RAMAN-SPECTRA OF SOME TRANSITION-METAL SQUARATE AND CROCONATE COMPLEXES

The Raman spectra of a series of transition metal squarate and croconate polymeric complexes have been obtained. The data suggest that in the case of the squarate complexes the D4h symmetry of the oxocarbon is conserved in the complexes, while in the case of the croconate complexes the symmetry is reduced to C2v. In both series the frequency values indicate that in the polymeric chains the interaction of the oxocarbons with the metal ions is to a great extent delocalized. In contrast, the Raman spectra of the sodium salts of the oxocarbons, reported here for the first time, suggest a substantial reduction in symmetry in their unit cells. In the case of the croconate, the Raman spectrum of the solid has enabled the identification of one of the fundamentals not reported in previous works.