Interesting Historical Paper On Xenon Chemistry.

[NNadir]

In 1962 Neil Bartlett, acting on a chemical hunch relating to the cationic chemistry of oxygen, made the remarkable discovery that noble gas chemistry existed. Up until that time, it had been widely assumed that all of the noble gases were inert and that chemical reactions involving them were more or less impossible.

Bartlett was able to synthesize xenon hexafluoroplatinate, and ultimately chemists would show that several fluorides of xenon, and a few oxyfluorides, as well as a pure oxide, and several oxo-anions could be readily made.

This was really, really, really cool.

Later chemists trying to understand the fission behavior of uranium in molten fluoride salts recognized that some strange behavior associated with xenon in molten reactors probably involved this chemistry.

I just came across a paper that touches on the work that was going on concerning the fluorochemistry of xenon.

A molten fluoride mixture containing UF4 has served as the fuel in a high temperature nuclear reactor . Xe and Kr are produced in such a fuel as fission products; Xe is a serious nuclear poison. Ease of removal of these elements from the liquid fuel depends on their solubility in the molten fluoride. Since He (or A) is commonly used as a protective blanket and/or sparging gas during reactor operation the fluoride fuel is saturated with He at the contact temperature; bubble formation, which could lead €0 undesirable perturbations in nuclear reactivity, might be a consequence of the dependence of He solubility on temperature within the reactor fuel circuit. Accordingly, both absolute solubility and its temperature dependence for noble gases in molten fluorides are of importance in operation of such reactors...

...Successful operation of the Aircraft Reactor Experiment (9,10) disclosed no detrimental effects due to behavior of the rare gases; it was observed that at least 95% of the Xe produced was evolved from the fuel.12,16 The lack of quantitative information on this subject has prompted examination of the solubilities of noble gases in fluoride mixtures of interest to nuclear reactors. The solubilities of He, Ne, A and Xe in a mixture of NaF with 47 mole% ZrF4 and of He and Xe in a mixture of NaF with 46 mole% ZrF4 and 4 mole % UF4 over the temperature interval from 600 to 800' are reported in this document.

J. Phys. Chem., 1958, 62 (7), pp 862–866

The "At least" proved to be interesting in this case. Probably up to 5% of the xenon in the reactor was, in fact, in the form of xenon fluorides, but no one realized it.

[Fenmick]

1. XeX6 et al

Neat paper. I am biased for those guys who make wierd molecules over those guys who like to bust apart wierd molecules (even though both are challenging).

[NNadir]

2. Makin' 'em's harder.