THE DIRHENIUM(III) COMPLEX COMPOUND WITH ARGININE

Abstract

Complex compounds of dirhenium(III), containing an unique quadruple metal-metal bond with low toxicity have a number of useful biological properties, such as antitumoral, antihemolytic, antiradical, hepato- and nephroprotective that stimulates the expansion of the range of such compounds due to the diversity of the ligand sphere. The method of synthesis of the dirhenium(III) complex compound with arginine was elaborated. For obtaining the target product the reaction of (NBu4)2Re2Cl8 with arginine in a molar ratio of 1:10 in an inert atmosphere was carried out. A mixture of polar organic solvents (acetone – acetonitrile in the ratio 4:1) was used. Obtained substance was recrystallized from ethyl acetate. The yield of product was 43%. The compound has a blue color, soluble in polar organic solvents and water. Composition and structure of the obtained cluster compound cis-[Re2(Arg)2Cl4ˑ2CH3CN]Cl2 were confirmed by elemental analysis, electronic absorption (EAS) and IR spectroscopy, molar electric conductivity. In the visible region of the EAS shift of the absorption band with 14700 cm –1 to 16670 cm –1 was observed. New position of the absorption band corresponds to d→d* electronic transition on d component of quadruple Re-Re bond and characterized complexes with cis-position of bridging carboxylates ligands to the cluster Re2 6+. In the IR spectra intense band characteristic of uncoordinated CO-group in the arginine absent and there vibrations at 1471 cm-1, which points to bridging coordination of carboxyl groups to the cluster Re2 6+. Protonation of amine group which situated near α-C atom can prove through bands at 1623 cm-1 δas(NH3 +), 1495 cm-1 δs(NH3 +). The presence in the spectral picture bands at 2875 cm-1, 1665 cm-1, and 740 cm-1 confirms the storage the guanidinium group in an uncoordinated state. It is shown, that is realized a bridging coordination of carboxyl group of arginine to the cluster Re2 6+ with coordination of two ligands of amino acids to cis-position.