title: Reversible photochemical and thermal isomerization of azaboratabisnorcaradiene to azaborabenzotropilidene.
abstract: Two new tricyclic 1,2-azaboratabisnorcaradiene molecules (1 b and 2 b) generated through the photoisomerization of N-methyl-2-phenylimidazolyl-chelated dimesitylboranes (1 a and 2 a) have been found to undergo unusual photoisomerization, producing the first examples of 1,2-azaborabenzotropilidenes (1 c and 2 c), accompanied by a distinct color change, upon irradiation at 350 nm. Compounds 1 c and 2 c contain a conjugated alkylideneborane unit and can be fully reverted back to 1 b and 2 b, and subsequently to 1 a and 2 a upon heating. The mechanistic pathway of the new isomerism has been established to involve "walk" rearrangements by DFT computational studies.
authors.affiliation: Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario (Canada).
authors.forename: Ying-Li
authors.initials: YL
authors.lastname: Rao
authors.forename: Christian
authors.initials: C
authors.lastname: Hörl
authors.forename: Holger
authors.initials: H
authors.lastname: Braunschweig
authors.forename: Suning
authors.initials: S
authors.lastname: Wang
keywords: boratanorcaradiene; boratropilidene; organoboron compounds; photochromism; thermochromism