Deuterium isotope effects on 15N, 13C and 1H chemical shifts of proton sponges

Grech, E.; Klimkiewicz, J.; Nowicka‐Scheibe, J.; Pietrzak, Mariusz; Schilf, Wojciech; Pozharski, A.F; Ozeryanskii, Valery A.; Bolvig, Simon; Abildgaard, Jens; Hansen, Poul Erik

doi:10.1016/s0022-2860(02)00216-8

Cited by 29 publications

(11 citation statements)

References 68 publications

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“…The decomposition process in chloroform, DMF, and acetonitrile solutions is much stronger than in DMSO, so the measurement of nitrogen signals of the NMe 2 groups can only be performed in DMSO solution. The results presented in Table 3 unambiguously confirm the proton transfer from the Schiff base site to the DMAN part, resulting in a nonsymmetrical [NHN] + structure: the nitrogen signals are shifted about 10 ppm upfield in relation to compounds 6 and 7 and two different 1 J N,H coupling values are observed 13d. In the solid state, the corresponding CPMAS spectra provide evidence for the undecomposed compound.…”

Section: Resultssupporting

confidence: 56%

Novel Polyfunctional Tautomeric Systems Containing Salicylideneamino and Proton Sponge Moieties

et al. 2006

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The first salicylidenearylamines containing a proton sponge residue with 5′‐bromo (6), 5′‐nitro (7), and 3′,5′‐dinitro (8) substituents have been synthesized. X‐ray diffraction and 1H, 13C, and 15N NMR and infrared spectra revealed that 6 and 7 contain very strong OHN bridges typical of o‐hydroxy Schiff bases. Additional π‐electron coupling with the dimethylaminonaphthyl ring is manifested both in geometrical and infrared parameters. In the case of 7, proton transfer to the imine nitrogen atom occurs in the solid state, accompanied by a remarkable shortening of the OHN bridge (2.553 Å). In dinitro derivative 8, the OH proton jumps to the dimethylamino groups, giving a new tautomeric form with the formation of a homoconjugated [NHN]+ cation. Protonation of 6 and 7, affecting the (dimethylamino)naphthyl moiety, disrupts the π‐coupling and makes these molecules, unlike common aromatic Schiff bases, highly sensitive to hydrolysis, while 8, being already self‐protonated, equilibrates in wet DMSO with the corresponding salicylaldehyde and arylamine in a ca. 1:1 ratio at room temperature.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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Section: Resultssupporting

confidence: 56%

Novel Polyfunctional Tautomeric Systems Containing Salicylideneamino and Proton Sponge Moieties

et al. 2006

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“…24 caused by deuteriation at the NH position are unusually small considering that we are dealing with a rather strong hydrogen bond. 26 However, we will see the same trend for acids (see below). This is in opposition to a twobond isotope effect for RAHB cases.…”

Section: Non-rahb Casessupporting

confidence: 59%

Isotope effect on chemical shifts in hydrogen‐bonded systems

Hansen¹

2007

Labelled Comp Radiopharmac

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“…The deuterium isotope effects on 13 C chemical shifts of the DMANH + part are like those reported previously showing that the counter ion has little effect.…”

Section: Discussionmentioning

confidence: 99%

Deuterium isotope effects on ¹³C chemical shifts of negatively charged NH…N systems

Pietrzak

Grech

Nowicka‐Scheibe

et al. 2013

Magnetic Reson in Chemistry

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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.

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Deuterium isotope effects on 15N, 13C and 1H chemical shifts of proton sponges

Cited by 29 publications

References 68 publications

Novel Polyfunctional Tautomeric Systems Containing Salicylideneamino and Proton Sponge Moieties

Novel Polyfunctional Tautomeric Systems Containing Salicylideneamino and Proton Sponge Moieties

Isotope effect on chemical shifts in hydrogen‐bonded systems

Deuterium isotope effects on ¹³C chemical shifts of negatively charged NH…N systems

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Deuterium isotope effects on 15N, 13C and 1H chemical shifts of proton sponges

Cited by 29 publications

References 68 publications

Novel Polyfunctional Tautomeric Systems Containing Salicylideneamino and Proton Sponge Moieties

Novel Polyfunctional Tautomeric Systems Containing Salicylideneamino and Proton Sponge Moieties

Isotope effect on chemical shifts in hydrogen‐bonded systems

Deuterium isotope effects on 13C chemical shifts of negatively charged NH…N systems

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Product

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Deuterium isotope effects on ¹³C chemical shifts of negatively charged NH…N systems