While Be(II) is one of the more common oxidation states, there is also further research on a Be(I) and Be(0) complex. Low-valent main group compounds have recently become desirable synthetic targets due to their interesting reactivity comparable to transition metal complexes. In one work, stabilized cyclic (alkyl)(amino)carbene ligands were used to isolate and characterize the first neutral compounds containing beryllium, with the Be(0) compound stabilized by a strongly σ-donating and π-accepting cyclic CAAC ligand.
Be(I) is another example of a rare phenomenon and few publications were reported, but one example of a Be(I) was a CAAC ligand already coordinated with Be. Gilliard and his group created a more stable beryllium radical cation. Because of well-established challenges concerning the reduction of Be(II) to Be(I), they pursued the radical via an oxidation strategy using TEMPO ((2,2,6,6-Tetramethylpiperidin-1-yl) oxyl). This reaction resulted in a Be(I) compound just by stabilizing the Be radical.