COMPLEXATION OF HEXAVALENT CHROMIUM TO GLUTATHIONE FROM RAMAN-SPECTROSCOPY

Potassium dichromate and its reaction with the tripeptide glutathione (GSH) was studied by Raman spectroscopy at room and cryogenic temperat ures. It is confirmed that glutathione binds to Cr(VI) through the cys teinyl thiolate group [nu(Cr-S(Cys)) = 432 cm-1], forming a GSCrO3- th ioester complex [S.L. Brauer and K.E. Wetterhahn, J. Am. Chem. Soc., 1 13 (1991) 3001]. Essentially all dichromate vibrational modes in both aqueous solution and crystalline state are assigned and cataloged. The observed band splittings in the Raman spectrum of solid K2Cr2O7 are c onsistent with the nonequivalent Cr2O72- anions in the single crystal unit cell. Also reported are the Raman spectra of HCl solutions of mon ochlorochromate ion at room and 77 K temperatures, which was used as a structural model for the GS-Cr(VI) complex.