Reaction of alkenyl carbonyl ruthenium(II) complexes with t-butyl isocyanide. Synthesis of η1-acylruthenium(II) complexes by intramolecular CO insertion

Reaction of Ru(CO)Cl(CHCHR)(PPh₃)₂ or Ru(CO)Cl(CHCHR)(PPh₃)₂L (L = py, Me₂Hpz) with 1 equivalent of t-butyl isocyanide gives the alkenyl derivatives Ru(CO)Cl(CHCHR)(PPh₃)₂(t-BuNC). When an excess of isocyanide is used, further reaction results in intramolecular CO insertion to yield η¹-acyl complexes [Ru(COCHCHR) (t-BuNC)₃(PPh₃)₂]Cl. Related complexes were obtained from [Ru(CO)(CHCHR)(MeCN)₂(PPh₃)₂]PF₆ and an excess of isocyanide.     

Chemistry of vinylidene complexes: IV. Synthesis and the crystal and molecular structure of (η5-C5H5)MnOs3(μ2-CHCHPh)(μ-H)(μ-CO)(CO)11, an unusual heterometallic cluster

By the reaction of Cp(CO)₂MnCCHPh (I) with H₂Os₃(CO)₁₀ (II) the tetranuclear mixed-metal complex CpMnOs₃(μ₂-CHCHPh)(μ-H)(μ-CO)(CO)₁₁ (III) was prepared. An X-ray study of the structure of III showed that it is a spiked, tetranuclear cluster with the Mn atom linked to one of the vertices of the osmium triangle; the MnOs bond is bridged by CO and CHCHPh groups, the latter being σ-bonded to Os and η²-coordinated by Mn. In the course of the formation of III, hydrogenation and n-π rearrangement of the initial phenylvinylidene ligand take place. In solution, complex III readily eliminates the [CpMn(CO)₂] fragment to give triosmium clusters containing unsaturated organic ligands: HOs₃(μ₂-CHCHPh)(CO)₁₀, H₂Os₃(μ₃-CHCPh)(CO)₉, and H₂Os₃(μ₃-CCHPh)(CO)₉.     

Addition of dimethylphenylphosphine at bridging vinyl,acetylene and phenylacetylide ligands in triosmium clusters

PMe₂Ph readily adds at carbon in the compounds HO_S3 (CHCH₂)(CO)₁₀, HO_S3(CCPh)(CO)₁₀ and O_S3 (CHCH)(CO)₁₀ to give zwitterionic 1:1 adducts; the addition to the vinyl compound is reversible and further reaction leads to O_S3 (CO)₁₀ (PMe₂Ph)₂ with ethylene displacement.     

Vinylidene complexes of transition metals : III. Derivatives of cyclopentadienyltricarbonyl rhenium with phenylvinylidene ligands. Crystal and molecular structure of Cp(CO)2Re[CC(Ph)C(Ph)CH2]Re(CO)2Cp

The novel complexes CpRe(CCHPh)(CO)₂ and Cp₂Re₂(μ-CCHPh)(CO)₄ containing a terminal and a bridging phenylvinylidene ligand respectively and the binuclear complex Cp(CO)₂Re[CC(Ph)C(Ph)CH₂]Re(CO)₂Cp were obtained in the reaction of CpRe(CO)₃ with PhCCH.According to an X-ray study of the latter complex the unusual bridging ligand is η¹-bonded to one Re atom and η²-bonded to the other.     

Oxide promoted isomerisation of an isonitrile complex,H2Os3(CO)10[CN(CH2)3Si(OEt)3]

The isomerisation of H₂Os₃(CO)₁₀[CN(CH₂)₃Si(OEt)₃] to HOs₃(CO)₁₀-[CN(H)(CH₂)₃Si(OEt)₃] is accelerated by interaction with some oxides; both complexes afford HOs₃(CO)₁₀[CN(H)(CH₂)₃Si(OEt)_3it-x(O)x] as oxide supported clusters.     

