Synthesis, crystal structure, magnetic susceptibility, and Mossbauer spectroscopy of a mixed-valence organic-inorganic hybrid compound:: (H3DETA)[Fe3(C2O4)2(HPO4)2(PO4)] (DETA = diethylenetriamine)

A mixed-valence organic-inorganic hybrid compound, (H(3)DETA) [Fe-3(C2O4)(2)(HPO4)(2)(PO4)] (DETA = diethylenetriamine), has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, magnetic susceptibility, 57 Fe powder absorption Mossbauer spectroscopy, and electric field gradient calculations. It crystallizes in the triclinic space group P (1) over bar (No. 2) with a = 9.6367(7) Angstrom, b = 10.1760(7) Angstrom, c = 12.6164(9) Angstrom, alpha = 86.302(1)degrees, beta = 68.880(1)degrees, gamma = 61.800(1)degrees, and Z = 2 with R-1 = 0.0397. The structure can be described as layers of trigonal bipyramidal (FeO5)-O-II, octahedral (FeO6)-O-III, tetrahedral PO4 moieties, and monobidentate oxalate ligands, which are pillared through bisbidentate oxalate ligands to form a 3-D framework structure. The title compound is not only the first oxalatophosphate that contains two types of oxalate ligands but also the first example of mixed-valence transition metal oxalatophosphate.