Xenon Trioxide Adducts of O‐Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3

Xenon trioxide (XeO₃ ) forms adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone by coordination of the ligand oxygen atoms to the Xe^VI atom of XeO₃ . The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction, and Raman spectroscopy. Unlike solid XeO₃ , which detonates when mechanically or thermally shocked, solid (C₅ H₅ NO)₃ (XeO₃ )₂ , [(C₆ H₅ )₃ PO]₂ XeO₃ , and [(CH₃ )₂ SO]₃ (XeO₃ )₂ are insensitive to mechanical shock. The [(CH₃ )₂ SO]₃ (XeO₃ )₂ adduct slowly decomposes over several days to (CH₃ )₂ SO₂ , Xe, and O₂ . All three complexes undergo rapid deflagration when ignited by a flame. Both [(C₆ H₅ )₃ PO]₂ XeO₃ and (C₅ H₅ NO)₃ (XeO₃ )₂ are room-temperature stable and the [(CH₃ )₂ CO]₃ XeO₃ complex dissociates at room temperature to form a stable solution of XeO₃ in acetone. The xenon coordination sphere of [(C₆ H₅ )₃ PO]₂ XeO₃ , a distorted square-pyramid, provides the first example of a five-coordinate XeO₃ complex with only two Xe- - -O adduct bonds. The xenon coordination spheres of the remaining adducts are distorted octahedra, comprised of three Xe- - -O secondary bonds that are approximately trans to the primary Xe-O bonds of XeO₃ . Quantum-chemical calculations were used to assess the nature of the Xe- - -O adduct bonds, which are described as predominantly electrostatic bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the electrophilic xenon atoms.