Synthesis and Electronic Characterization of Iridium-Aluminum and Rhodium-Aluminum Heterobimetallic Complexes Bridged by 3-Oxypyridine and 4-Oxypyridine

We demonstrate the synthesis and characterization of regioisomeric late transition metal-aluminum heterobimetallic complexes containing 3- and 4-oxypyridine ligands which bridge between the aluminum and transition metal center (Rh or Ir). Combined experimental and theoretical data allow for direct comparison of the electronic effect of the two different aluminum-containing ligands on the late transition metal center. In combination with electronic data regarding previously reported 2-oxypyridine bridged systems, we report a measurable decrease in ligand donor power as the regiosubstitution of the oxypyridine bridge is varied from 2- to 4- to 3-. In all cases, addition of aluminum is found have a minimal effect on the donor ability of the oxypyridine bridge in dichloromethane solution