Vibrational Spectra of Molecules and Complex Ions in Crystals. IX. Boric Acid

The infrared spectrum of boric acid was studied at 25°C and —195°C in the form of randomly oriented crystallites and as a single crystal section at 25°C. The spectrum can be interpreted as skeletal vibrations of B(OH)3 molecules plus the hydrogen vibrations, which are those of the hexagonal O–H≡O rings. The spectrum demonstrates that the symmetry about the B atoms is less than trigonal. There is no evidence of proton disorder.