Hydrothermal synthesis and characterization of a new iron phosphate structure of ladder-like chains and coordination directly by an organo-nitrogen ligand: [Fe(phen)(HPO4)(H2PO4)·0.5H2O] (phen=1,10-phenanthroline)

A coordination iron phosphate, Fe(phen)(HPO₄)(H₂PO₄)·0.5H₂O (I), has been hydrothermally synthesized and characterized by elemental analysis, IR spectral analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group C2/m (No. 12), with cell parameters M=438.03, a=21.421(5) Å, b=6.4292(1) Å, c=12.190(3) Å, β=105.964(9)°, V=1614.1(6) Å³, Z=4, R₁I>2σ(I)]=0.0545, wR₂I>2σ(I)]=0.1186. This compound displays a new structure of ladder-like chains, in which each one-dimensional chain is constituted by the distorted octahedral units of Fe³⁺ bridged through PO₄ tetrahedron. The phen ligands in the compound bind in a bidentate fashion to the metal atoms and the ladder-like structure of the compound extends into a three-dimensional supramolecular array via π-π stacking interactions of phen ligands. Mössbauer spectroscopy shows the presence of Fe³⁺ in the octahedral coordination. Magnetic susceptibility measurement studies show that this material may model as anti-ferromagnetic.