Reactivity of zirconocene azametallacyclobutenes: insertion of aldehydes, carbon monoxide, and formation of alpha,beta-unsaturated imines. Formation and trapping of (Cp2Zr=O) in a (4 + 2) retrocycloaddition

Zirconocene azametallacyclobutene subjected to an insertion reaction with carbon monoxide forms an acyl complex. The reaction with aldehydes RCOH results in the addition of the aldehyde into the Zr-C bond to form complexes. The aldehyde insertion products form alpha,beta-unsaturated imines and (Cp2Zr=O) via a retro (4 + 2) reaction. The acetone addition results in an enolate complex formation due to deprotonation and no insertion occurs.