Year: 2016
Type: article
Abstract: The downfield shift of the NMR signal of the bridging proton in a H-bond (HB) is composed of two elements. The formation of the HB causes charge transfer and polarization that lead to a deshielding. A second factor is the mere presence of the proton-accepting group, whose electron density and response to an external magnetic field induce effects at the position of the bridging proton, exclusive of any H-bonding phenomenon. This second positional shielding must be subtracted from the full observed shift in order to assess the deshielding of the proton caused purely by HB formation. This concept is applied to a number of H-bonded systems, both intramolecular and intermolecular. When the positional shielding is removed, the remaining chemical shift is in much better coincidence with other measures of HB strength.
Source: Molecules
Author: Steve Scheiner
Institution: Utah State University
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,258
OpenAlex ID: W2544018950