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Ligand‐site exchange in intramolecular complexes of silicon: substituent effects
Author(s) -
Kuznetsova Olga V.,
Egorochkin Alexey N.,
Negrebetsky Vadim V.,
Khamaletdinova Nadiya M.,
DomratchevaLvova Lada G.
Publication year - 2012
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1958
Subject(s) - chemistry , intramolecular force , steric effects , polarizability , substituent , ligand (biochemistry) , electronic effect , atom (system on chip) , acceptor , computational chemistry , stereochemistry , crystallography , molecule , organic chemistry , biochemistry , physics , receptor , computer science , embedded system , condensed matter physics
The intramolecular complexes containing coordination bonds Si←N or Si←O are distinguished for their stereochemical nonrigidity resulting in interconversion between isomers, that is, ligand‐site exchange. The influence of the substituents bound to the silicon atom on the free energies of activation for ligand exchange Δ G ≠ of specific interest is poorly understood. In this work, the literature data on substituent influence on the energies Δ G ≠ for 13 series of the complexes have been considered, using the correlation analysis. On the basis of the obedience of the energies Δ G ≠ to the linear free energy relationship, it has been established for the first time that the Δ G ≠ values depend not only on the inductive and resonance effects but also on the polarizability and steric effects of substituents. The reason for the occurrence of the polarizability effect is the appearance of excess charges on Si and N (or O) atoms as a result of intramolecular coordination consisting in the charge transfer from the donor center (N or O atom) to the acceptor one (Si atom). In some series the contribution of the polarizability or steric effect to the overall change in Δ G ≠ because of the influence of substituents is a maximum. An understanding of these effects may give a better insight into the mechanism of nucleophilic substitution , involving organoelement compounds. Copyright © 2012 John Wiley & Sons, Ltd.