Hydrothermal Synthesis, Structure Determination, and Magnetic Properties of a New Layered Oxyfluorinated Iron Phosphate Templated by 1,4-Diaminobutane

[Fe III 5 F 3 (PO 4 ) 6 (H 2 O) 3 ](H 2 O) 2 ·(H 3 N(CH 2 ) 4 NH 3 ) 3 (labeled MIL-4) was synthesized hydrothermally from a mixture of Fe 2 O 3:P 2 O 5:HF:1,4-diaminobutane:H 2 O in the molar ratio 1:1:2:1.5:80. Its structure was solved by single-crystal X-ray diffraction in the noncentrosymmetric orthorhombic space group P 2 1 2 1 2 1 (No. 19) with lattice parameters a = 9.5852(1) Å, b = 15.5879(3) Å, c = 29.2556(2) Å, V = 4371.2(1) Å 3, Z = 4. MIL-4 is a layered compound whose inorganic layers are characterized by the presence of helicoidal chains of Fe III X 6 (X = O, H 2 O, F) corner-shared octahedra. The organic cations located between the layers ensure both the electroneutrality of the compound and the stability of the framework by strong hydrogen bonds. The magnetic measurements show that MIL-4 exhibits a ferrimagnetic behavior under T C = 7(1) K.