Xenon Trioxide Adducts of O-Donor Ligands; [(CH 3 ) 2 CO] 3 XeO 3 , [(CH 3 ) 2 SO] 3 (XeO 3 ) 2 , (C 5 H 5 NO) 3 (XeO 3 ) 2 , and [(C 6 H 5 ) 3 PO] 2 XeO 3

Xenon trioxide (XeO ) forms adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone by coordination of the ligand oxygen atoms to the Xe atom of XeO . The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction, and Raman spectroscopy. Unlike solid XeO , which detonates when mechanically or thermally shocked, solid (C H NO) (XeO ) , [(C H ) PO] XeO , and [(CH ) SO] (XeO ) are insensitive to mechanical shock. The [(CH ) SO] (XeO ) adduct slowly decomposes over several days to (CH ) SO , Xe, and O . All three complexes undergo rapid deflagration when ignited by a flame. Both [(C H ) PO] XeO and (C H NO) (XeO ) are room-temperature stable and the [(CH ) CO] XeO complex dissociates at room temperature to form a stable solution of XeO in acetone. The xenon coordination sphere of [(C H ) PO] XeO , a distorted square-pyramid, provides the first example of a five-coordinate XeO 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 XeO . 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.