Intrinsic Oxidation States: in Transition Metal Complexes

In Chapter 1, a bonding analysis of a cobalt complex in five oxidation states (from -I to III) is presented, using localized and delocalized orbitals. The Intrinsic OS method, which matches the formal OS of cobalt, is detailed with descriptors σ-gain and π-loss to characterize electron-sharing covalency in metal-ligand bonds. This method is applied to various TM complexes, distinguishing between delocalized inverted ligand fields (ILFs) and locally inverted bonds. Chapter 2 discusses the molecule [Cu(CF₃)₄]¹⁻, central to debates about OS, contrasting d¹⁰ copper(I) and d⁸ copper(III) assignments, and concludes with perspectives on bonding in transition metal complexes. Chapter 3 explores the analogy between copper(III) and gold(III) complexes, applying computational analysis to gold complexes, presenting X-ray absorption spectra, and reflecting on the connection between Intrinsic OS and spectroscopic properties, with implications for gold catalysis. Chapter 4 examines a complex with an unusual gold formal OS (-I) using Energy Decomposition Analysis and orbital analysis, supporting a nonformal gold(0) assignment. Chapter 5 characterizes a dinuclear gold(II) hydroxide complex via UV Vis, IR, NMR, and EPR spectroscopy, demonstrating its ability to activate C-X bonds through proton-coupled electron transfer (PCET) reactions. The mechanism of PCET reactions is probed, showing an unusual concerted PCET with electron transfer to the remote metal center, and IBOs are used to analyze changes in the gold centers' configuration during reactions, including d⁹d⁹, d¹⁰d⁹, and d¹⁰d¹⁰.