Interaction of trans-tetrachlorodi-m-carboxylates of dirhenium(III) with dipeptides of the glycyl series

Abstract

The paper reports the methods for the synthesis of new cluster compounds of trans-tetrachlorodi--carboxylates of dirhenium(III) with dipeptides of the glycyl series. The compositions and the structures were determined by electron absorption and IR spectroscopies as well as by elemental analysis for the following newly synthesized compounds: trans-[Re2(H3N+–CH2–СO–NH–CH(COO)–CH2–CH(CH3)–CH3)2Cl42СН3CN]Cl2 (І) and trans-[Re2(H3N+–CH2–СO–NH–CH(COO)–CH2–C6H5)2Cl42СН3CN]Cl2 (ІІ). Analysis of the electronic absorption spectra of the solutions of the synthesized substances showed the presence of a doublet pattern (12500 and 16129 сm–1), which corresponds to the *-electronic transition of the Re–Re quadruple bond characteristic of solutions of trans-tetrachlorodi--carboxylates of dirhenium(III). The appearance of oscillations at 1485 сm–1 for І and 1486 сm–1 for ІІ, characteristic of the s(CO) of the coordinated carboxylate group, was detected on the IR spectra, which indicates the bridging coordination of this group to the Re26+ binuclear fragment. The protonation of the amino group is indicated by the appearance of a wide band of valence oscillations (NH3+) in the range of 3400–3350 сm–1 and deformation oscillations (NH3+) at 1557 сm–1 and 1614 сm–1 for I and II, respectively. The stability of the obtained complex compounds in aqueous solutions was determined. It was shown that the hydrolysis of the synthesized substances takes place in 4–5 days, which is accompanied by a decrease in the pH of the reaction solution.