Coordination of KrF₂ to a Naked Metal Cation, Mg²⁺

Abstract

Examples of coordination compounds in which KrF2 functions as a ligand are very rare. In contrast, XeF2 provides a rich coordination chemistry with a variety of main‐group and transition metal cations. The reactions of Mg(AsF6)2 and KrF2 in HF or BrF5 solvent have afforded [Mg(KrF2)4(AsF6)2] and [Mg(KrF2)4(AsF6)2]⋅2 BrF5, respectively, the first examples of a metal cation ligated by KrF2. Their X‐ray crystal structures and Raman spectra show that the KrF2 ligands and [AsF6]− anions are F‐coordinated to a naked Mg2+ cation. Quantum‐chemical calculations are consistent with essentially non‐covalent ligand‐metal bonding. These compounds significantly extend the XeF2–KrF2 analogy and the limited chemistry of krypton by introducing a new class of coordination compound in which KrF2 functions as a ligand towards a naked metal cation.