| Summary: | Measurements of infrared and Raman spectra have been used to obtain structural information on a range of transition-metal-oxygen complexes. In order to apply the Raman technique with mercury arc excitation to as many of the systems as possible, the studies have generally been restricted to the colourless or pale yellow complexes of the metals of Groups IVa, Va and VIa in their highest oxidation states. By recording the Raman spectra and complementary infrared spectra of alkaline solutions of oxyvanadium(V) anions at various pH values, it has been possible to identify the species present in such solutions and to suggest structures for these. This technique has also been used to investigate the possible existence of monomeric tetrahedral oxyanions of niobium and tantalum in solutions of high pH, and the existence of low molecular weight polymers in isopolytungstate solutions. A study has also been made of the species present in acid solutions of the early transition metals; the complexes present are mainly anionic, and formulae and structures are proposed for them. During this study, the presence of complexes with two cis oxy groups was postulated. The infrared and Raman spectra of a number of dioxy complexes were therefore measured, and the cis dioxy configuration found to be more widespread than generally realised. The spectral characteristics of such 6. compounds, and also of some trioxy complexes, have been tabulated, and an explanation proposed for the relative existence of cis and trans dioxy systems. The spectral characteristics of a number of peroxy complexes have also been recorded; it is thought that the results may be used to identify the mode of bonding of peroxy groups in unknown complexes. Finally infrared and Raman spectroscopic measurements have been used to suggest structures for a number of early transition metal peroxyoxalato complexes.
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