Mixed-metal sandwich complexes [MII2(H2O)2FeIII2(P2W15O56)2]14− (MII = Co, Mn): Synthesis and stability. The molecular structure of [MII2(H2O)2FeIII2(P2W15O56)2]14−

Abstract

Two new mixed-metal sandwich complexes [M^II₂(H₂O)₂Fe^III₂(P₂W₁₅O₅₆)₂]¹⁴⁻ (abbreviated {M₂Fe₂P₄W₃₀}, M^II = Co^II, Mn^II) were obtained at pH 3 by addition of M²⁺ to [Na₂(H₂O)₂Fe^III₂(P₂W₁₅O₅₆)₂]¹⁶⁻ (abbreviated {Na₂Fe₂P₄W₃₀}) without substitution in the α-[P₂W₁₅O₅₆]¹²⁻ (abbreviated {P₂W₁₅}) units. Their X-ray structures are reported. At lower pH, back conversion to {Na₂Fe₂P₄W₃₀} was followed by ³¹P NMR, electrochemistry and UV-visible spectroscopy. The preparation and the characterization in solution of the lacunary intermediate [NaCo^II(H₂O)₂Fe^III₂(P₂W₁₅O₅₆)₂]¹⁵⁻ (abbreviated {NaCoFe₂P₄W₃₀}) is also described.