Nature of the XeVI-N Bonds in F6XeNCCH3 and F6Xe(NCCH3)2 and the Stereochemical Activity of Their Xenon Valence Electron Lone Pairs

The recently reported syntheses and X-ray crystal structures of the highly endothermic compounds F6XeNCCH3 and F6Xe(NCCH3)(2)CH3CN provide the first, albeit weakly covalent, Xe-VI-N bonds. The XeF6 unit of F6XeNCCH3 possesses distorted octahedral (C-3v) symmetry similar to gas-phase XeF6, whereas the XeF6 unit of F6Xe(NCCH3)(2)CH3CN possesses C-2v symmetry. Herein, the natural bond orbital (NBO), atoms in molecules (AIM), electron localization function (ELF), and molecular electrostatic potential surface (MEPS) analyses show that the Xe valence electron lone pairs (VELPs) of both compounds are stereochemically active. The Xe VELPS are diffuse and ineffectively screen their Xe cores so that the Xe VELP positions correspond to the most electrophilic regions of the MEPS, which enables the opposing N VELP of CH3CN to coordinate to this region. These bonds are predominantly electrostatic in nature and are interpreted as sigma-hole interactions.