Does NHC Directly Participate in the CO2 Insertion into the UIII–N Bond? A Density Functional Theory Study

The mechanisms of CO2 insertion into the U–N bond of a silylamido NHC (N-heterocyclic carbene) U­(III) complex were investigated theoretically. An earlier reported mechanism involving a reversible NHC carboxylation was found to be energetically too demanding, and a novel four-step mechanism featuring a direct CO2 insertion into the U–N bond is proposed.