Synthesis, Crystal Structure, and Magnetic Properties of Bis(1,2‐benzoquinonediimide)‐1,2‐benzosemiquinonediimidocobalt (II)‐tetraphenylborate‐pentahydrateCo (II)‐salts catalyze the autoxidation of 1,2‐diaminobenzene in slightly alkaline solution. Deeply coloured metal complexes are formed during the reaction suggesting intermediate radical or semiquinonediimide stages of the aromatic ligands. Starting from [CoII (1,2‐diaminobenzene)3] (ClO4)2 two different intermediate complexes can be isolated, the magnetic properties of which point to a high‐spin cobalt (II)‐complex and a low‐spin cobalt (II)‐complex with a radical ligand respectively. The X‐ray structure determination of the latter complex yielded a square pyramidal arrangement, the Co‐N4‐plane distance being only 0.5 Å. The dark blue coloured complex is diamagnetic. Two of the aromatic ligands have the oxidation state of a benzoquinonediimide while the third, coordinated by one amino group only, is pseudosemiquinonoid. Crystals of C42H48BCoN6O5 are monoclinic, a = 14.493 (5), b = 18.341 (7), c = 15.492 (5) Å, β = 99.198 (5), space group P21/n. Dobs. = 1.290, Dcalc. = 1.289 g/cm3 for Z = 4. The structure was solved by Patterson's method and refined by least‐squares techniques to R = 0.088 for 2866 of 5014 independent reflexions.