American Chemical Society
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Ionothermal Synthesis of Metal Oxalatophosphonates with a Three-Dimensional Framework Structure:  Na2M3(C2O4)3(CH3PO3H)2 (M = FeII and MnII)

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posted on 2006-08-07, 00:00 authored by Chun-Po Tsao, Chyi-Yang Sheu, Ninh Nguyen, Kwang-Hwa Lii
Two isostructural transition-metal oxalatophosphonates, Na2M3(C2O4)3(CH3PO3H)2 (M = FeII and MnII), have been synthesized by using a low-melting-point eutectic mixture of choline chloride and malonic acid as a solvent and characterized by single-crystal X-ray diffraction and 57Fe Mössbauer spectroscopy. The 3D framework structure consists of a corner-sharing octahedral trimer that is linked with other trimers through two distinct oxalate ligands with unusual linkage types, phosphonate tetrahedra, and H bonds to form infinite channels along the [101] direction where the Na+ cations are located. They are the first examples for the use of an ionic liquid as a solvent in the synthesis of metal oxalatophosphonates. Crystal data for the Fe compound follow:  monoclinic, P21/n (No. 14), a = 5.8063(1) Å, b = 10.3867(3) Å, c = 14.8094(4) Å, β = 96.926(1)°, and Z = 2. Crystal data for the Mn compound are the same as those for the Fe compound except a = 5.8734(9) Å, b = 10.557(2) Å, c = 14.863(2) Å, and β = 96.691(2)°.