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

Abstract

Reaction of [Re₂(CO)₉(MeCN)] with cis-1,2-bis(diphenylphosphino)ethylene (cis-Ph₂PCH=CHPPh₂) in boiling benzene (80 ^°C) afforded two compounds, ax-[Re₂(CO)₉(κ¹-cis-Ph₂PCH=CHPPh₂)] (1) and ax-[Re₂(CO)₉{κ¹-cis-Ph₂PCH=CHPh₂P(O)}] (2) where the ligand is axially coordinated in a κ¹ monodentate fashion through phosphorus. The close-bridged compound [Re₂(CO)₈(μ-κ²-cis-Ph₂PCH=CHPPh₂)] (3) was obtained from a similar reaction of the same ligand with [Re₂(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, ¹H NMR, ³¹P{¹H} NMR spectroscopy and single crystal X-ray diffraction analyses.