Multi-Iron Tungstodiarsenates. Synthesis, Characterization, and Electrocatalytic Studies of αββα-(FeIIIOH2)2FeIII2(As2W15O56)212-
- 23 January 2003
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 42 (4), 1163-1169
- https://doi.org/10.1021/ic0261169
Abstract
Reaction of the trivacant lacunary complex, alpha-Na(12)[As(2)W(15)O(56)], with an aqueous solution of Fe(NO(3))(3).9H(2)O yields the sandwich-type polyoxometalate, alphabetabetaalpha-Na(12)(Fe(III)OH(2))(2)Fe(III)(2)(As(2)W(15)O(56))(2) (Na1). The structure of this complex, determined by single-crystal X-ray crystallography (a = 13.434(1) A, b = 13.763(1) A, c = 22.999(2) A, alpha = 90.246(2) degrees, beta = 102.887(2) degrees, gamma = 116.972(1) degrees, triclinic, Ponemacr;, R1 = 5.5%, based on 25342 independent reflections), consists of an Fe(III)(4) unit sandwiched between two trivacant alpha-As(2)W(15)O(56)(12)(-) moieties. UV-vis, infrared, cyclic voltammetry, and elemental analysis data are all consistent with the structure determined from X-ray analysis. Magnetization studies confirm that the four Fe(III) centers are antiferromagnetically coupled. A cyclic voltammogram of Na1 reveals that a three-wave W(VI) system replaces the two-wave W(VI) system found in the precursor alpha-As(2)W(15)O(56)(12)(-) complex. The observed modifications in the CV patterns of Na1 and alpha-As(2)W(15)O(56)(12)(-) are most likely due to subsequent changes in the acid-base properties of two reduced POMs that occur as a result of Fe(III) incorporation. Na1 is shown to be more efficient than the monosubstituted complex alpha(2)-As(2)(Fe(III)OH(2))W(17)O(61)(7)(-) in the electrocatalytic reduction of dioxygen. This is attributed to cooperativity effects among the adjacent Fe(III) centers in Na1.Keywords
This publication has 27 references indexed in Scilit:
- Dioxygen and hydrogen peroxide electrocatalytic reduction: evidence for a cooperativity of Mo and Cu centres in substituted heteropolyanionsElectrochemistry Communications, 2002
- Di- and Tricobalt Dawson Sandwich Complexes: Synthesis, Spectroscopic Characterization, and Electrochemical Behavior of Na18[(NaOH2)2Co2(P2W15O56)2] and Na17[(NaOH2)Co3(H2O)(P2W15O56)2]Inorganic Chemistry, 2002
- Asymmetric Sandwich-Type Polyoxoanions. Synthesis, Characterization, and X-ray Crystal Structures of Diferric Complexes [TMIIFeIII2(P2W15O56)(P2TMII2W13O52)]16-, TM = Cu or CoInorganic Chemistry, 2001
- Polyoxometalates in MedicineChemical Reviews, 1998
- Heterogeneous CatalysisChemical Reviews, 1998
- Iron-Substituted Dawson-Type Tungstodiphosphates: Synthesis, Characterization, and Single or Multiple Initial Electronation Due to the Substituent Nature or PositionInorganic Chemistry, 1997
- Structure of sodium bis(pentadecatungstodiphosphato)diaquatetrazincate hydrate (16∶1∶50)Journal of Chemical Crystallography, 1994
- Effects of solvent and anomeric configuration upon the circular dichroism, temperature dependence of amide proton chemical shifts, amide proton exchange rates, and infrared absorption of methyl 2-acetamido-2-deoxy-D-glucopyranosidesJournal of the American Chemical Society, 1989
- Metastable ion characteristics. XV. Hydrogen scrambling in organic ions as a function of internal energy. Extension of the energy rangeJournal of the American Chemical Society, 1970
- Pentadienyl Cations and Their Rearrangements in FSO3H-SbF5Solution1Journal of the American Chemical Society, 1966