Formation of five-connected three-dimensional coordination polymers through the bridging function of the anions

New coordination polymers based on 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (L) with the composition [M2(L)4A(NCS)2] (M2+ = Co2+, Zn2+, Cd2+; A2− = SiF 6 2− , SeO 4 2− ) have been synthesized and characterized by IR spectroscopy and X-ray diffraction. According to X-ray diffraction data, cobalt compounds crystallize in the orthorhombic system with the following unit cell parameters, [Co2(L)4SiF6(NCS)2] · 3CHCl3 · CH3OH: a = 20.568(4), b = 14.568(3), c = 22.929(5) Å, α = β = γ = 90°, V = 6870(2) Å3, space group Pbca (no. 61), R(I > 2σ(I)) = 0.0514; [Co2(L)4SeO4(NCS)2] · 2CHCl3 · 2CH3OH · H2O: a = 13.721(2), b = 21.539(3), c = 22.417(3) Å, α = β = γ = 90°, V = 6625(2) Å3, space group P212121 (no. 19), R(I > 2σ(I)) = 0.0452. The 3D structure of the coordination polymers is composed of wavelike two-dimensional coordination layers [ML2]n connected by bridging anions SiF 6 2− , or Se O 4 2− . The complexes have the same five-bonded topology but different symmetry.