Symmetry of carboxylate ions. Infrared spectra of 18O labelled sodium deuterioformate

The band shifts in the i.r. spectra of solid 40–60 %18O enriched sodium deuterioformate show unambiguously that the two C–O force constants are equal and the charge and bond delocalisation in the carboxylate group is complete. This is in contrast to Spinner's conclusion.