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The Origin of the Difference Between the13C and17O Shift Behaviour of Carbonyl Compounds RCOX:Ab initio Calculation of the Shielding Tensors

Autor: Hans Dahn, Pierre-Alain Carrupt

Publikováno v: Magnetic Resonance in Chemistry. 35:577-588

In carbonyl compounds RCOX (X = H, Me, SiR3,SR, Cl, F, OMe, OH, NH2, O-; R = H, Me), the O-17 shift values of the carbonyl group depend on the electron donor-acceptor properties of X, whereas the C-13 shift values are determined by other factors too.

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::7e3324e4f8bb5c74e616ab76af61c19f
https://doi.org/10.1002/(sici)1097-458x(199709)35:9<577::aid-omr129>3.0.co

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NMR of Terminal Oxygen—17—Ab initio IGLO Study of the High Shielding of O (and C, N) in Linear Heteronuclear π-Systems

Autor: Peter Péchy, Pierre-Alain Carrupt, Hans Dahn

Publikováno v: Magnetic Resonance in Chemistry, Vol. 34, No 4 (1996) pp. 283-288

Linear heteronuclear pi-systems of sp character, when compared with corresponding sp(2) systems, show increased shift to higher field for all atoms concerned (O, C, N); acetylene compared with ethylene is a model case. In O-17 NMR, the molecules NO+,

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::28ac53cb0e9e5cfc30b35af61f68fd88
https://doi.org/10.1002/(sici)1097-458x(199604)34:4<283::aid-omr876>3.0.co

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NMR of terminal oxygen. 16—17O NMR of amide-analogousN-acyl derivatives of non-basic nitrogen groups: The question of amide resonances

Autor: Vien Van Toan, Peter Péchy, Hans Dahn

Publikováno v: Magnetic Resonance in Chemistry. 33:686-689

Natural abundance 17O NMR data for six classes of N-acyl compounds RCONX are reported: acylazide, acylisocyanate, acylisothiocyanate, diacyldiimide, 1-acylimidazole and N,N′-carbonyldiimidazole. Compared with the normal amide group, they all show s

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::a30ed4ab6172a07caa0b90d9d26273af
https://doi.org/10.1002/mrc.1260330812

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NMR of terminal oxygen. 1517O NMR spectra of the N+O− group:tert-Amine oxides R3N+O−, nitrones HC  N+(O−), azoxy derivatives N  N+(O−), nitrile oxides  C  N+O− and related compounds. Shielding anisotropy in linear heteroatomar π-systems

Autor: Hans Dahn, Peter Péchy, Pierre-Alain Carrupt, Vien Van Toan

Publikováno v: Magnetic Resonance in Chemistry. 33:273-279

The O-17 NMR signals of trimethylamine oxide and of six (para-substituted) N-aryldimethylamine oxides appear at 240-260 ppm, ca. 200 ppm more deshielded than hydroxylamines. The influence of the arene group and its substituents is small, confirming t

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::ef2d6ca2d207cafcdc61ef2037bcfe12
https://doi.org/10.1002/mrc.1260330408

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NMR of Terminal Oxygen. Part 14. Kinetically stabilized simple enols containing methylated uracil groups: Application of a17O-NMR test of H-bonding

Autor: Jin Cong Zhuo, Hans Dahn, Hugo Wyler, Peter Péchy

Publikováno v: Helvetica Chimica Acta. 77:317-322

In the crystalline N,N′-dimethylated uracil derivatives 2a, b, the kinetically stabilized enol group forms an H-bond with OC(4), as demonstrated by increased shielding of specifically labelled 2a and 2b in the 17O-NMR spectra (Δδ(17O)(C(4)—O) �

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::6707d1048155ede20612d2912e610241
https://doi.org/10.1002/hlca.19940770131

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NMR of Terminal Oxygen. Part 13.17O-NMR spectra ofC-nitroso compounds, thionitrites and NO+Ion: Resonance effects in ON-X compounds and correlation with CD spectra

Autor: Hans Dahn, Rainer Flögel, Peter Péchy

Publikováno v: Helvetica Chimica Acta. 77:306-316

The 17O-NMR signals of four true C-nitroso compounds 1–4 appear at particularly low field (1550–1265 ppm), whereas the dimers (azodioxy type) resonate at ca. 400 ppm and the ‘isonitroso compounds’ ( quinone-oximes; 5 and 6) at ca. 250 ppm. S-

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::c79117a71c0a51024e02c1d4533c5c54
https://doi.org/10.1002/hlca.19940770130

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NMR of terminal oxygen. Part 12. SO2and isoelectronic compounds with a true π-bond:17O NMR spectra of sulfinylamines R–NSO and sulfines RR′CSO. The conformation of ortho-substituted diaryl sulfines

Autor: Germana Mazzanti, Peter Pechy, Hans Dahn, Giovanni Cerioni, Bianca F. Bonini, Binne Zwanenburg, Vien Van Toan, Lodovico Lunazzi

Publikováno v: J. Chem. Soc., Perkin Trans. 2. :1881-1885

The 17O NMR shift values δo of 20 sulfinylamines R–NSO 2 and of 14 sulfines RR′CSO 3(R and R′ mostly arene groups) were compared with those of the isoelectronic SO21. They show δo at much lower field than practically all other classes of S–

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::2f81b652af29985438c3a02204f58f56
https://doi.org/10.1039/p29930001881

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NMR of terminal oxygen. Part 10.17O NMR spectra of carbonyl phosphonium ylides and diazocarbonyl compounds: resonance stabilization, bond order and excitation energy

Autor: Hans Dahn, Peter Pechy

Publikováno v: J. Chem. Soc., Perkin Trans. 2. :67-70

On the scale of carbonyl electrophilicities, measured by 17O NMR spectroscopy, carbonyl groups in aroyl (1), acetyl (2) and ethoxycarbonyl (3) phosphonium ylides are similar to those of amide groups, showing a considerable effect of resonance donatio

Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::11bb2551ad0239b0785fe100b1007d7d
https://doi.org/10.1039/p29930000067

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