Reaction of molybdenum and tungsten alkylidyne complexes with 2,6-xylyl isocyanide and carbon monoxide; structural and mechanistic evidence for novel insertion reactions

Abstract

Reaction of alkylidyne complexes [M(CCH₂Bu^t)-{P(OMe)₃}₂(η-C₅H₅)](M = Mo, W) with 2,6-xylyl isocyanide affords first [M(CCH₂Bu^t)(CN-2,6-Me₂C₆H₃)-{P(OMe)₃}(η-C₅H₅)] then [M{η³-RNCC(CH₂Bu^t)CNR}(CNR)₂(η-C₅H₅)](R = 2,6-Me₂C₆H₃), the molybdenum complex being identified by X-ray crystallography; in contrast, CO displaces the phosphite ligands to give sequentially [Mo(CCH₂Bu^t)(CO){P(OMe)₃}(η-C₅H₅)] and [Mo(CCH₂Bu^t)(CO)₂(η-C₅H₅)].