Correlated Rotations in Benzylfluorene Derivatives: Structure, Conformation, and Stereodynamics

Fluorene derivatives, having substituted benzyl groups bonded to position 9, have been investigated by
variable temperature NMR spectroscopy. Stereodynamic processes involving restricted rotation about
the fluorenyl−CH2 and aryl−CH2 bonds have been observed, leading to conformers and enantiomeric
forms, and the corresponding barriers were determined by line shape simulation. These dynamic processes
are interpreted as being due to correlated rotation pathways, on the basis of DFT computations that
satisfactorily reproduce the experimental barriers. The structures of two such compounds were also
determined by single-crystal X-ray diffraction