Some salts of protonated azobenzene and the conversion of azobenzene into benzidine by copper(I) halides in hydrochloric acid

Abstract

The salt [ABH]FeCl₄(ABH = protonated azobenzene) has been isolated from hydrochloric acid solution and the salts [ABH]₂CoBr₄ and [ABH]₂CuBr₄ from mixtures of hydrobromic and acetic acids. The reactions of copper(I) chloride in hydrochloric acid and copper(I) bromide in hydrobromic acid with azobenzene lead to precipitation of salts of the protonated benzidine cation; these have the formulae [BH₂]CuCl₃,HCl (BH₂= diprotonated benzidine) and [BH₂]Cu₂Br₆ respectively. The same chloride complex of copper(I) has been prepared from benzidine in hydrochloric acid. The spectra of the compounds are reported and their structures discussed.