A system with three contiguous planar tetracoordinate carbons is viable:: a computational study on a C6H62+ isomer

Ab initio and density functional theory calculations indicate that a benzene dication isomer (1: C6H62+) with three contiguous planar tetracoordinate carbons is at a minimum on the potential energy surface. The remarkable preference for the planar structure for 1 is traced to the aromatic stabilization present in the three membered ring formed by the three planar tetracoordinate carbon atoms. (C) 2003 Elsevier Ltd. All rights reserved.