Twisted Push–Pull Alkenes Bearing Geminal Cyclicdiamino and Difluoroaryl Substituents

The systematic combination of N-heterocyclic olefins (NHOs) with
fluoroarenes resulted in twisted push–pull alkenes. These alkenes
carry electron-donating cyclicdiamino substituents and two electron-withdrawing
fluoroaryl substituents in the geminal positions. The synthetic method
can be extended to a variety of substituted push–pull alkenes
by varying the NHO as well as the fluoroarenes. Solid-state molecular
structures of these molecules reveal a notable elongation of the central
C–C bond and a twisted geometry in the alkene motif. Absorption
properties were investigated with UV–vis spectroscopy. The
redox properties of the twisted push–pull alkenes were probed
with electrochemistry as well as UV–vis/NIR and EPR spectroelectrochemistry,
while the electronic structures were computationally evaluated and
validated.