Effect of Annulation Pattern on the Antiaromaticity of Thioether‐ and Sulfone‐Substituted Dinaphthopentalenes

Abstract As non‐alternant hydrocarbons with antiaromatic character, diarenopentalenes are of significant interest. By varying the nature and attachment geometry of the annulated aromatic units, their antiaromaticity and optoelectronic properties can be influenced. Herein, we present a series of thioether‐ and sulfone‐substituted dinaphtho[ a , e ]pentalenes as well as their optical, electronic, and structural properties. Quantum chemical calculations provide insight into their antiaromaticity. Depending on the orientation of annulation of the naphtho units to the pentalene core, the calculated nucleus‐independent chemical shifts (NICS) gives higher values, indicative of an increased antiaromaticity for the [2,1‐ a ] annulated dinaphthopentalene compared to the linearly [1,2‐ b ]‐annulated isomers. The trend in NICS value can be linked to the length of the fused bond between the pentalene and naphthalene fragments, suggesting this bond length as a descriptor for antiaromaticity. This article provides insight into the correlation between structural design and antiaromaticity of diarenopentalenes.