A new metal organic framework constructed of Co(II) ions six and seven-coordinated: Synthesis, structure and magnetism

In this work are presented the synthesis, structure and magnetic measurements for the [Co(μ2-biim)62Co(μ-H2O)(OH)6] (biim = 2,2′-biimidazole) metal-organic framework. The compound crystallizes in the cubic system, space group Pa3¯ (a = 16.0312(6) Å, V = 4120.0(3) Å3and Z = 4), containing two crystallographically distinct divalent cobalt ions Co(1) and Co(2) six- and seven-coordinated, respectively. The two metal centers are linked by 2,2′-biimidazole bridging ligand through the N(6) nitrogen donor and Co(2) forming a dimer via bridged water molecule with Co–Co distance of 4.313(3) Å, originating a 3D structure. Topological analysis of this compound revealed that the structure is an abi-nodal 3,4-connected network with total point symbol {83}{86}. By fitting of susceptibility data to the Curie–Weiss law it was possible to estimate the magnetic parameters θp and peff. Magnetic susceptibility results suggest an antiferromagnetic order in the system.

Synthesis and crystal packing of [Co(μ2-biim)62CO(μ-H2O)(OH)6] along a   axis. The purple polyhedra represent the Co centers. The compound crystallizes in the cubic system, space group Pa3¯ (a = 16.0312(6) Å, V = 4120.0(3) Å3 and Z = 4), containing two crystallographically distinct cobalt ions Co(1) and Co(2) six- and seven-coordinated, respectively.Figure optionsDownload as PowerPoint slide