A survey study of the vibrational spectra of some aquo-halogenocomplexes

I.r. (and a few Raman) spectra are reporeted for the series M2I[MX5(H2O)], M2I[MX4(H2O)2], MX2,2H2O, and MX2,6H2O. From shifts in frequency with change of cation, metal, and halogen (X) the wagging mode of coordinated water is assigned at higher frequency than the rocking mode, contrary to currently accepted wisdom. Use of deuteriation has enabled identification of ν(Mâ†�OH2) and δ(M–O) modes in many cases. It is suggested that CoBr2,6H2O has the structure [CoBr2(H2O)4],2H2O and does not contain the hexa-aquo ion.