Computational Studies of Actinyl Peroxide Nanoclusters

Abstract

This PhD thesis examines the chemistry of actinyl peroxide nanoclusters, as well as their constituent subunits. A review of the relevant literature pertaining to this topic can be found in chapter 1. The studies conducted on these complexes was achieved via a series of DFT studies using the TURBOMOLE quantum chemical package, the background theory of the techniques employed are discussed in chapter 2, and the results of the studies are laid out in chapters 3-5 of this thesis. Chapter 3 of this work examines the basic building block of the actinyl peroxide nanocluster; the actinyl peroxide dimer, challenging/building upon the previous literature regarding the nature of the U-(O-O)-U interaction that is characteristic of this group. Understanding the nature of this motif is important to actinyl peroxide nanoclusters as it is the flexibility of this dihedral angle that enables the formation of the larger cage complexes. Chapter 4 expands upon previous work by examining the high spin ground state An-20 family of matryoshka actinyl peroxide nanoclusters. This is a targeted and systematic study of the energies of nanoclusters containing 20 uranyl and 20 plutonyl units (U-20 and Pu-20 respectively) as the central valence complete unit was altered/removed as well as changing the nanoclusters’ spin state. Examinations of the molecular orbitals via Mulliken analysis was also employed to understand why the addition of a central valence-complete unit was required to stabilise the high spin ground states. Chapter 5 extends chapter 4 to look at nanoclusters containing 24 actinyl moieties (An-24) to see if these systems display a similar need for a central valence complete unit to stabilise their high spin ground state configurations. This was carried out for both the U-24 and Pu-24 nanoclusters. Additionally, a suite of single point energy calculations were performed to model a counterion leaving its optimal position within the complex and leaving the cage, in order to model the semi permeability displayed by these complexes.

Date of Award	6 Jan 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Louise Natrajan (Supervisor) & Nikolas Kaltsoyannis (Supervisor)