Formation of cisoid-η4(5e)-butadienylrhenium complexes by coupling of alkene and alkyne ligands

Abstract

The reaction of the η²(4e)-bonded alkyne complexes [ReBr₂(η²-RC₂Ph)(η-C₅H₅)](R = Me or Ph) with o-diphenylphosphinostyrene and 2 equiv. AgBF₄ in THF surprisingly affords HBF₄, AgBr and excellent yields of the cationic η⁴(5e)-butadienyl complexes [ReC(Ph)-η³-{C(R)CHCHC₆H₄PPh₂-o}(η-C₅H₅)][BF₄]; the methyl-substituted system being structurally characterised by a single-crystal X-ray diffraction study.