A new one-dimensional hybrid material lattice: AC conductivity and structural characterization of [C₇H₁₂N₂][CdCl₄]

Abstract

The present paper reports the synthesis, crystal structure, ¹³C and ¹¹¹Cd cross-polarization magic-angle spinning nuclear magnetic resonance(CP-MAS-NMR) analysis and ac conductivity for a new organic–inorganic hybrid salt, [C₇H₁₂N₂][CdCl₄]. The compound crystallizes in the triclinic system, space group P$\overline 1$, with unit cell dimensions: a = 7.1050(3) Å, b = 8.9579(3) Å, c = 9.4482(3) Å, α = 81.415(1)°, β = 89.710(2)°, γ = 85.765(1)°, V = 592.97(4) Å³, and Z = 2. The asymmetric unit is composed of one-2,4-diammonium toluene cation and one [CdCl₄]²⁻ anion. The Cd atom is in a slightly distorted octahedra coordination environment. Its structure can be described by infinite chains of CdCl₆ octahedron linked to organic cations by a strong charge-assisted N–H∙∙∙Cl interactions in order to build organic–inorganic layers staked along $\left[ {0\overline 1 1} \right]$ direction. The solid state ¹³C CP-MAS-NMR spectra has shown seven isotropic resonances, confirming the existence of seven non-equivalent carbon atoms, which is consistent with crystal structure determined by X-ray diffraction. As for ¹¹¹Cd MAS-NMR, it has shown one cadmium site with isotropic chemical shift observed at 167.2 ppm. The complex impedance of the compound has been investigated in the temperature range of 403–460 K and in the frequency range of 200 Hz–5 MHz. The impedance plots have shown semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed to explain the impedance results. The circuits consist of the parallel combination of bulk resistance R _p and constant phase elements.