Water oxidation catalysed by a mononuclear Co(II) polypyridine complex; possible reaction intermediates and the role of the chloride ligand.

A mononuclear cobalt(II) complex as a homogeneous molecular catalyst for photochemically, electrochemically and chemically induced oxygen evolution reactions is presented. Experimental evidence points towards the presence of a chloride ligand at the cobalt centre throughout the catalytic cycle, and the temporary detachment of a pyridine ligand to open a coordination site for substrate binding.