Electronic Properties and Redox Chemistry of Various Late Transition Metal Complexes

Inorganic and organometallic catalysis plays an important role in energy related catalysis including transformations like water oxidation, proton and carbon dioxide reduction, and oxidative methane oligomerization. In order to understand and improve catalysts, this dissertation focuses on the development of alternate polydentate ligands and their late transition metal complexes and a full study on their electrochemical properties. Two polydentate pyridinophane ligands, N,N’-di(2-methylpyridine)-2,11-diaza[3.3](2,6)pyridinophane, PicN4,and N-(2methylpyridine)-N’-methyl-2,11-diaza[3.3](2,6)pyridinophane, PicMeN4, were synthesized to stabilize uncommon oxidation states. Unlike previous RN4 ligands, these polydentate ligands employed functionalized amines to interact with the metal center to increase stability. PicN4 when bound with copper formed a complex with a highly reversible CuII/I redox couple. The self-exchange rate constant for this redox couple was determined in the goal of comparing to copper containing electron transfer enzymes. Similarly, the silver complex PicN4AgI was also synthesized in which the PicN4 ligand stabilized the AgI/II redox couple. These pyridinophane ligands maximized magnetic moment by stabilizing d5 manganese and iron complexes as possible MRI contrast agents. A mononuclear NiIII complex was isolated. NiIII is a commonly proposed intermediate in cross-coupling reactions. Palladium when bound to both PicN4 and PicMeN4, the binding mode for the PdII dictated the stability of the redox couples. PicN4Pd was reduced to a mononuclear PdI while the asymmetric PicMeN4PdII preferentially is oxidized. Additionally, PicMeN4Pd undergoes a C-H activation spontaneously through a proposed concerted metalation deprotonation mechanism