**2.2 Functional models for biological Water Oxidizing Complex**

There are a few manganese complexes that produce oxygen in the presence of different oxidants (Cady et al., 2008; Yagi & Kaneko, 2001; Ruttinger & Dismukes 1997). It is important to know that even if the oxidants may do donate O-atoms that end up in the product oxygen, can nevertheless play an important role in identifying potentially useful catalytic components for water photolysis and electrolysis.
