Charge-transfer complexes. Part II. Complex formation between halogenomethanes and aromatic amines

The spectra of n-hexane solutions of NN-dimethylaniline and NNN′N′-tetramethyl-p-phenylenediamine with added carbon tetrachloride, chloroform, and dichloromethane have been studied. The results have been interpreted in terms of weak donor–acceptor complex formation between the amine and the halogenomethane. Values for the association constants of the complexes, derived from the Benesi–Hildebrand equation, are discussed in terms of current theories on the role of solvent in the evaluation of association constants for weak complexes. Inaccuracies in the evaluation of association constants when a halogenomethane is used as solvent are discussed in terms of a competition between the solvent and the acceptor for the available donor. Some reactions of carbon tetrachloride are interpreted in terms of an intermediate donor–carbon tetrachloride complex.