https://doi.org/10.1351/goldbook.O04351
An outer-sphere @E02011@ is a reaction in which the @E02011@ takes place with no or very weak (\(4-16\ \text{kJ mol}^{-1}\)) electronic interaction between the reactants in the @T06468@. If instead the donor and the acceptor exhibit a strong electronic @C01025@, the reaction is described as @I03052@. The two terms derive from studies concerning metal complexes and it has been suggested that for organic reactions the terms 'nonbonded' and 'bonded' @E02011@ should be used.
See also:
inner-sphere electron transfer