Theoretical Study of Electron Density Delocalization in the Excited States of Transition Metal Complexes

Abstract

This paper presents a theoretical study of electron density delocalization effects over an electron-accepting ligand in metal-to-ligand charge-transfer (MLCT) complexes in the excited states, where the ligand is 4,4'-X2-2,2'-bpy (X = H, NH2, CH3, Ph, Cl, CO2Et, NO2, bpy = 2,2'-bipyridine) or terpy (2,2':6',2''-terpyridine). Optimal geometry calculations are performed for neutral ligand molecules and their radical anions modeling the state of the ligands during MLCT excitations. Spin density distribution over atoms in the radical anions is used as a measure of the degree of delocalization. The role of spin density distribution in excitation-induced changes of geometrical parameters of the ligands is considered.