Systematic Characterization of Gas Phase Binary Pre-Nucleation Complexes\nContaining H₂SO₄ + X, [ X = NH₃,\n(CH₃)NH₂, (CH₃)₂NH, (CH₃)₃N, H₂O, (CH₃)OH, (CH₃)₂O, HF, CH₃F, PH₃, (CH₃)PH₂, (CH₃)₂PH, (CH₃)₃P, H₂S, (CH₃)SH, (CH₃)₂S, HCl, (CH₃)Cl)]. A Computational Study

Abstract

A systematic\ncharacterization of gas phase binary prenucleation complexes between\nH₂SO₄ (SA) and other molecules present in the\natmosphere (NH₃, (CH₃)­NH₂, (CH₃)₂NH, (CH₃)₃N, H₂O, (CH₃)­OH, (CH₃)₂O, HF, CH₃ F, PH₃, (CH₃)­PH₂, (CH₃)₂PH, (CH₃)₃P, H₂S, (CH₃)­SH, (CH₃)₂S, HCl, (CH₃)­Cl) has been carried out using the ωB97X-D/6-311++(2d,2p)\nmethod at the DFT level of theory. A relationship between the energy\ngap of the SA’s LUMO and the partner molecule’s HOMO,\nand the increasing number of methyl groups −CH₃ in\nthe SA’s partner molecule is provided. The binding energies\nof the bimolecular complexes are found to be related to the electron\ndensity in the hydrogen bond critical point, the HOMO–LUMO\nenergy gap, the nature of the hydrogen acceptor atom, and the frequencies\nshift of acid OH bonds. The results show how the frontier orbital\ncompatibility determines the binding energy and that the properties\nof SA’s OH bond which remains free of interactions are affected\nby the bimolecular adduct formation.