THEORETICAL-STUDY OF THE TRANSITION ENERGIES OF THE VISIBLE ABSORPTION-SPECTRA OF [RHCL6](3-) AND [RHCL5(H2O)](2-) COMPLEXES IN AQUEOUS-SOLUTION

Electron absorption spectra of [RhCl6](3-) and [RhCl5(H2O)](2-) comple xes are studied theoretically by the ab initio symmetry adapted cluste r (SAC)/SAC-CI method. Two maximum peaks of the visible absorption spe ctra in the range of 300-600 nm observed in aqueous solution are assig ned to (T-1(1g); T-1(2g)) and mixing-(1B(1), 1A(2), 1B(2); 2B(1), 2A(2 ), 2B(2)) states for [RhCl6](3-) and [RhCl5(H2O)](2-) complexes, respe ctively, in good agreement. These states are due to the forbidden d-d transitions from the Rh(d pi)+Ligand(p pi) bonding MOs to the Rh(d sig ma)-Ligand(p sigma) antibonding MOs, leading to an weakening of the me tal-ligand bonds.