Photoinduced Disproportionation Enables Oxidative Addition of Aryl Iodides at a Gallium(I) Center

Oxidative addition at transition metals underpins modern cross-coupling reactions but remains largely unrealized at main-group centers for aryl halides. Here, we show that photoinduced disproportionation can serve as an enabling strategy for such transformations. Visible light promotes the oxidative addition of aryl iodides to a Ga(I) metallylene, providing, to our knowledge, the first example of aryl C-I activation at a group 13 center. Mechanistic studies suggest that this transformation is not consistent with direct excited-state reactivity with the Ga(I) complex. Instead, photoexcitation generates a triplet state of gallylene that undergoes intermolecular electron transfer with ground-state gallylene, triggering disproportionation to a reactive radical ion pair. This radical ion-pair manifold, which is enabled by ligand-centered redox ambivalence, provides a viable pathway to bond activation. These findings suggest that photoinduced disproportionation could represent a distinct activation mode for achieving transition-metal-like oxidative addition at main-group elements.