Syntheses, Crystal Structures and Fluorescence of Cadmium(Ⅱ) Coordination Polymers with Pyrazine-1,4-dioxide, 2-Methylpyrazine-1,4-dioxide and Thiocyanate as Mixed Bridge Ligands

摘要

Two Cd(Ⅱ) coordination polymers have been synthesized with pyrazine-1,4-dioxide (L1), 2-methylpyrazine-1,4-dioxide (L2), and thiocyanate anion as mixed bridge ligands. Crystal data for complex 1 [Cd(μ_(1,3)-SCN~-)_2(L1)]_n: monoclinic system, space group P2_1 with a = 6.8342(11), b = 14.349(2), c = 10.5443(16) A, β = 98.534(2)°, V = 1022.5(3) A~3, Z = 4, C_6H_4CdN_4O_2S_2, M_r = 340.65, D_c = 2.213 g/cm~3, F(000) = 656 and μ = 2.527 mm~(-1); and those for 2: triclinic system, space group P1 with a = 7.877(3), b = 8.693(3), c = 8.754(3) A, α = 102.297(6), β = 102.464(6), γ = 98.480(6)°, V = 560.0(3) A~3, Z = 2, C_7H_6CdN_4O_2S_2, M_r = 354.68, D_c = 2.103 g/cm~3, F(000) = 344 and μ = 2.311 mm~(-1). 1 shows a three-dimensional network structure, and along the c direction a one-dimensional chain is constructed by the coordination of Cd(Ⅱ) ions with μ_(1,3)-SCN~- ligands, and the L1 bridging ligands made the chains connect each other leading to the formation of a three-dimensional structure. For 2, the one-dimensional chains along the b axis are generated by the coordination of L2 bridging ligands with Cd(Ⅱ) ions, and the chains are further joined by μ_(1,3)-SCN~- bridging ligands forming a two-dimensional sheet structure on the (10-1) plane. Both complexes 1 and 2 exhibit strong fluorescence emission.