Synthesis of Os3W alkylidyne and alkylidene clusters by solid-state pyrolysis; direct C–O bond cleavage of co-ordinated ketenyl ligand

Abstract

The heterometallic tetranuclear ketenyl compound [Os₃(CO)₁₀(µ-H){C(O)CH₂W(CO)₃(η-C₅Me₅)}]1 possessing a pendant W(η-C₅Me₅)(CO)₃ substituent is prepared by condensation of [Os₃(CO)₁₀(NCMe)₂] with the aldehyde complex [W(η-C₅Me₅)(CO)₃(CH₂CHO)]. Pyrolysis of 1 in the solid state at 185 °C afforded four tetrahedral compounds [WOs₃(η-C₅Me₅)(CO)₉(µ-O)(µ₃-CMe)]2, [WOs₃(η-C₅Me₅)(CO)₉(µ-O)(µ-H)(µ-CHMe)]5, [WOs₃(η-C₅Me₅)(CO)₁₁(µ₃-CMe)]3 and [WOs₃(η-C₅Me₅)(CO)₁₁(µ₃-CH)]4, demonstrating a unique example of C–O bond scission for the ligated ketene fragment. Since treatment of 2 with H₂ in toluene also afforded 5 in moderate yield, it is highly probable that the latter is produced via reaction with trace amounts of H₂ generated from the decomposition of 1. The molecular structures of 2 and 4 have been determined by single-crystal X-Ray analysis.