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 on our report of the first coordination complex between a noble‐gas compound and a crown ether, (CH 2 CH 2 O) 5 XeO 3 , the reactions and structures of XeO 3 complexes with 12‐crown‐4 and 18‐crown‐6 were investigated. The reactions of 12‐crown‐4 and 18‐crown‐6 with XeO 3 in dilute aqueous HF solutions yielded (CH 2 CH 2 O) 4 XeO 3 and [(CH 2 CH 2 O) 6 (H 2 O)XeO 3 ] 2 ⋅ 2H 2 O ⋅ HF, whereas reactions of 12‐crown‐4 and 18‐crown‐6 with moist solid XeO 3 in acetone solutions yielded (CH 2 CH 2 O) 4 XeO 3 and [(CH 2 CH 2 O) 6 (H 2 O)XeO 3 ] ⋅ H 2 O. The (CH 2 CH 2 O) 4 XeO 3 and [(CH 2 CH 2 O) 6 (H 2 O)XeO 3 ] ⋅ H 2 O complexes are air‐stable and shock‐insensitive, whereas [(CH 2 CH 2 O) 6 (H 2 O)XeO 3 ] 2 ⋅ 2H 2 O ⋅ HF is a treacherous, shock‐sensitive detonator. Low‐temperature X‐ray crystal structures show that XeO 3 is coordinated to the crown ether and H 2 O through short Xe‐ ‐ ‐O contacts. Mappings of the XeO 3 Hirshfeld surfaces onto 12‐crown‐4 and 18‐crown‐6 in (CH 2 CH 2 O) 4 XeO 3 and [(CH 2 CH 2 O) 6 (H 2 O)XeO 3 ] ⋅ H 2 O 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 XeO 3 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‐ ‐ ‐ contacts as σ‐hole bonds. The 12‐crown‐4, 15‐crown‐5, and 18‐crown‐6 complexes of XeO 3 are also compared with the X‐ray crystal structures and calculated gas‐phase structures of their SbF 3 and SbCl 3 analogues.