Spin canting in a novel (3,4)-connected mixed-valence cobalt coordination polymer based on oxalates and [Co(Hbiim)3] (H2biim = 2,2'-biimidazole) building blocks

摘要

Hydrothermal treatment of cobalt chloride, 2,2'-biimidazole (H2biim), oxalate acid and NaOH at 160 °C for five days produced a three-dimensional mixed-valence metal-organic framework [Co~(III)(Hbiim)3]2[Co~(II)3 (ox)3] ·4H2O (1). Compound 1 exhibits a 3D network with tri-nodal (3-c)2(4-c)3 topology, in which [Co~(III) (Hbiim)3] building blocks as 3-connected nodes, and Co~(II) ions as 4-connected nodes. The magnetic measurements reveal that compound 1 exhibits a spin canting antiferromagnetic coupling between adjacent Co~(II) ions.