Triosmium-antimony clusters containing the μ,η-phenylene ligand: Unusually long osmium-osmium bonds

The reaction of the osmium-antimony cluster Os₃(μ-H)(μ-SbPh₂)(μ₃,η²-C₆H₄)(CO)₉ with AsPh₃ at room temperature afforded the o-phenylene cluster Os₃(μ-H)(SbPh₂)(μ₂,η²-C₆H₄)(CO)₉(AsPh₃) by nucleophilic addition via a metal-metal bond cleavage, and the substitution product Os₃(μ-H)(SbPh₂)(μ₃,η²-C₆H₄)(CO)₈(AsPh₃). It reacted with ^tBuNC to afford the adduct Os₃(μ-H)(SbPh₂)(μ₂,η²-C₆H₄)(CO)₉(CN^tBu) quantitatively. This adduct isomerised slowly on standing via migration of the isonitrile, while photolysis led to decarbonylation to Os₃(μ-H)(SbPh₂)(μ₂,η²-C₆H₄)(CO)₈(CN^tBu). All the products have been characterised completely, including by X-ray crystallography, and their structures exhibit very long Os-Os bonds.     

The preparation,characterisation and some reactions of Os3(CO)9(μ2-H)(μ3-SR) (R  Me or Et)

The complex Os₃(CO)₉(μ₂-H)₂(μ₃-S) reacts with KOH/MeOH to produce the anionic complex [Os₃(CO)₉(μ₂-H)(μ₃-S)^?, which reacts in turn with RO⁺ (R = Me, Et) to form HOs₃(CO)₉SR. This complex is especially reactive towards ligands L (L = C₂H₄, CO, PR₃ and MeCN) to generate complexes of the type Os₃(CO)₉(μ₂-H)(μ₂-SR)(L). At 125°C the complex Os₃(CO)₉(μ₂-H)(μ₂-SR)(C₂H₄) (in the presence of C₂H₄) ejects RH and CO to form Os₃(CO)₈(μ₂-H)?(μ₃-S)(CHCH₂). The structures of the new complexes are described and the probable reaction pathways discussed.     

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.     

Cage Opening of a Carborane Ligand by Metal Cluster Complexes

The reaction of Os₃(CO)₁₀(NCMe)₂ with closo‐o‐C₂B₁₀H₁₀ has yielded two interconvertible isomers Os₃(CO)₉(μ₃‐4,5,9‐C₂B₁₀H₈)(μ‐H)₂ ( 1 a ) and Os₃(CO)₉(μ₃‐3,4,8‐C₂B₁₀H₈)(μ‐H)₂ ( 1 b ) formed by the loss of the two NCMe ligands and one CO ligand from the Os₃ cluster. Two BH bonds of the o‐C₂B₁₀H₁₀ were activated in its addition to the osmium cluster. A second triosmium cluster was added to the 1 a / 1 b mixture to yield the complex Os₃(CO)₉(μ‐H)₂(μ₃‐4,5,9‐μ₃‐7,11,12‐C₂B₁₀H₇)Os₃(CO)₉(μ‐H)₃ ( 2 ) that contains two triosmium triangles attached to the same carborane cage. When heated, 2 was transformed to the complex Os₃(CO)₉(μ‐H)(μ₃‐3,4,8‐μ₃‐7,11,12‐C₂B₁₀H₈)Os₃(CO)₉(μ‐H) ( 3 ) by a novel opening of the carborane cage with loss of H₂.     

Reaction of ethylene with the unsaturated cluster complex H2Os3 (CO)10

Treatment of H₂Os₃(CO)₁₀ with excess ethylene forms ethane and a hydridovinyl cluster complex HOs₃(CO)₁₀(CHCH₂), which rearranges in refluxing octane to the vinylidene complex H₂Os₃(CO)₉(CCH₂).     

Synthesis and characterization of triosmium and triruthenium pyrene clusters

The reaction between 1-pyrenecarboxaldehyde (C₁₆H₉CHO) and the labile triosmium cluster [Os₃(CO)₁₀(CH₃CN)₂] gives rise to the formation of two new compounds by competitive oxidative addition between the aldehydic group and an arene C-H bond, to afford the acyl complex [Os₃(CO)₁₀(μ-H)(μ-COC₁₆H₉)] (1) and the compound [Os₃(CO)₁₀(μ-H) (C₁₆H₈CHO)] (2), respectively. Thermolysis of [Os₃(CO)₁₀(μ-H)(μ-C₁₆H₉CO)] (1) in n-octane affords two new complexes in good yields, [Os₃(CO)₉(μ-H)₂(μ-COC₁₆H₈)] (3) and the pyryne complex [Os₃(CO)₉(μ-H)₂(μ₃-η¹:η¹:η²-C₁₆H₈)] (4).In contrast, when 1-pyrenecarboxaldehyde reacts with [Ru₃(CO)₁₂] only one product is obtained, [Ru₃(CO)₉(μ-H)₂(μ₃-η¹:η¹:η²-C₁₆H₈)] (5), a nonacarbonyl cluster bearing a pyrene ligand. All compounds were characterized by analytical and spectroscopic data, and crystal structures for 1, 2, 4 and 5 were obtained.     

