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 Ru-2(CO)(6)(mu-bpcd) and Ru-2(CO)(6)[mu-(Z)-Ph2PCH=CHPPh2] in the presence of dimethyl acetylenedicarboxylate (dmad) gives the dimetalated alkene complexes Ru-2(CO)(6)[mu-(Z)-MeO2CC=CCO2Me](mu-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 Ru-2(CO)(6)[mu-(Z)-MeO2CC=CCO2Me](mu-bpcd) confirms the formal oxidative addition of the dmad ligand across the dative Ru-Ru bond. (C) 2000 Elsevier Science S.A. All rights reserved.