Coordination polymers of various architectures built with mixed imidazole/benzimidazole and carboxylate donor ligands and different metal ions: syntheses, structural features and magnetic properties

Ten coordination polymers {[Cd(L-1)(2)]}(n) (1), {[Cu(L-1)(2)]}(n) (2), {[Cd-2(L-1)(2)(HCOO)(2)(H2O)]}(n) (3), {[Cd-2(L-1)(4)]center dot 3H(2)O}(n) (4), {[Cd(L-1)(CH3COO)]}(n) (5), {[Cd(L-1)(2)(C5H5N)]center dot 2.5H(2)O}(n) (6), {[Zn(L-2)(2)]}(n) (7), {[Cd-2(L-2)(4)]center dot H2O}(n) (8), {[Cd-3(L-2)(6)(H2O)]center dot 2EtOH center dot H2O}(n) (9) and {[Cd(L-3)(2)]center dot 2DMF center dot 4H(2)O}(n) (10), where HL1 - 4-imidazole-1-yl-benzoic acid, HL2 - 3-imidazole-1-yl-benzoic acid and HL3 = 4-benzmidazole-1-yl-benzoic acid, have been synthesized under different experimental conditions. Their structures are determined by single-crystal X-ray diffraction analyses and further characterized by IR spectra, thermogravimetric (TG) and elemental analyses. The structure of 1 is a 2D -> 2D (2D = two dimensional) interpenetrating network with (4,4) grid topology while 2 has an interesting Kagome structure. Compounds 4 and 6 crystallize in 4- and 3-fold interpenetrating diamondoid frameworks respectively. Compound 7 is a layered non-interpenetrating (4,4) grid network whereas 8 has an unprecedented self-penetrating structure with 2D framework. Compound 9 is a self-penetrating 3D structure while 10 crystallizes in a non-interpenetrating (4,4) square-grid with one-dimensional (1D) channels. From these results, it is demonstrated that the structures of the coordination polymers are strongly dependent on the geometry of L-1, L-2 and reaction conditions. Variable temperature magnetic susceptibility study of 2 has also been performed.