An Investigation on some Sulphato Complexes in Aqueous Solution with Infrared Spectroscopy
Infrared spectra in the range 1400 – 850 K have been recorded for several metal sulphates in aqueous solution. For this purpose 8,8 µ thick cells with “IRTRAN — 2” windows have been used. In the frequency region mentioned the free sulphate ion absorbs radiation at 1104 K corresponding to the asymmetric S-O vibration (ν 3). From solid state investigations (1) it is known that in the spectrum of sulphato complexes this absorption peak is split into two or three new peaks depending upon whether the symmetry of the sulphate ion is decreased to C3v or C2v. This corresponds to a mononuclear, unidentate complex and a polynuclear or possibly a mononuclear bidentate complex, respectively. Furthermore, the symmetric S -O vibration (ν 1), which is infrared inactive for the free ion, becomes apparent in the spectra of sulphato complexes.