2. Oxidizing addition characteristics

The above addition reactions do not alter the oxidation state of the metal. There has simply been a gift of a doublet, even if a gift in return has been exerted to stabilize the whole.

Another way of providing electrons is by oxidation. If chlorine, a highly oxidizing element, is used, iridium's oxidation state III can be restored by attaching two chlorine atoms, and an octahedral environment is observed in which the three chlorine atoms adopt a meridional symmetry.

This oxidation and addition reaction is called an oxidative addition reaction....