Journal of the American Chemical Society, Vol.119, No.30, 7048-7054, 1997
Does Pi-Sigma-Pi Through-Bond Coupling Significantly Increase C-C Bond Lengths
Orbital effects ascribed to pi-sigma-pi through-bond coupling are the result primarily of destabilizing filled-filled interactions; little to no mixing occurs between the antisymmetric pi combination and sigma*. The magnitude of through-bond coupling does not correlate with bond lengthening. Previous conclusions that through-bond coupling induces long bonds relied in some cases on poor X-ray data and/or inappropriate molecular orbital theories to deduce geometries. Comparison of semiempirical and empirical force field data as a test for through-bond coupling is unwarranted. Standard force fields underestimate the steric bulk of the benzene face, but addition of so-called "through-bond coupling" terms does not provide a physically significant measure of through-bond coupling.
Keywords:CARBON-CARBON BOND;ORBITAL INTERACTIONS;BASIS-SETS;MOLECULES;POLAR/PI;1;8-DIARYLNAPHTHALENES;SPECTROSCOPY;CONSEQUENCES;PHOTODIMER;DOMINANCE