Advanced Electron Paramagnetic Resonance Spectroscopy Methods Used for the Study of Lanthanide and Actinide Complexes

Abstract

A thesis submitted to The University of Manchester for the degree of Doctor of Philosophy in the Faculty of Science and Engineering. This PhD research employs electron paramagnetic resonance (EPR) spectroscopy to study actinide and lanthanide organometallic complexes, focusing on their electronic structure, bonding properties, hyperfine interaction with the ligands, and spin density delocalisation. Chapter 1 provides an overview of key EPR techniques and a concise literature review, positioning the research within the broader field. Chapters 2 and 3 combine pulsed EPR spectroscopy and ab initio calculations to investigate thorium(III) and uranium(III) tris-cyclopentadienyl complexes, as well as a uranium(III) isocyanide adduct. Hyperfine interaction analysis reveals spin density delocalisation of ~12%, ~0.5%, and ~0.9% over the ligands for these three complexes, respectively, corroborated by computational data. Chapter 4 applies the same methodology to a novel uranium(V) carbene complex, demonstrating negligible spin density delocalisation onto the ligands, consistent with the more ionic nature of U(V), no 13C data was observed in the pulsed EPR spectra. Chapters 5 and 6 explore a series of rare-earth metal [M(NHAriPr6)2] (2M, M = Sc(II), Y(II), La(II), Sm(II), Eu(II), Tm(II), Yb(II); NHAriPr6 = {N(H)C6H3-2,6-(C6H2-2,4,6-iPr3)2}) complexes, where cw EPR characterises the dx2-y2 SOMO ground state in the Sc, Y, La complexes. Pulsed EPR methods and DFT calculations confirm up to 76% of the Mulliken spin density delocalised onto the closely bound Tripp group in the Sc, Y, La complexes.

Date of Award	21 Jan 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Collison (Co Supervisor), Eric Mcinnes (Main Supervisor) & Floriana Tuna (Co Supervisor)