AM1 treatment of certain cyclophane-fused tetraazaporphyrins

An AM1-type semiempirical molecular orbital treatment has been performed on certain [2(2)]-type cyclophane-fused tetraazaporphyrins. It has been found that within the isomeric set of structures the most and the least endother mic porphyrins are the ones having non-Hamiltonian and Hamiltonian cyclopha ne moieties respectively. On the other hand, the lowest HOMO and LUMO and t he highest HOMO energies are possessed by the structures bearing Hamiltonia n and non-Hamiltonian cyclophane moieties respectively, whereas the highest LUMO energy belongs to a Hamiltonian cyclophane-fused system within the sa me type of isomeric structures. Copyright (C) 1999 John Wiley & Sons, Ltd.