Complex formation between copper (II) and amines in N,N-dimethylformamide (author's transl)

Abstract

Dimethylformamide solutions containing copper (II) perchlorate and amines were studied by absorption spectra and by magnetic measurement. Solutions of [butylamine]/[Cu (II)]=2-8 were yellow with a considerable absorption in the 400-nm region. The absorption can be ascribed to the presence of dimeric or oligomeric copper species, which was supported by the results of magnetic measurements. Solutions of the ratio over 10 were blue and their spectra had an absorption peak at 640 nm and no appreciable absorption in the 400-nm region. In these solutions copper was concluded to be present as Cu (amine)42+. Similar results were obtained with benzylamine and ammonia. Solutions containing Cu (II) and aniline had an intense absorption at 384 nm, which disappeared on acidification or on addition of amines with complexing ability. A similar absorption was produced by p-anisidine, p-toluidine, and m-toluidine but not by diphenylamine, ethyl p-aminobenzoate, or 2, 6-dimethylaniline. Magnetic measurement indicated Cu (II) species to be monomeric in the solutions. These results are interpreted in terms of the formation of a weak Cu (II)-aniline complex, possibly Cu (aniline)2+.