Semiempirical and ab initio calculations on geometry and stability of intermediates. Stability of intermediates for nucleophilic reactions of carbonyl compounds in the gas phase and in solution

Abstract

Semiempirical CNDO/2, CNDO/BW, MINDO/2, MINDO/3, MNDO and MNDO/H, ab initio STO-3G, 4-31G and 6-31G* methods have been used to calculate the stability and equilibrium geometries of intermediates for nucleophilic reactions of carbonyl compounds in the gas phase and in solution. The solvent effects have been introduced within the supermolecular approach. The limitations of semiempirical methods have been examined. It was found that the MNDO results are in good agreement with the ab initio 4-31G and 6-31G* data. The solvent may change the gas phase data in a remarkable way.