Page 330 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

THE NOBLE GASES
310
a reactive oxygen species we encountered in Section 6.8.

H
−
O O − H
− OH (8.36)
HO Xe OH O O + Xe
OH

The H O then readily falls apart. A cyclic transition state is depicted below; however, a
2 3
hydroxide-mediated E2 mechanism might also be envisioned for the process.

H H

O H O O H O O 2 + 2 H 2 O (8.37)
H O H O
O H O H
It’s worth emphasizing that, like many complex mechanisms in this book, the above
pathway is highly speculative, with some parts more so than others. The electrophilicity of
xenon-bound oxygens is probably one of the more speculative aspects of the above mech-
anism. While we expect that the protonation state of a given xenon-oxo species plays a
decisive role in determining the electrophilicity of a xenon-bound oxygen, we make no
guarantees that the Xe–O species in the above reactions are all depicted in their optimal
protonation states. That said, we do believe that there is a good chance that the above
mechanism is “correct” in its essentials.

REVIEW PROBLEM 8.6

Barium perxenate reacts with sulfuric acid to yield unstable perxenic acid, which
mostly dehydrates to xenon tetroxide, as shown below:

Ba XeO + 2H SO → 2 BaSO + H XeO
2 6 2 4 4 4 6
H XeO → XeO + 2H O
4
2
6
4
Any remaining perxenic acid decomposes slowly to xenic acid and oxygen:
2H XeO → 2H XeO + O + 2H O
2
2
4
4
2
6
Suggest mechanisms for these reactions.
8.7 HYDROLYSIS OF XeF
4
Here is another, rather complex reaction:

6XeF + 12 H O → 2XeO + 4Xe + 3O + 24 HF (8.38)
4
2
3
2