levels. The dibenzoylethylene concentration and the current had no significant effect on efficiency. Other phosphines (PR3, R = Me and/or Ph or Bu), P(OMe)3 and Bu1NC show similar reactivity.
- Xu, Lin,Gipson, Stephen L.
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- Tetranuclear rhodium-triruthenium carbonyl clusters containing phosphorus(III) ligands; crystal and molecular structure of 5-C5H5)>
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The reactions of 5-C5H5)> with triphenylphosphine and trimethylphosphite and of 5-C5Me5)> with triphenylphosphine yield clusters 9-n(PR3)nC
- Grand, Jean-Luc Le,Lindsell, W. Edward,McCullough, Kevin J.
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- Homogeneous hydrogenation of diphenylacetylene in the presence of Ru3(CO)9L3 (L=PPh3, PEt3). The crystal structure of Ru3(CO)10(PEt3)2: A reaction intermediate?
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The phosphine-substituted clusters Ru3(CO)9L3 (L=PPh3, 1; L=PEt3, 2) are active homogeneous catalysts for the hydrogenation of diphenylacetylene. In the catalytic reactions involving complex 2, formation of Ru3(CO)10(PEt3)2 (3) has been observed. This complex shows a hydrogenating activity greater than that of the parent complex 2. In the light of these results and of the observed effect of dihydrogen pressure and substrate/cluster ratio, reaction mechanisms are discussed. The structure of 3 has been characterized by X-ray diffraction and is compared with those of other phosphine-substituted triruthenium clusters. Compound 3 crystallizes in the monoclinic space group P21 with a=9.368(7), b=12.20(2), c=13.554(9) A, β=102.63(8)° and Z=2. Refinement of 4975 data gave R1=0.0417 and wR2=0.1105. The two phosphorus ligands occupy equatorial positions on adjacent metal atoms so that they are trans to each other at the ends of the Ru-Ru vector. The presence of bent semi-bridging carbonyl groups makes the molecule chiral and its absolute structure was determined.
- Gervasio, Giuliana,Giordano, Roberto,Marabello, Domenica,Sappa, Enrico
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- Control of the photochemistry of Ru3(CO)12 and Os3(CO)12 by variation of the solvent1
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The synthetic potential of the photosubstitution of CO by two-electron donor ligands in M3(CO)12 [M=Ru, Os] has been investigated. When used as photolysis media, diethyl ether, ethyl acetate and acetonitrile act as photofragmentation quenchers allowing for the synthesis of photosubstitution products in high yield. UV photolysis of M3(CO)12 with added triphenylphosphine in these photolysis media leads to M3(CO)12-n(PPh3)n (n=1, 2 or 3). Prolonged photolysis with added tricyclohexylphosphine generates the highly sterically crowded complex M3(CO)9(PCy3)3. Photolysis with thiols, RSH (R=Et, Ph), leads to the thiolato complexes HM3(μ-SR)(CO)10, prolonged photolysis of which generates the corresponding sulphido cluster M3(μ3-S)(CO)10. Photolysis of M3(CO)12 in acetonitrile with no added ligand results in the generation of M3(CO)12-n(MeCN)n (n=1 or 2). This offers a route to these complexes without the need for the use of oxidising agents such as trimethylamine-N-oxide. Photolysis of an ethene-saturated diethyl ether or ethyl acetate solution of M3(CO)12 leads to no net photoreaction in the case of ruthenium, whereas, for osmium, the olefin complex Os(CO)4(η2-C2H4) is formed. This highlights the difference in the photosubstitution mechanism for Ru3(CO)12 and Os3(CO)12.
- Leadbeater, Nicholas E.
