KINETICS OF DIOSMACYCLOBUTANE EXCHANGE-REACTIONS

Diosmacyclobutanes Os-2(CO)(8)(olefin) undergo facile exchange reactio ns with olefins and acetylenes. An associative mechanism is excluded b y the observation of saturation kinetics as the concentration of the e ntering olefin (butyl acrylate) is increased. Multivariate analysis of the rate as a function of [C2H4] (determined from solubility measurem ents in decane/butyl acrylate mixtures) and [butyl acrylate] suggests a stepwise mechanism in which the departing olefin migrates to a termi nal position and then undergoes associative exchange with the entering olefin. The straightforward dissociative exchange of the olefin ligan ds in Os(CO)(4)(olefin) shows saturation at much lower concentrations of entering olefin.