Crystal and Electronic Structures of [5]Radialene Substituted with Quintuple 1,3‐Dithiol‐2‐ylidenes and Its Oxidative Species

X‐ray structure analysis of the [5]radialene with quintuple 1,3‐benzodithiol‐2‐ylidenes ( 4 ) and its tetracation salt, 4 a ⋅CS 2 and ( 4 a ) 4+ (ReO 4 – ) 4 (CH 3 CN), was successfully carried out. The neutral [5]radialene molecule in 4 ⋅CS 2 adopted a non‐planar structure with an envelope conformation of the central five‐membered ring. In contrast, the central five‐membered ring of 4 a 4+ in ( 4 a ) 4+ (ReO 4 − ) 4 (CH 3 CN) adopted a planar structure with significant contribution of an aromatic cyclopentadienide structure. An anion‐π interaction was observed between the ReO 4 – anion and the central five‐membered ring in ( 4 a ) 4+ (ReO 4 – ) 4 (CH 3 CN). The electronic structures of 4 a and its oxidative species ( 4 a 2+ and 4 a 4+ ) were estimated by density functional theory (DFT) calculations. The optimized structure of 4 2+ suggested the delocalization of a positive charges over two 1,3‐benzodithiol‐2‐ylidene units through the central five‐membered ring.