Inorganic-organic hybrid structure: Synthesis, structure and magnetic properties of a cobalt phosphite-oxalate, [C 4N 2H 12][Co 4(HPO 3) 2(C 2O 4) 3]

A hydrothermal reaction of a mixture of cobalt (II) oxalate, phosphorous acid, piperazine and water at 150 °C for 96 h followed by heating at 180 °C for 24 h gave rise to a new inorganic-organic hybrid solid, [C ₄N ₂H ₁₂][Co ₄(HPO ₃) ₂(C ₂O ₄) ₃], I. The structure consists of edge-shared CoO ₆ octahedra forming a [Co ₂O ₁₀] dimers that are connected by HPO ₃ and C ₂O ₄ units forming a three-dimensional structure with one-dimensional channels. The amine molecules are positioned within these channels. The oxalate units have a dual role of connecting within the plane of the layer as well as out of the plane. Magnetic susceptibility measurement shows the compound orders antiferromagnetically at low temperature ( T=22 K). Crystal data: I, monoclinic, space group= P2 ₁/ c (No. 14). a=7.614(15), b=7.514(14), c=17.750(3) Å, β=97.351(3)°, V=1007.30(3) ų, Z=2, ρ_calc=2.466 g/cm, μ=3.496 mm, R₁=0.0310 and wR₂=0.0807 data [I>2σ(I)].