The dependence on temperature and concentration of 129Xe NMR chemical shift values of organoxenon(II) salts [RXe][Y] and of the parent molecule XeF2

The dependence of the 129Xe NMR chemical shift value of XeF2 on temperature and concentration was determined in a variety of prototypic media: in acidic (anhydrous HF, aHF), nonprotic but polar (dichloromethane), and basic (CD3CN-EtCN, 1:3 v/v) solvents. The 129Xe NMR spectra of a representative series of organoxenon(II) salts RXe]Y] (R = C6F5, heptafluoro-1,4-cyclohexadien-1-yl (cyclo-1,4-C6F7), pentafluoro-1,4-cyclohexadien-3-on-1-yl (cyclo-3-O-1,4-C6F5), CF2=C(CF3), (CF3)2CFCtriple bond]C, C4H9Ctriple bond]C; Y = BF4, AsF6) in aHF showed, compared with XeF2-aHF, a quantitatively less distinct but qualitatively related dependence of delta(129Xe) vs temperature. The dependence of their delta(129Xe) values on concentration in aHF is negligible. An explanation for the different behavior of RXe]Y] and XeF2 is offered.