Synthesis and reactions of terminal osmium and ruthenium complexed phosphinidenes [(eta6-Ar)(L)M=PMes*].

Novel, very stable ruthenium and osmium containing terminal phosphinidene complexes [(η6-Ar)(L)MPMes*] (Ar=benzene, p-cymene; L=PR3, CO, and RNC) have been prepared by dehydrohalogenation of novel [(η6-Ar)MX2(PH2Mes*)] complexes in the presence of a stabilizing ligand. Xray crystal structures are reported for [(η6-C6H6)(PPh3)RuPMes*] (9) and [(η6-pCy)(PPh3)OsPMes*] (4). Dehydrohalogenation in the absence of a stabilizing ligand resulted in the new Pspiroannulated Ru2P2-ring structure 16. Dehydrohalogenation in the presence of but-2-yne gave a novel phosphaallyl complex [(η6-Ar)Ru(η3-R2PC(Me)CHMe)] 26, for which an Xray crystal structure is reported. The mechanism by which 16 and 26 are obtained is presumed to involve the intermediate formation of the 16-electron (η6-benzene)RuPMes* phosphinidene complex.