HYDROGEN-BOND PATTERNS IN SOLID-STATE CARBOXYLIC-ACIDS - VIBRATIONAL STUDY OF THE HYDROGEN-BOND PATTERNS IN OXAMIC, MALONAMIC AND SUCCINAMIC ACID

The vibrational spectra of oxamic, malonamic and succinamic acid are reported, Although these molecules exhibit identical functional groups, their solid state hydrogen bond patterns can be divided in two different types, which can be clearly distinguished through the combination of infrared and Raman spectroscopy at variable temperatures and through the vibrational behaviour of the deuterated compounds, Oxamic acid behaves as a linear hydrogen bonded polymer with cyclic acid-acid and cyclic amide-amide dimers while the other discussed carboxylic acid derivatives exhibit a cyclic acid-amide hydrogen bond pattern, A model is proposed to investigate the peculiar vibrational behaviour of oxamic ai:id theoretically. Spectroscopic studies of the cyclic heterogenic acid-amide hydrogen bond pattern are studied for the first time.