bicycle-pedal (BP) mechanism
Volume-conserving mechanism proposed for the @P04622@ of conjugated double bonds. Two alternating double bonds rotate concertedly with only the two CH units turning in and out of the plane of the molecule.
See also:
hula-twist mechanism
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 308 [Terms] [Paper]