Self-assembly of conducting cocrystals via iodine⋯π(Cp) interactions

Abstract

Conducting crystals of alternating ferrocene and diiodoacetylene units assembled into supramolecular 1-D chains via I⋯π(Cp) halogen bonds were prepared and structurally characterized. Their structure and conductivity were compared with the ferrocene cocrystals with phenyliodoacetylene (C₆H₅C₂I) and 1,4-di(ethynyliodo)phenylene. Electrical conductivity measurements of the ferrocene-based cocrystals revealed comparatively high electron–hole type conductivity in the ferrocene (FcH)–diiodoacetylene (C₂I₂) pair, a 3-order decrease in combination with the 1,4-di(ethynyliodo)phenylene linker, and it is virtually extinguished with the monotopic 1,2-phenyliodoacetylene. The increased electric conductivity of compound 1 is rationalized in terms of a weak charge transfer through the I⋯πCp halogen bonds in the [Cp–Fe–Cp⋯I–CC–I⋯]_n polymeric chains.