Xenon Trioxide Coordination Complexes of Crown Ethers: (CH2CH2O)4XeO3, and Xe(VI) Hydrates [(CH2CH2O)6(H2O)XeO3]∙H2O and [(CH2CH2O)6(H2O)XeO3]2∙2H2O∙HF

Abstract

Following our report of the first coordination complex between a noble-gas compound and a crown ether, (CH2CH2O)5XeO3, the reactions and structures of XeO3 complexes with 12-crown-4 and 18-crown-6 were investigated. The reactions of 12-crown-4 and 18-crown-6 with XeO3 in dilute aqueous HF solutions yielded (CH2CH2O)4XeO3 and [(CH2CH2O)6(H2O)XeO3]2∙2H2O∙HF, whereas reactions of 12-crown-4 and 18-crown-6 in acetone solutions with moist solid XeO3 yielded (CH2CH2O)4XeO3 and [(CH2CH2O)6(H2O)XeO3]∙H2O. The (CH2CH2O)4XeO3 and [(CH2CH2O)6(H2O)XeO3]∙H2O complexes are air-stable and shock-insensitive, whereas [(CH2CH2O)6(H2O)XeO3]2∙2H2O∙HF is a treacherous, shock-sensitive detonator. Low-temperature X-ray crystal structures show that XeO3 is coordinated to the crown ether and H2O through short Xe---O contacts. Mappings of the XeO3 Hirshfeld surfaces onto 12-crown-4 and 18-crown-6 in (CH2CH2O)4XeO3 and [(CH2CH2O)6(H2O)XeO3]∙H2O reveal regions of negative electrostatic potential (EP) on the oxygen atoms of the crown ethers and regions of high positive EP on the Xe(VI) atom of XeO3 that are consistent with σ-hole bonds. The calculated gas-phase geometries, Wiberg bond valences and indices, and empirical bond valences corroborate the descriptions of the shortest Xe---Ocrown/H2O contacts as σ-hole bonds. The 12-crown-4, 15-crown-5, and 18-crown-6 complexes of XeO3 are also compared with the X-ray crystal structures and calculated gas-phase structures of their SbF3 and SbCl3 analogues.