Reactions of triosmium clusters with organic azides; x-ray crystal structures of [Os3(CO)10(NCMe)(N3COPh)], [Os3(μ-H)(CO)10(HN3Ph)], and [Os3(μ-H)2(CO)9(μ3-NPh)]

Organic azides [N₃R] react with [Os₃(CO)₁₁(NCMe)] and with [Os₃(μ-H)₂(CO)₁₀] to form [Os₃(CO)₁₀(NCMe)(N₃COR)] (R  Ph) and [Os₃(μ-H)(CO)₁₀(HN₃R)] (R  Ph, n-Bu, CH₂Ph, cyclo-C₆H₁₁), respectively; the latter may be converted to [Os₃(μ-H)₂(CO)₉(μ₃-NR)] by thermolysis; the molecular structure of the phenyl derivative of each class of compound has been confirmed by x-ray analysis.     

Reactions involving hydrogen transfer from triosmium clusters to an activated nitrile

The reactions of H₂Os₃(CO)₁₀, Ia and H₂Os₃(CO)₉PMe₂Ph, Ib with CF₃CN have been investigated. Both la and Ib react with CF₃CN to give the products HOs₃[μ-η₂-(CF₃)CNH](CO)₉Land HOs₃[μ-η¹-NC(H)CF3](CO)₉L, IIa, IIIa, L = CO; IIb and IIIb, L = PMe₂Ph. IIb and IIIb have been characterized crystallographically. In each, one nitrile molecule was added to the cluster and one hydride ligand was transferred to the nitrile ligand, but in IIb the hydride was transferred to the nitrogen atom to form a CF₃CNH ligand which bridges an edge of the cluster while in IIIb the hydride was transferred to the carbon atom to form a CF₃(H)CN ligand which also bridges an edge of the cluster. On the basis of spectroscopic measurements IIa and IIIa are believed to have analogous structures. An isotope scrambling experiment established that the formation of Ilia occurs by an intramolecular process. IIa was decarbonylated to yield the compound HOs₃[μ₃-η₂-(CF₃)CNH](CO)₉, which is believed to contain a triply-bridging iminyl ligand. Ilia reacts with PMe₂Ph to give two mono-substitution products, one of which is IIIb.     

Synthesis of organometallic hydrotris(pyrazol-1-yl)boratoruthenium(II) complexes

The reactions of K[HB(pz)₃] (pz = pyrazol-1-yl) with the coordinatively unsaturated σ-vinyl complexes [Ru(CRCHR)Cl(CO)(PPh₃)₂] (R = H, Me, C₆H₅) proceed with loss of a chloride and a phosphine ligand to provide the compounds [Ru(CRCHR)(CO)(PPh₃){HB(pz)₃}] in high yield. Similar treatment of the complex [Ru(C₆H₄Me-4)Cl(CO)(PPh₃)₂] leads to the related σ-aryl derivative [Ru(C₆H₄Me-4)(CO)(PPh₃){HB(pz)₃}] whilst the complex [RuClH(CO)(PPh₃)₃] treated successively with diphenylbutadiyne and K[HB(pz)₃] provides the unusual derivative [Ru{C(CCPh)CHPh}(CO)(PPh₃){HB(pz)₃}].     

Synthetic studies of the reaction between aldehydes and the triosmium cluster [Os3(CO)10(NCMe)2]

The reaction of [Os₃(CO)₁₀(NCMe)₂] (1) with aldehydes in refluxing cyclohexane affords the metal clusters [Os₃(CO)₁₀(μ-H)(COR)] (2, R = Me, Ph, CH₂Ph or C₆H₁₃) in ca. 50% yield. The compound 2 (R = CH₂Ph) undergoes hydrogenation under pressure to give the corresponding alcohol, while decarbonylation occurs in the presence of Me₃NO to give the Me₃N-substituted derivative [Os₃(CO)₉(NMe₃)(μ-H)(COCH₂Ph)] in 90% yield.     

