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The E1/2 potential associated with reduction of the linearly-functionalized 6,6′-biazulenic scaffold is accurately correlated to the combined σp 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. [ABSTRACT FROM AUTHOR]

N -benzyl-cinchonidinium bromide, C 26 H 29 N 2 O + ·Br - , with the systematic name ( R )-[(2 S ,4 S ,5 R )-1-benzyl-5-ethenyl-1-azoniabi-cyclo-[2.2.2]octan-2-yl](quinolin-4-yl)-methanol bromide, is a quaternary ammonium salt of the cinchona alkaloid cinchonidine. This salt is widely used as a chiral phase-transfer catalyst and chiral resolution agent. Both classical and non-classical hydrogen-bonding inter-actions, as well as anion effects have been shown to play key mechanistic roles in the catalysis of cinchona alkaloids. In an effort to understand the effects of water on these inter-molecular inter-actions, the structures of anhydrous N -benzyl-cinchonidinium bromide, (I), and the sesquihydrate, C 26 H 29 N 2 O + ·Br - ·1.5H 2 O, (II), were determined., (© Janzen et al. 2022.)