Ab initio calculations of 1-heterocyclic 1,4-cyclohexadienes derivatives

The molecular structure of 1.4-cyclohexadienes derivatives with one heteroatom (O, NH, S, Se) are studied using ab initio methods with HF/STO-3G, HF/6-31G* and B3LYP/6-31G* basis sets. These compounds have 6pi-electrons and homoaromatic character. This leads to stabilize the planar or shallow boat conformations. In a group of compounds, the dihedral angles increase using bulky substituents at 4-position due to steric effects. The torsion angles also increase with changing of oxygen toward selenium in same substituents. These molecules have a flat energy minimum scanning through torsion angles. (C) 2004 Elsevier B.V. All rights reserved.