DFT study on multi-carbonylation in a valence-switchable model

This report describes a transition metal-catalyzed switchable carbonylation model that enables selective carbonylation reactions. Mono-/dicarbonylation reactions catalyzed by copper(I) are investigated to validate the proposed model. Mechanistic studies indicate that a low-valent metal center captures a CO molecule to afford the corresponding metal-acyl species. Then, the alkyl bromide, with a weak oxidation potential, reacts with the metal-acyl species via halogen atom transfer, which generates an acyl radical species, leading to the dicarbonylation product. Alternatively, in the presence of alkyl iodide, which has a stronger oxidation potential, the low-valent metal center is preferentially oxidized to higher valence, with concomitant generation of only the monocarbonylation product. Finally, energy decomposition analysis based on absolutely localized molecular orbitals and variational forward–backward analysis reveals the origin of the observed chemoselectivity.