Ab initio MRSDCI calculations of the [formula omitted] components of [Cu(H 2O) 6] 2+ complexes

Abstract

The geometrical structure, electronic states and g- tensor values of the hydrated Cu 2+ ion, [Cu(H 2O) 6] 2+ complex, have been studied by means of ab initio MO and MRSDCI methods. The ground state potential energy surface calculated as functions of the axial and equatorial CuO bond distances ( r ax and r eq) show two energy minima which correspond to elongated and compressed structures of the [Cu(H 2O) 6] 2+ complex. For the elongated structure, the optimized geometry and ratio of the bond lengths ( r ax/ r eq) were in good agreement with the structure determined by ESR and the EXAFS experiments. On the basis of second-order perturbation theory, g- tensor components of the complexes were calculated with the natural orbitals obtained by an MRSDCI calculation. For the elongated structure, the g ‖ value is larger than g τ ( g ‖ = 2.400 and g τ = 2.098) which is in agreement with the ESR experiment.