Two-dimensional coordination polymer of [Hg(μ3-mmtz)2]n (1) and centrosymmetric dinuclear complexes of {[H2en][Hg2(mmtz)4(μ-Br)2]} (2) and {[H2en][Hg2(mmtz)4(μ-I)2]} (3) (where Hmmtz is 1-methyl-1,2,3,4-tetrazole-5-thiol and en is ethylene diamine) were synthesized from the reaction of Hmmtz and en with HgCl2, HgBr2 and HgI2, respectively, in CH3OH. Complex 1 was also synthesized from the reaction of Hmmtz and en with HgX2 (X = OAc and SCN) in CH3OH. These three complexes were thoroughly characterized by elemental analysis (CHN), thermal gravimetric analysis (TGA), differential thermal analyses (DTA), infrared, UV-Vis, 1H NMR, and luminescence spectroscopy, and their structures were determined by single-crystal X-ray diffraction