Hydrogen bond types, binding energies, and H-1 NMR chemical shifts

Citation
Je. Del Bene et al., Hydrogen bond types, binding energies, and H-1 NMR chemical shifts, J PHYS CH A, 103(40), 1999, pp. 8121-8124
Citations number
26
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY A
ISSN journal
10895639 → ACNP
Volume
103
Issue
40
Year of publication
1999
Pages
8121 - 8124
Database
ISI
SICI code
1089-5639(19991007)103:40<8121:HBTBEA>2.0.ZU;2-I
Abstract
Ab initio calculations at the MBPT(2)/(qzp,qz2p) level of theory were carri ed out using the gauge-invariant atomic orbital method to evaluate H-1 NMR chemical Shifts for the hydrogen-bonded proton in two series of complexes, the first containing Cl-H-N and Cl-H-Cl hydrogen bonds, and the second O-HT O, N-H-O, and N-H-N hydrogen bonds. In both series a correlation exists bet ween increasing hydrogen bond strength and increasing proton chemical shift relative to the corresponding neutral proton donor molecule. However, whil e this correlation does not hold between the two series, complexes with pro ton-shared hydrogen bonds have similar chemical shifts of about 20 ppm for the hydrogen-bonded proton in both series, independent of the binding energ y of the complex. H-1 NMR chemical shifts computed along the proton-transfe r coordinate for ClH:NH3 also approach 20 ppm for a proton-shared hydrogen bond.