Vibrational Spectra and Structure of Solid Sulfamic Acid and the Sulfamate Ion

Abstract

The infrared spectra of finely powdered samples in pressed disks of KBr have been obtained for sulfamic acid, sodium and potassium sulfamates, and the corresponding deutero-compounds in the region from 4000 to 500 cm—1 at several temperatures. Satisfactory vibrational assignments could be made for the zwitterion model of the acid, H3N+–SO3—, with site symmetry in the crystal of C1 in agreement with x-ray data. The sulfamate ion spectra can satisfactorily be interpreted on the basis of the C8 model, H2NSO3—. The N–S stretching modes were found at somewhat lower frequencies than previously postulated, 682 and 790 cm—1, respectively, for the acid and salt.