Addition of diphenylphosphine to molybdenum alkynyl complexes

Abstract

The reaction of [CpMo(CO) 3(CCR)] (Cp=η-C 5H 5) with PPh 2H in the presence of Me 3NO gives the expected substituted complex [CpMo(CO) 2(PPh 2H)(CCPh)] as the major product when R=Ph. The phosphine ligand in this compound can be subjected to a deprotonation–alkylation sequence to afford [CpMo(CO) 2(PPh 2Me)(CCPh)]. In contrast, when R=CO 2Me, treatment of [CpMo(CO) 3(CCR)] with PPh 2H and Me 3NO leads directly to [CpMo(CO) 2(PPh 2CCHCO 2Me)] by addition of the PH bond across the alkynyl triple bond; this compound has been structurally characterised and contains a three-membered (MoPC) ring with an exocyclic CHCO 2Me group.