Theoretical Study on Metal NMR Chemical Shifts. Electronic Mechanism of the Xe Chemical Shift

Abstract

Abstract The 129Xe chemical shifts of the complexes XeF2n, XeF2n−1+ and XeOnF6−2n (n = 1—3) are studied theoretically by ab initio finite perturbation method. The first-order higher basis functions (FOBFs) are added to the standard basis set for removing the gauge-dependence. The calculated values of the Xe chemical shifts agree reasonably with the experimental values. Though the electronic configuration of Xe is the closed shell 5s25p6, the electronic mechanism of the Xe chemical shift is shown to be the p-mechanism. Namely, the dominant term in the Xe chemical shift is the paramagnetic term and it is mainly governed by the Xe valence p AO contribution. Actually, as expected, the Xe chemical shifts show the U-shaped dependence on the number of the Xe valence p electrons. The diamagnetic term is small and depends linearly on the number of the ligands.