Theoretical Study on the Structures, Electronic Properties, and Aromaticity of Thiophene Analogues of Anti-Kekulene

We predict the geometries, electronic properties, and aromaticity of thiophene analogues anti-kekulene with six to nine rings 1–4, together those cyclobutadithiophenes (CDTs) as reference compounds, using density functional theory calculations. Investigation simplest CDTs, reveals that local their is influenced by fused position (b- or c-bond) four-membered ring (4MR). A at b-position (b-TR) retains its aromatic character some extent, whereas one c-position attenuated. The 4MR two b-TRs a strong anti-aromatic character. Thiophene eight 1–3 favor bowl-shaped structures, in contrast planar structure anti-kekulene, because shorter distances sulfur bridges. Compound 4, rings, adopts structure. anti-aromaticity are significantly attenuated 1–4 compared CDTs anti-kekulene. This can be attributed considerable contribution quinoidal 1–4. present study provides new insight into nature systems containing cyclobutadienothiophene.