A new layered organically templated iron(II) phosphite, (C2H10N2)[Fe3(HPO3)4]. Hydrothermal synthesis, crystal structure and spectroscopic and magnetic properties

The (C₂H₁₀N₂)Fe₃(HPO₃)₄] compound has been synthesized by using mild hydrothermal conditions under autogeneous pressure and the ethylenediamine molecule as templating agent. The compound crystallizes in the triclinic space group with unit-cell parameters a=5.416(1), b=5.416(1), c=13.977(2) Å, α=80.64(2), β=85.25(1), γ=60.03(1)° and Z=1. The final R-factors were R₁=0.053 wR₂=0.092]. The crystal structure is constructed of layers stacked along the c-axis. The sheets contain FeO₆ octahedra linked by (HPO₃)²⁻ phosphite oxoanions to give rise to Fe₃O₁₂ trimeric units sharing faces. The IR spectrum shows the characteristic bands of the phosphite and ethylenediammonium ions. From the diffuse reflectance spectrum, the Dq parameter of 805 cm⁻¹ has been calculated for the iron(II) cation in slightly distorted octahedral geometry. The Mössbauer spectrum exhibits two doublets characteristic of two crystallographically independent iron(II) ions in octahedral symmetry. Magnetic measurements indicate the existence of antiferromagnetic interactions.