The mechanism of the reaction between $\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}$ and $\left[\mathrm{Fe}\left(\mathrm{bpy}_{3}\right)\right]^{3+}$ (bpy = 2,2'-bipyridine) is
(a)outer-sphere electron-transfer
(b)inner - sphere electron - transfer
(c)self-exchange reaction
(d)ligand-exchange followed by electron transfer
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
Both complexes are substitution-inert with no bridging ligand — outer-sphere electron transfer (a).