Reductive Cyclotrimerization of Carbon Monoxide to the Deltate Dianion by an Organometallic Uranium Complex

Despite the long history of the Fischer-Tropsch reaction, carbon monoxide has proven remarkably resistant to selective homologation under mild conditions. Here, we find that an organouranium(III) complex induces efficient reductive trimerization of carbon monoxide at room temperature and pressure. The result is a triangular, cyclic C3O32-, or deltate, dianion held between two uranium(IV) units. The bonding within the C 3O32- unit and its coordination to the two U centers have been analyzed by x-ray diffraction and density functional theory computational studies, which show a stabilizing C-C agostic interaction between the C3 core and one U center. Solution nuclear magnetic resonance studies reveal a rapid equilibration of the deltate unit between the U centers.