Structures of lithium salts of substituted 1-phenylpropynes: 13C NMR and MNDO study

13C NMR spectroscopy has been used to study the structure of ambident carbanions in contact (CIP) and solvent-separated (SSIP) ion pairs of lithium salts of substituted 1-phenylpropynes. It was shown that the structures of carbanions in SSIP are close to the propargylic type, whereas, with the decre...

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Published inJournal of organometallic chemistry Vol. 438; no. 3; pp. 265 - 288
Main Authors Dem'yanov, Piotr I., Styrkov, Igor M., Krut'ko, Dmitry P., Vener, Michail V., Petrosyan, Valery S.
Format Journal Article
LanguageEnglish
Published Lausanne Elsevier B.V 01.10.1992
Elsevier Science
Subjects
Atomic and molecular physics
Exact sciences and technology
Molecular properties and interactions with photons
Nuclear resonance and relaxation
Physics
Chemical solution
Temperature
Acetylenic compound
Aliphatic compound
Theoretical study
Bond order
Carbanion
Experimental study
Lithium Compounds
Chemical shift
MNDO method
NMR spectrum
Atomic charge
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Summary:13C NMR spectroscopy has been used to study the structure of ambident carbanions in contact (CIP) and solvent-separated (SSIP) ion pairs of lithium salts of substituted 1-phenylpropynes. It was shown that the structures of carbanions in SSIP are close to the propargylic type, whereas, with the decrease in delocalizing ability of substituents at the propargylic centre, their structure shifts to the allenylic type, in fair agreement with theoretical predictions by the MNDO semi-empirical method. In CIP, the structures of carbanions are progressively changed from near-to-propargylic to allenylic with decrease of delocalizing ability of the substituents.
ISSN:0022-328X
1872-8561
DOI:10.1016/0022-328X(92)83411-A