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Deuterium isotope effects on 13 C chemical shifts of negatively charged NH…N systems
Author(s) -
Pietrzak Mariusz,
Grech Eugeniusz,
NowickaScheibe J.,
Hansen Poul Erik
Publication year - 2013
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.4000
Subject(s) - chemistry , deuterium , chemical shift , kinetic isotope effect , deuterium nmr , hydrogen bond , naphthalene , hydrogen , proton , ion , computational chemistry , carbon 13 nmr , molecule , stereochemistry , organic chemistry , atomic physics , physics , quantum mechanics
Deuterium isotope effects on 13 C chemical shifts are investigated in anions of 1,8‐bis(4‐toluenesulphonamido)naphthalenes together with N , N ‐(naphthalene‐1,8‐diyl)bis(2,2,2‐trifluoracetamide) all with bis(1,8‐dimethylamino)napthaleneH + as counter ion. These compounds represent both “static” and equilibrium cases. NMR assignments of the former have been revised. The NH proton is deuteriated. The isotope effects on 13 C chemical shifts are rather unusual in these strongly hydrogen bonded systems between a NH and a negatively charged nitrogen atom. The formal four‐bond effects are found to be negative indicating transmission via the hydrogen bond. In addition, unusual long range effects are seen. Structures, 1 H and 13 C NMR chemical shifts and changes in nuclear shieldings upon deuteriation are calculated using density functional theory methods. Copyright © 2013 John Wiley & Sons, Ltd.