Characterisation of 1,3-diammonium propylselenate monohydrate by XRD, FT-IR, FT-Raman, DSC and DFT studies

Abstract

The crystals of 1,3-diammonium propylselenate monohydrate (DAPS) were prepared and characterised X–ray diffraction (XRD), FT-IR, FT-Raman spectroscopy, and DFT/B3LYP methods. It comprises protonated propyl ammonium moieties (diammonium propyl cations), selenate anions and water molecule which are held together by a number of hydrogen bonds and form infinite chains. The XRD data confirm the transfer of two protons from selenic acid to 1,3-diaminopropane molecule. The DAPS complex is stabilised by the presence of O–H···O and N–H···O hydrogen bonds and the electrostatic interactions as well. The N···O and O···O bond distances are 2.82–2.91 and 2.77 Å, respectively. The FT–IR and FT–Raman spectra of 1,3-diammonium propyl selenate monohydrate are recorded and the complete vibrational assignments have been discussed. The geometry is optimised by B3LYP method using 6–311G, 6–311+G and 6–311+G* basis sets and the energy, structural parameters, vibrational frequencies, IR and Raman intensities are determined. Differential scanning colorimetry (DSC) data were also presented to analyse the possibility of the phase transition. Complete natural bonding orbital (NBO) analysis is carried out to analyse the intramolecular electronic interactions and their stabilisation energies. The electrostatic potential of the complex lies in the range +1.902e × 10−2 to −1.902e × 10−2. The limits of total electron density of the complex is +8.43e × 10−2 to −8.43e × 10−2.