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Low‐temperature ionization of neutral hexacoordinate to ionic pentacoordinate silicon complexes. Unusual temperature, solvent and substituent effects
Author(s) -
Kost Daniel,
Kalikhman Inna,
Kingston Vijeyakumar,
Gostevskii Boris
Publication year - 2002
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.551
Subject(s) - chemistry , hexacoordinate , substituent , ionic bonding , solvent , silicon , ionization , ionic liquid , inorganic chemistry , solvent effects , computational chemistry , organic chemistry , ion , catalysis
Neutral hexacoordinate complexes of silicon ( 1 ) ionize to pentacoordinate siliconium chloride salts ( 2 ) in CH 2 Cl 2 , CHCl 3 or CHFCl 2 solutions. 29 Si NMR measurements prove that the extent of ionization increases as the temperature of the solution is lowered. The ionizations are slightly exothermic, and have negative entropies. It is shown that increased solvent polarity drives the reaction to the ionic side, i.e. that ion solvation is responsible for the ionization. The lack of a common‐ion effect on addition of tetrabutylammonium chloride indicates the formation of unseparated ion pairs. Copyright © 2002 John Wiley & Sons, Ltd.