Structural versatility of six transition metal complexes based on M(II)(2,2′-biimidazole) building blocks and co-ligands

Reaction of transition metal(II) salts with 2,2'-biimidazole (H2biim) and co-ligands formed a series of new complexes, [M(H(2)biim)(2)(biPY)(2)](NO3)(2)center dot 2H(2)O (1-3) (M = Co, Ni, Zn), [Co(H(2)biim)(2)(biPY)](ClO4)(2)center dot 3H(2)O (4), {[Cu(H(2)biim)(2)](3)(mu-C3H3O4)(2) (C3H2O4)(2)}center dot 6H(2)O (5), Ko(H(2)biim)(2)(H2O)(2)](C3H3O4)(2) (6) (bipy = 4,4'-bipyridine, C3H2O4 = malonate dianion, C3H3O4 = malonate anion). These complexes were characterized by single-crystal X-ray diffraction, and elemental analysis. All complexes except 4 were also characterized by luminescence spectra and thermogravimetric analysis. The crystal packing of these six complexes shows that cationic M(II)(2,2'-biimidazole) fragments are self-assembled to construct the 3D supramolecular networks by hydrogen bonding and 7C It interactions. The 3D supramolecular networks are significantly affected by counter anion and co-ligands. In complexes 1-3, there are two sets of (4,4) nets which pass through each other to form inclined 2D interpenetration. Complex 4 is obtained by similar reactions as 1 Compared with 1, the only difference in 4 with the reactant Co(NO3)2.6H20 replaced by Co(ClO4)center dot 6H(2)O, but it has a very different structure. In 4, the 3D networks containing cavities of 23 x 23 angstrom is formed. In complex 5, the uncoordinated waters form an infinite 1D pipe structure which is embedded in the 3D porous network. The acid-water ring and R-2(2)(9) synthons in complex 6 lead to the formation of (4,4) 2D network. (C) 2015 Elsevier Ltd. All rights reserved.