Three Wrongs Make a Right: A Computational Investigation of [4n]–[4n]–[4n] Fused π-Systems

Abstract

Fusing antiaromatic units to other antiaromatic units could afford delocalized [4n]–[4n]–[4n] π-systems with reduced paratropicity (or even weak diatropicity), while retaining narrow HOMO–LUMO gaps. Through a computational investigation of bis-annelated borole-fused cyclobutadiene, pentalene, s-indacene, and cyclooctatetraene isomers, we find that these effects are topology-dependent. Comparisons to analogous [4n+2]–[4n]–[4n+2] systems show that [4n]–[4n]–[4n] fusion represents a counterintuitive design strategy to access functional antiaromatic π-systems.