Chemical preparation, crystal structure reinvestigation, and vibrational study of meta-carboxyphenyl ammonium dihydrogenomonophosphate (C7H4NH3OOH)H2PO4 (m-C AMP)

Abstract

Chemical preparation, X-ray diffraction data collection on a single crystal and IR spectroscopy studies of the monophosphate (C7H4NH3OOH)H2PO4, meta-carboxyphenyl ammonium dihydrogenophosphate crystal (m-CPAMP) were developped at room temperature. The title compound crystallizes in the monoclinic system, with the centrosymmetric space group P21/c (Z = 4). Its unit-cell dimensions are a = 12.9361 (7) (Å), b = 11.7735 (6) (Å), c = 6.5764 (4) (Å), β = 102.668 (2)° and V = 977.22 (9) Å3. The structure determined gives a clear description of the hydrogen bonds connecting the hydrogen phosphate H2PO4- with the organic matrix. In the structure of this compound, each (H2PO4)− aggregates with cation through hydrogen-bond interactions of O-H----O(P) and N-H····O(P) types, and with another (H2PO4)− via hydrogen bonding O1-H····O3, forming symmetrical (H4P2O8)2 − anionic units.The Infrared spectrum of (C7H4NH3OOH)H2PO4 compound is studied in comparison to that of the cation C7H4NH3OOH considered in its free symmetry.