Formation of the triosmium μ-carbyne complex in the reaction of with dimethylphenylphosphine. X-ray structure of HOs3(CO)10{μ-CC(Ph)CC(Ph)Re(CO)4PMe2Ph}

The μ-acyl complex B″O

(I) reacts with PMe₂Ph to yield the allenyl-substituted μ-carbyne complex HOs₃(CO)₁₀{μ-CC(Ph)CC(Ph)Re(CO)₄PMe₂Ph} (II). Complex II has been characterized by an X-ray structural study.     

Coordination,oligomerisation and transfer hydrogenation of acetylenes by some ruthenium and osmium carboxylates: Crystal and molecular structures of bis(trifluoroacetato)carbonyl-(methanol) bis(triphenylphosphine)ruthenium(II) and (1,4-diphenylbut-1-en-3-yn-2-yl)trifluoroacetato-(carbonyl) bis(triphenylphosphine)ruthenium(II)

The hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] (M = Ru or Os) react with disubstituted acetylenes PhCCPh and PhCCMe to afford vinylic products [M{C(Ph)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] and [M{C(Ph)CHMe}(O₂CCF₃)(CO) (PPh₃)₂]/[M{C(Me)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] respectively. Acidolysis of these products with trifluoroacetic acid in cold ethanol liberates cis-stilbene and cis-PhHCCHMe respectively thus establishing the cis-stereochemistry of the vinylic ligands. The complexes [M(O₂CCF₃)₂(CO)(PPh₃)₂] formed during the acidolysis step undergo facile alcoholysis followed by β-elimination of aldehyde to regenerate the parent hydrides [MH(O₂CCF₃)(CO)(PPh₃)₂] and thereby complete a catalytic cycle for the transfer hydrogenation of acetylenes. The molecular structure of the methanol-adduct intermediate, [Ru(O₂CCF₃)₂(MeOH)(CO)(PPh₃)₂] has been determined by X-ray methods and shows that the coordinated methanol is involved in H-bonding with the monodentate trifluoroacetate ligand [MEO-H---OC(O)CF₃; O...O = 2.54 Å]. The hydrides [MH(O₂CCF₃)(CO) (PPh₃)₂]react with 1,4-diphenylbutadiyne to afford the complexes [M{C(CCPh)CHPh} (O₂CCF₃)(CO)(PPh₃)₂]. The ruthenium product, which has also been obtained by treatment of [RuH(O₂CCF₃)(CO)(PPh₃)₂] with phenylacetylene, has been shown by X-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand. The osmium complexes [Os(O₂CCF₃)₂(CO)(PPh₃)₂], [OsH(O₂CCF₃)(CO)(PPh₃)₂] and [Os{C(CCPh)CHPh}(O₂CCF₃)(CO)(PPh₃)₂] all serve as catalysts for the oligomerisation of phenylacetylene. Acetylene reacts with [Ru(O₂CCF₃)₂(CO)(PPh₃)₂] in ethanol to afford the vinyl complex [Ru(CHCH₂)(O₂CCF₃)(CO)(PPh₃)₂].     

The Preparation and 13C nmr Spectra of some Trinuclear Osmium Complexes Containing an O-Alkylated Carbonyl Group.

The new osmium clusters [HOs₃(CO)₉(CNBu^t)(COR)] (R = Me or Et) and [HOs₃(CO)₉(CNBu^t)(COMe)] have been prepared via the alkylation of [HOs₃(CO)₁₁]^?. These clusters contain an O-alkylated carbonyl group and are structurally different from the isomeric bridging acyl complexes [HOs₃(CO)₁₀(COR)] which have been reported previously. The two isomers do not interconvert even at elevated temperatures.The ¹³C nmr spectra of the new complexes are reported together with the ¹³C spectrum of the analogous iron complex [HFe₃(CO)₁₀ (COMe)]. Alkyl group ‘flipping’ and polytopal rearrangement of the M(CO)₄ and M(CO)₃ units are observed for M = Os and Fe but there is no scrambling of CO groups between metal centres on the nmr timescale.     

