In summary, we provide the first crystallographic and computational evidence for Bi(I) as the heaviest halogen bond acceptor. The crystal structure of this highly reactive adduct 3 displays Bi … I distances significantly below the sum of van der Waals radii as well as elongated C-I bonds of the fluorinated aryl iodide moieties. Upon warming, it decomposes to the Bi(III) species RBiI2 4. Consequently, this crystal structure can be regarded as a snapshot of an intermediate formed during an oxidative addition reaction of an aryl iodide with a low valent main group element.