Intermolecular hydrogen bonds interactions in water clusters of ammonium sulfamate: FTIR, X-ray diffraction, AIM, DFT, RDG, ELF, NBO analysis

Abstract Ammonium sulfamate is an important sulfamic acid derivative. It has found wide application as a herbicide, fire-resistant agent, etc. In this work, we investigated intermolecular aqueous clusters of ammonium sulfamate. According to FTIR spectroscopy data, the introduction of water molecules increases the intensity of the absorption bands in the FTIR spectra. In addition, there is a significant increase in the intensity of absorption bands (by a factor of 6) in the range of 3550–3200 cm−1, which correspond to intermolecular interactions of OH groups. It was shown by X-ray diffraction that the introduction of water molecules into the structure of ammonium sulfamate significantly changes the intensities of the absorption bands in the diffraction patterns. The geometry optimization of aqueous clusters of ammonium sulfamate with a content of water molecules from 1 to 15 was carried out in the gas phase using the DFT B3LYP/6-311 ++ G (d, p) level. The nature of the molecular interactions between water and ammonium sulfamate via hydrogen bonds has been investigated using the Atoms in Molecules (AIM), Electron Localization Function (ELF) and non-covalent reduced density gradient (NC-RDG) analyses. Thermodynamic and NLO properties of ammonium sulfamate-water clusters have been carried outusing the DFT/B3LYP/6-31+G(d,p) methodology.