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p. 211 - 216
(2007/10/03)
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- Wavelegth-, Medium-, and Temperature-Dependent Competition between Photosubstitution and Photofragmentation in Ru3(CO)12 and Fe3(CO)12: Detection and Characterization of Coordinatively Unsaturated M3(CO)11 Complexes
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Irradiation of 0.1 mM Ru3(CO)12 (λ = 313 nm) or 0.02 mM Fe3(CO)12 (λ = 366 nm) in a methylcyclohexane or 2-methyltetrahydrofuran (2-MeTHF) glass at 90 K yields loss of one CO as the only IR detectable photoreaction to yield products formulated as M3(CO)11 or M3(CO)11(2-MeTHF), respectively.An initially observed axially vacant form of Ru3(CO)11 (II) having no bridging CO's rearranges at 90 K to an axially vacant form (III), having at least one bridging CO, also adopted by Fe3(CO)11 in an alkane glass.An initially observrd, equatorially substituted form of Ru3(CO)11(2-MeTHF) (I') rearranges at 90 K to III or a 2-MeTHF adduct of III.I' is extremely photosensitive with respect to further substitution by 2-MeTHF for up to three CO ligands.Ru3(CO)11 (III) reacts with N2 or 13CO to yield Ru3(CO)11(N2) or axial-13CO-Ru3(CO)11(13CO) complexes, respectively.Ru3(CO)11 and Fe3(CO)11 react with C2H4 to yield M3(CO)11(C2H4) complexes.M3(CO)11 (III) reacts with PPh3 to yield Ru3(CO)11(Ph3) at 298 K and Fe3(CO)11(PPh3) at 195 K.Long wavelegth excitation of Ru3(CO)12 (λ = 366 nm) or Fe3(CO)12 (λ = 436 nm) yields negligible photochemistry in alkane or 2-MeTHF glasses but yields associative photosubstitution of C2H4, C5H10, and 13CO but not N2 or 2-MeTHF for CO at 90 K.Long wavelegth (λ > 540 nm) excitation of Fe3(CO)12 yields no photochemistry at 90 K but gives assymetric fragmentation in C2H4-containing alkane solutions at 298 K to yield 1 equiv each of Fe(CO)5, Fe(CO)4(C2H4), and Fe(CO)3(C2H4)2; competitive photosubstitution occurs in the presence of PPh3 to yield Fe3(CO)11(PPh3).At 195 K, the Fe3(CO)11L/Fe(CO)5-n(L)n (L = C2H4, PPh3; n = 0-2) product ratios increase with decreasing irradiation wavelegth.Long wavelegth (λ > 420 nm) irradiation of o.2 mM Ru3(CO)12 in 195 K alkane solutions containing excess L = CO or C2H4 initially yields 1 equiv each of Ru(CO)4L and Ru2(CO)8L; Ru2(CO)8(C2H4) fragments at 195 K to yield 2 more equiv of Ru(CO)4(C2H4).Long wavelength irradiation of Ru3(CO)12 in PPh3-containing solutions at 195 K yields conversion to a CO-bridged product which reacts thermally at 195 K to form Ru(CO)11(PPh3), in competition with Ru3(CO)12 regeneration; Ru(CO)4(PPh3) and Ru(CO)3(PPh3)2 are only observed as secondary photoproducts at 195 K.The low temperature photochemistry of Ru3(CO)12 is discussed in terms of a wavelength-dependent competition between dissociative loss of equatorial CO from higher energy excitation and generation of a nonradical, reactive isomer of Ru(CO)12 from long wavelength excitation.Implications of the new results for the photocatalyzed isomerization of 1-pentene to cis- and trans-2-pentene by M3(CO)12 (M = Ru, Fe) precursors are discussed.
- Bentsen, James G.,Wrighton, Mark S.
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p. 4530 - 4544
(2007/10/02)
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- ELECTRON TRANSFER IN ORGANOMETALLIC CLUSTERS XI. REDOX CHEMISTRY OF M3(CO)12 (M = Ru, Os) AND PPh3 DERIVATIVES; MECHANISM OF CATALYSED NUCLEOPHILIC SUBSTITUTION
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The generality of a two-electron reduction process involving an mechanism has been established for M3(CO)12 and M3(CO)12-n(PPh3)n (M = Ru, Os) clusters in all solvents.Detailed coulometric and spectral studies in CH2Cl2 provide strong evidence for the formation of an 'opened' M3(CO)122- species the triangulo radical anions M3(CO)12 having a half-life of -6 s in CH2Cl2.However, the electrochemical response is sensitive to the presence of water and is concentration dependent.An electrochemical response for 'opened' M3(CO)122- is only detected at low concentrations -4 mol dm-3 and under drybox condition.The electroactive species found at higher concentrations and in the presence of water M3(CO)112- and M6(CO)182- were confirmed by a study of the electrochemistry of these anions in CH2Cl2; HM3(CO)11- is not a product.The couple -/2- is chemically reversible under certain conditions but oxidation of HM3(CO)11- is chemically irreversible.Different electrochemical behaviour for Ru3(CO)12 is found when (X = OAc-, Cl-) salts are supporting electrolytes.In these solutions formation of the ultimate electroactive species - at the electrode is stopped under CO or at low temperatures but Ru3(CO)12- is still trapped by reversible attack by X presumably as 1-C(O)XRu3(CO)11>-.It is shown that electrode-initiated electron catalysed substitution of M3(CO)12 only takes place on the electrochemical timescale when M = Ru, it is slow, inefficient and non-selective, whereas BPK-initiated nucleophilic substitution of Ru3(CO)12 is only specific and fast in ether solvents particularly THF.Metal-metal bond cleavage is the most important influence on the rate and specificity of catalytic substitution by electron or -initiation.The redox chemistry of M3(CO)12 clusters (M = Fe, Ru, Os) is a consequence of the relative rates of metal-metal bond dissociation, metal-metal bond strength and ligand dissociation and in many aspects resembles their photochemistry.
- Downard, Alison J.,Robinson, Brian H.,Simpson, Jim,Bond, Alan M.
