Oxygenation reaction and aging mechanism of the triethylenetetramine cobalt complex

The triethylenetetramine-cobalt complex (trien-Co) was synthesized by solid state reaction. The oxygenation of trien-Co and the structure evolution of the oxygenated complexes were investigated by electrospray ionization tandem mass spectrometry, the UV-Vis spectrophotometry, Raman spectrum and Infrared spectroscopy. The experimental results indicated that the uptaking of dioxygen is a dynamic process, and the structures of the oxygenated complex were changed from dinuclear diperoxo-dibridged complex to dinuclear hydroxo-hydroxo dibridge complex in the evolution of oxygenation.¹⁸O₂ isotope labeling experiments proved the existence of Co-O-O-Co. Furthermore, the acid dissociation tests reveal that the development of hydroxo dibridge species was the reason for the poor reversibility of trien-Co complex. These results provide a new method and experimental basis for investigating the oxygenation and auto-oxidation mechanism of polyamine-Co complexes.