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

The full details of synthesis and characterization of diiron(III)-substituted γ-Keggin silicotungstate, [γ(1,2)-SiW 10 {Fe(OH 2 )} 2 O 38 ] 6 - (abbreviated as I ) were reported. This complex was synthesized by the reaction of the lacunary [γ-SiW 10 O 36 ] 8 - with Fe(NO 3 ) 3 in an acidic aqueous solution and isolated as the tetra- n -butylammonium salt (TBA- I ). TBA- I has been characterized by infrared, Raman, 183 W NMR, UV−visible, Mössbauer, and ESR spectroscopy, TG/DTA, FAB-mass, and magnetic susceptibility measurements, elemental analysis, and acid/base titration. The 183 W NMR, infrared, Raman, and UV−visible spectroscopy indicated that I has a γ-Keggin structure with C 2v 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 Fe 3+ centers.