| Abstract: | A computational study of chromium(VI) and (V) peroxides, which exhibit important genotoxic and mutagenic activity, is reported. Energies and equilibrium geometries for CrVI(O)(O2)2(OH)]−, CrVI(O)(O2)2(OH2)], CrVI(O)(O2)2(py)], CrVI(OH)(O2)2(OH2)]+, CrV(O)(O2)2(OH2)]− and species were calculated using molecular mechanics calculations (MMFF94 and MM+), quantum calculations with semi-empirical methods (RHF and UHF/PM3) and density functional theory (pBP86/DN* or pBP/DN* and B3LYP/6-31G(d). Equilibrium geometries for the compounds CrV(O2)3(OH)]2− and CrV(O2)4]3− were determined by molecular mechanics. Vibrational frequencies, standard thermodynamic quantities and electronic spectra were calculated using B3LYP/6-31G(d). The structural relationship between all these species and an explanation of the formation of peroxo species in the acid-basic pH range are given. An experimental study of peroxo species in basic medium was also performed (synthesis, X-ray powder diffraction patterns and infrared spectra of the peroxo complexes isolated) but did not confirm the existence of a tri-peroxo complex in the solid phase. |
