One-bond C-C coupling constants in ethers are not primarily determined by N-sigma delocalization.
One-bond carbon-carbon coupling constants, 1JCC, were measured for a series of cyclic and acyclic ethers. Surprisingly, the dependence on COCC dihedral angle, tau, parallels cos(tau), rather than the cos(2tau) characteristic of n-sigma* delocalization. These results complement recently calculated 1JCH values in three ethers. The variations in 1J are not primarily determined by delocalization but instead are attributed to a dipolar interaction that affects electron density, perhaps via the hybridization.
Perrin
Charles L
CL
Department of Chemistry, University of California, San Diego, La Jolla, California 92093-0358, USA. cperrin@ucsd.edu
Erdélyi
Máté
M
D004987:Ethers / Q000737:chemistry*; D005583:Fourier Analysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D015394:Molecular Structure
D004987:Ethers