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- Associative_substitution abstract "Associative substitution describes a pathway by which compounds interchange ligands. The terminology is typically applied to coordination and organometallic complexes, but resembles the Sn2 mechanism in organic chemistry. The opposite pathway is dissociative substitution, being analogous to Sn1 pathway. Intermediate pathways exist between the pure associative and pure dissociative pathways, these are called interchange mechanisms.Associative pathways are characterized by binding of the attacking (nucleophile) to give a discrete, detectable intermediate followed by loss of another ligand. Complexes that undergo associative substitution are either coordinatively unsaturated or contain a ligand that can change its bonding to the metal, e.g. change in hapticity or bending of NO. In homogeneous catalysis, the associative pathway is desirable because the binding event, and hence the selectivity of the reaction, depends not only on the nature of the metal catalyst but also on the substrate.Examples of associative mechanisms are commonly found in the chemistry of 16e square planar metal complexes, e.g. Vaska's complex and tetrachloroplatinate. These compounds (MX4) bind the incoming (substituting) ligand Y to form pentacoordinate intermediates MX4Y that in a subsequent step dissociates one of their ligands. Dissociation of Y results in no reaction, but dissociation of X results in net substitution, giving the 16e complex MX3Y. The first step is typically rate determining. Thus, the entropy of activation is negative, which indicates an increase in order in the system. These reactions follow second order kinetics: the rate of the appearance of product depends on the concentration of MX4 and Y. The rate law is governed by the Eigen–Wilkins Mechanism.".
- Associative_substitution thumbnail AssveRxn.png?width=300.
- Associative_substitution wikiPageID "21789230".
- Associative_substitution wikiPageRevisionID "555369765".
- Associative_substitution hasPhotoCollection Associative_substitution.
- Associative_substitution subject Category:Chemical_reactions.
- Associative_substitution subject Category:Coordination_chemistry.
- Associative_substitution subject Category:Organometallic_chemistry.
- Associative_substitution subject Category:Reaction_mechanisms.
- Associative_substitution subject Category:Substitution_reactions.
- Associative_substitution type ChemicalProcess113446390.
- Associative_substitution type ChemicalReaction113447361.
- Associative_substitution type ChemicalReactions.
- Associative_substitution type Mechanism113512506.
- Associative_substitution type NaturalProcess113518963.
- Associative_substitution type PhysicalEntity100001930.
- Associative_substitution type Process100029677.
- Associative_substitution type ReactionMechanisms.
- Associative_substitution comment "Associative substitution describes a pathway by which compounds interchange ligands. The terminology is typically applied to coordination and organometallic complexes, but resembles the Sn2 mechanism in organic chemistry. The opposite pathway is dissociative substitution, being analogous to Sn1 pathway.".
- Associative_substitution label "Associative substitution".
- Associative_substitution label "Eigen-Wilkins-Mechanismus".
- Associative_substitution label "Sustitución asociativa".
- Associative_substitution sameAs Eigen-Wilkins-Mechanismus.
- Associative_substitution sameAs Sustitución_asociativa.
- Associative_substitution sameAs m.05mqxph.
- Associative_substitution sameAs Q1303017.
- Associative_substitution sameAs Q1303017.
- Associative_substitution sameAs Associative_substitution.
- Associative_substitution wasDerivedFrom Associative_substitution?oldid=555369765.
- Associative_substitution depiction AssveRxn.png.
- Associative_substitution isPrimaryTopicOf Associative_substitution.