Herstellung,Kristallstruktur und magnetische Eigenschaften von Bis (1,2-benzochinondiimid)-1,2-benzosemichinondiimidokobalt (II)-tetraphenylborat-pentahydrat

Synthesis, Crystal Structure, and Magnetic Properties of Bis(1,2-benzoquinonediimide)-1,2-benzosemiquinonediimidocobalt (II)-tetraphenylborate-pentahydrate Co (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 [Co^II (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. D_obs. = 1.290, D_calc. = 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.