Syntheses and Structural Characterizations of the Cl(V) Coordination Complex, [O2Cl(FXeF)2][AsF6], and β-[ClO2][AsF6

Abstract

The synthesis and structural characterization of the first Cl(V) coordination complex of XeF2, [O2Cl(FXeF)2][AsF6], is described. The reaction of α-[ClO2][AsF6] with XeF2 at −78 °C in anhydrous HF (aHF) solvent yields [O2Cl(FXeF)2][AsF6], a rare example of noble-gas difluoride coordination to a main-group Lewis acid center. The low-temperature (LT) phase of β-[ClO2][AsF6] was obtained by recrystallization of α-[ClO2][AsF6] from aHF solvent at –10 °C. The compounds were characterized by LT single-crystal X-ray diffraction and LT Raman spectroscopy. Quantum-chemical calculations were carried out for the model gas-phase ([O2Cl(FXeF)2][AsF6]2)− anion to aid in the assignments of fundamental vibrational frequencies and 35/37Cl isotope shifts for [O2Cl(FXeF)2][AsF6] and to assess its chemical bonding by use of an NBO analysis. The [O2Cl(FXeF)2]+ cations and [AsF6]− anions of [O2Cl(FXeF)2][AsF6] are intimate ion-pairs with secondary Cl---FAs and Cl---FXe bonds that are significantly shorter than the sums of the Cl and F van der Waals radii, and are consistent with noncovalent σ-hole bonding. MEPS and NBO analyses were also carried out for the gas-phase [XO2]+ (X = Cl, Br, I) cations.