Molecular Cocrystals of Carboxylic Acids. XXV The Utility of Urea in Structure Making with Carboxylic Acids and the Crystal Structures of a Set of Six Adducts with Aromatic Acids

Abstract

Molecular adducts of urea with six aromatic carboxylic acids have been prepared and characterized by using X-ray diffraction methods and infrared spectroscopy. These compounds are with 5-nitrosalicylic acid [(C7H5NO5)2(CH4N2O)] (1), 3,5-dinitrosalicylic acid [(C7H4N2O7)(CH4N2O)] (2), 4-aminobenzoic acid [(C7H7NO2)2(CH4N2O)] (3), o-phthalic acid [(C8H6O4)(CH4N2O)] (4), pyrazine-2,3-dicarboxylic acid [(C4H4N2O4)(CH4N2O)] (5) and pyridine-2,6-dicarboxylic acid [(C7H5NO4)(CH4N2O)2] (6). In the majority of the adducts, all six potential interactive sites on the urea molecules are utilized in hydrogen bonding, giving polymeric structures.