S. Milicev, FREQUENCY AND INTENSITY RELATIONS IN RAMAN-SPECTRA OF XEF5+ AND XE2F11+ IN THEIR SOLID FLUOROMETALATE COMPLEXES, Vibrational spectroscopy, 8(2), 1995, pp. 309-314
Raman spectra of XeF6 in its solid fluorometalate complexes, in which
it appears as XeF5+ or Xe2F11+ ion, show appreciable variations and th
e observed two distributions of intensities were explained by the effe
cts of deformation of the ions or by the coupling of their vibrations.
However, there is a number of exceptions. It is demonstrated here tha
t in addition to kinematic, electronic effects also influence the shap
e of spectra. Partial charge on the F ligand of the anion governs the
geometry of XeF5+ with the consequent shifts and changes in intensitie
s of the Raman bands. In known spectra of XeF5+.MF(x)(-) salts, nu(1)
(axial XeF stretch) shifts to lower frequencies and becomes more inten
sive than nu(2) (symmetric basal Xe-F stretch) when the negative parti
al charge on the F ligand of the anion exceeds ca. 0.33, estimated by
the Sanderson method, and one type of spectra transforms into the othe
r. For other compositions of examined XeF5+ compounds the same is obse
rved. The deformation of XeF5+ in compounds with polymeric anions or d
ifferent interactions in compounds with monomeric anions of various co
mposition have, in the examples studied, minor influences. Xe2F11+ com
pounds are a separate family. Effect of the partial charge of the F li
gand is not observed and the reasons for frequency shifts of nu(1) are
to be searched for elsewhere.