SYNTHESIS AND CHARACTERIZATION OF SOME CHROMIUM(III) COMPLEXES WITH GLUTATHIONE

The glutathione (H5L) complexes K2[Cr(H3L)(H2L)].cntdot.3H2O, K2[Cr(H2L)(A)].cntdot.nH2O (A = the dianion of the amino acids L-cysteine, L-glutamic acid, or L-aspartic acid), and K2[Cr(H2L)(gly)(OH)].cntdot.2H2O [gly = glycinate(1-)] have been synthesized. All the complexes exhibit an intense u.v. charge-transfer band which is characterized of a Cr.sbd.S bond. The sulphydryl to chromium linkage undergoes an acid-catalysed hydrolysis. The complexes have been characterized by elemental and thermogravimetric analyses, electronic and i.r. spectroscopy, and circular dichroism. Comparison of these properties with those of known chromium(III) complexes leads to the conclusion that glutathione is bound to chromium(III) by the terminal glycine group (N,O) and the deprotonated sulphur of cysteine. The glutamic acid residue of glutathione does not apparently interact with the chromium centre in these complexes.