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N—H bond stretching in histidine complexes: a solid‐state NMR study
Author(s) -
Song Xiangjin,
Rienstra Chad M.,
McDermott Ann E.
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.956
Subject(s) - chemistry , heteronuclear molecule , hydrogen bond , bond length , solid state nuclear magnetic resonance , crystallography , covalent bond , magnetic dipole–dipole interaction , stereochemistry , computational chemistry , dipole , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , molecule , crystal structure , organic chemistry , physics
Abstract N—H bond lengths in imidazolium–carboxylate pairs were studied as models for enzyme active site motifs. The bond lengths were measured using ‘2D 2ϕ‐DipShift,’ a solid‐state NMR method wherein the N,H dipolar coupling is determined using heteronuclear dipolar spinning sideband patterns. Like the situation for compressed O—H···O systems, some complexes exhibit very short N···O distances and weaker N,H dipolar coupling. The weaker time‐average N,H dipolar coupling for systems with short N···O hydrogen bonds can be most likely associated with an altered potential well for the proton, or a ‘stretched’ covalent bond, although other interpretations involving a double well potential are discussed. The range or variation in average bond lengths seen in this study is much narrower than that previously reported for O—H···O systems (1.01–1.07 Å for N—H vs 1.0–1.3 Å for O—H bonds). Copyright © 2001 John Wiley & Sons, Ltd.