[Co(NH3)6]2[Cd8(C2O4)11(H2O)4]·8H2O: A 5-connected sqp topological metal–organic framework co-templated by Co(NH3)63+ cation and (H2O)4 cluster

In our efforts to construct new metal–organic frameworks (MOFs) by template-directing method, a new cadmium oxalate, [Co(NH3)6]2[Cd8(C2O4)11(H2O)4]·8H2O (denoted HNU-1), has been synthesized under hydrothermal condition in the presence of Co(NH3)6Cl3. The crystal structure of HNU-1 was determined by single-crystal X-ray diffraction (monoclinic, C2/c), a = 11.126(2) Å, b = 17.361(4) Å, c = 16.119(3) Å, β = 102.40(3)°, V = 3040.8(10) Å3 and Z = 8. The open framework of HNU-1 contains 12-ring channels and exhibits a 5-connected sqp topological network with dinuclear Cd(II) clusters acting as nodes. The Co(NH3)63+ cations and unusual hydrogen-bonded (H2O)4 clusters are found in the 12-ring channels with an alternative arrangement. It is believed that the (H2O)4 clusters play a co-templating role in the crystallization of HNU-1.

Graphical abstractA novel metal–organic cadmium oxalate compound has been hydrothermally synthesized. Its open-framework presents a 5-connected sqp topology based on dinuclear Cd cluster, with a unique hydrogen-bonded (H2O)4 cluster and Co(NH3)63+ cations alternately arranged inside the 12-ring channels as co-template.Figure optionsDownload full-size imageDownload as PowerPoint slide