Synthesis, Structure and Magnetic Properties of Some New Metal(II) Phosphonates: Layered Fe(C2H5PO3).H2O, α-Cu(C2H5PO3) and Co(t-C4H9PO3).H2O, Tubular β-Cu(CH3PO3)

Fe(II)C2H5PO3. H2O has been prepared via prolonged reaction between iron oxychloride and ethylphosphonic acid in acetone, in a sealed tube. The lamellar structure is very similar to that of previously reported divalent metal phosphonates M(II)(RPO3). H2O (M= Mg, Mn, Ni, Zn). The compound shows sign of 2D antiferromagnetic correlations above the Néel temperatureTN=24K and a weak ferromagnetic behavior is observed below TN. We also report on the preparation methods and the crystal structures of two new anhydrous copper phosphonates α-Cu(II)(C2H5PO3), and β-Cu(II)(CH3PO3) which exhibits an original tubular three-dimensional structure. The reactivity of bulky phosphonic acids is also described, with the case of Co(II)(t-C4H9PO3).H2O.