https://doi.org/10.1351/goldbook.I03052
Historically an @E02011@ between two metal centres sharing a ligand or atom in their respective @C01329@ shells. The definition has more recently been extended to any situation in which the interaction between the donor and acceptor centres in the @T06468@ is significant (\(> 20\ \text{kJ mol}^{-1}\)).
See also:
outer-sphere electron transfer