The Origin of One‐Bond C–H Coupling Constants in OCH Fragments: Not Primarily n_O→${{\rm \sigma} {{\ast \hfill \atop {\rm CH}\hfill}}}$ Delocalization

Abstract

Conforming couples: Coupling constants 1JCH and CH bond lengths were calculated for various conformations of tetrahydropyran, ethyl methyl ether, and dimethyl ether. The dependence of 1JCH on the H-C-O-C dihedral angle does not parallel the nO→ delocalization (see picture). Dipolar interactions that affect electron densities are proposed to be responsible. Supporting information for this article (separation of 1JCH values into Fermi contact, paramagnetic spin-orbit, and diamagnetic spin-orbit contributions; variation of dCH with HCOC dihedral angle; coordinates of tetrahydropyran conformers) is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z461583_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.