Sterically induced reduction

In chemistry, a sterically induced reduction happens when an oxidized metal behaves as, and exhibits similar reducing properties to, the more reduced form of the metal. This effect is mainly caused by the surrounding ligands that are complexed to the metal and it is the ligands that are involved in the reduction chemistry instead of the metal due to electronic destabilization by being significantly distanced from the metal.

Source: Wikipedia — Sterically induced reduction (CC BY-SA 4.0)