Abstract
AbstractThe coefficients which determine the electric field dependence at first and second order of the shielding of protons in CH bonds were calculated by a finite‐field SCF method for the molecules, CH4, C2H6, CH3F, CH3Cl, CH3CN, C2H4, H2CO, HCN and C2H2. Values are given for individual tensor components and for the rotationally averaged coefficients. Diamagnetic and paramagnetic parts of the coefficients are generally of the same order of magnitude. This differs from carbon, nitrogen, oxygen and fluorine shielding studied previously where the paramagnetic parts are often very much larger than their diamagnetic counterparts. The linear electric field coefficients Az (electric field along the CH bond from C to H) for the above molecules (except H2CO and HCN) are very similar in value, with a mean of 70.0 ppm a.u. This is very close to an empirical value of 72.2 ppm a.u. obtained by Zürcher in a classic study of steroids. It further appears that the value may be transferable among all C(sp3)H bonds. A representative value for the mean quadratic coefficient B is 68.0 ppm a.u. Empirical values of this vary widely.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
