Towards design of the smallest planar tetracoordinate carbon and boron systems.

A series of cyclic hydrocarbons analogs where a carbon displays unusual planar tetracoordinate structure is proposed, employing hybrid density functional theory calculations using B3LYP functional and 6-311+G** basis set. Various strategies were employed to design the neutral planar tetracoordinate hydrocarbon analogs. The same strategy is employed for designing the planar tetracoordinate boron systems. The simplest neutral planar tetracoordinate hydrocarbons were proposed and the effect of substitution on their stability has been assessed. The aromatic stabilization is gauged with nucleus independent chemical shift calculations. The activation barriers for the ring opening reaction, the highest occupied molecular orbital and lowest unoccupied molecular orbitals gap and singlet-triplet energy difference were estimated to gauge the plausibility experimental realization. Copyright (c) 2006 Wiley Periodicals, Inc.