Insights into the xenon-silver halide interaction from a rotational spectroscopic study of XeAgF and XeAgCl

XeAgF and XeAgCl have been prepared by laser ablation of Ag metal in the presence of xenon and SF6 or xenon and Cl-2, respectively. Rotational spectra for 12 isotoporners of XeAgF and 16 isotopomers of XeAgCl have been recorded. Analysis of the spectra indicates that (i) both chemical systems are unusually strongly bound compared to conventional van der Waals complexes, (ii) significant charge rearrangement occurs at the xenon nucleus upon formation of both XeAgF and XeAgCl as shown by the Xe-131 nuclear quadrupole coupling constants and (iii) in both XeAgF and XeAgCl the Xe-Ag distance is small compared to the sum of the Xe van der Waals radius and the Ag+ ionic radius. An ab initio study of the two species has been performed. The combined experimental and theoretical investigations indicate that the Xe-Ag interaction is not easily described, but that there is some evidence for weak chemical bonding.