Inorganic-organic hybrid compounds: Synthesis, structure, and magnetic properties of the first organically templated iron oxalate-phosphite, [C 4N2H12][FeII 4(HPO 3)2(C2O4)3], possessing infinite Fe-O-Fe chains

A hydrothermal reaction of a mixture containing iron(II) oxalate dihydrate, phosphorus acid, piperazine, and water at 150°C for 72 h gave light-yellow cubes of a new hybrid iron oxalate-phosphite, [C4N2H 12]-[FeII 4(HPO3)2(C 2O4)3], I. The structure, formed by FeO 6, HPO3, and oxalate building units, possesses infinite one-dimensional chains of Fe-O-Fe, formed by Fe2O10 dimers. The phosphite units are grafted to these chains, and the oxalate moieties bond with the iron center through in-plane and out-of-plane connectivity forming a three-dimensional structure with intersecting channels. The organic amine molecule occupies the middle of the channels. The connectivity between the phosphite units and the Fe-O-Fe chains resembles the tancoite structure. Magnetic investigations reveal that the iron is present in the +2 oxidation state and orders antiferromagnetically. © 2005 American Chemical Society.