Charge-transfer properties of some paraquat salts
Abstract
A series of salts of the dication, NN′-dimethyl-4,4′-bipyridyl, with anions of the type MX4n–, where M can be a unibi-, or ter-valent cation and X is chloride, bromide, or iodide, has been prepared. Their formulae have been obtained chemically and in certain cases by complete structure analyses. The absorption spectra of the solids have been measured and an intermolecular charge-transfer band, from anion to cation, has been assigned. E.p.r. spectra of the FeCl42– and of the Cu2Cl42– compound shows that these solids contain some of the reduced radical cation and some oxidised anion. The electrical conductivity of this type of compound is high. The relevance of the observations to the effect of the cation (paraquat) on electron-transfer in photosynthesis and oxidative phosphorylation is discussed.