Trapping X‐ray Radiation Damage from Homolytic Se−C Bond Cleavage in BnSeSeBn Crystals (Bn=benzyl, CH₂C₆H₅)

Abstract

Irradiation of dibenzyl diselenide BnSeSeBn with X-ray or UV-light cleaves the SeÀ C and the SeÀ Se bonds, inducing stable and metastable radical states. They are inevitably important to all natural and life sciences. Structural changes due to X-ray-induced SeÀ C bond-cleavage could be pin-pointed in various highresolution X-ray diffraction experiments for the first time. Extended DFT methods were applied to characterize the solid-state structure and support the refinement of the observed residuals as contributions from the BnSeSe * radical species. The X-ray or UV-irradiated crystalline samples of BnSeSeBn were characterized by solid-state EPR. This paper provides insight that in the course of X-ray structure analysis of selenium compounds not only organo-selenide radicals like RSe * may occur, but also organo diselenide BnSeSe * radicals and organic radicals R * are generated, particularly important to know in structural biology.

Taming the Dichalcogenides: Isolation, Characterization, and Reactivity of Elusive Perselenide, Persulfide, Thioselenide, and Selenosulfide Anions

“…Further reactivity of this motif was not investigated. To the best of our knowledge, RSeS – and RSeSe – motifs have not yet been structurally characterized, although the related perselenanyl radical (RSeSe • ) was recently reported by Stalke and co-workers by photolysis of Bn 2 Se 2 in the solid state …”

“…To the best of our knowledge, RSeS − and RSeSe − motifs have not yet been structurally characterized, although the related perselenanyl radical (RSeSe • ) was recently reported by Stalke and co-workers by photolysis of Bn 2 Se 2 in the solid state. 37 Given the biological relevance of these understudied dichalcogenide motifs, we viewed that the direct characterization of RSSe − , RSeS − , RSS − , and RSeSe − compounds would provide a useful platform for not only structural characterization but also for probing initial reactivity. Moreover, understanding the chemical reactivity of these compounds could also provide new synthetic strategies to access established H 2 S releasing scaffolds such as functionalized selenylsulfides (RSSeR′), thioselenic acids (RSeSH), and hydropersulfides (RSSH).…”