| Autor: |
Huang, Chung-Hsi, Knop, Osvald, Othen, David A., Woodhams, Frank W. D., Howie, R. Allan |
| Zdroj: |
Canadian Journal of Chemistry; January 1975, Vol. 53 Issue: 1 p79-91, 13p |
| Abstrakt: |
Cubic M4+P2O7pyrophosphates of Ti, Zr, Hf, Sn, and Pb have been examined by X-ray powder diffractometry and by infrared, Raman, and Mössbauer 119Sn spectroscopy. The tin compound appeared to be of Chaunac's type I(with P2O7groups oriented at random) and could be converted to type II(with ordered P2O7groups) by heating to high temperatures. All the other preparations were of Chaunac's type II. Evidence from lattice parameters and intensity features of the Raman spectra suggests that the cubic MP2O7pyrophosphates fall in two groups, one containing the compounds of the typical elements (Ge, Sn, Pb) and the other, the compounds of the transition elements. No support has been found for the view that the P—O—P groupings of the pyrophosphate anion in these compounds are linear. The 119Sn chemical shift in SnP2O7is only slightly less negative than the shift in CuSnF6.4H2O, which makes SnP2O7one of the most ionic compounds of tetravalent tin known. The observed quadrupole splitting in the Mössbauer spectrum of SnP2O7arises largely from the contribution of the valence term to the electric field gradient at the Sn atom. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
