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15 N, 15 N spin–spin coupling constants across N—H—N and N—H + —N hydrogen bonds: can coupling constants provide reliable estimates of N—N distances in biomolecules?
Author(s) -
Del Bene Janet E.,
Perera S. Ajith,
Bartlett Rodney J.
Publication year - 2001
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.913
Subject(s) - chemistry , coupling constant , hydrogen bond , intermolecular force , coupling (piping) , spin (aerodynamics) , proton , computational chemistry , chemical physics , crystallography , molecular physics , molecule , thermodynamics , quantum mechanics , physics , organic chemistry , mechanical engineering , engineering
Predictive quantum chemical methods based upon coupled cluster theory of spin–spin coupling constants offer a direct tool to explore a variety of questions concerning the relationship between coupling constants and intermolecular distances, molecular orientation, changes in hybridization and related issues. Of particular interest are 2h J ( 15 N, 15 N) couplings across hydrogen bonds. In this work we present EOM–CCSD coupling constants [ 2h J ( 15 N, 15 N)] for a series of cationic complexes stabilized by either traditional or proton‐shared N—H + —N hydrogen bonds, and relate these to 15 N, 15 N coupling constants in neutral complexes with N—H—N hydrogen bonds. The computed 15 N, 15 N coupling constants in these complexes vary smoothly with N—N distance, regardless of the charge or the particular binding at the N atoms. We propose that the curves which show this dependence have sufficient generality that they should be useful for determining N—N distances from experimentally measured coupling constants. Copyright © 2001 John Wiley & Sons, Ltd.