Coordination of KrF2 to a Naked Metal Cation, Mg2+

Angewandte Chemie - International Edition

5 years ago

Coordination of KrF2 to a Naked Metal Cation, Mg2+

Hélène P. A. Mercier, David S. Brock, Boris Žemva, Matic Lozinšek, Gary J. Schrobilgen

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. Krypton difluoride, a thermodynamically unstable and potent oxidative fluorinator, coordinates to Mg2+ to form the coordination complexes, [Mg(KrF2)4(AsF6)2] and [Mg(KrF2)4(AsF6)2]⋅2 BrF5. The complexes were characterized by low-temperature single-crystal X-ray diffraction and low-temperature Raman spectroscopy. Computational studies show that the Mg−F bonds are essentially non-covalent, weakly electrostatic interactions.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/anie.201611534