bullvalene

Bullvalene is a hydrocarbon with the chemical formula . The molecule has a cage-like structure formed by the fusion of one cyclopropane and three cyclohepta-1,4-diene rings. Bullvalene is unusual as an organic molecule due to the and bonds forming and breaking rapidly through Cope rearrangements; this property makes it a fluxional molecule.

==Stereodynamics== The bullvalene molecule is a cyclopropane platform with three vinylene arms conjoined at a methine group. This arrangement enables a degenerate Cope rearrangement with the result that all carbon atoms and hydrogen atoms appear equivalent on the NMR timescale. At room temperature the 1H NMR signals average to a rounded peak at 5.76 ppm. At lower temperatures the peak broadens into a mound-like appearance, and at very low temperatures the fluxional behavior of bullvalene is reduced, allowing for 4 total signals to be seen. This pattern is consistent with an exchange process whose rate k is close to the frequency separation of the four contributing resonances. The number of possible valence tautomers of a bullvalene depends on the number of unique substituents. The number of isomers with ten distinguishable substituents is 10!/3 = 1,209,600. class=skin-invert-image