Premium
Intramolecular van der waals interactions and chemical shifts: A model for β‐ and γ‐effects
Author(s) -
Li S.,
Chesnut D. B.
Publication year - 1985
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260230807
Subject(s) - chemistry , van der waals force , chemical shift , intramolecular force , steric effects , van der waals strain , van der waals surface , force field (fiction) , computational chemistry , shielding effect , van der waals radius , chemical physics , stereochemistry , organic chemistry , molecule , quantum mechanics , layer (electronics) , physics
A correlation has been discovered between the local steric van der Waals energy as calculated by the MM2 force field and the chemical shift of a resonant nucleus within classes of saturated aliphatic phosphines, amines, hydrocarbons and monofunctional alcohols. Root‐mean‐square errors found for 37 phosphorus, 35 nitrogen and 164 carbon nuclei are 10.9, 5.9 and 2.8 ppm, respectively. It is found that repulsive van der Waals interactions are associated with deshielding effects in the observed chemical shifts, and attractive interactions with smaller shielding effects. A simple physical picture emerges which describes both β‐ and γ‐effects under one common model. It is found that β‐effects are associated with repulsive interactions while, contrary to earlier approaches γ‐effects are due basically to attractive interactions.