View PDF Version
 
DOI: 10.1039/A900088G (Paper) Reference Section for: Chem. Commun., 1999, 533-534

Lifting the lid on metatungstate. 1H and 183W NMR study of the six electron reduced anion [(H)2{WIV3(OH2)3}WVI9O34(OH)3]3–

(Note: The full text of this document is currently only available in the PDF Version )

Colette Boskovic, Anthony G. Wedd, Maruse Sadek, Robert T. C. Brownlee and Alan M. Bond

Abstract

The distribution of the eleven protons present in a six-electron reduced form of metatungstate, [(H)2{WIV3- (OH2)3}WVI9O34(OH)3]3–, in dry CD3CN is mapped by 1H and 183W NMR, allowing assessment of structural changes which accompany reduction.

References

  1. M. T. Pope, Heteropoly and Isopoly Oxometalates, Springer-Verlag, New York, 1983 Search PubMed.
  2. J. P. Launay, J. Inorg. Nucl. Chem., 1976, 38, 807 CAS.
  3. K. Piepgrass and M. T. Pope, J. Am. Chem. Soc., 1987, 109, 1586 CrossRef CAS.
  4. K. Piepgrass and M. T. Pope, J. Am. Chem. Soc., 1989, 111, 753 CrossRef CAS.
  5. Y. Jeannin, J. P. Launay and M. A. Seid Sedjadi, Inorg. Chem., 1980, 19, 2933 CrossRef CAS.
  6. T. Yamase and E. Ishikawa, J. Chem. Soc., Dalton Trans., 1996, 1619 RSC.
  7. A solution of ammonium metatungstate in HCl was reduced to the 6e– level.3 The ammonium salt was isolated after volume reduction and precipitation with MeOH. Phase transfer4 mediated via a solution of NBu4Br in CH2Cl2 led to the NBu4Br salt..
  8. J. P. Launay, M. Boyer and F. Chauveau, J. Inorg. Nucl. Chem., 1976, 38, 243 CAS.
  9. 183W spectra were acquired on a Bruker DRX500 spectrometer equipped with a broadband probe at 30 °C. Spectra were acquired at 20.837 MHz using a 60° pulse of 26 µs. Spectra were processed with a line broadening of 1 Hz. COSY 90 spectra were acquired using a 90° pulse of 39 µs. Experiments over the WVI and WIV chemical shift regions were acquired separately owing to their large separation. Gradient non-phase sensitive HMQC experiments were acquired on a Bruker DRX400 spectrometer equipped with an inverse probe at 25 °C. The probe was tuned to 400.130 MHz for 1H and 16.671 MHz for 183W. 90° pulses of 13.5, 15.3 and 25.7 µs for 1H and 44 µs for 183W were employed..
  10. He shifts by < 0.1 ppm (W1/2, 5–9 Hz) in the range 0–100 equiv. added H2O. Resonances Ha, Hb and Hc, Hd broaden beyond detectability at ≈ 100 and 25 equiv. added H2O, respectively..
  11. J. Lefebvre, F. Chauveau, P. Doppelt and C. Brevard, J. Am. Chem. Soc., 1981, 103, 4589 CrossRef CAS Coupling characteristic of edge sharing is not resolved (ref. 4); the situation is also complicated by long range WW coupling.
  12. The assignments of WD and WF are strengthened by the absence of Dd and the presence of Fd and Gd crosspeaks..
  13. M. Ardon and A. Bino, Struct. Bonding (Berlin), 1987, 65, 1 CAS.
Click here to see how this site uses Cookies. View our privacy policy here.