For inner sphere electron transfer
The reductant to the oxidant share a ligand in their primary
coordination sphere, the electron being transfered across a bridging group.
Prerequisites for Inner Sphere Mechanism
- One reactant (usually the oxidant) possess at least one ligand capable of
binding simultaneously to two metal ions.
- The other reactant is substitutionally labile; i.e. one ligandmust be
replaced by the bridging ligand.
Examples
Ligand transfer is not a requirement for inner sphere mechanism.
Taube's Conlcusion
Inner sphere mechanism can be unequivocally assigned when both oxidant and
oxidised reducing agent are substitution inert and when ligand transder from
oxodant to reductant has accompanied electron transfer