The oxidation mechanism of TiCl3 as a reductant for an electroless deposition process was studied by ab initio molecular orbital method. The reaction process of TiCl3 proceeds with the substitution of Cl- to OH-. Net charge and spin density of the reactant, product, and intermediates were evaluated. It was suggested that the electron emission of TiCl3, which is originated by the oxidation of Ti(III) to Ti(IV), took place when Cl is replaced by OH- to form Ti(OH)4. The catalytic activity of the metal surface, which is one of the most important factors for the electroless deposition process, was studied using a Pd4 cluster as a model surface. It was suggested that the Pd4 cluster enhanced the reaction of TiCl3 to emit the electron. The effect of solvation is also taken into account in terms of the dielectric field constant. It was indicated that the heat of oxidation reaction shifted to an exothermic reaction with decreasing dielectric constant, indicating that the reaction preferentially proceeds in the vicinity of solid/liquid interface. However, it was indicated that the reaction could proceed in the bulk solution, suggesting that appropriate stabilization such as formation of complex is required for the application of the TiCl3 to the electroless deposition process.
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