Hydrothermal synthesis, structural approach, magnetic and Mossbauer study of the layered Fe(III) carboxyethylphosphonate [Fe(OH)(H2O)(O3P-(CH2)(2)-CO2H)] or MIL-37

[Fe(OH)(H2O)(O3P-(CH2)(2)-CO2H)] or MIL-37 was synthesized hydrothermally ( 443 K, 24 h) under autogenous pressure. Its layered structure was determine d by single crystal X-ray diffraction (space group Pbc2(1) (n degrees 29), a = 7.4364(2) Angstrom, b = 9.5646(4) Angstrom, c = 20.4537(7)Angstrom, V= 1454.79(9) Angstrom (3), Z = 8). It is built up from [FeO3(OH)(2)(H2O)] oct ahedral chains linked via hydroxyl vertices; these chains are then bonded b y [PO3C] tetrahedra in such a way that each octahedron shares three oxygen atoms with three different tetrahedra. This layout leads to inorganic sheet s which are well-known in phosphates, for instance in the iron phosphate UL M-11. At the other end of the organic chains, carboxylic groups are danglin g. A Mossbauer study and magnetic measurements reveal a canted antiferromag netic behaviour below T-N= 20(1) K. (C) 2000 Editions scientifiques et medi cales Elsevier SAS. All rights reserved.