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

Oxygen coordination to the Xe(VI) atom of XeO 3 was observed in its adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone. The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO 3 , which detonates when mechanically or thermally shocked, the solid [(C 6 H 5 ) 3 PO] 2 XeO 3 , [(CH 3 ) 2 SO] 3 (XeO 3 ) 2 , and (C 5 H 5 NO) 3 (XeO 3 ) 2 adducts are insensitive to mechanical shock, but undergo rapid deflagration when ignited by a flame. Both [(C 6 H 5 ) 3 PO] 2 XeO 3 and (C 5 H 5 NO) 3 (XeO 3 ) 2 are air-stable whereas [(CH 3 ) 2 SO] 3 (XeO 3 ) 2 slowly decomposes over several days and [(CH 3 ) 2 CO] 3 XeO 3 undergoes adduct dissociation at room temperature. The xenon coordination sphere of [(C 6 H 5 ) 3 PO] 2 XeO 3 is a distorted square pyramid which provides the first example of a five-coordinate XeO 3 adduct. The xenon coordination spheres of the remaining adducts are distorted octahedra comprised of three Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO 3 . Quantum-chemical calculations were used to assess the Xe---O adduct bonds, which are predominantly electrostatic σ-hole bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the xenon atoms.