AM1 STUDIES OF HEXASUBSTITUTED BENZENES I - PYRROLYL-DERIVATIVE, IMIDAZOLYL-DERATIVE AND PYRAZOLYL-DERIVATIVE

Using the semiempirical quantum-chemical AM1 method, the geometries of hexapyrrolylbenzene, hexaimidazolylbenzene and hexapyrazolylbenzene i n various bonding modes were optimized. A tendency for the symmetry to decrease from a six-fold to a three-fold rotation axis may be observe d. The inter-plane angle of the central and side rings depends on the bonding mode of the side rings. The side-rings in experimental structu res are bonded via nitrogen atoms, whereas our calculations indicate b onding via the neighboring carbon atoms in the most stable systems. (C ) 1998 Elsevier Science B.V. All rights reserved.