Tuning the redox profile of the 6,6-biazulenic platform through functionalization along its molecular axis

The E-1/2 potential associated with reduction of the linearly-functionalized 6,6 '-biazulenic scaffold is accurately correlated to the combined sigma(p) Hammett parameters of the substituents over >600 mV range. X-ray crystallographic analysis of the 2,2 '-dichloro-substituted derivative revealed unexpectedly short C-Cl bond distances, along with other metric changes, suggesting a non-trivial cycloheptafulvalene-like structural contribution.