Lionel P. Clarke

Reaction of [Os3H2(CO)10] with the diyne Me3SiC2C2SiMe3 and the reactivity of the products towards [Co2(CO)8]: the X-ray structures of [Os3(μ-H)(CO)10{μ-η1-η2-HC2(SiMe3)C2(SiMe3)}], [Os3(μ-CO)(CO)9{μ3-η2-Me3SiC2C2SiMe3}] and [Os3(μ-H)(CO)9{μ3-η1:η2-;μ-η2-Me3SiC2C2[Co2(CO)6]}]

Abstract The reaction of [Os3H2(CO)10] with Me3SiC2C2SiMe3 affords both [Os3(μ-H) (CO)10{μ-η1-η2-HC2(SiMe3)C2(SiMe3)}] (1) and [Os3(μ-CO)(CO)9(μ3-η2-Me3SiC2C2SiMe3)] (2) in good yield, 2 being favoured with an excess of diyne. In 1, one edge of the triosmium unit is bridged by the vinyl moiety of a transformed bis(trimethylsilyl)-1,4-butadiyne ligand that has undergone a hydride transfer and a 1,2-trimethylsilyl shift. Compound 2 is selectively desilylated in methanol to produce a single isomer of the known cluster [Os3(μ-CO)(CO)9{μ3-η2-HC2C2SiMe3}] (3). Whereas reaction of 3 with [Co2(CO)8] results in the production of the previously reported cluster [Os3{μ3-η2-:μ-η2-(Me3SiC2C2H)[Co2(CO)6]}(μ-CO)(CO)9] (4) and a second product [Os3(μ-H)(CO)9{μ3-η1:η2-;μ-η2-Me3SiC2C2[Co2(CO)6]}] (5), the reaction of 1 and 2 results in recovery of the starting material or transfer of the alkyne ligand to the Co2 unit. Compound 4 undergoes a transformation to 5 in visible light. All the cluster complexes have been characterized spectroscopically, and the solid-state structures of 1, 2 and 5 have been determined by single-crystal X-ray diffraction.

Reactions of [Os-3(CO)(10)(NCMe)(2)] with symmetric diynes and their reactivity towards [Co-2(CO)(8)]

Abstract The reaction between [Os3(CO)10(NCMe)2] and MeC2C2Me yields the known cluster [Os3(CO)9(μ-CO)(μ3-η2-MeC2C2Me)] (1) and three previously uncharacterised products [Os3(CO)9(μ-CO){μ3-η2:μ3-η1:η1:η3-MeC2C2MeOC5Me2)Os3(μ-CO)(CO)9] (2), [Os3(CO)9{μ3-η4-[(MeC2)C2(Me)]CO[(Me)C2(C2Me)]}] (3) and [Os3(CO)9{μ3-η4-[(MeC2)C2(Me)]CO[(MeC2)C2(Me)]}] (4). The structures of 2 and 3 have been determined by X-ray crystallography. Cluster 2 incorporates two linked triosmium clusters joined by an unsaturated five-membered metallacycloether ring and 3 exhibits an alkyne-functionalised metallacyclohexadieneone ring. 1–4 and [Os3(CO)9(μ-CO)(μ3-η2-PhC2C2Ph)] (5) react with [Co2(CO)8] to form products 6–11 in which one free alkyne function coordinates to a Co2(CO)6 unit in each case; the cluster [{Os3(CO)10}{Co2(CO)6}{μ3-η2-‖-(MeCC)(μ2-η2(CCMe)}] (6) has been structurally characterised. The reaction of 1 and 5 with Me3NO–MeCN leads to the replacement of one CO ligand with MeCN, the products 12 and 13 reacting with H2O to form [Os3(CO)9(μ-OH)(μ3-η1:η2:η2-RC3CHR)] (R=Me (two isomers 14, 15), Ph (16)); the X-ray structure of 16 is reported. Reaction of 3 with Me3NO–MeCN results in the substitution of a CO ligand with either a MeCN or NMe3 ligand at the metallocyclic Os atom to afford the clusters [Os3(CO)8(L)(μ3-η1:η1:η2:η2-{(MeC2)C2(Me)}2CO)] (L=NCMe (17), NMe3 (18)).

