Borotungstate Polyoxometalates: Multinuclear NMR Structural Characterization and Conversions in Solutions Full article
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Inorganic Chemistry
ISSN: 0020-1669 , E-ISSN: 1520-510X |
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Output data | Year: 2011, Volume: 50, Number: 11, Pages: 4725-4731 Pages count : 7 DOI: 10.1021/ic101996f | ||
Tags | NUCLEAR-MAGNETIC-RESONANCE; HETEROPOLY ACID H3PW12O40; W-183 NMR; CHEMICAL-SHIFTS; O-17; POLYOXOTUNGSTATES; SPECTROSCOPY; ASSIGNMENT; ANIONS | ||
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Abstract:
The unique heteropolyanion [H(3)BW(13)O(46)](8-) (BW(13)), previously suggested on the basis of indirect evidence, and protonated lacunary heteropolyanion [HBW(11)O(39)](8-) (BW(11)) have been identified in aqueous solutions at pH 5-7.5 from NMR spectra. The pattern of tungsten-tungsten connectivities based on the analysis of the (2)J(W-O-W) coupling satellites in the (183)W NMR spectrum of BW(11), containing six peaks of relative intensities ∼2:2:2:1:2:2, indicates that the latter is the α isomer. The (17)O NMR spectrum confirms the protonated state of the polyanion with the proton delocalized on two out of four terminal O atoms surrounding the tungsten vacancy. The (183)W NMR spectrum of BW(13) contains seven peaks of relative intensities ∼2:1:2:2:2:2:2 with additional large couplings due to the connectivity between BW(11) and [W(2)O(7)](2-) fragments. According to the (17)O NMR spectrum, two protons of [BW(13)O(46)H(3)](8-) are delocalized on the two terminal trans O atoms of the dimeric fragment while the third one is linked to its bridging O atom. The conversions of BW(11) and BW(13) in solution were followed by using (183)W NMR spectra at a "fingerprint" level. In the pH range from ∼7.5 to 6, BW(11) transforms to BW(13), transforming further to [BW(12)O(40)](5-) (BW(12)) and [B(3)W(39)O(132)H(n)](n-21) (B(3)W(39)) in different ratios. Conversion of BW(13) to BW(12) proceeds through an intermediate complex of suggested composition [BW(11)O(39)·WO(2)](7-). At high acidity (pH ∼ 0), B(3)W(39) gradually decomposes into tungstic acid, BW(12) and H(3)BO(3). Polyanion BW(12) persists in the pH range ∼0-7.5.
Cite:
Maksimovskaya R.I.
, Maksimov G.M.
Borotungstate Polyoxometalates: Multinuclear NMR Structural Characterization and Conversions in Solutions
Inorganic Chemistry. 2011. V.50. N11. P.4725-4731. DOI: 10.1021/ic101996f WOS Scopus РИНЦ
Borotungstate Polyoxometalates: Multinuclear NMR Structural Characterization and Conversions in Solutions
Inorganic Chemistry. 2011. V.50. N11. P.4725-4731. DOI: 10.1021/ic101996f WOS Scopus РИНЦ
Dates:
Submitted: | Sep 29, 2010 |
Published online: | Apr 28, 2011 |
Published print: | Jun 6, 2011 |
Identifiers:
Web of science | WOS:000290978400013 |
Scopus | 2-s2.0-79958098137 |
Elibrary | 17001957 |
Chemical Abstracts | 2011:532843 |
Chemical Abstracts (print) | 154:578668 |
PMID | 21526755 |
OpenAlex | W2323558329 |