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

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(μ13-SCN-)2(L1)]n: monoclinic system, space group P21/n 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,C6H4CdN4O2S2, Mr = 340.65, Dc. = 2.213 g/cm3, F(000) = 656 andμ = 2.527 mm-1; and those for2: 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, C7H6CdN4O2S2, Mr = 354.68,Dc = 2.103 g/cm3, 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 withμ1,3-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 byμ1,3-SCN- bridging ligands forming a two-dimensional sheet structure on the (1 0 -1) plane. Both complexes 1 and 2 exhibit strong fluorescence emission.