Alkali-Metal Complexes of XeF2: Synthesis and Structural Characterization of [Li(XeF2)3PtF6], [Na(XeF2)PtF6], and [K(XeF2)2PtF6]

Reactions of alkali-metal hexafluoridoplatinates(V), MPtF6 (M = Li, Na, K, Rb), with xenon difluoride in anhydrous hydrogen fluoride were investigated. These reactions afforded the XeF2 coordination compounds [Li(XeF2)3PtF6], [Na(XeF2)PtF6], and [K(XeF2)2PtF6], whereas no Rb+ complex was isolated. The products were characterized by low-temperature single-crystal X-ray diffraction and Raman spectroscopy, complemented by periodic density functional theory calculations. The alkali-metal coordination number increases progressively from six for Li+ to seven for Na+ and eight for K+. This series expands the currently limited set of XeF2 complexes with monovalent cations and provides the first example of XeF2 coordination to K+ as well as the first monovalent cation with a homoleptic XeF2 coordination sphere, [Li(XeF2)6]+, observed in [Li(XeF2)3PtF6]. In addition, single-crystal structures and Raman spectra of the parent salts LiPtF6, NaPtF6, KPtF6, and RbPtF6 are reported.