Matrix Isolation and Computational Study of the Photochemistry of 1,3,2,4-Benzodithiadiazine

Photolysis of 1,3,2,4-benzodithiadiazine (1) at ambient temperature yields stable 1,2,3-benzodithiazolyl radicals.
In order to reveal the mechanism of this unusual transformation, the photochemistry of 1 was studied in
argon matrices using IR and UV−vis spectroscopy. A series of intermediates, including four- and five-membered heterocyclic and o-quinoid acyclic species, were characterized spectroscopically with the help of
quantum chemical calculations. With selective irradiation, these intermediates can be mutually interconverted
as well as converted back to the starting compound 1.

室温下对1,3,2,4-苯并二噻二嗪(1)进行光解，可得到稳定的1,2,3-苯并二噻唑基自由基。为阐明该反常转化的反应机理，研究团队采用红外(IR)与紫外-可见(UV−vis)光谱法，在氩基质中对化合物1开展了光化学研究。借助量子化学计算，通过光谱表征手段对一系列中间体进行了结构鉴定，其中涵盖四元、五元杂环物种以及邻醌型非环物种。经选择性辐照，这些中间体既可发生相互转化，也可逆向转化为起始化合物1。