Synthesis, Structural and Magnetochemical Studies of Iron Phosphonate Cages Based on {Fe₃O}⁷⁺ Core

We report the synthesis, structures, and magnetic properties of twelve iron(III) phosphonate cages: [Fe4(μ3-O)Cl(PhCO2)3(PhPO3)3(py)5] 1, [Fe4(μ3-O)(tBuCO2)4(C10H17PO3)3(py)4] 2 (C10H17PO3H2 = camphylphosphonic acid), [Fe7(μ3-O)2(PhPO3)4(MeCO2)9(py)6] 3, [Fe7(μ3-O)2(PhPO3)4(PhCO2)9(py)6] 4, [Fe7(μ3-O)2(tBuPO3)4(tBuCO2)8(py)8](NO3) 5, [Fe7(μ3-O)2(PhPO3)4(MeCO2)8(py)8] 6, [Fe9(μ3-O)2(μ2-OH)(PhPO3)6(tBuCO2)10(MeCN)(H2O)5] 7, [Fe9(μ3-O)2(μ2-OH)(C10H17PO3)6(PhCO2)10(H2O)6] 8, [Fe6(μ3-O)2(O2)(tBuCO2)8(PhPO3)2(H2O)2] 9, [Fe6(μ3-O)2(O2)(tBuCO2)8(C10H17PO3)2(H2O)2] 10, [Fe6(μ3-O)2(O2)(tBuCO2)8(tBuPO3)2(py)2] 11, and [Fe14(μ3-O)4(O2)2(PhPO3)8(tBuCO2)12(H2O)12](NO3)2 12. The results have allowed us to compare the magnetic exchange found with magneto-structural correlations found previously for iron-oxo cages.