Syntheses and Structures of F6 XeNCCH3 and F6 Xe(NCCH3)2.

Acetonitrile and the potent oxidative fluorinating agent XeF6 react at -40 °C in Freon-114 to form the highly energetic, shock-sensitive compounds F6XeNCCH3 (1) and F6Xe(NCCH3)2⋅CH3CN (2⋅CH3CN). Their low-temperature single-crystal X-ray structures show that the adducted XeF6 molecules of these compounds are the most isolated XeF6 moieties thus far encountered in the solid state and also provide the first examples of Xe(VI)-N bonds. The geometry of the XeF6 moiety in 1 is nearly identical to the calculated distorted octahedral (C3v) geometry of gas-phase XeF6. The C2v geometry of the XeF6 moiety in 2 resembles the transition state proposed to account for the fluxionality of gas-phase XeF6. The energy-minimized gas-phase geometries and vibrational frequencies were calculated for 1 and 2, and their respective binding energies with CH3CN were determined. The Raman spectra of 1 and 2⋅CH3CN were assigned by comparison with their calculated vibrational frequencies and intensities.