PCM study of the solvent and substituent effects on bond dissociation energies in O-nitrosyl carboxylate compounds

A PCM continuum model, at B3LYP, B3P86, and B3PW91 three-parameter hybrid DFT methods with 6-31G∗∗ and 6-311G∗∗ basis sets, is used to study the bond dissociation energies (BDEs) of O-nitrosyl carboxylate compounds. Compared the computed results with the experimental values, it is noted that B3P86/6-31G∗∗ is the best method to compute the bond dissociation energies of O-nitrosyl carboxylate compounds. The solvent effects on the BDEs of the O-NO bond are analyzed and it is shown that the O-NO BDEs computed by using B3LYP/6-311G∗∗ method in a vacuum are the closest to the computed values in acetonitrile and the average solvent effect is 0.4 kcal/mol. Subsequently, the substituent effects on the BDEs of the O-NO bond are further analyzed and it is found that electron donating group stabilizes the radical and as a result BDE decreases; whereas electron withdrawing group stabilizes the ground state of the molecule and thus increases the BDE from the parent molecule.