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

Abstract

Three new divalent transitional metal succinates with an additional bipy (bipy=4,4 ′-bipyridine) ligand have been synthesized by hydrothermal reactions and structurally determined. The structure of [Cu(C 4H 4O 4)(bipy)(H 2O) 2] · 2H 2O ( 1) features a 3D open framework formed by 1D [Cu(bipy)] 2+ chains along the diagonal axis of b and - c that are interconnected by Cu(C 4H 4O 4) helixes along the c-axis. The lattice water molecules are located at the cavities of the framework. In Zn(C 4H 4O 4)(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 ZnO 4N 2 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)(H 2O) 4] (C 4H 4O 4) · 4H 2O ( 3), each pair of octahedral cobalt(II) ions is bridged by a bipy ligand, resulting in a 1D [Co(bipy)(H 2O) 4] 2+ chain, and the succinate ligands and lattice water molecules are sandwiched between two [Co(bipy)(H 2O) 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.