A @CT01038@ is said to be fluxional if it undergoes rapid @D01559@ (generally detectable by methods which allow the observation of the behaviour of individual nuclei in a rearranged chemical species, e.g. NMR, X-ray). Example: bullvalene (1 209 600 interconvertible arrangements of the ten CH groups).
The term is also used to designate positional change among @L03518@ of complex compounds and organometallics. In these cases, the change is not necessarily degenerate.
See also:
valence tautomerization
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1115 [Terms] [Paper]