Synthesis, spectral and structure analysis of mono and binuclear cadmium and mercury complexes

Three mono and binuclear cadmium and mercury complexes of 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine (dppt) formulated as Cd(dppt)2X2 (X = Br, I) (complexes: 1 and 2) and Hg2(dppt)2Cl2(complex: 3) were synthesized and characterized by physical and spectral (IR, 1H and 13C NMR) analyses. Moreover, structural analyses of these complexes were investigated by single crystal X-ray diffraction method. The complex 1 and 2 crystallize in the orthorhombic crystal system with space groups of Pna21, and Pbca respectively while the complex 3 crystallizes in monoclinic crystal system with space group P21/n. In all the complexes, the dppt ligand is coordinated via its N atoms of pyridyl and triazine rings to metal ion. In each cadmium complex, in addition to two bonded dppt ligands, the coordination sphere is completed by two halide anions and therefore the geometry around metal can be described as distorted octahedral. In spite of mononuclear cadmium complexes, the mercury compound is found as a centro-symmetric dimer complex including two Hg-Cl-Hg bridges, a terminal chloride and a dppt ligand on each mercury center. In this way, a distorted square pyramidal structure can be defined for the geometry around each mercury center.