bicycle-pedal mechanism (BP mechanism)

https://doi.org/10.1351/goldbook.BT07330
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.
BT07330.png
See also:
hula-twist mechanism
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 308 [Terms] [Paper]