Synthesis of the cluster dianion [Os11C(CO)27]2– by pyrolysis and its reactions with electrophiles; X-ray structure analysis of the mixed-metal derivative [PMePh3][Os11C(CO)27{Cu(NCMe)}]·CH2Cl2 and the hydrido derivative [PMePh3][Os11C(CO)27H]

Abstract

The new cluster species [Os₁₁C(CO)₂₇]^2–(2) has been identified as one of the products resulting from the pyrolysis of [Os₃(CO)₁₂]. It reacts with [Cu(NCMe)₄] BF₄ to yield the monoanion [Os₁₁C(CO)₂₇{Cu(NCMe)}]^–(4) and [Os₁₁C(CO)₂₇{Cu(NCMe)}₂](5). The reaction of (2) with iodine-iodide produces a series of iodo-clusters [Os₁₁C(CO)₂₇I]^–(8) and [Os₁₁C(CO)₂₇I₂](9) which are converted back into (2) by addition of halide ions. The unstable monoanionic species [Os₁₁C(CO)₂₇{M(PMe₂Ph)}]^–[M = Au (3) or Cu (7)] are obtained on reaction of (2) with [M(PMe₂Ph)]⁺, and further reaction of (3) yields [Os₁₁C(CO)₂₇{Au(PMe₂Ph)}₂](6). The dianionic cluster (2) reacts with acid to give the monoanion [Os₁₁C(CO)₂₇H]^–(10) and [Os₁₁C(CO)₂₇H₂](11). The reaction with Hg(C₆Cl₅)(O₂CCF₃) yields initially the unstable monoanion [Os₁₁C(CO)₂₇{Hg(C₆Cl₅)}]^–(12) which is rapidly converted into the known cluster dianion [Os₂₀Hg(C)₂(CO)₄₈]^2–. X-Ray analysis of the [PMePh₃]⁺ salts of (4) and (10) reveal identical Os₁₁ core geometries, but in (4) the copper ligand occupies a µ₃-bridging position, while the hydride in (10) appears to be located in an interstitial site.