The Tetranuclear Macrocyclic Mercury(II) Complex of [Hg4{S2CN(CH3)2}4Cl4]: Preparation, Molecular and Supramolecular Structures, and Thermal Behavior

The tetranuclear mercury(II) dithiocarbamatо-chloridо complex [Hg₄(S₂CNMe₂)₄Cl₄] (I), whose molecule includes the centrosymmetric 16-membered metallacycle [Hg₄S₈C₄], was prepared by the reaction of solutions of HgCl₂ and sodium dimethyldithiocarbamate (Me₂Dtc). The crystal, molecular, and supramolecular structures of I were established using direct method of single-crystal X-ray diffraction (CCDC no. 2364847). In complex I, the non-equivalent μ₂-bridging dithiocarbamate ligands link neighboring mercury atoms in pairs, thus forming a tetranuclear macrocyclic molecule. The intramolecular Hg···S and Hg···Cl secondary bonds stabilize the spatial configuration of this macrometallacycle. The supramolecular self-organization of the complex is due to the relatively weak, pairwise S···Cl and Hg···Cl secondary interactions, which combine the tetranuclear molecules of I into 2D pseudo-polymer layers; numerous non-classical C–H···Cl and C–H···S hydrogen bonds connect these layers to form a 3D framework. According to simultaneous thermal analysis data, the thermal decomposition of I is accompanied by the formation of HgS and release of HgCl₂.