A Homoleptic KrF2 Complex, [Hg(KrF2 )8 ][AsF6 ]2 ⋅2 HF.

The reaction of Hg(AsF6 )2 with a large molar excess of KrF2 in anhydrous HF has afforded the first homoleptic KrF2 coordination complex of a metal cation, [Hg(KrF2 )8 ][AsF6 ]2 ⋅2 HF. The [Hg(KrF2 )8 ]2+ dication is well-isolated in the low-temperature crystal structure of its HF-solvated [AsF6 ]- salt, and consists of eight KrF2 molecules that are terminally coordinated to Hg2+ by means of Hg-F(KrF) bonds to form a slightly distorted, square-antiprismatic coordination sphere around mercury. The Raman spectrum of [Hg(KrF2 )8 ]2+ was assigned with the aid of calculated gas-phase vibrational frequencies. Computational studies indicate that both electrostatic and orbital interactions are important for metal-ligand bonding and provide insight into the geometry of the [Hg(KrF2 )8 ]2+ cation and the nature of noble-gas difluoride ligand bonding.