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An ab initio study of solvent polarity and hydrogen bonding effects on the nitrogen NMR shieldings of N , N ‐dimethylacetamidine
Author(s) -
Manalo Marlon N.,
de Dios Angel C.
Publication year - 2002
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.1095
Subject(s) - supermolecule , chemistry , polarizable continuum model , hydrogen bond , electromagnetic shielding , solvent , computational chemistry , solvent effects , density functional theory , ab initio , yield (engineering) , nitrogen , polarity (international relations) , ab initio quantum chemistry methods , molecule , thermodynamics , organic chemistry , biochemistry , physics , cell , electrical engineering , engineering
Density functional theory combined with the polarizable continuum model (PCM) and continuous set of gauge transformations method is applied to investigate the effects of solvent polarity on the nitrogen NMR shieldings of N , N ‐dimethylacetamidine. Hydrogen bonding effects on shielding are likewise calculated using a supermolecule approach, where the imino group of the solute is hydrogen bonded with solvent. Theoretical results are compared with published experimental data. The PCM shielding calculations utilizing PCM‐optimized solute geometries yield results comparable to those obtained with the supermolecule approach. Geometry optimization of the solute appears to be more important in PCM shielding calculations than in the supermolecule approach. The large solvent shifts observed in water can only be reproduced when the N·H distance used in the calculation indicates full proton transfer from water to the imino nitrogen of the solute. Copyright © 2002 John Wiley & Sons, Ltd.