Syntheses and Characterizations of the Mixed Noble‐Gas Compounds, [FKrIIFXeIIF][AsF6]⋅0.5 KrIIF2⋅2 HF, ([KrII2F3][AsF6])2⋅XeIVF4, and XeIVF4⋅KrIIF2

Reaction of [XeF][AsF₆ ] with excess KrF₂ at -78 °C in anhydrous HF (aHF) solvent has yielded the first mixed Kr^II /Xe^II noble-gas compound, [FKrFXeF][AsF₆ ] ⋅0.5 KrF₂ ⋅2 HF, a salt of the [FKrFXeF]⁺ cation. The potent oxidative fluorinating properties of Kr^II fluoride species resulted in oxidation of Xe^II to Xe^IV in aHF at -60 °C to form the mixed Kr^II /Xe^IV cocrystals, ([Kr₂ F₃ ][AsF₆ ])₂ ⋅XeF₄ and XeF₄ ⋅KrF₂ . Further decomposition at 22 °C resulted in oxidation of Xe^IV to Xe^VI to give the recently reported Kr^II /Xe^VI complexes, [F₅ Xe(FKrF)_n ][AsF₆ ] (n=1, 2), [F₅ Xe][AsF₆ ], and a new Kr^II /Xe^VI complex, [(F₅ Xe)₂ (μ-FKrF)(AsF₆ )₂ ], which was characterized by low-temperature (LT) Raman spectroscopy. The [FKrFXeF][AsF₆ ]⋅0.5 KrF₂ ⋅2 HF, ([Kr₂ F₃ ][AsF₆ ])₂ ⋅XeF₄  , and XeF₄ ⋅KrF₂ compounds were characterized by LT Raman spectroscopy and single-crystal X-ray diffraction. Quantum-chemical calculations were used to assess the bonding in [FKrFXeF]⁺ , [Kr₂ F₃ ]⁺ , and [Xe₂ F₃ ]⁺ and to aid in their vibrational assignments.