Photochemistry of (η3-allyl)tricarbonyecobaet in frozen gas matrices at 12 K. Infrared spectroscopic evidence for the formation of (η3-allyl) dicarbonylcobalt, (η3-allyl)dicarbonyl(dinitrogen)cobalt, (σ-allyl)tetracarbonylcobalt, and tetracarbonylcobalt complexes

Abstract

Infrared spectroscopic evidence is presented to show that photolysis of [Co(η³-allyl)(CO)₃] in gas matrices at 12 K gives [Co(η₃-allyl)(CO)₂](in Ar or CH₄), [Co(η³-allyl)(CO)₂(N₂)](in N₂), and [Co(σ-allyl)(CO)₄] followed by [Co(CO)₄](in CO). The detection of [Co(η³-allyl)(CO)₂] is consistent with the results of kinetic studies, which have been interpreted in terms of a dissociative path and a co-ordinatively unsaturated intermediate in the thermal CO substitution reactions, and theoretical calculations which show a low M–C(O) bond order a detection of [Co(σ-allyl)(CO)₄] and the reversibility of the reaction [Co(η³-allyl)(CO)₃]+ CO ⇄[Co(σ-allyl)(CO)₄] suggest that there may be a contribution to the reactivity of [Co(η³-allyl)(CO)₃] from the hitherto neglected associative path.