Increasing the oxidation power of TCNQ by coordination of B(C6F5)3

Abstract

The oxidation power of the cyanocarbon TCNQ (tetracyano-quinodimethane) can be significantly increased to approximately E = +0.9 V vs. Cp₂Fe by coordination of up to four equivalents of the strong fluorinated Lewis acid B(C₆F₅)₃, resulting in a highly reactive but easy-to-use oxidation system. Thianthrene and tris(4-bromophenyl)amine were oxidized to the corresponding radical cations. Dianionic [TCNQ·4 B(C₆F₅)₃]²⁻ was formed upon reduction with two equivalents of ferrocene or decamethylcobaltocene. [TCNQ·4 B(C₆F₅)₃]⁻ and [TCNQ·4 B(C₆F₅)₃]²⁻ are rare cases of redox-active weakly-coordinating anions.