“…Simplicio and Wilkins showed that oxygen uptake by ammoniacal cobalt(II) solutions is due mainly to the reaction of the pentakis(ammine) aqua complex [Co(NH 3 ) 5 [27,28] While such species do add oxygen when the nitrogen donor atoms are incorporated into chelate ligands, oxygenation is clearly enhanced as a consequence of an increasing number of ammine or amino groups coordinated to cobalt. [11] A variety of chelating pentaamines, including an early example of a tetrapodal pentadentate ligand, [29,30] have been investigated in this context, and a number of µperoxo complexes thus obtained have been structurally characterised.…”