Extended barbaralanes: sigmatropic shiftamers or sigma-polyacenes?

J Am Chem Soc. 2004 Apr 7;126(13):4256-63. doi: 10.1021/ja0392364.

Abstract

Starting from fused barbaralanes, we come (theoretically) to a new class of delocalized molecules in which two polyenyl radical chains interact with each other through space in a bonding way, but do not form full sigma-bonds. These molecules resemble sigma-homologues of polyacenes and are bishomoaromatic.