Alkylidyne-alkylidyne and alkylidyne-carbonyl coupling on the triosmium framework

Hydrogenation of Os₃(CO)₉ (μ₃-CPh)(μ₃-COMe) (1) at one atmosphere results in alkylidyne-alkylidyne coupling, forming the alkyne complex (μ-H)₂Os₃(CO)₉(μ₃, η²-C₂(OMe)Ph) (3). Reduction of 1 by two equiv. of sodium benzophenone ketyl, followed by protonation with tetrafluoroboric acid, yields the phenylacetylide complex(μ-H)OS₃(CO)₉(μ₃,η²-CCHPh) (4). Sequential reduction/protonation involving (μ-H)OS₃(CO)₁₀(μ₃-CPh) (2) also generates 4, apparently via benzylidyne-carbonyl coupling.     

Reactions of the triosmium cluster Os3(μ-H)(μ-OH)(CO)10 with naphthols

Reaction of the cluster Os₃(μ-H)(μ-OH)(CO)₁₀ (1) with 1-naphthol afforded the isomeric clusters 2a and 3a with the formulae Os₃(μ-H)₂(μ₃-1-OC₁₀H₆)(CO)₉. A similar reaction with 2-naphthol, however, gave Os₃(μ-H)(μ-2-OC₁₀H₇)(CO)₁₀, 4b, and the analogue of 2a. These clusters have been structurally characterised to confirm the mode of anchoring of the naphthols.     

Reactions of metal carbonyl cluster complexes with multidentate phosphine ligands; preparation of bis(diphenylphosphino)methane derivatives of the trinuclear complexes M3(CO)12 (M = Fe,Ru and Os) and the X-ray crystal structure of Os3(CO)9(μ-dppm)(η1-dppm) (dppm = Ph2pch2ppH2)

The reaction of bis(diphenylphosphino)methane (dppm) with Fe₃(CO)₁₂ gave the known complexes Fe(CO)₄ (dppm), Fe₂(CO)₇ (dppm), in addition to Fe₂CO)₅(dppm)₂. Two new dppm derivatives of Ru₃CO)₁₂, Ru₃(CO)₉(μ-dppm)(η¹-dppm) and Ru₃(CO)₆(dppm)₃ have been isolated and spectroscopically characterised. From the reaction of Os₃(CO)₁₂ with dppm, the derivatives Os₃(CO)₁₀(dppm), Os₃(CO)₉(μ-dppm)(η¹-dppm) and Os₃(CO)₈(dppm)₂ have been isolated. The crystal structure of Os₃(CO)₉(μ-dppm)(η¹-dppm) has been determined.     

Addition reactions of a polynuclear osmium hydrido compound leading to associative carbonyl substitution and catalytic alkene isomerisation

The ability of H₂Os₃(CO)₁₀ to undergo addition reactions under mild conditions allows associative CO substitution via isolable intermediates of the type H₂Os₃(CO)₁₀ (L = CO, PMe₂Ph, PPh₃ or PhCN) whose spectra and structures are discussed. It is probable that simple addition of alkenes to H₂Os₃(CO)₁₀ is in part responsible for its facile catalysis of alkene isomerisation. The kinetics of catalytic conversion of terminal to internal alkenes and of allylic alcohols to aldehydes or ketones are reported and discussed. The reactions of H₂Os₃(CO)₁₀ with allylic halides to give the complexes HOs₃X(CO)₁₀ and Os₃X₂(CO)₁₀ where X = Cl, Br or I are described. Compound H₂Os₃(CO)₁₀ complies with the 18ρ-rule but nevertheless has a chemistry much like that of coordinatively unsaturated molecules.     

