Mechanistic Insights into the Reactions of Co(III) Salens with Diazoacetates

The rates and products from the gas-phase reactions of Co(III) salens with ethyl and t-butyl diazoacetate were examined. Addition with loss of N(2) is observed, and substituent effects as well as DFT calculations indicate that addition is rate determining. Calculations suggest that the carbene species involve novel structures with the carbenic carbon bridging between the cobalt and a salen oxygen. Collision-induced dissociation leads to an unusual, bridged metal/ketene species.