LAUSR

Abstract Nature of the chemical bonds and intermolecular interactions in the multifunctional ionic liquid tris(2-aminothiazolium) hydrogen sulfate sulfate monohydrate ([tr(2-AT]+[HSO4]−.SO42−.H2O) are investigated in the current work by means of density functional theory at B3LYP/6–311++G(d,p) level. For that purpose, detailed structural, natural bond orbital (NBO), Hirshfeld surface (HS) and reduced density gradient (RDG) analyses are employed. In addition, the Quantum theory of atoms in molecules (QTAIM) is applied as well. Structural, NBO and HS analyses showed that the bond lengths in the title compound depend strongly on intermolecular O···H interactions between amine ((N H)am) and thiazole ((N H)thzl) hydrogen atoms in cationic ([tr(2-AT]+) fragments with oxygen atoms in anionic ([HSO4]− and SO42−) and H2O moieties. Moreover, hydrogen bonds between H2O with [HSO4]− and SO42− are also observed. QTAIM and RDG data revealed that the (N H)am···(O S)s and (N H)thzl···(O S)s bonds are partly covalent in nature. In contrary, the interactions (N H)am···(O S)hs, (N H)thzl···(O S)hs and (N H)am···(O H)w are define as electrostatic, being observed in a greater extent for (N H)am···(O H)w.