PREPARATION AND CRYSTAL-STRUCTURE OF A NEW ACENTRIC CESIUM IRON HYDROGENPHOSPHATE, CS3FE3H15(PO4)(9)

Single crystals of caesium iron hydrogen phosphate, Cs3Fe3H15(PO4)(9), 2, were prepared hydrothermally by heating caesium iron dihydrogenpho sphate, CsFe(H2PO4)(4), 1, with a small amount of water. 2 crystallize s orthorhombic, space group Pna2(1) (No. 33 Int. Tab.) with Z = 4 and a = 2718(1), b = 908.1(3), c = 1280.8(4)pm The crystal structure was s olved by using 4734 unique reflections I > 2 sigma(I) with a final wR2 value of 0.0801 (SHELXL-93). The main feature of the crystal structur e are channels formed by combined PO4-tetrahedra and FeO6-octahedra al ong the [001] direction. Cs+ is placed inside of the channels. Effecti ve Coordination Numbers (ECoN), Mean Fictive Ionic Radii (MEFIR), Char ge Distribution (CHARDI) and the Madelung Part of Lattice Energy (MAPL E) are calculated for the title compound.