Raman study of molecular dynamics of inorganic fluoroxidizers in nonaqueous solutions: part 4. Xenon tetrafluoride and xenon hexafluoride in hydrogen fluoride.

Raman spectra of XeF4 and XeF6 in the nonaqueous HF solutions at various concentrations and vibrational spectra of the [XeF5]+ cation in the solid state and in the HF solutions over a wide range of vibrational frequencies have been studied. The assignments of the observed vibrational bands of the [XeF5]+ cation and XeF6-HF system has been made. A number of associates or solvates being formed as a result of the donor-acceptor interaction between Lewis base and Lewis acid has been shown to exist alongside with ionized monomeric and polymeric modifications of XeF6 in the HF solution such as ([XeF5]+ F-)n (n = 1, 2, 4). The contours of the nu1(A1g) band of XeF4 with frequency 552 cm(-1) and bands of stretching modes of ([XeF5]+ F-)n (n = 1, 2, 4) with frequency in the range of 600-670 cm(-1) are analysed. The correlation functions of the vibrational and rotational relaxation as well as the corresponding characteristic time for these processes have been calculated. A conclusion has been driven at that it is vibrational dephasing that makes the major contribution to the formation of ([XeF5]+ F)4 and ([XeF5]+ F-)2 band contours, while in the case of [XeF5]+ F- and XeF4 the contributions of vibrational dephasing and rotational relaxation nearly coincide.