title: A B-B bond-containing polycyclic pi-electron system: dithieno-1,2-dihydro-1,2-diborin and its dianion.
abstract: As a B-B bond-containing polycyclic pi-electron system, a dithieno[3,2-c:2',3'-e](1,2-dihydro-1,2-diborin) derivative and its dianion salts were successfully prepared, and their structures were determined by X-ray crystallography. The neutral dithieno-1,2-dihydro-1,2-diborin has a twisted diborin ring in which both the sigma-pi and p-pi* orbital interactions between the bithiophene pi framework and the B-B bond moiety effectively take place, giving rise to an absorption that is significantly red-shifted compared with that of the parent bithiophene. Upon a two-electron reduction, the dithienodiborin pi framework becomes planar and has a characteristic peripheral pi conjugation through the B-B bond with 14 pi electrons. Furthermore, the dianion salts show an intriguing countercation effect on their photophysical properties, indicative of possible electronic tuning by the countercations.
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan. wakamiya@chem.nagoya-u.ac.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Wakamiya
authors.forename: Kenji
authors.initials: K
authors.lastname: Mori
authors.forename: Takafumi
authors.initials: T
authors.lastname: Araki
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Yamaguchi