Group 6 Oxyfluoro‐Anion Salts of [XeF5]+ and [Xe2F11]+: Syntheses and Structures of [XeF5][M2O2F9] (M=Mo, W), [Xe2F11][M′OF5] (M′=Cr, Mo, W), [XeF5][HF2]⋅CrOF4, and [XeF5][WOF5]⋅XeOF4 Journal Articles uri icon

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abstract

  • AbstractThe reactions of the fluoride‐ion donor, XeF6, with the fluoride‐ion acceptors, M′OF4 (M′=Cr, Mo, W), yield [XeF5]+ and [Xe2F11]+ salts of [M′OF5]− and [M2O2F9]− (M=Mo, W). Xenon hexafluoride and MOF4 react in anhydrous hydrogen fluoride (aHF) to give equilibrium mixtures of [Xe2F11]+, [XeF5]+, [(HF)nF]−, [MOF5]−, and [M2O2F9]− from which the title salts were crystallized. The [XeF5][CrOF5] and [Xe2F11][CrOF5] salts could not be formed from mixtures of CrOF4 and XeF6 in aHF at low temperature (LT) owing to the low fluoride‐ion affinity of CrOF4, but yielded [XeF5][HF2]⋅CrOF4 instead. In contrast, MoOF4 and WOF4 are sufficiently Lewis acidic to abstract F− ion from [(HF)nF]− in aHF to give the [MOF5]− and [M2O2F9]− salts of [XeF5]+ and [Xe2F11]+. To circumvent [(HF)nF]− formation, [Xe2F11][CrOF5] was synthesized at LT in CF2ClCF2Cl solvent. The salts were characterized by LT Raman spectroscopy and LT single‐crystal X‐ray diffraction, which provided the first X‐ray crystal structure of the [CrOF5]− anion and high‐precision geometric parameters for [MOF5]− and [M2O2F9]−. Hydrolysis of [Xe2F11][WOF5] by water contaminant in HF solvent yielded [XeF5][WOF5]⋅XeOF4. Quantum‐chemical calculations were carried out for M′OF4, [M′OF5]−, [M′2O2F9]−, {[Xe2F11][CrOF5]}2, [Xe2F11][MOF5], and {[XeF5][M2O2F9]}2 to obtain their gas‐phase geometries and vibrational frequencies to aid in their vibrational mode assignments and to assess chemical bonding.

publication date

  • July 22, 2020