Synthesis, Characterization, Crystal Structure, and Properties of a Mercury(Ii) Complex Containing Dmit Ligand and N,N’-Ethylidenedipyridium Cation

Abstract

A new mercury(II) complex containing dmit ligand and biquaternary ammonium cation, DPyE[Hg(dmit)2] (1) (DPyE2+ = N,N’-ethylidenedipyridinium, dmit = 1,3-dithiol-2-thione-4,5-dithiolate), was synthesized and fully characterized by elemental analysis, IR, 1H-NMR, UV–Vis, TG, single crystal X-ray diffraction, and powder X-ray diffraction. Moreover, the electrochemical properties and conductivities of complex 1 were studied by cyclic voltammetry and four-probe AC technique, respectively. Complex 1 crystallizes in the monoclinic space group P 21/n with a = 8.1815(2) Å, b = 12.8701(5) Å, c = 23.2681(7) Å, β = 90.922(3)°, Z = 4, V = 2449.75(14) Å3, Dc = 2.114 g·cm–3. The crystal structure shows that the dihedral angle of two dmit ligands of [Hg(dmit)2]2– anion is closed to vertical, which results in the formation of a distorted HgS4 tetrahedral geometry. The S···S short contacts assemble [Hg(dmit)2]2– anions into 1D, 2D, and 3D supramolecular network. The DPyE2+ cations are located in the caves, providing additional stabilization to crystal packing via C–H···S hydrogen bonds to [Hg(dmit)2]2– anions. The crystal packing of 1 is characterized by face-to-face π-π contacts between DPyE2+ cations and [Hg(dmit)2]2– anions, which result in two orthogonally oriented and mixed stacking columns. These stacking columns interweave into a 2D network, which is further connected to a 3D network via interplanar S···S contacts. In addition, the temperature-dependent conductivity in the range of 50–300 K reveals semi-conducting properties of complex 1, and a room temperature conductivity of 1.53 × 10–3 S·cm–1 is observed.