Page 321 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

THE NOBLE GASES 301

Reproduction of Neil Bartlett’s historic paper.
Figure 8.1

Some general trends in noble gas chemistry are as follows.

• Despite the remarkable progress in xenon chemistry over the last few decades, the
noble gases are all exceedingly unreactive, as expected on the basis of their closed
valence shells (i.e., their noble gas configurations). Their ionization potentials are so
high that all but the most electronegative ligands reduce them back to their elemental
state. The ionization potentials of Kr, Xe, and Rn, however, are just low enough that
they form a few compounds with fluorine and oxygen, the two most electronegative
elements. In addition, xenon forms a few compounds with electronegative groups such
as OTeF ,N(SO F) ,N(SO CF ) ,CF ,C(SO CF ) , and so on. The three uncharged
3 3
2
2
3
2
2
3 2
5
molecular fluorides, XeF ,XeF , and XeF , serve as the source of pretty much all
6
4
2
xenon compounds.
F
F F F F
F Xe F Xe Xe
F F
F F
F
XeF 2 XeF 4 XeF 6
• All noble gas compounds (except for proton adducts such as the gas-phase species
+
HeH ) are hypervalent; that is, they have more than eight electrons in the noble gas
−
valence shell. In addition, XeF and XeF are susceptible to nucleophilic attack by F ,
6
4
which further increases their coordination number. Fluoride ligands are also common
leaving or migrating groups in much of xenon chemistry.