Oxygen activation at a dicobalt centre of a dipyridylethane naphthyridine complexElectronic supplementary information (ESI) available: Single crystal X-ray diffraction data; NMR data. CCDC 1838762 and 1838763. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8dt01598h

• Main Authors: Brodsky, Casey N, Passard, Guillaume, Ullman, Andrew M, Jaramillo, David E, Bloch, Eric D, Huynh, Michael, Gygi, David, Costentin, Cyrille, Nocera, Daniel G
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt01598h

The mechanism of oxygen activation at a dicobalt bis-μ-hydroxo core is probed by the implementation of synthetic methods to isolate reaction intermediates. Reduction of a dicobalt( iii , iii ) core ligated by the polypyridyl ligand dipyridylethane naphthyridine (DPEN) by two electrons and subsequent protonation result in the release of one water moiety to furnish a dicobalt( ii , ii ) center with an open binding site. This reduced core may be independently isolated by chemical reduction. Variable-temperature 1 H NMR and SQUID magnetometry reveal the reduced dicobalt( ii , ii ) intermediate to consist of two low spin Co( ii ) centers coupled antiferromagnetically. Binding of O 2 to the open coordination site of the dicobalt( ii , ii ) core results in the production of an oxygen adduct, which is proposed to be a dicobalt( iii , iii ) peroxo. Electrochemical studies show that the addition of two electrons results in cleavage of the O-O bond. The mechanism of oxygen activation at a dicobalt bis-μ-hydroxo core is probed by the implementation of synthetic methods to isolate reaction intermediates.