Formation of ammonium halide particles from pure ammonia and hydrogen halide gases: A theoretical study on small molecular clusters (NH3–HX)n (n=1, 2, 4; X=F, Cl, Br)

Abstract

Articles you may be interested inModeling the hydration of mono-atomic anions from the gas phase to the bulk phase: The case of the halide ions F−, Cl−, and Br− J. Chem. Phys. 136, 044509 (2012); 10.1063/1.3678294Hydrogen-bond interaction in 1:1 complexes of tetrahydrofuran with water, hydrogen fluoride, and ammonia: A theoretical studyThe mechanism for the gas-phase production of particulate ammonium halides is studied by density functional theory and ab initio calculations on the molecular clusters of ammonia-hydrogen halide, ͑NH 3 -HX) n , nϭ1, 2, 4; XϭF, Cl, Br. The equilibrium structures of the clusters demonstrate an abrupt transition from hydrogen-bonding in the single unit of NH 3 -HX to the NH 4 ϩ¯XϪ ion-pair interactions in ͑NH 3 -HX) 4 resulting from spontaneous proton transfer from hydrogen halide to ammonia. The onset of the ion-pair form is at nϭ2 for HCl and HBr and at nϭ4 for HF. The ion-pair structure is the stable form of the larger clusters to maximize favorable electrostatic interactions and to closely resemble the crystal structures of ammonium halides. The calculated vibrational frequencies of the clusters provide additional evidence in support of the transition from hydrogen-bonding to ion-pair interactions as cluster size increases. The study shows that it is possible to form particulate ammonium halides directly from pure NH 3 and HX vapors in the homogeneous gas phase.

Toward a uniform description of hydrogen bonds and halogen bonds: correlations of interaction energies with various geometric, electronic and topological parameters

“…The same results were also reported in previous studies of the hydrogen bonding interactions of HX with ammonia 51,52 and water, 53 as well as methanol derivatives. 54 However, for the hydrogen-bonded complexes formed between HX and benzene, which is a much weaker hydrogen bond acceptor, the calculated binding energies follow the opposite order, i.e., DE(HBr) > DE(HCl) > DE(HF).…”

Electron-Driven Acid-Base Chemistry: Proton Transfer from Hydrogen Chloride to Ammonia

“…In a series of experiments 20 years ago, however, Legon showed conclusively by rotational spectroscopy that in beams of neutral [(HCl)(NH 3 )] heterodimers (2,3), no appreciable proton transfer occurs; instead, the spectra are consistent with linear, hydrogen-bonded ClH … NH 3 complexes. Modern theoretical studies agree (4)(5)(6)(7)(8)(9)(10)(11). Therefore, as counterintuitive as it may seem, ammonia and hydrogen chloride do not react under isolated conditions.…”

Fate of ammonia in the atmosphere?a review for applicability to hazardous releases

“…Advanced ab initio calculations by Tao and co-workers [161][162][163][164] support the formation and stability of NH4CI in the gas phase. The single NH3-HCI complex is hydrogen bonded only.…”