Modification of the acid-base properties of hydroxycarbonyl complexes of iridium(III) by substitution of carbon monoxide by a tertiary phosphine ligand

A dichloromethane solution of the cationic carbonyl complex [IrCl₂(CO)(PMe₂Ph)₃)][ClO₄] reacts with aqueous KOH to give [IrCl₂(CO₂H)(PMe₂Ph)₃] which has been characterised spectroscopically. This CO₂H compound is very much more basic and very much less acidic than [IrCl₂(CO₂H)(CO)(PMe₂Ph)₂). Tertiary amines will not deprotonate [IrCl₂(CO₂H)(PMe₂Ph)₃] while Li[N(SiMe₃)₂] leads to decarboxylation products trans, mer- and cis, mer-[IrHCl₂(PMe₂Ph)₃]. The mechanisms of these reactions are considered and the hydroxycarbonyl complex is compared with its formato isomer which decarboxylates much less readily.     

Insertion of acetylene into osmium-hydrogen bonds incluster complexes

Complex H₂ Os₃ (CO)₁₀ reacts with acetylene or methyl-substituted acetylenes to give complexes of type HOs₃ (CH=CHR)(CO)₁₀ (R = H or Me) and Os₃ (R₁ C₂ R₂)(CO)₁₀ (R₁ and R₂ are H or Me) which convert to nonacarbonyl complexes with hydrogen transfer from ligand to metal.     

Addition and elimination of hydrogen and ligand substitution on triosmium clusters. Kinetics and mechanism

The kinetics of the reversible reaction HOs₃(μ-COMe)(CO)₁₀ + H₂ ? H₃Os₃(μ³-COMe)(CO)₉ + CO has been investigated. The reaction of HOs₃(μ-COMe)(CO)₁₀ with hydrogen involves dissociation of a CO ligand prior to the rate-determining step, which is proposed to be the oxidative addition of molecular hydrogen. The reaction of H₃Os₃(μ₃-COMe)(CO)₉ with CO involves rate-limiting hydrogen loss. The equilibrium constant and the competition ratio for hydrogen and CO for the unsaturated intermediate were determined. The mechanism of substitution by AsPh₃ on HOs₃(μ-COMe)(CO)₁₀ also involves a CO dissociative mechanism. Based upon relative rate constants for CO, AsPh₃, and hydrogen addition to HOs₃(COMe)(CO)₉, CO dissociation and hydrogen addition are proposed to occur at different metal sites.     

Synthesis and structural characterisation of an unsaturated osmium-gold cluster HOs3Au(CO)10(PR3) (R  Et,Ph); x-ray crystal structures of HOs3Au(CO)10(PPh3) and Os3Au(CO)10(PPh3)(SCN)

The reaction of [HOs₃(CO)₁₁]^? with AuClPR₃ (R  Et, Ph) yields the complex HOs₃Au(CO)₁₀(PR₃), and the PPh₃ derivative has been characterised by an X-ray analysis; the structure is compared with that of Os₃Au(CO)₁₀(PPh₃)-(SCN) and is shown to contain a formally unsaturated OsOs bond.     

[Fec3(μ3-CR)(CO)10]− Cluster anions as building blocks for the synthesis of mixed-metal clusters: II. Synthesis of HFe3Rh(μ4-η2-CCHR)(CO)11 clusters (R = H or C6H5) and study of their catalytic activity (R = C6H5) under hydroformylation and hydrogenation conditions

