Investigation of the Spectroscopic, Thermal and Electrochemical Properties of Tris-(glycinato)chromium(III)

摘要

The tris-glycinatochromium(III) complex ([Cr(gly)3]) has been proposed as a nutritional supplement and treatment for Type 2 diabetes. The exact mode of action of this and other Cr(III) supplements is not known but may involve redox reactions with biomolecules. In this study fac-[Cr(gly)3] was synthesized and the electrochemical properties investigated by cyclic voltammetry. The complex undergoes a reversible one electron reduction with E1/2= -0.66 to -0.69 V that is essentially independent of scan rate. Thermal decomposition was explored by differential scanning calorimetry under nonisothermal conditions from 30-10008C. Structural parameters obtained from DFT calculations are in good agreement with crystallographic data. The reduced form of the complex has a high-spin quintet electronic configuration due to the small crystal field splitting from the weak p-donor ligands. Both the theoretical calculations and the electrochemical measurements demonstrate that the complex is stable in the anionic form. These results indicate that [Cr(gly)3] can undergo reversible electron transfer, which may play a role in it's biological activity.