Di-iron-substituted silicotungstate

The y-isomer Keggin-type silicodecatungstate [y-SiWio036]8- has been used as a structural motif for di-metal-substituted POMs with bis- i-oxo(or hydroxo)-dimetal cores [97-102]. The di-iron-substituted silicotungstate [y-SiWi0 Fe(OH2) 2O3g]6 was synthesized by the reaction of [y-SiWi0O36]8- with Fe(N03)3 in acidic aqueous... 

N. Mizuno, C. Nozaki, I. Kiyoto, M. Misono, Selective oxidation of alkenes catalyzed by di-iron-substituted silicotungstate with highly efficient utilization of hydrogen peroxide, f. Catal 182 (1999) 285. 

Mizuno et al. found that a water soluble potassium salt of di-iron-substituted silicotungstate, SiWto Fe(OH2) 203g catalyzes the conversion of methanol to methylformate (10.2%) > methanol (0.3%) > formic acid (0.2%) together with CO2 (16.6%). The work was attempted to demonstrate catalytic oxidation of methane with hydrogen peroxide in water. Interestingly, mono- and tri-iron-substituted silicotungstates is much less active and nonselective for the oxidation. The catalyst... 

Figure 2 shows turnover numbers for cyclohexane oxidation with molecular oxygen catalyzed by iron-substituted silicotungstates. The turnover number of TBA-I was higher than those of non-, mono- and fn-iron-substituted silicotungstates, showing that the di-iron site in TBA-I is an effective center for the oxidation. Such a structure dependency of the... 

Catalyzed by di-Iron(III)-Substituted Silicotungstate, y-SiWio(Fe(OH2) 20,i8 Including Radical-Chain Mechanism, Chem. Lett., 1998, 1263. 

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