Reactions of dodecacarbonyltriosmium with dienic ligands

Dodecacabonyltriosmium reacts with diene ligands (D) such as 2,4-trans, trans- and 2,4-cis, trans-hexadiene and 1,6- and 1,5-heptadiene to give H₂Os₃D(CO)₉, H₄Os₄(CO)₁₂ and two isomers of molecular formula HOs₃-(D  H)(CO)₉ in addition to Os₂(D  2H)(CO)₆ and OsD(CO)₃. The structures of the trimetal complexes show that dehydrogenation, isomerization and rearrangement of the organic substrates occur before the coordination to the metal cluster. 2,3-Dimethyl-1,3-butadiene and dodecacabonyltriosmium give only the well known bi- and mono-metal complexes. The results are compared with those obtained in the reactions of the some organic molecules with dodecacabonyltriruthenium.     

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.     

Triosmium-induced dehydrogenation of triethylamine. The crystal structure of HOs3 (CO)10 (−CHCH+NEt2)

The reaction of Os₃ (CO)₁₀(NCCH₃)₂ and triethylamine provides H₂ Os₃ (CO)₁₀ and HOs₃ (CO)₁₀(CHCHNEt₂) in equimolar amounts. The structure of the latter compound has been shown to involve an iminium ion center anchored to the Os₃ framework by a bridging (substituted) methylene moiety.     

The photochemical and thermal reactions of a triosmium cluster carrying a γ-pyrone ligand with alkynes

The reaction of the cluster Os₃(CO)₁₀(μ-H)(μ-γ-C₅H₃O₂) (1) with a number of alkynes under thermal or visible light irradiation conditions, afforded in most cases the dinuclear complexes Os₂(CO)₆(μ-γ-C₅H₃O₂)(μ-LH) (L=PhCCPh, ^tBuCCH, ^tBuCCMe or EtCCEt) (2) or the trinuclear chain complexes Os₃(CO)₉(μ-H)(μ-γ-C₅H₃O₂)(μ-RCCHC₆H₄) (R=H, Ph) (3). In the case of PhCCPh, a new isomer of Os₃(CO)₈(PhCCPh)₂, viz., Os₃(CO)₈(μ-PhCCPh)(μ-PhCCHC₆H₄) (7) has been isolated and characterised.     

Neutron diffraction structure analysis of [(μ-H)(μ-NCHCF3)Os3(CO)10] at 20 K

The characterisation of (μ-H)(μ-NCHCF₃)Os₃(CO)₁₀ by neutron single crystal structure analysis at 20 K is reported. The 1,1,1-trifluoroethylidenimido ligand derived from the reaction of trifluoroacetonitrile with H₂Os₃(CO)₁₀ bonds as a three-electron donor, symmetrically bridging the same edge of the Os₃ cluster as the μ-hydride ligand.     

Products of the reaction of H2Os3(CO)10 with cyclonona-1,2diene

Treatment of H₂Os₃(CO)₁₀ with cyclonona-l,2-diene produced HOs₃(CO)₉C₉H₁₃ and Os₂(CO)₆(C₉H₄)₂. Single crystal X ray analysis has shown that the latter is not isostructural with Fe₂(CO)₆(C₉H₁₄)₂.     

Triosmium clusters with μ3-AsR group as a building block for hexaosmium-arsenic cluster synthesis. Synthesis and characterisation of [(CO)11Os3As(Os3(CO)9H3)] and [(CO)9H3Os3As(Os3(CO)9H3)]. Crystal structure of [(CO)11Os3As(Os3(CO)9H3)]

Reaction of the activated cluster [Os₃(CO)₁₁(CNMe)] with primary arsine AsH₃ forms the arsinidine compound [H₂Os₃(μ₃-AsH)(CO)₁₁] (1a, 1b), which on further reaction with [Os₃(CO)₁₁(NCMe)] yields [(CO)₁₁Os₃As(Os₃(CO)₉H₃)] (2) and with [H₂Os₃(CO)₁₀] yields [H₂Os₃(CO)₉As(Os₃(CO)₉H₂)] (3). Similarly [H₂Os₃(CO)₁₀] reacts with AsH₃ at room temperature to afford 3 in good yields. Thermal degradation and rearrangement of 2 gives the pentanuclear cluster [H₂Os₅(CO)₁₇AsH] (4).     

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.     

Synthesis and crystal structure of HOs3(CO)9(CCSiMe3)

The functionalised cluster Os₃(CO)₁₀(CH₃CN)₂ reacts at room temperature with trimethylsilylacetylene to afford the orange derivative Os₃(CO)₁₀(Me₃SiC₂H) which undergoes decarbonylation and hydrogen migration to give the cluster HOs₃(CO)₉(CCSiMe₃), which has been fully characterised by an X-ray diffraction study.     

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.