A study of the structures and vibrations of C 6 H 5 NH 2, C 6 H 5 NHD, C 6 H 5 ND 2, C 6 D 5 NH 2, C 6 D 5 NHD, and C 6 D 5 ND 2 in the S 1 state by ab initio calculations

Abstract

The structures and vibrations of C 6 H 5 NH 2, C 6 H 5 NHD, C 6 H 5 ND 2, C 6 D 5 NH 2, C 6 D 5 NHD, and C 6 D 5 ND 2 have been studied using ab initio molecular orbital (MO) calculations. Calculations at the CIS/6-31+G* level successfully predict that aniline is planar in the S 1 state, and contracts along the long in-plane axis with a quinoid-like resonance structure. A comparison of the S 0 and S 1 state vibrational modes is presented and discussed in terms of the changes in reduced masses, force constants, and mode mixing for aniline and its isotopic species. The computed frequencies are found to be in very good agreement with the available experimental values. © 1998 Elsevier Science B.V.