We report a systematic and comprehensive investigation on the electronic structures and chemical bonding of a series of tri-yttrium oxide clusters,using density functional theory (DFT) calculations. Generalized Koopmans' theorem is applied to predict the vertical detachment energies (VDEs) and simulate the photoelectron spectra (PES) for Y 3 O x − (x = 0−6) clusters. A trend of sequential oxidation is observed from Y 3 O − to Y 3 O 6 − . All of these clusters tend to form the structures with a capped oxygen atom. For Y 3 O x −/0 (x = 2−4), the O atoms are shown to prefer the bridging sites of Y 3 O −/0 , whereas the fifth O atoms for Y 3 O 5 −/0 are bonded to the terminal sites. As for the oxygen-rich clusters Y 3 O 6 − and Y 3 O 6 , O 2 2− and O 2 −• units occur which can be regarded as the products reduced dioxygen by Y 3 O 4 − and Y 3 O 4 , respectively. σ-and π-aromaticity is found in Y 3 − by molecular orbital analysis and Adaptive Natural Density Partitioning (AdNDP) analysis. Molecular orbitalanalyses are performed to analyze the chemical bonding in the tri-yttrium oxide clusters and to elucidate their electronic and structural evolution.

Density functional theory (DFT) calculations have been performed to explore the gas-phase hydrolysis reaction of mononuclear thorium halide clusters ThX4 (X = F, Cl). We have found that the hydrolysis of ThCl4 is easier than that of ThF4. Furthermore, their hydrolysis reactions favor pathways of direct dehydration of Th(OH)4 instead of further hydrolysis of ThOX2. There are some differences between the hydrolysis of ThCl4 and that of MCl4 (M = Ti, Zr and Hf). The X-HY (X = F, Cl; Y = F, Cl and OH) hydrogen bonds play an important role in the hydrogen transfer process of the hydrolysis reaction. The differences in the steric effects and bonding may be important factors that are related to the disparities in the hydrolysis of the above-mentioned metal halides.

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 ThO 3 are compared with the stoichiometric ThO 2 . 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 O 2 2À in ThO 3 is converted to the HOOÀ ligand, behaving like the terminal O 2À in the hydrolysis which is transformed into the HOÀ 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.