The [Os3(µ-H)(CO)10(MeCN)2]+ cation: synthesis and X-ray crystal structure of [Os3(µ-H)(CO)10(MeCN)2][Os(CO)3Cl3]

Abstract

The clusters [Os₃(CO)₁₁(MeCN)] and [Os₃(CO)₁₀(MeCN)₂] react with acids HX (X = BF₄ or PF₆) to form the cationic derivatives [Os₃(µ-H)(CO)₁₁(MeCN)]X and [Os₃(µ-H)(CO)₁₀(MeCN)₂]X, respectively. The cluster [Os₃(CO)₁₀(MeCN)₂] also reacts with dry HCl to form the salt [Os₃(µ-H)-(CO)₁₀(MeCN)₂][Os(CO)₃Cl₃]. X-Ray analysis of this salt shows that the Os atoms in the cation lie at the vertices of an isosceles triangle. A hydride bridges the long Os–Os edge, and the two acetonitrile ligands occupy trans axial sites. Reaction of [Os₃(µ-H)(µ-OH)(CO)₁₀] with HBF₄ in MeCN also produces [Os₃(µ-H)(CO)₁₀(MeCN)₂]⁺. In this reaction direct attack of H⁺ on the co-ordinated OH^– ligand is considered to occur with the resultant liberation of H₂O. Treatment of [Os₃(µ-H)(CO)_10^–(MeCN)₂]⁺ with [Os(CO)₄]^–2 leads to the formation of the neutral complex [Os₄H₂(CO)₁₄(MeCN)]. The bridging hydride of the cation may also be replaced by a bridging nitrosyl ligand by reaction with NO⁺.