Methyl group mobility and conversion into methyne at a diruthenium centre

Abstract

Protonation of [Ru₂(CO)₂(µ-CO)(µ-CH₂)(η-C₅H₅)₂] yields the µ-methyl complex [Ru₂(CO)₂(µ-CO)(µ-CH₃)(η-C₅H₅)₂]⁺ as cis and trans isomers which interconvert (ΔG^‡ca. 55 kJ mol^–1) on the n.m.r. time scale, proposed to occur via an intermediate with a terminally bound methyl group; proportion of [Ru₂(µ-dppm)(µ-CO)(µ-CH₂)(η-C₅H₅)₂][dppm = bis(diphenylphosphino)methane] gives [Ru₂(µ-dppm)(µ-CO)(µ-CH₃)(η-C₅H₅)₂]⁺ similarly, but in solution this converts into the µ-methyne cation [Ru₂(µ-dppm)(µ-CO)(µ-CH)(η-C₅H₅)₂]⁺, whose structure has been established by X-ray diffraction.