Abstract: | The strikingly different reactivity of a series of homo‐ and heterodinuclear (MIII)(μ‐O)2(MIII)′]2+ (M=Ni; M′=Fe, Co, Ni and M=M′=Co) complexes with β‐diketiminate ligands in electrophilic and nucleophilic oxidation reactions is reported, and can be correlated to the spectroscopic features of the (MIII)(μ‐O)2(MIII)′]2+ core. In particular, the unprecedented nucleophilic reactivity of the symmetric NiIII(μ‐O)2NiIII]2+ complex and the decay of the asymmetric NiIII(μ‐O)2CoIII]2+ core through aromatic hydroxylation reactions represent a new domain for high‐valent bis(μ‐oxido)dimetal reactivity. |