Under thermal gradient in solution phase, the reaction of Hg(II) and Cd(II) salts with 2,3,5,6-tetrakis-(2-pyridyl)pyrazine (tppz) in 1:1 molar ratio afforded dinuclear [{Hgl(2)}2(titppz)] (1) and mononuclear [CdI2(tppz)] (2) complexes. Single -crystal X-ray diffraction structural analysis reveals that the tppz acts as bis-tridentate and tridentate chelating ligands in 1 and 2, respectively. Metal(II) ions adopt a distorted square pyramidal geometry and have the same coordination environment in both complexes. Based on the H-1 NMR spectroscopy measurements, both complexes decompose in solution and release free tppz.