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Zinc and Cadmium Coordination Polymers with Bis(tetrazole) Ligands Bearing Flexible Spacers: Synthesis, Crystal Structures, and Properties

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posted on 06.05.2009, 00:00 by Xiao-Lan Tong, Duo-Zhi Wang, Tong-Liang Hu, Wei-Chao Song, Ying Tao, Xian-He Bu
Seven new metal complexes with the formulas, [Zn2(L1)2(H2O)]n (1), [Cd2(L1)Cl2(H2O)]n (2), [Cd3(L1)3(H2O)12]n (3), [Zn(L2)]n (4), [Cd2(L2)Cl2]n (5), {[Zn(L3)(H2O)4]·(H2O)2}n (6), and {[Cd3(L3)2Cl4]·(H2O)4}n (7), have been synthesized by the reactions of ZnII or CdII salts with three structurally related flexible bis(tetrazol-5-yl)alkanes, 1,2-bis(tetrazol-5-yl)ethane (H2L1), 1,3-bis(tetrazol-5-yl)propane (H2L2), and 1,4-bis(tetrazol-5-yl)butane (H2L3), and characterized by single crystal X-ray diffraction analysis, IR spectroscopy, and thermogravimetric (TG) analysis. Because of the geometrical requirements of different metal ions and the diverse coordination modes of the tetrazolate rings of flexible bis(tetrazole) ligands as well as the different reaction conditions, the obtained complexes show diverse structures from one-dimensional (1D) chain to three-dimensional (3D) coordination polymers. 1, 4, and 6 are ZnII complexes in which the ZnII ions show tetrahedral coordination geometries. 1 and 4 are 3D frameworks, while 6 is 1D chain structure. 2, 3, 5, and 7 are CdII complexes, and the CdII ions show octahedral coordination geometries. 3 is a two-dimensional (2D) sheet and 2, 5, 7 are all 3D frameworks. The tetrazolate rings of the structurally related ligands adopt either μ1-tetrazolyl, μ2-tetrazolyl, μ3-tetrazolyl, or μ4-tetrazolyl modes in our obtained complexes. The fluorescent properties of these complexes have also been investigated in the solid state at room temperature.