less, is closer to planarity, with an angle between the planes of 10.379 Cyclopentane
might be expected to be planar, since the angles of a regular pentagon are 108,
but it is not so, also because of eclipsing effects.380 There are two puckered conformations,
the envelope and the half-chair. There is little energy difference
between these two forms and many five-membered ring systems have conformations
somewhere in between them.381 Although in the envelope conformation one
carbon is shown above the others, ring motions cause each of the carbons in