Synthesis and characterization of a novel one-dimensional iron phosphate: [C2H12N2]1.5[Fe-2(OH)(H2PO4)(HPO4)(2)(PO4)]center dot 0.5H(2)O

An organically templated Fe-III phosphate, [C4H12N2](1.5)[Fe-2(OH)(H2PO4)(H PO4)(2)(PO4)]. 0.5H(2)O, has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, Mossbauer spectrosc opy and thermogravimetric analysis. The compound crystallizes in the tricli nic space group P (1) over bar (no. 2) with a = 6.3347(2), b = 13.0075(4), c = 13.7810(5) Angstrom, alpha = 62.834(1), beta = 81.404(1), gamma = 82.68 8(1)degrees, U = 996.67(8) Angstrom(3) and Z = 2. The compound is unusual i n that it is not only one of the few examples of 1-D organically templated iron phosphate, but also has a new type of chain structure which is built u p from tetranuclear iron-oxygen clusters. The tetramer involves an edge-sha ring dimer which further links at the shared corners to two more octahedra. These clusters are connected into the 1-D chain by PO4 tetrahedra and have terminal HPO4 and H2PO4 groups, with the piperazinium cations between the chains.