Conformational analysis of 4,4’-dibromodiphenyl disulfide

Diaryl disulfides are important in chemistry and materials science, yet their conformational equilibria often remain experimentally unexplored due to conformer predominance or indistinguishable signals. High-level DFT calculations for 4,4’-dibromodiphenyl disulfide (1) reveal a preference for conformer B, characterized by sliding ring planes during S–S rotation, over conformer A, where the planes approach or distance themselves. Bromine substituents enhance π-π interactions, stabilizing conformer B, unlike in diphenyl disulfide (2). Notably, only conformer A appears in the solid state. NBO analysis attributes conformer B’s stability to weaker steric effects, while AIM analysis confirms an attractive interaction between the C2 atoms of both rings. These findings highlight the role of substituents in conformational behavior and provide insights for designing materials with optimized properties.