Synthesis and Characterization of Diiron(III)-Substituted Silicotungstate, [γ(1,2)-SiW₁₀{Fe(OH₂)}₂O₃₈]⁶^-

Abstract

The full details of synthesis and characterization of diiron(III)-substituted γ-Keggin silicotungstate, [γ(1,2)-SiW10{Fe(OH2)}2O38]6- (abbreviated as I) were reported. This complex was synthesized by the reaction of the lacunary [γ-SiW10O36]8- with Fe(NO3)3 in an acidic aqueous solution and isolated as the tetra-n-butylammonium salt (TBA-I). TBA-I has been characterized by infrared, Raman, 183W NMR, UV−visible, Mössbauer, and ESR spectroscopy, TG/DTA, FAB-mass, and magnetic susceptibility measurements, elemental analysis, and acid/base titration. The 183W NMR, infrared, Raman, and UV−visible spectroscopy indicated that I has a γ-Keggin structure with C2v symmetry. It was shown by the magnetic susceptibility measurement and Mössbauer, ESR, and UV−visible spectroscopy that I shows an antiferromagnetic coupling of the two high-spin Fe3+ centers.