The intrinsic stability of the noble gas-coordinated transition-metal complex ions

Density-functional-theory and high-level ab initio calculations have been p erformed on the [AuXe4](2+) ion and some other hypothetical xenon-, krypton -, and argon-coordinated transition-metal complex cations in the gas phase. Geometry optimization at the QCISD(T) level using a (6s7p4d2f1g) basis set for Au and a (4s4p2d1f) set for Xe predicted Au-Xe bond lengths in good ag reement with the AuXe42+(Sb2F11-)(2) crystal structure. The Ligand-binding energies of the [AuXe4](2+), [AuXe4](3+), and [PtXe4](2+) ions were predict ed to be 229, 565, and 233 kcal/mol, respectively, at the CCSD(T) level. It is found that higher-level correlation effects are important to obtain acc urate geometry parameters. The calculated results also indicated that vario us trivalent, tetravalent, and hexavalent transition-metal complexes of xen on or krypton might also be intrinsically stable.