C-H and N-H bond dissociation energies of five- and six-membered ring aromatic compounds

C-H and N-H bond dissociation energies (BDEs) of various five- and six-membered ring aromatic compounds were calculated using composite ab initio CBS-Q, G3 and G3B3 methods. It was found that all these composite ab initio methods provided very similar BDEs, despite the fact that different geometries and different procedures in the extrapolation to complete incorporation of electron correlation and complete basis set limit were used. Therefore, the calculated BDEs should be reliable. In addition, we found interesting dependences of the C-H BDEs on the bond angles, spins and charges. A good quantitative structure-activity relationship (QSAR) model for the C-H BDEs of aromatic compounds was also established. Copyright (C) 2003 John Wiley Sons, Ltd.