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Conformational Study by ESR. of Some Alkyl Substituted 6a‐Thiathiophthene Radical Anions
Author(s) -
Gerson Fabian,
Heinzer Josef,
Stavaux Madeleine
Publication year - 1973
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19730560604
Subject(s) - chemistry , isopropyl , alkyl , coupling constant , crystallography , conformational isomerism , medicinal chemistry , stereochemistry , computational chemistry , molecule , organic chemistry , physics , particle physics
ESR. data are reported for the radical anions (II ⊖ to VI ⊖ ) of five alkyl substituted 6a‐thiathiophthenes . Rates and activation parameters for the inversion of the 3,4‐trimethylene chain in IV ⊖ , V ⊖ and VI ⊖ have been obtained by means of an iterative least squares computer program ESRCEX. Preferential conformations of the alkyl substituents are discussed in terms of the 〈cos 2 θ〉 dependence of the β‐proton coupling constants and with the aid of molecular models. Experimental evidence strongly suggests that the partial rotation of the ethyl and isopropyl groups in V ⊖ and VI ⊖ is correlated with the inversion of the 3,4‐trimethylene chain.