inner-sphere reaction

chemistry

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June 29, 2026

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In chemistry, an inner-sphere reaction is a type of oxidation-reduction (redox) process where electron transfer occurs through a bridging ligand that directly connects two metal ions. This happens within an intermediate complex formed by the two metal ions. This contrasts with outer-sphere reactions, where electron transfer occurs without breaking bonds within the coordination spheres of the reacting complexes.12

Inner-sphere mechanisms require the loss of a bound water molecule by one of the metals to form the bridged intermediate. This process is crucial in understanding the mechanisms of redox reactions involving metal ions, particularly transition metals which commonly exhibit multiple stable oxidation states. The rate of electron transfer can vary significantly depending on the specific bridging ligand and metal ions involved.12

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coordination compound
Oxidation-reduction
…transfer, commonly designated outer-sphere and inner-sphere mechanisms, have been recognized. Outer-sphere electron transfer occurs without dissociation or disruption of the coordination sphere of either complex—i.e., through both intact coordination spheres. The first reaction above is of this type. On the other hand, inner-sphere electron transfer—e.g., the second reaction above—proceeds by…
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…transfer, commonly designated outer-sphere and inner-sphere mechanisms, have been recognized. Outer-sphere electron transfer occurs without dissociation or disruption of the coordination sphere of either complex—i.e., through both intact coordination spheres. The first reaction above is of this type. On the other hand, inner-sphere electron transfer—e.g., the second reaction above—proceeds by…
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oxidation-reduction reaction
Mechanisms of redox reactions
…metal ions has been the inner sphere–outer sphere dichotomy. Outer-sphere reactions are those that take place without breaking any bonds between a metal and a group such as water or hydroxide ion bound to it. Both the simple electron- and hydrogen-atom-transfer mechanisms are outer-sphere processes. If, on the other hand,…
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…metal ions has been the inner sphere–outer sphere dichotomy. Outer-sphere reactions are those that take place without breaking any bonds between a metal and a group such as water or hydroxide ion bound to it. Both the simple electron- and hydrogen-atom-transfer mechanisms are outer-sphere processes. If, on the other hand,…
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