Hydrolysis Mechanism of the NAMI-A-type Antitumor Complex (HL)trans-RuCl₄L(dmso-S) (L=1-methyl-1,2,4-triazole)

The hydrolysis process of Ru(III) complex (HL)trans-RuCl₄L(dmso-S) (L=1-methyl-1,2,4-triazole and dmso-S=S-dimethyl sulfoxide) (1), a potential antitumor complex similar to the well-known antitumor agent (Him)trans-RuCl₄L(dmso-S)(im) (NAMI-A, im=imidazole), was investigated using density functional theory combined with the conductor-like polarizable continuum model approach. The structural characteristics and the detailed energy profiles for the hydrolysis processes of this complex were obtained. For the first hydrolysis step, complex 1 has slightly higher barrier energies than the reported anticancer drug NAMI-A, and the result is in accordance with the experimental evidence indicating larger half-life for complex 1. For the second hydrolysis step, the formation of cis-diaqua species is thermodynamic preferred to that of trans isomers. In addition, on the basis of the analysis of electronic characteristics of species in the hydrolysis process, the trend in nucleophilic attack abilities of hydrolysis products by pertinent biomolecules is revealed and predicted.