Über Reaktionen oxygenierter Kobalt(II)‐Chelate. VI . Präparative Darstellung von diastereoisomeren Tetrakis(äthylendiamin)‐μ‐peroxo‐μ‐hydroxodikobalt(III)‐perchloraten

On Reactions of oxygenated Cobalt(II) Chelates. VI. Preparation of diastereoisomeric tetrakis(ethylenediamine)‐μ‐peroxo‐μl‐hydroxo‐dicobalt(III) Perchlorates Oxygenation of Co(en) 2 2+ leads to a mixture of two isomeric forms of [(en) 2 Co(O 2 , OH)‐Co(en) 2 ] (ClO 4 ) 3 · H 2 O from which the less soluble meso form can be readily crystallized. Further crystallization from the mother liquor yields the racemate ΔΔ/ΔΔ. The pure racemate may be obtained by either of the following methods: (a) By ligand exchange starting from mono bridged [(NH 3 ) 5 CoO 2 Co(NH 3 ) 5 ] (NO 3 ) 4 or from doubly bridged [(SCN) (NH 3 ) 3 Co(O 2 , OH)Co(NH 3 ) 3 (SCN)] SCN · 2H 2 O. (b) By reaction of cis ‐[Co(en) 2 (OH 2 ) 2 ] 3+ with H 2 O 2 . Reaction (b) proceeds via an intermediate cis ‐[Co(en) 2 (OOH) (OH 2 )] (ClO 4 ) 2 · H 2 O which at higher pH reacts with [Co(en) 2 (OH) (OH 2 )] 2+ to yield the desired doubly bridged ΔΔ/ΔΔ tetrakis(ethylenediamine)‐μ‐peroxo‐μ‐hydroxodikobalt(III)‐perchlorate.