Synthesis, structure and metamagnetic behaviour of a three-dimensional Fe(II) carboxyethylphosphonate: [Fe3(OH)2(H2O)4(O3P(CH2)2CO2H)2] or MIL-38

Abstract

Abstract [FeII3(OH)2(H2O)4(O3P(CH2)2CO2H)2] labelled MIL-38 was hydrothermally synthesized (170 °C, 48 h, autogeneous pressure). Its three-dimensional open structure was solved by single crystal X-ray diffraction (monoclinic, space group P21/c (No. 14), a=4.6308(5), b=10.4322(10), c=17.711(2) A, β=96.051(2)°, Z=2, V=850.8(2) A3). It is built up from linear trimers of edge-sharing iron(II) octahedra linked by organic moieties thus delimiting empty channels along [1 0 0] . This new compound was characterized by 57Fe Mossbauer spectrometry and magnetic measurements: it adopts a metamagnetic behaviour below 10 K, antiferromagnetic at low fields and ferromagnetic above 1.5 T.