Guilty, innocent, or just molecules doing their thing? Structural, spectroscopic, and reactivity studies of iridium complexes with redox-active ligands

Abstract

Advances in inorg. spectroscopy and theor. methods have spurred reevaluation of the electronic structures of many compds. comprising the canon of coordination chem. X-ray absorption (XAS) and ESR (EPR) spectroscopies, in concert with d. functional theory (DFT) calcns., have been of particular value in demonstrating that many classic ligands, such as 2, 2'-bipyridine, are redox-active. Such studies are less straightforward when directed at systems in which late, third-row metals are coordinated. This lecture will discuss electronic structure studies of [tris-(penatfluorophenylcorrole)]iridium bis-pyridine complexes and trismaleonitridiledithialato iridium complexes. Their electronic structures and redox chem. will be compared to cobalt and rhodium congeners. From these studies we affirm that, with high-valent iridium, covalency is the rule and thus redox is mol. - partitioning of redox events as "ligand-centered" or "metal-centered" inaccurately describes these systems.