LOW-LYING EXCITED-STATES OF 4-DIMETHYLAMINOBENZONITRILE - EQUILIBRIUMGEOMETRIES, VIBRATIONAL FREQUENCIES AND CHARGE-TRANSFER CHARACTER

Equilibrium geometries and vibrational frequencies of the ground and l ow-lying excited states of 4(dimethylamino)benzonitrile (DMABN) are re ported (6-31G* basis set, ab initio RKF and CI-singles methods). The results suggest that: (i) the ground state structure is planar (C-s sy mmetry); (ii) the (relaxed) locally excited state has the dimethylamin o group twisted somewhat about the N-Ar bond (C-1 symmetry); and (iii) the TICT state is actually a transition stale between two mirror imag e locally excited state structures in the gas phase, where the Me-N bo nds are perpendicular to the N-Ar bond.