title: Deuterium isotope effects on 13C chemical shifts of negatively charged NH…N systems.
abstract: 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.
authors.affiliation: Institute of Physical Chemistry, Polish Academy of Sciences, 01-224, Warsaw, Poland.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Pietrzak
authors.forename: Eugeniusz
authors.initials: E
authors.lastname: Grech
authors.forename: J
authors.initials: J
authors.lastname: Nowicka-Scheibe
authors.forename: Poul Erik
authors.initials: PE
authors.lastname: Hansen
keywords: DFT calculations; anion of N,N‐(naphthalene‐1,8‐diyl)bis(2,2,2‐trifluoracetamide); anions of 1,8‐bis(4‐toluenesulphonamido)naphthalenes; deuterium isotope effects on 13C chemical shifts; intramolecular hydrogen bonds