Main-Group Metallomimetics: Transition Metal-like Photolytic CO Substitution at Boron

The carbon monoxide adduct of an unhindered and highly reactive CAAC-bound arylborylene, [(CAAC)­B­(CO)­Ar] (CAAC = cyclic (alkyl) (amino)­carbene), has been prepared using a transfer reaction from the linear iron borylene complex [(PMe3) (CO)3Fe=BAr]. [(CAAC)­B­(CO)­Ar] is a source of the dicoordinate [(CAAC)­ArB:] borylene that can be liberated by selective photolytic CO extrusion and that, although highly reactive, is sufficiently long-lived to react intermolecularly. Through trapping of the borylene generated in this manner, we present, among others, the first metal-free borylene­(I) species containing a nitrogen-based donor, as well as a new boron-containing radical.