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p. 363 - 384
(2007/10/02)
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- Synthesis and Structural Characterisation of the Hexanuclear, Bimetallic, Ladder-like Cluster HRu5Cu(CO)18PPh3
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The bimetallic cluster HRu5Cu(CO)18PPh3 has been prepared by the reaction of CO with H3Ru4(CO)12CuPPh3, characterised by X-ray crystal structure analysis, and shown to contain a 'ladder-like' arrangement of Ru5Cu based on triangular units.
- Evans, John,Street, Andrew C.,Webster, Michael
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p. 637 - 638
(2007/10/02)
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- Photoreactions of the Triruthenium Cluster Ru3(CO)12 and Substituted Analogues
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Reported is a comprehensive investigation of the medium, ligand, and wavelength effects on the quantum yields and flash photolysis kinetics for the photofragmentation and photosubstitution reactions of the trinuclear ruthenium cluster Ru3(CO)12.Also described are some related studies of the substituted clusters Ru3(CO)12-nLn (L =P(OCH3)3, PPh3, P(p-tolyl)3, or P(O(o-tolyl))3).These results are interpreted in terms of the following model for Ru3(CO)12 photochemistry.Photofragmentation (e.g.Ru3(CO)12 + 3L -> 3Ru(CO)4L) occurs predominantly from the lowest energy excited state and proceeds via an intermediate (I) isomeric to Ru3(CO)12 but not a diradical.I is proposed to have one coordinatively unsaturated ruthenium center trapable by a two-electron donor, i.e., L, to give a second intermediate Ru3(CO)12L which is the precursor to the photofragmentation products.Kinetic flash photolysis observations demonstrate that the lifetime of the latter intermediate is markedly dependent on the nature of L.Photosubstitution reactions (e.g., Ru3(CO)12 + L -> Ru3(CO)11L + CO) are proposed to occur largely from higher energy excited states via CO dissociation to give the unsaturated intermediate Ru3(CO)11, and flash photolysis studies establish the reactivity of this species with various L to follow the order CO > P(OCH3)3 > PPh3.
- Desrosiers, Marc F.,Wink, David A.,Trautman, Ray,Friedman, Alan E.,Ford, Peter C.
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p. 1917 - 1927
(2007/10/02)
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- THE PREPARATION, CHARACTERIZATION AND SOME REACTIONS OF AND
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The clusters and have been prepared from the reaction of with NMe3O in the presence of CH3CN.Thus, these new clusters have been shown to be convenient precursors in the preparation of other Ru3 cluster spec
- Foulds, G. A.,Johnson, B. F. G.,Lewis, J.
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p. 147 - 154
(2007/10/02)
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- CLUSTER CHEMISTRY. XVII. RADICAL ION-INITIATED SYNTHESES OF RUTHENIUM CLUSTER CARBONYLS CONTAINING TERTIARY PHOSPHINES, PHOSPHITES, ARSINES, SbPh3 OR ISOCYANIDES
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The syntheses of over sixty known and new derivatives of Ru3(CO)12 and H4Ru4(CO)12 by substitution reactions initiated by sodium diphenylketyl are described.The range of ligands studied includes isocyanides, tertiary phosphines and phosphites, tertiary ar
- Bruce, Michael I.,Matisons, Janis G.,Nicholson, Brian K.
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p. 321 - 344
(2007/10/02)
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- Cluster Chemistry. V. Reactions Between t)> and and Related Chemistry: Crystal and Molecular Structures of Di-μ-carbonyl->-dicarbonyl(triphenylphosphine)ruthenium(2Ru-Pt)(Pt-Pt), ...
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The reaction between t)> and (Pt(η-C2H4)(PPh3)2> at -30 deg C affords the thermally unstable intermediate complex (A), which decomposes at room temperature affording, inter alia, (1), (2), t)(PPh3)> (5) and t)(PPh3)> (6).The hexanuclear complexes t)(PPh3)4+n> are obtained, with t)(PPh3)4> (16), from reactions at 80 deg C.Related Ru2Pt and RuPt2 complexes are obtained from reactions between complex (A) and CO, CNBut, PMe3, P(C6H4Me-p)3, or P(OMe)3; related reactions between t)> and 4>, and between t)2> and , are also described.The crystal structure of has been determined by single-crystal X-ray diffraction methods at 295(1) K and refined by least squares to a residual of 0.035 for 6774 'observed' reflections.Crystals are triclinic, P1, a 15.893(5), b 15.400(5), c 12.651(4) Angstroem, α 57.04(2), β 77.09(3), γ 84.10(3) deg, Z 2.Crystals of the dibenzene solvate of complex are monoclinic, P21/c, a 11.868(4), b 18.647(8), c 29.24(1) Angstroem, β 98.35(3) deg, Z 4, the structure being refined to a residual of 0.057 for 4530 'observed' reflections.Ligand dispositions are compared in detail with those observed in the analogous compound previously described with the methyldiphenylphosphine ligand.
- Bruce, Michael I.,Matisons, Janis G.,Skelton, Brian W.,White, Allan H.
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p. 687 - 708
(2007/10/02)
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