Ion conductive characteristics of boron stabilized carbanion derived from organoboron π-conjugated systems

Summary

Ion conductive properties of boron stabilized carbanions (BSC) have been studied as a model of π-conjugated ion conductive polymer in which counter anion of lithium ion is delocalized in π-conjugated system. After treatment of the BSC precursor (trimesitylborane or dimesityl-9-anthrylborane) with an organolithium reagent, the color of the reaction mixture dramatically turned to dark red or purple. Interestingly, BSC derived from dimesityl-9-anthrylborane showed moderate ion conductivities of 4.02×10⁻⁷ S/cm at 50°C even in bulk, indicating high dissociation degree of the BSC lithium salt. This can be attributed to the decreace in site hopping energy of the lithium ion, since anionic charge is delocalized via vacant p-orbital of the boron atom. These observations might have important implication for potential capability of ion conductive π-conjugated systems.