METALLACYCLOBUTADIENE COMPLEXES FROM LIGAND COMBINATION OF CS AND ACETYLENE ON OSMIUM

Article abstract of DOI:10.1016/0022-328X(83)85084-0

The zerovalent thiocarbonyl Os(CS)(CO)(PPh3)3 reacts with the disubstituted acetylene PhC<*>CPh to give an equal mixture of the metallacycle and the coordinatively unsaturated acetylene complex Os(η²-PhC<*>CPh)(CS)(PPh3)2.Addition of CO converts the latter compound to the metallacycle which is readily alkylated on S to give, formally, a metallacyclobutadiene, e.g. .HCl addition to Os(η²-PhC<*>CPh)(CS)(PPh3)2 gives a coordinatively unsaturated monohapto-vinyl derivative OsCl(η¹-CPh=CHPh)(CS)(PPh3)2.This complex adds CNR (R=p-tolyl) forming a six-coordinate complex OsCl(η¹-CPh=CHPh)(CS)(CNR)(PPh3)2 but uptake of CO is accompanied by immediate rearrangement to the dihapto-thioacyl, Os(η²-C-CPh=CHPh)Cl(CO)(PPh3)2.