The mixed-metal vinylidene clusters HFe₃Rh(CO)₁₁(CCHR) (R = H, C₆H₅) have been synthesized via the reaction of [HFe₃(CO)₃CCHR][P(C₆H₅)₄] with [RhCl(CO)₂]₂ in the presence of a thallium salt. The reaction initially gives the [Fe₃Rh(CO)₁₁]CCHR][P(C₆H₅)₄] cluster which leads to the final products by protonation. Spectroscopic data indicate a μ₄-η² mode of bonding for the vinylidene ligand. A structure with a Fe₃Rh core in a butterfly configuration and in which the rhodium atom occupy a wing-tip site is proposed. The catalytic activity of HFe₃Rh(CO)₁₁(CCH(C₆H₅)) (80% yield) has been checked in hydroformylation and hydrogenation. In hydroformylation the cluster shows the same activity as Rh₄(CO)₁₂, whereas in hydrogenation the mixed-metal system shows specific activity; isomerization of 1-heptene to cis and trans 2-heptene takes place with no more than 14% heptane formation. The cluster is broken down during the catalysis, and some H₃Fe₃CO)₉(μ₃-CCH₂(C₆H₅)) is formed. The latter cluster is not an active catalyst, and under the same conditions use of Rh₄(CO)₁₂ results mainly in hydrogenation of 1-heptene. These observations suggest that the active species is a mixed iron-rhodium system.     

Synthesis and X-ray structure of the osmium carbonyl anion [HOs3(CO)10 · O2C · Os6(CO)20]−

The reaction of [HOs₃(CO)₁₁]⁻¹¹ with [Os₃(CO)₁₀(MeCN)₂] in acetone gives the green-blue anion [HOs₃(CO)₁₀·O₂C·Os₆(CO)₂₀]⁻ (1) amongst several other products; this anion has been structurally characterised by a single crystal X-ray study of its Bu₄P⁺ salt.     

The synthesis of thionitrosodimethylamine (Me2NNS) complexes of ruthenium,osmium, and iridium

Neutral hydrido complexes [ML]ClH(PPh₃)₃ ([ML] = Ru(CO), Os(CO) and Ir(Cl)] react with thionitrosodimethylamine, Me₂NNS, to give [ML]ClH-(SNNMe₂)(PPh₃)₂ with H trans to Me₂NNS, while the hydrido cations cis,trans-[[ML]H(SNNMe₂)₂(PPh₃)₂]⁺ are obtained from Me₂NNS and [Ru(NCMe)₂(CO)-(PPh₃)₂]⁺, [OsH(OH₂)(CO)(PPh₃)₃]⁺ and [IrClH(NCMe)₂(PPh₃)₂]⁺, respectively. The coordinatively unsaturated aryl complexes [ML′]Cl(p-tolyl)(PPh₃)₂ ([ML′]Ru(CO), Os(CO) and Os(CS)) coordinate one molecule of Me₂NNS to give [ML′]Cl(p-tolyl)(SNNMe₂)(PPh₃)₂, the chloride ligands of which are labile. Spectroscopic data suggest that in all these complexes the Me₂NNS ligand adopts a η¹(S) coordination mode.     

Hydride-phosphoniodithiocarboxylate/ phosphonium-betaine isomerism in Cy3PCS2 complexes of ruthenium

Reaction of Cy₃PCS₂ (Cy = cyclohexyl) with the hydrido complexes [RuClH(CA)(PPh₃)₃] (A  O, S), [RuH(CO)(NCMe)₂(PPh₃)₂]⁺, and [RuH(OClO₃)(CO)(CN^tBu)(PPh₃)₂] leads to the complex cations [RuH(CA)(PPh₃)₂(η²-S₂CPCy₃)]⁺, [Ru(η²-S₂CHPCy₃)(CO) (PPh₃)₂]⁺, [RuH(η¹-S₂CPCy₃)(CO)(CN^tBu)(PPh₃)₂]⁺. The σ-vinyl complex [Ru(CHCHC₆H₄Me-4)Cl(CO)(PPh₃)₂] reacts with Cy₃PCS₂ to give the cationic complex [Ru(CHCHC₆H₄Me-4) (CO)(PPh₃)₂(η²-S₂CPCy₃)]⁺, but this complex is not formed by hydroruthenation of HCCC₆H₄Me-4 by [RuH(CO)(PPh₃)₂(η²-S₂CPCy₃)]⁺. The inter-relationships between the above complexes are discussed.