Redox Potential Tuning by Mixed-Ligand Quadruply Bonded Dimolybdenum Compounds

Oxidation-reduction reactions are crucial in chemistry. They are vital for biochemical reactions such as cellular respiration and photosynthesis. Redox reactions are also important in industrial processes, such as the reduction of ores to obtain metals and to produce electrochemical cells. While this field of chemistry has been studied extensively, this project attempts to get a better understanding of electron donor properties of basic ligands attached to bimetallic units. The more basic a ligand is, the better its electron donor properties are which allows us to stabilize higher oxidations states. Guanidine ligands have been found to be able to stabilize higher oxidation state bimetallic compounds compared to formamidine ligands. We expect that with each addition of a guanidine ligand the redox potentials will shift to negative values. In order to show this, we synthesized bimetallic units with four ligands attached to it. We have synthesized different combinations of Mo2(DAniF)x(hpp)4-x, (where DAniF is the anion of N,N\u27-di-p-anisylformamidine and hpp is the anion of hexahydro-2H-pyrimido[1,2-a]pyrimidine), Mo2(hpp)x(Oac)4-x, and Mo2(OAc)x(DAniF)4-x to measure their redox potentials by electrochemical and spectroscopy methods. We observed that the redox potentials shift to negative potentials with the addition of more guanidine ligands