Cyclic (alkyl)(amino)carbenes (CAACs) are key compounds en route to a plethora of unprecedented low-valent and radical complexes of transition metals and main group elements. For p-block elements of the sixth period, however, low-valent and radical complexes of CAACs are extremely rare, and even simple adducts with CAACs are difficult to access. Here we report the full characterization of the first adduct between a CAAC and a bismuth trihalide, [BiCl