Infrared and Raman spectra of solutions of zinc, cadmium, and mercury(II) nitrates in acetonitrile

Abstract

Infrared and Raman spectra are reported for acetonitrile solutions of zinc, cadmium, and mercury(II) nitrates and some of their halides. The nitrate spectra are, in each case, consistent with strong perturbation of nitrate ions by solvated cations, but only in the case of mercury(II) has a metal–oxygen vibration frequency been observed. This is discussed in terms of the lower stability of the mercury(II) compound. Examination of the perturbation of the vibrational spectra of free acetonitrile caused by co-ordination to zinc shows that the C–N stretching frequency is increased by ca. 40 cm.^–1 rather than 63 cm.^–1 as previously reported. Raman intensity studies of the relation between Zn(NO₃)₂ concentration and the C–N band intensity of acetonitrile establish that in concentrated solutions the principal zinc species present is [Zn(CH₃CN)₂](NO₃)₂.