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13 C n.m.r. of organosulphur compounds: II— 13 C chemical shifts and conformational analysis of methyl substituted thiacyclohexanes
Author(s) -
Barbarella Giovanna,
Dembech Pasquale,
Garbesi Anna,
Fava Antonino
Publication year - 1976
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270080908
Subject(s) - substituent , heteroatom , chemistry , ring (chemistry) , carbon atom , chemical shift , carbon 13 , methyl group , stereochemistry , group (periodic table) , organic chemistry , physics , quantum mechanics
13 C n.m.r. spectra of methyl substituted thianes and thianium cations have been determined. The magnitude of the 13 C substituent effects of an equatorial methyl group or of a gem ‐dimethyl grouping appear to depend in a systematic way on whether the carbon atom concerned is adjacent to, or removed from, the heteroatom. The shieldings are discussed in relation to the conformational properties of the thiane ring. Moreover, the average 13 C substituent parameters obtained from conformationally biased systems are applied to potentially mobile systems to assess the position of the conformational equilibrium.