Synthesis and Characterization of Highly Pure Form of Sodium Salt of Anionic, Thiomalatogold(I) Complex with Antiarthritic Activity. Analogs of Anionic, Thiomalatosilver(I) Complex with Antimicrobial Activity

Abstract

Abstract Sodium salt of anionic Au(I) complex with a trianion of thiomalic acid tma3− (H3tma = HOOCCH(SH)CH2COOH), known as an effective antiarthritic drug, was prepared in highly pure form by one-step synthesis from NaAuCl4 and tma3− in aqueous solution. The reaction consisted of a reduction of Au(III) by tma3− and the following complexation of Au(I) with tma3− ligand. The disulfide species of tma3− formed by this reduction was removed by passing through an anion-exchange resin column and the contaminating NaCl by passing through a gel filtration column. The tma–Au(I) complex was also prepared by another reaction based on ligand exchange of the intermediate complex AuCl(thiodiglycol) with tma3−. It was purified using the anion-exchange resin and gel filtration columns. The target compound, finally isolated in 30% yield in highly pure form, has been characterized by complete elemental analyses, TG/DTA, FT-IR, 1H and 13C NMR spectroscopies, and molecular weight was determined in aqueous solution by molmass measurement based on the cryoscopic method combined with dissociation degree determination based on the [Na+] measurement in equilibrium state using a Na+-ion selective electrode. This Au(I) complex was an oligomer with a formula of {Na2[Au(tma)]·1.75H2O}n (n = 3—10; MW = 1260—4220). This polymerization degree, low in comparison with previously proposed data, was determined in the neutral aqueous solution without any other electrolytes under the concentration range CNa = 0.914—182.9 mmol dm−3. The tma–Au(I) complex exists in an oligomeric form both in the solid and in aqueous solution. The properties of the oligomeric tma–Au(I) complex were compared with those of the previously reported complex and a commercially available sample, and also with those of the recently prepared, oligomeric tma–Ag(I) complex with antimicrobial activity.