Solid-state conductivities of CPQ. [1,1′-bis(p-cyanophenyl)-4,4′-bipyridilium] salts, redox-state mixtures and a new intervalence adduct

Abstract

The solid-state conductivity, σ, has been determined for cyanophenyl paraquat (CPQ: 1,1′-bis(p-cyanophenyl)-4, 4′-bipyridilium), for salts containing dication and radical cation redox states and for mixtures of the two. A plot of σvs. mole fraction of CPQ⁺ showed a maximum corresponding to a composition [CPQ²⁺(CPQ⁺)₂(anion^–)₄], which led to a new solid-state adduct of this stoichiometry, crystallised from a 1 : 2 CPQ²⁺–CPQ⁺ solution. The adduct differed spectroscopically from the parent species, and had substantially enhanced conductivity (1.0 × 10^–3S cm^–1). Adduct-like mixtures containing possibly varying proportions of the two CPQ redox states were prepared by reductive precipitation from CPQ²⁺-containing colloid.