Gas Phase Multiply Charged Metal-Ligand Complexes

Ion solvation in the gas phase allows a systematic method for studying development of solvent structure in the absence of interference from either solvent molecules or counter ions. These studies can probe the fundamental metal-ligand interactions that underpin the stability, reactivity and structure of many inorganic, bioinorganic and organometallic complexes. This thesis contains a series of calculations on Cu(II), Ag(II) and Pb(II) complexes using a variety of ab initio methods and these studies are complemented with experimental gas-phase studies. Density functional theory (DFT) calculations have been performed on various Cu(II)-pyridine and Ag(II)-pyridine complexes. These allowed incremental and average binding energies to be calculated for the range of coordination numbers 1-6. Structural isomers were also calculated for the 4- and, 6-coordinate structures. Delta SCF and group theory were utilised to identify a range of electronically and vibronically allowed transitions for the different stereoisomers of the 4 coordinate structures. This provided a quantitative explanation of the electronic excitations contributing to the experimental ligand-field photofragmentation spectra of the Cu(II)-pyridine4 and Ag(II)-pyridine4 complexes. . Calculations were performed, using traditional ab initio methods, on various hydrolysis reaction pathways of [Pb(L)n(H20hl2+ complexes, where L was a nonaqueous ligand. It was found that the barrier to proton transfer increased and the exothermicity of the reaction decreased on addition of a non-aqueous ligand. It was shown that the barrier to proton transfer correlates well with the gas phase proton affinity of the non-aqueous ligand. As a result of this work gas phase experiments were performed on several mixed aqueous arid non-aqueous Pb(II) ligand systems. Unfortunately, pyridine, which appeared to be the most successful at stabilising the hydrate, was unsuccessful experimentally. It was found that both CO2 and acetonitrile could stabilise Pb-hydrate complexes to the extent that doubly charged species were experimentally observed in the gas phase for the first time.EThOS - Electronic Theses Online ServiceGBUnited Kingdo