Crystal structures and extended X-ray absorption fine structure spectra of [Fe{O(CH2CO2)2}(H2O)2X](X = Cl or Br)

Abstract

The crystal structures of the complexes [Fe{O(CH₂CO₂)₂}(H₂O)₂X](X = Cl or Br) have been determined by X-ray diffraction. They are isostructural six-co-ordinate monomers, the only significant structural difference being the iron–halogen bond lengths: Fe–Cl 2.231 (1)Å and Fe–Br 2.370(1)Å. In both cases the oxydiacetate ligand has a virtually planar skeleton of C and O atoms, is terdentate (with the ether oxygen atom trans to the halide) and occupies meridional positions of a slightly distorted octahedron which is completed by the two mutually trans water molecules. Iron and bromine K-edge extended X-ray absorption fine structure spectral data are described and discussed. Infrared spectra show both iron–halogen bond stretching vibrations. A nitrato-complex (X = NO₃) has also been prepared and characterised.