Photochemically mediated alkyne metalation in the donor–acceptor complexes Ru2(CO)6(μ-PP) [where PP=bpcd, (Z)-Ph2PCHCHPPh2]. X-ray diffraction structure of the zwitterionic compound Ru2(CO)6[μ-(Z)-MeO2CCCCO2Me](μ-bpcd)

Near-UV irradiation of the donor–acceptor complexes Ru2(CO)6(μ-bpcd) and Ru2(CO)6[μ-(Z)-Ph2PCHCHPPh2] in the presence of dimethyl acetylenedicarboxylate (dmad) gives the dimetalated alkene complexes Ru2(CO)6[μ-(Z)-MeO2CCCCO2Me](μ-diphosphine). Each new alkene complex was characterized in solution and by X-ray diffraction analysis in the case of the bpcd-substituted derivative. The X-ray structure of Ru2(CO)6[μ-(Z)-MeO2CCCCO2Me](μ-bpcd) confirms the formal oxidative addition of the dmad ligand across the dative RuRu bond.