title: Highly electron-deficient and air-stable conjugated thienylboranes.
abstract: Introduced herein is a series of conjugated thienylboranes, which are inert to air and moisture, and even resist acids and strong bases. X-ray analyses reveal a coplanar arrangement of the thiophene rings, an arrangement which facilitates p-π conjugation through the boron atoms despite the presence of highly bulky 2,4,6-tri-tert-butylphenyl (Mes*) or 2,4,6-tris(trifluoromethyl)phenyl ((F)Mes) groups. Short B⋅⋅⋅F contacts, which lead to a pseudotrigonal bipyramidal geometry in the (F)Mes species, have been further studied by DFT and AIM analysis. In contrast to the Mes* groups, the highly electron-withdrawing (F) Mes groups do not diminish the Lewis acidity of boron toward F(-) anions. These compounds can be lithiated or iodinated under electrophilic conditions without decomposition, thus offering a promising route to larger conjugated structures with electron-acceptor character.
authors.affiliation: Department of Chemistry, Rutgers University - Newark, 73 Warren Street, Newark, NJ 07102 (USA) http://chemistry.rutgers.edu/fjaekle.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yin
authors.forename: Jiawei
authors.initials: J
authors.lastname: Chen
authors.forename: Roger A
authors.initials: RA
authors.lastname: Lalancette
authors.forename: Todd B
authors.initials: TB
authors.lastname: Marder
authors.forename: Frieder
authors.initials: F
authors.lastname: Jäkle
keywords: Lewis acids; boron; conjugation; fluoride; heterocycles