Molecular rearrangements of diynes coordinated to triosmium carbonyl clusters: reactions of [Os3(μ-H)2(CO)10] and [Os3(CO)10(MeCN)2] with 1,4-dipyridylbuta-1,3-diyne

Reaction of [Os3(μ-H)2(CO)10] with 1,4-dipyridylbuta-1,3-diyne yields two clusters, [Os3(μ-H)(CO)10{μ-η1:η1-(C8H5N)–C–(C5H4N)}] 1 and [Os3(μ-H)(CO)10-{μ3-η1:η1:η1-(C5H4N)–C–C(C8H6N)}] 2, in which the diyne has rearranged to form a substituted indolizine ring system. Complex 1 converts slowly to 2 at room temperature, and may be decarbonylated to yield [Os3(μ-H)(CO)9{μ-η1:η2:η1-(C8H5N)–C–(C5H4N)}] 3. An analogous reaction involving [Os3(CO)10(MeCN)2] generates three products, [Os3(μ-H)(CO)10{μ-η1:η1-(NC5H3)–C2C2–(C5H5N)}] 4 and [{Os3(μ-H)(CO)10}2{μ-η1:η1-(NC5H3)–C2–}2] 5, both coordinated via orthometallated pyridyl rings, and a minor product [{Os3(CO)10}2{μ3-η1:η1:η1-C2-(NC5H4)}2] 6, coordinated via μ-carbene and σ-N interactions, the linking ligand retaining its central CC bond. Complex 4 reacts with [Os3(μ-H)2(CO)10] to form the linked cluster [{Os3(μ-H)(CO)10}2{μ-η1:η1,μ-η1:η1-(C8H5N)–C–(C5H3N)}] 7, also forming an indolizine ring system. The structures of 1–3, 6, 6·2[CH2Cl2] and 7 have been established by X-ray crystallography.

Polynuclear carbonyl clusters containing heterocyclic hydrocarbons. The synthesis and X-ray crystal structure of [Os3H(CO)9(NMe3) (μ-COC4H4N)] {μ-CONC4H4 = 2-acylpyrrole}

Abstract The reaction between the acyl-substituted triosmium cluster [Os 3 H(CO) 10 (μ-COC 4 H 4 N)] and trimethylamine-N-oxide, at −78°C, yields not the expected pyrrole-linked cluster but the novel trimethylamine complex [Os 3 H(CO) 9 (NMe 3 )(μ-COC 4 H 4 N)] ( 1 ). An X-ray crystal structure of the product shows that it consists of an η 2 -2-acylpyrrole bridged triosmium unit incorporating a terminally coordinated trimethylamine ligand which occupies an equatorial site on the osmium triangle.

Synthesis, characterisation and electrochemistry of the novel ferrocenyl-dienediyltriosmium cluster [Os3(CO)9{µ3-η4-Fe[C5H4(C2SiMe3)]2}]

The reaction between [Os3(CO)10(MeCN)2] and [Fe{C5H4(C2SiMe3)}2] yielded [Os3(CO)10{µ3-η2-Fe[C5H4(C2SiMe3)]2}]1 and the decarbonylated product of this complex, [Os3(CO)9{µ3-η4-Fe[C5H4(C2SiMe3)]2}]2, the structure of which has been shown by X-ray crystallography to incorporate a triosmium cluster linked via a metallobutadienyl ligand to a ferrocene unit; the cyclic voltammogram of 2 shows a reversible one-electron oxidation of the ferrocene unit and an irreversible two-electron reduction for the triosmium unit.

A new two-strand chain cluster: the synthesis and characterisation of [Os3(CO)11{μ3-η4-(C4H3S)C2C2(C4H3S)}]

Reaction of the labile triosmium cluster [Os3(CO)10(NCMe)2] with the thienyl substituted diyne [(C4H3S)C2C2(C4H3S)] affords [Os3(CO)10{μ3-η2-(C4H3S)C2C2(C4H3S)}] 1 and the novel co-linear cluster [Os3(CO)11{μ3-η4-(C4H3S)C2C2(C4H3S)}] 2 in reasonable yield; the X-ray structure of 2 shows that the diyne is coordinated to an ‘open’ triosmium unit as a 1,2,3-triene-1,4-diyl unit with essentially equal CC bond distances.