Abstract
Heterobimetallic complexes containing an early transition metal directly interacting with a late transition metal have been shown to have various degrees of reactivity with small molecules. The differences in the electron donating and receiving abilities between the two metals and the ligand substituents coordinated cause the M-M interaction to be highly polarized, which in turn allows tuning of the potentials required to reduce the complexes. Our group has synthesized Zr-Co heterobimetallic species containing phosphinoamide ligands, which we have shown to reduce at potentials ~1 V more positive than their analogous homometallic species. The 2 electron reduction of the synthesized complexes induced the coordination of a N2(g) adduct on the terminal end of the Co center. Due to the stabilization imparted by the phosphinoamide ligands the shortest early/late heterobimetallic interatomic distance has been produced along with the stabilization of an unprecedented open axial coordination site around a trigonal pyramidal Zr geometry. The species were found to be highly reactive toward small molecules especially CO2, showing the ability to activate and cleave one of the C—O bond producing a bridging µ-O and a terminal CO. This research shows promise in the use of CO2 as a feedstock for synthesis and more specifically the design of a catalytic cycle for the rWGS reaction.