Premium
Stereochemistry, Stereodynamics, and Redox and Complexation Behaviors of 2,2′‐Diaryl‐1,1′‐Biazulenes
Author(s) -
Tsuchiya Takahiro,
Katsuoka Yuka,
Yoza Kenji,
Sato Hiroyasu,
Mazaki Yasuhiro
Publication year - 2019
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201900262
Subject(s) - redox , chemistry , stereochemistry , computational chemistry , combinatorial chemistry , organic chemistry
2,2′‐Diaryl‐1,1′‐biazulenes were synthesized and electronic communication between the azulene subunits was suggested based on redox measurements. The linkage of azulene at the 1‐position also appeared to increase the HOMO levels. In addition, cyclic voltammetry measurements of 2‐arylazulenes showed a return peak associated with the oxidation, which was not observed for azulene. The stabilization of the single‐electron oxidant may be due to the SOMO‐HOMO energy inversion phenomenon. X‐ray crystallography of the azulene dimers revealed that this species possessed a syn ‐type structure in which both aryl groups in the 2‐positions formed π‐stacks. The twisted structure was indicated to be in the ( R )‐ or ( S )‐configuration for all molecules in the unit cell. Spontaneous resolution was also shown. Furthermore, from the solid circular dichroism (CD) spectral measurements, the relationship between the absolute configuration of the molecules and the CD spectra was determined. A racemization rotational barrier of ca. 27 kcal mol −1 was calculated. Moreover, the pyridylazulene dimer cyclized upon reaction with PdCl 2 to form a 3 : 3 complex, in which the biazulene units cyclized to give ratios between the ( R )‐ and ( S )‐forms of either 2 : 1 or 1 : 2.