Metal-Coordinated Ligand Radicals: Structure and Reactivity

Saha, Anannya (2021) Metal-Coordinated Ligand Radicals: Structure and Reactivity. PhD thesis, Indian Institute of Science Education and Research Kolkata.

Text (PhD thesis of Anannya Saha (14RS019)) 14RS019_DCS.pdf - Submitted Version Restricted to Repository staff only Download (20MB)

Abstract

The purpose of this thesis work is two-fold. First, the understanding of the electronic structure of the transition-metal complexes, synthesized and described in the thesis, comprising the oxidation and spin state of the metal ion and the redox level(s) of redox-active (non-innocent) 2,4-di-tert-butylphenol-based ligands. Analysis of the molecular structures by X-ray crystallography, collection and scrutinization of various spectroscopic, magnetic and redox data, and density function theory (DFT) calculations for detailed characterization of the synthesized complexes and to assign the electronic structure of the transition metal complexes correctly. Secondly, the purpose has been to explore the possibility of selected synthesized complexes to act as potential catalysts for reactions such as (i) oxidation of primary alcohol to aldehyde, inspired by copper-containing metalloenzyme galactose oxidase, which has a tyrosyl radical in its active site and (ii) oxidation chemistry of various C–H bonds of selected organic substrates. For catalysis work, emphasis is directed to mechanistic details, supported by DFT calculations. Moreover, to rationalize the observed results, three-point goals include (i) metal-ligand cooperativity for multi-electron redox processes, (ii) effect of ligand structures, and (iii) correlation between reactivity and redox potential (metal-centred and ligand-centred) values. A number of control experiments, kinetic studies, and various spectroscopic measurements (UV-vis, ESI-MS) have been done to get a clear view of the reaction mechanism.

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