Syntheses and crystal structures of three open-frameworks of metal succinates containing a 4,<f>4′</f>-bipyridine ligand

Three new divalent transitional metal succinates with an additional bipy (bipy=4,<f>4′</f>-bipyridine) ligand have been synthesized by hydrothermal reactions and structurally determined. The structure of [Cu(C4H4O4)(bipy)(H2O)2] <f>·</f> 2H2O (1) features a 3D open framework formed by 1D [Cu(bipy)]2+ chains along the diagonal axis of <f>b</f> and -<f>c</f> that are interconnected by Cu(C4H4O4) helixes along the <f>c</f>-axis. The lattice water molecules are located at the cavities of the framework. In Zn(C4H4O4)(bipy) (2), each zinc cation is octahedrally coordinated by two chelate carboxylate groups from two succinates and 2 N atoms from two bipy molecules, and the ZnO4N2 octahedra are interconnected by bridging succinate ligands into a 1D chain along the 〈0 1 1〉 direction. Such chains are further linked into a 〈0 1 1〉 layer via π–π stacking interaction between the pyridine rings. In [Co(bipy)(H2O)4] (C4H4O4) <f>·</f> 4H2O (3), each pair of octahedral cobalt(II) ions is bridged by a bipy ligand, resulting in a 1D [Co(bipy)(H2O)4]2+ chain, and the succinate ligands and lattice water molecules are sandwiched between two [Co(bipy)(H2O)4]2+ chains to form a 〈0 1 1〉 layer via hydrogen bonding. The layers are further interconnected into a 3D network via hydrogen bonds among carboxylate oxygen atoms, aqua ligands, and lattice water molecules. [Copyright &y& Elsevier]