Mononuclear thorium halide clusters ThX4 (X = F, Cl): gas-phase hydrolysis reactions

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.

Exploring the Reaction Mechanism of H2S Decomposition with MS3 (M = Mo, W) Clusters

H₂S is abundantly available in nature, and it is a common byproduct in industries. Molybdenum sulfides have been proved to be active in the catalytic decomposition of hydrogen sulfide (H₂S) to produce hydrogen. In this study, density functional theory (DFT) calculations are carried out to explore the reaction mechanisms of H₂S with MS₃ (M = Mo, W) clusters. The reaction mechanism of H₂S with MoS₃ is roughly the same as that of the reaction with WS₃, and the free-energy profile of the reaction with MoS₃ is slightly higher than that of the reaction with WS₃. The overall driving forces (-ΔG) are positive, and the overall reaction barriers (ΔG _b) are rather small, indicating that such H₂ productions are product-favored. MS₃ (M = Mo, W) clusters have clawlike structures, which have electrophilic metal sites to receive the approaching H₂S molecule. After several hydrogen-atom transfer (HAT) processes, the final MS₄·H₂ (IM-4) complexes are formed, which could desorb H₂ at a relatively low temperature. The singlet product MS₄ clusters contain the singlet S₂ moiety, similar to the adsorbed singlet S₂ on the surface of sulfide catalysts. The theoretical results are compared with the experiments of heterogeneous catalytic decomposition of H₂S by MoS₂ catalysts. Our work may provide some insights into the optimal design of the relevant catalysts.

Reaction mechanism of synthetic thorium sulfides: theoretical calculation study

Actinide sulfides are especially significant in actinide chemistry because of their potentials that are used as nuclear fuel and the wide variety of their stoichiometries and physical properties. It is essential for studying the synthesis mechanism of actinide sulfides. In this study, the reactions of thorium cation Th²⁺ with the facile sulfur-atom donor OCS to produce thorium sulfides have been systematically explored by using density functional. The detailed insights of the primary reaction and secondary reaction paths are reported. We investigated that the multiple bonding characters and complexes involved in reaction exhibit significant covalent character. The reaction rate indicated that the tunneling effect is small compared with the effect of temperature on the rate. This study addresses some of the current limitation in understanding the detailed reaction information of Th²⁺+OCS.