Normal Coordinate Analyses of Hydrogen-Bonded Compounds. IV. The Acid Carbonate Ion

Abstract

The infrared spectra of potassium acid carbonate and its deutero analog have been obtained from 4000 to 160 cm⁻¹. The Raman spectrum of the latter has also been obtained in the crystalline state. A normal coordinate analysis has been carried out to estimate the force constants as well as to make theoretical band assignments. The infrared bands of the nondeuterated compound at ∼2620, 1405, and 248 cm⁻¹ have been assigned to the O–H stretching, O–H···O in‐plane bending, and O···H stretching coupled with C=O bending modes, respectively. The corresponding force constants are: O–H stretching, 3.20, O–H···O bending, 0.22, and O···H stretching, 0.76 mdyn/Å. Plots of these force constants versus O–H···O distances for three compounds thus far investigated yield a linear relationship for each force constant.