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Vibration-spectral studies of carboxylate ions. Part III. Sodium formate, HCO2Na and DCO2Na; Raman-spectral depolarisation ratios in aqueous solution, and band splitting in the solid-state infrared spectrum

1967; Royal Society of Chemistry; Linguagem: Inglês

10.1039/j29670000879

2050-5590

E. Spinner,

Molecular Spectroscopy and Structure

Accurate measurement of the depolarisation ratios showed that maximum depolarisation (6//7) is observed only for the out-of-plane bending vibration. The (band area) depolarisation ratio for the CD in-plane bending band of DCO2–, 0·80, is slightly less, and that of the CH in-plane bending band of HCO2–, 0·64, considerably less than the maximum. In HCO2– CH in-plane bending steals polarisation from the CO stretching band at 1354 cm.–1. These findings are in agreement with Cs(i.e., planarity) but not C2v symmetry for the formate ion. The splitting of the corresponding band in the solid-state infrared spectrum (at 1366 cm.–1) is only slight for pure HCO2Na but is very pronounced for HCO2Na present as an impurity in the host crystal of DCO2Na. No such splitting is permitted for a formate ion of C2v symmetry in a crystal of space-group C2h6.