Structure of Penta-1,3-diene

Penta-1,3-diene contains two double bonds which are separated by one sigma bond. Hence, these double bonds are "conjugated". As with the case of butadiene, the best conformation about the C(sp2)-C(sp2) bond is trans. Finally, note the methyl group's conformation. Is the in-plane methyl C-H bond on the side of the double bond or on the opposite side?


Figure. The MP2(full)/6-31G* optimized structure of penta-1,3-diene exemplifies conjugated double bonds in a diene.