Structural, vibrational and DSC investigations of the bis-4-benzyl piperidinium tetraoxoselenate monohydrate crystal

A new organic–inorganic salt, bis-4-benzyl piperidinium tetraoxoselenate monohydrate has been synthesized and characterized by X-ray diffraction, FT-IR and FT-Raman spectroscopies. The title compound crystallizes in the monoclinic system P21/c at room temperature with the following parameters: a = 8.617(3) Å, b = 27.140(9) Å, c = 10.926(5) Å, β = 96.46(4)° and Z = 4. Its vibrational spectra have been discussed on the basis on quantum chemical density theory (DFT) calculation using B3LYP/6-31G∗ approach. The role of the intermolecular interaction in this crystal is analyzed. Acidic protons of the selenate group were transferred to the organic cation giving the singly-protonated cation. The ability of ions to form spontaneous three-dimensional structure through O–H⋯O and N–H⋯O hydrogen bond is fully utilized. These hydrogen bonds give notable vibrational effects.

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► The 4-BPP crystallizes in the monoclinic system P21/c.
► Two peaks endothermic were shown at almost 300 and 338 K.
► Phase transitions may be interpreted by a dynamic order disorder mechanism.
► The experimental vibrational bands have been discussed and assigned to normal mode.