4-carboxyanilinium phosphite: A structural, vibrational, thermal and computational study

•A new organo-phosphite compound, 4-carboxyanilinium dihydrogen phosphite (4-CAPI) was synthesized. It crystallised in the triclinic space group, P-1, Z = 4, with two 4-carboxyanilinium cation (4-CA) and two phosphite (H2PO3−) anions in an asymmetric unit.•Vibration band assignment of 4-CAPI was carried out by comparing its spectrum with that of the partially deuterated 4-CAPI and the reported assignment of the parent compounds 4-ABA and H3PO3.•Using the computational tool of energy framework analysis the intermolecular interaction topology has been quantitatively analyzed for 4-CAPI. For the hydrogen bonded anion–cation pairs in the crystal structure of 4-CAPI, very high values of interaction energies are found. A new organo- phosphite adduct, 4-carboxyanilinium dihydrogen phosphite (4-CAPI) was synthesized and characterized by single-crystal X-ray diffraction, FTIR and DSC. 4-CAPI crystallises in the Triclinic space group, P-1, Z = 4, with two 4-CA cations and two H2PO3− anions in an asymmetric unit. In 4-CAPI crystal the organic layer containing 4-CA cations and the inorganic layer containing phosphite anions are connected through a three-dimensional network of strong charge-assisted N–H⋯O and C–OH⋯O hydrogen bonds. The cations, 4-CA exists as a cyclic acid dimer. The infrared vibrational frequencies of 4-CAPI were assigned and the spectral features of 4-CAPI obtained suggest presence of a stronger NH⋯O and C–OH⋯O hydrogen bond interactions thus corroborating with the x-ray result. The intermolecular interaction topology of 4-CAPI has been quantitatively analyzed using the computational tool of energy framework analysis, A very high values of interaction energies are found for the hydrogen bonded anion–cation pairs. The major contribution is from electrostatic interaction. [Display omitted]