Oxidative addition, and its microscopic reverse, reductive elimination, are some of the most fundamental kcal mol -1 . Both the anti-aromatic character and strain of the four-membered ring contribute to the weakening of this C-C -bond. In contrast, a C-C bond within the six-membered ring system has been estimated as 114.4 kcal mol -1 . Addition of transition metals to biphenylene results exclusively in -C-C bond activation via oxidative addition at the central C4 ring (M = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Au). Very recently, selective cleavage of the C-C bonds in biphenylene during potassium reduction of rareearth metal complexes (Sc, Lu) was reported. In 2020, Kinjo and co-workers reported an aluminyl anion stabilised by a cyclic (alkyl)(amino) ligand, prepared by potassium graphite reduction of the corresponding aluminium dimer in the presence of 12crown-4-ether.