Combining Distibene, Diazoolefins, and Visible Light: Synthesis and Reactivity of Inorganic Rings

The chemistry of heterocycles containing "diaza" units has been extensively studied due to their applications ranging from pharmaceuticals to advanced materials. In contrast, heterocycles incorporating heavier elements, such as Sb and Bi, remain exceedingly rare and lack straightforward synthetic methodologies. Herein, we present a comprehensive experimental and theoretical investigation of the first diazadistiboylidenes (1a, 1b), synthesized via a [3 + 2]-cycloaddition between a distibene and diazoolefins. These stiboylidenes are key intermediates to promote selective nucleophilic substitution, leading to a rare example of diantimonyl anion. Furthermore, upon visible-light irradiation, we could isolate the first example of methylenedistibiranes, heavier analogs of methylenediaziridine (C2H4N2). These findings offer a novel platform for heavy dipnictogen chemistry, showcasing that diazoolefins, in combination with visible light, can facilitate the formation of unprecedented heavy heterocycles and serve as a platform to promote CO2 activation.