UNSPECIFIED. (2004) Oxygen-17 NMR study of aqueous peroxotungstates. DALTON TRANSACTIONS (3). pp. 476-481. ISSN 1477-9226

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Abstract

Aqueous peroxotungstates have been studied from pH 0.5 to 9.0, over a range of peroxide concentrations. Although equilibria are not always established, many anions can be identified by O-17 NMR because the ratio of delta(O)(W anion)/delta(O)(known Mo anion) is consistently 79 +/- 3%. They are [WO3(HO2)](-); [WO(OH)(O-2)(2)](-); [WO(OH2)(O-2)(2)](0); [W2O3(O-2)(4)](2-); [W2O3(OH)(O-2)(4)](3-); [W4O12(O-2)(2)](4-); [W7O23(O-2)](6-) and [W7O22(O-2)(2)](6-). Their pK(a) values, where measurable, are about 2 units lower than the corresponding peroxomolybdates, e.g. 0.0 for [WO(OH2)(O-2)(2)](0) and 8.0 for [W2O3(O-2)(4)](2-). Other peroxotungstate species are also present but can only be broadly identified. These include Keggin structures with relatively low peroxo content, and a very unsymmetrical anion appearing at pH ca. 7 that bears no obvious structural relationship to any species previously reported. The main product from the reaction of powdered W metal with 30% aqueous peroxide is provisionally identified as the symmetrical anion [W6O13(OH)(2)(OH2)(2)(O-2)(5)](2-), although other minor species are also formed, probably having fewer peroxo substituents.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry
Journal or Publication Title:	DALTON TRANSACTIONS
Publisher:	ROYAL SOC CHEMISTRY
ISSN:	1477-9226
Date:	2004
Number:	3
Number of Pages:	6
Page Range:	pp. 476-481
Identification Number:	10.1039/b313243a
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/8854

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