Reaction of a Molybdenum Bis(dinitrogen) Complex with Carbon Dioxide: A Combined Experimental and Computational Investigation

Abstract

Refluxing Mo(CO)(6) in the presence of the phosphine-functionalized alpha-diimine ligand (DI)-D-Ph2PPr allowed for substitution and formation of the dicarbonyl complex, ((DI)-D-Ph2PPr)-Mo(CO)(2). Oxidation with I-2 followed by heating resulted in further CO dissociation and isolation of the corresponding diiodide complex, ((DI)-D-Ph2PPr)MoI2. Reduction of this complex under a N-2 atmosphere afforded the corresponding bis(dinitrogen) complex, ((DI)-D-Ph2PPr)Mo(N-2)(2). The solid-state structures of all three compounds were found to feature a tetradentate chelate and cis-monodentate ligands. Notably, the addition of CO2 to ((DI)-D-Ph2PPr)-MO(N-2)(2) is proposed to result in head-to-tail CO2 coupling to generate the corresponding metallacycle and ultimately a mixture of ((DI)-D-Ph2PPr)Mo(CO)(2) and the bis(oxo) dimer, [(kappa(3)-(DI)-D-Ph2PPr)Mo(O)(mu-O)](2). Computational studies have been performed to gain insight into the reaction and evaluate the importance of cis-coordination sites for selective head-to-tail CO2 reductive coupling, CO deinsertion, disproportionation, and stepwise CO2 deinsertion.