Dirhenium carbonyl compounds bearing cis -1,2-bis(diphenylphosphino)ethylene and cis -1,2-bis(diphenylphosphino)ethylene oxide ligands

Reaction of [Re 2 (CO) 9 (MeCN)] with cis -1,2-bis(diphenylphosphino)ethylene ( cis -Ph 2 PCH=CHPPh 2 ) in boiling benzene (80 ° C) afforded two compounds, ax -[Re 2 (CO) 9 (κ 1 - cis -Ph 2 PCH=CHPPh 2 )] ( 1 ) and ax -[Re 2 (CO) 9 {κ 1 - cis -Ph 2 PCH=CHPh 2 P(O)}] ( 2 ) where the ligand is axially coordinated in a κ 1 monodentate fashion through phosphorus. The close-bridged compound [Re 2 (CO) 8 (μ-κ 2 - cis -Ph 2 PCH=CHPPh 2 )] ( 3 ) was obtained from a similar reaction of the same ligand with [Re 2 (CO) 8 (NCMe) 2 ] in refluxing benzene. In this case the diphosphine is equatorially coordinated to two Re atoms in a symmetrical bridging fashion. Compounds 1 − 3 have been characterized by IR, 1 H NMR, 31 P{ 1 H} NMR spectroscopy and single crystal X-ray diffraction analyses.