The Complexity of the Complexes. A Twelve-fold Anchored Ligand in a Co(II) Hybrid Polymeric Material with Ferromagnetic Order

Single crystals of the new organo-inorganic polymer Co 2 [O 8 C 10 H 2 ] were hydrothermally obtained. Conditions for the synthesis are reported. The crystal structure of this material was established by single-crystal X-ray diffraction: monoclinic, space group C 2/ m, a = 6.161(1) Å, b = 17.478(4) Å, c = 4.554(1) Å, β = 115.735(4)°. The 3D structure can be envisaged in terms of edge-sharing CoO 6 octahedra chains running along the [100] direction kept together in the [001] direction through the carboxylate groups and in the [010] direction through the multidentate benzene-1,2,4,5,-tetracarboxylate ligand. In this organo-inorganic hybrid compound, the ligand coordinates to 12 different cobalt atoms. This kind of coordination forces the formation of 1D chains in which the Co atoms are very close to each other and confers on the material interesting magnetic properties. Long-range 3D ferromagnetic order is obtained at T C = 14.9 K, with a saturation magnetization of 4.3 μ B /formula unit and H C = 2.2 kOe.