Stereochemical control of alkyne oligomerisation at a diruthenium centre: X-ray structures of [Ru2(CO)(µ-CO)(µ-C4H4CMe2)(η-C5H5)2] and [Ru2(µ-CO){µ-C4(CO2Me)4CH2}(η-C5H5)2]

Abstract

The µ-carbene complexes [Ru₂(CO)₂(µ-CO)(µ-CMe₂)(η-C₅H₅)₂] and [Ru₂(CO)₂(µ-CO)(η-CH₂)(η-C₅H₅)₂] undergo double insertion with ethyne and dimethyl acetylenedicarboxylate, respectively, to yield the title compounds; these complexes have been shown by X-ray diffraction to contain five-carbon chains of differing stereochemistry, attributed to the different steric demands of the carbene substituents.