Chemical Shift. V. Further Studies on the Long-range Shielding Effects of the C—H and C=O Bonds

Publisher Website
Google Scholar
Abstract
The long-range shielding effects of the C=O and C—H bonds were reexamined by the method described in part IV of this series, with the objective of resolving the discrepancies between some of the conclusions presented and earlier findings by Zürcher. The C—H bond magnetic anisotropy was treated as a variable and found to be small enough to be negligible. Upon omission of this term, both electrostatic and magnetic anisotropy effects had to be invoked to account for the shielding effects of the carbonyl group.The necessary geometric quantities were calculated from atomic coordinates for androsterone, as determined by X-ray crystallography, and freely rotating methyl groups were approximated by superpositions of 24 conformations of the group. The results were in essential agreement with those obtained with the use of geometric factors computed as described in part IV.

This publication has 0 references indexed in Scilit: