FREQUENCY AND INTENSITY RELATIONS IN RAMAN-SPECTRA OF XEF5+ AND XE2F11+ IN THEIR SOLID FLUOROMETALATE COMPLEXES

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.