Crystal structure, quantum mechanical investigation, IR and NMR spectroscopy of two new organic perchlorates: (C6H18N3)·(ClO4)3H2O (I) and (C9H11N2)·ClO4(II).

The reaction of perchloric acid with 1-(2-aminoethyl)piperazine or 5,6-dimethyl-benzimidazole results in the formation of 1-(2-amonioethyl)piperazine-1,4-dium triperchlorate hydrate (C 6 H 18 N 3 )·(ClO 4 ) 3 ·H 2 O (I) or 5,6-dimethyl-benzylimidazolium perchlorate (C 9 H 11 N 2 )·ClO 4 (II) . Both compounds were fully structurally characterized including single crystal X-ray diffraction analysis. Compound (I) crystallizes in the centrosymmetric triclinic space group P 1 ¯ with the lattice parameters a = 7.455 (2), b = 10.462 (2), c = 10.824 (2) Å, α = 80.832 (2), β = 88.243 (2), γ = 88.160 (2) °, Z = 2 and V = 832.77 (3) Å 3 . Compound (II) has been found to belong to the P 2 1 /c space group of the monoclinic system, with a  = 7.590 (3), b  = 9.266 (3), c  = 16.503 (6) Å, β = 107.38 (2) °, V = 1107.69 (7) Å 3 and Z = 4. The structures of (I) and (II) consist of slightly distorted [ClO 4 ] - tetrahedra anions and 1-(2-amonioethyl)piperazine-1,4-dium trication (I) or 5,6-dimethyl-benzylimidazolium cations (II) and additionally a lattice water in (I) . The crystal structures of ( I) and ( II) exhibit complex three-dimensional networks of H-bonds connecting all their components. In the atomic arrangement of (I) , the ClO 4 − anions form corrugated chains, while in (II) the atomic arrangement exhibits wide pseudo-hexagonal channels of ClO 4 tetrahedra including the organic entities. The lattice water serves as a link between pairs of cations and pairs of anions via several O H⋯O and N-H⋯O interactions in compound (I) . The vibrational absorption bands were identified by infrared spectroscopy. These compounds were also investigated by solid-state 13 C, 35 Cl and 15 N NMR spectroscopy. DFT calculations allowed the attribution of the IR and NMR bands. Intermolecular interactions were investigated by Hirshfeld surfaces. Electronic properties such as HOMO and LUMO energies were derived. [ABSTRACT FROM AUTHOR]