Premium
Dynamic stereochemistry at sp 2 sp 3 bonds part II —the importance of ground‐state strain in the determination of apparent spatial requirements of substituents
Author(s) -
Roussel Christian,
Blaive Bruno,
Gallo Roger,
Metzger Jacques,
Sandström Jan
Publication year - 1980
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.1270140304
Subject(s) - ground state , strain (injury) , chemistry , rotation (mathematics) , computational chemistry , stereochemistry , crystallography , physics , atomic physics , mathematics , medicine , geometry
The barriers to rotation of RCH 2 groups (R Me, Et and Isopr) as 3‐substituents in 4‐Me‐δ 4 ‐thiazoline‐2‐thiones, their 4‐ t ‐Bu analogues, and the methiodides of the latter compounds have been studied by 1 H DNMR and by molecular mechanics calculations. The barriers in the 4‐ t ‐Bu compounds are rather insensitive to the size of R, which is shown to be caused by strain in the ground state. More generally, it is shown that when δ G ‡ values are used in various methods for estimating the apparent spatial requirements of substituents, such ground‐state strain may lead to erroneous results in non‐circumspect treatments.