The first examples of carbodicarbene (CDC)-s-block complexes have been synthesized. The addition of base or reducing agent to a CDC-beryllium (chloride)(hexamethyldisilazide) adduct results in the unprecedented activation of a pendant C(sp3)-H bond and cyclization of the CDC to form a five-membered beryllium metallacycle. This also represents the first example of chemical activation of a CDC which transforms the ligand from monodentate neutral to chelating anionic.