Electronic and infrared spectra of chromium(III) complexes isolated from the bioinorganic system: [Cr(VI) ascorbic acid]; Cr(VI)=K2Cr2O7, KCrO3Cl, CrO2Cl2

Six novel Cr(III) complexes obtained from the redox system [Cr(VI)-H(2)asc] have been isolated and physicochemically characterized. The stoichiometrie s of the species were found to be dependent on both the initial Cr(VI) comp ound and the solvent. Spectroscopic evidence suggested that the binding of the L-ascorbic acid to the chromium(III) ion is through oxygen C(3)-O, C(1) -O and C(2)-O, C(1)-O atoms. The coordination sphere of Cr(III) has been de scribed assuming tetragonal deformation of the octahedral symmetry resultin g from the presence of the oxygen atoms in various ligands and/or different positions of oxygen atoms in the H(2)asc molecule. Comparison with our res ults obtained earlier suggests the stronger covalency of the Cr-O bond foun d in the complexes studied in this work. (C) 1999 Elsevier Science B.V. All rights reserved.