Xenon forms three binary fluorides, XeF2,XeF4 and XeF6 by the direct reaction of elements under appropriate experimental conditions. Xe has a complete filled 5p configuration. As a result, when it undergoes bonding with an odd number (3 or 5) of F atoms it leaves behind one unpaired electron. This causes the molecule to become unstable. As a result XeF3, XeF5 are not possible.
Xe(g)+F2(g)673K,1 bar−−−−−−→XeF2(s)
(xenon in excess)
Xe(g)+2F2(g)873K,7 bar−−−−−−→XeF4(s)
(1:5 ratio)
Xe(g)+3F2(g)573K,60−70 bar−−−−−−−−−→XeF6(s)
(1:20 ratio)
Only even number of fluorides can combine with Xe. Therefore, XeF3 and XeF5 cannot be formed.