Crystal structure of a Cu(II) complex with a bridging ligand: poly[[penta-kis-[μ2-1,1'-(butane-1,4-di-yl)bis-(1H-imidazole)-κ(2) N (3):N (3')]dicopper(II)] tetranitrate tetra-hydrate].

A novel two-dimensional→three-dimensional Cu(II) coordination polymer, {[Cu2(C10H14N4)5](NO3)4·4H2O} n , based on the 1,1'-(butane-1,4-di-yl)bis-(1H-imidazole) (biim) ligand and containing one crystallographically unique Cu(II) atom, has been synthesized under hydro-thermal conditions. The Cu(II) atom is coordinated by five N atoms from biim ligands, one of which has crystallographically imposed inversion symmetry, giving rise to a slightly distorted CuN5 square-pyramidal geometry. The Cu(II) cations are linked by biim ligands to give a 4(4) layer; the layers are further bridged by biim ligands, generating a double sheet with a thickness of 14.61 Å. The sheet features rhombic Cu4(biim)4 windows built up from four Cu(II) centers and four biim ligands with dimensions of 14.11 × 14.07 Å(2). Each window of a layer is penetrated directly by the biim ligand of the adjacent net, giving a two-dimensional→three-dimensional entangled framework.