Probing Chemical Bonding and Electronic Structures in ThO- by Anion Photoelectron Imaging and Theoretical Calculations

Reactions of Thorium Oxide Clusters with Water: The Effects of Oxygen Content

Thorium oxide has many important applications in industry. In this article, theoretical calculations have been carried out to explore the hydrolysis reactions of the ThO_n (n=1-3) clusters. The reaction mechanisms of the O-deficient ThO and the O-rich ThO₃ are compared with the stoichiometric ThO₂ . The theoretical results show good agreement with the prior experiments. It is shown that the hydrolysis mainly occurred on the singlet potential surface. The overall reactions consist of two hydrolysis steps which are all favourable in energy. The effects of oxygen content on the hydrolysis are elucidated. Interestingly, among them, the peroxo group O₂ ^2- in ThO₃ is converted to the HOO- ligand, behaving like the terminal O^2- in the hydrolysis which is transformed into the HO- groups. In addition, natural bond orbital (NBO) analyses were employed to further understand the bonding of the pertinent species and to interpret the differences in hydrolysis.

Anion Photoelectron Spectroscopy and Theoretical Study of HAuCN and [HAuCN]-: Spin-Orbit Coupling and Low-Lying Excited States

We report a study of the electronic structures and chemical bonding of gaseous [HAuCN]^- and the corresponding neutral molecule using photoelectron spectroscopy and relativistic quantum chemistry calculations. The electron affinity of the neutral HAuCN is reported to be 4.75 eV for the first time. The low-lying excited states of neutral molecule are observed and assigned according to the calculations utilizing a sophisticated electron correlation method incorporating both the scalar and spin-orbit relativistic effects. Our theoretical calculations suggest the geometry will be distorted from linear structure to the bent during the process of detaching one electron from the anion. Various chemical bonding analyses based on theoretical calculations have been performed for the titled complexes, and the apparent covalent natures of interactions between gold and the studied ligands have been verified.

Carbon monoxide activation by atomic thorium: ground and excited state reaction pathways

Multi-reference configuration interaction (MRCI) and single reference coupled cluster calculations are performed for the ThCO and OThC isomers. Scalar and spin-orbit relativistic effects are considered through a relativistic pseudopotential and the coupling of MRCI wavefunctions via the Breit-Pauli spin-orbit Hamiltonian. Optimized geometries, excitation energies, and vibrational frequencies are reported for both isomers. Full potential energy profiles are constructed for the Th+CO reaction and the conversion of the produced ThCO to OThC. Linear ThCO was found to be more stable than the highly ionic bent OThC system by about 4 kcal mol^-1. The interconversion barrier is estimated to be around 30 kcal mol^-1. Our results are in agreement with earlier experimental data for the two isomers. The lowest lying states of Th do not populate f-orbitals and resemble the electronic structure of Ti. Therefore, the ability of the two atoms to activate the C[triple bond, length as m-dash]O bond is compared. OTiC is found to be about 40 kcal mol^-1 less stable than TiCO revealing the efficiency of Th and possibly other f-block elements to activate multiple chemical bonds as opposed to d-block metals.