scholarly journals Azapentalenes. XLIV.1H and13C-NMR study of mesoionic pyrazolo[1,2-a]pyrazoles

1997 ◽  
Vol 13 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Rosa María Claramunt ◽  
Sviatoslav Trofimenko ◽  
Isabel Rozas ◽  
José Elguero
Keyword(s):  
Chemical Shifts ◽  
Additive Models ◽  
Coupling Constants ◽  
Pyrazole Derivatives ◽  
1H And13c Nmr ◽  
Nmr Study ◽  
Semi Empirical

The1H and13C chemical shifts as well as the1H–1H and1H–13C coupling constants of sixteen pyrazolo[1,2-a]pyrazole derivatives have been measured. The most relevant features are discussed using resonance forms and simple additive models. AM1 semi-empirical calculations have been carried out to provide a rationale for the NMR results.

scholarly journals 1H and13C NMR study of perdeuterated pyrazoles

1997 ◽  
Vol 13 (4) ◽  
pp. 291-294 ◽  
Author(s):  
María Luisa Jimeno ◽  
Nadine Jagerovic ◽  
José Elguero ◽  
Thomas Junk ◽  
W. James Catallo
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
1H And13c Nmr ◽  
Nmr Study

The1H and13C chemical shifts as well as the1H–2H and2H–13C coupling constants of perdeuterated 3,5-dimethylpyrazole and 3,5-diphenylpyrazole have been measured and the values compared with those of the unlabelled compounds.

15N NMR study of amino-imino tautomerism in derivatives of 1,4-bis(substituted amino)-9,10-anthraquinones and 1,4-bis(substituted amino)-2,3-dihydro-9,10-anthraquinones

1987 ◽  
Vol 52 (3) ◽  
pp. 736-741 ◽  
Author(s):  
Antonín Lyčka ◽  
Libuše Havlíčková ◽  
Alois Koloničný ◽  
Josef Jirman
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Study ◽  
Derivatives Of ◽  
Tautomeric Mixture

The 15N chemical shifts and 1J(15N, H) coupling constants of 1,4-bis(substituted amino)-9,10-anthraquinones and 1,4-bis(substituted amino)-2,3-dihydro-9,10-anthraquinones indicate that these derivatives exist as true aminoderivatives except for 1,4-bis(phenylamino)-2,3-dihydro-9,10-anthraquinone which forms a tautomeric mixture of the amino and imino forms in deuteriochloroform and hexadeuteriodimethyl sulphoxide.

14N- und 15N-NMR-Spektroskopie von Diazaphospholen und die lineare Korrelation der chemischen Verschiebung von zweifach koordiniertem N und P / 14N and 15N NMR Spectroscopy of Diazaphospholes and the Linear Correlation of the Chemical Shift of Two-Coordinate N and P

1986 ◽  
Vol 41 (5) ◽  
pp. 553-559 ◽  
Author(s):  
Alfred Schmidpeter ◽  
Bernd Wrackmeyer
Keyword(s):  
Linear Correlation ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Ground State Structure ◽  
Nitrogen And Phosphorus ◽  
System A ◽  
Nmr Study ◽  
15N Nmr Spectroscopy ◽  
Scalar Relaxation

A systematic natural abundance 15N NMR study of diazaphospholes is presented for the first time, giving accurate values for chemical shifts, δN , and coupling constants J(31P15N), J(15N1H ). 14N NMR spectra can be used to predict the magnitude of 1J( 31P14N) if the broadening of the 31P resonance by scalar relaxation is known. The relaxation behaviour of the 14N nuclei corresponds to that found in azoles indicating a comparable electronic ground state structure. The comparison of the chemical shifts, δN, in the diazaphospholes with δN of corresponding triazoles reveals differences which can be traced to the N-P σ-bonds and to the influence o f the phosphorus atom on the π-system. A linear correlation δN/δP exists coordinate nitrogen and phosphorus, respectively.

Proton, carbon-13, and fluorine-19 NMR study of N-arylpyridinium salts: Attempted calculations of the σ1 and σR0 values for N-pyridinium substituents

1981 ◽  
Vol 46 (3) ◽  
pp. 584-596 ◽  
Author(s):  
Rosa Maria Claramunt ◽  
José Elguero
Keyword(s):  
Electronic Properties ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Nmr Study

The synthesis and NMR study of fourteen N-arylpyridinium salts have been done. Chemical shifts and coupling constants (1H-1H, 1H-13C, 1H-19F, and 13C-19F) have been measured in hexadeuteriodimethyl sulphoxide. Conformation about the phenylpyridinium bond is discussed. The electronic properties of the three pyridinium substituents ( pyridinium, 2,4,6-trimethylpyridinium, and 2,4,6-triphenylpyridinium) have been determined (Hammet and Taft's σ values) and compared with those of the trimethylammonium substituent.

Synthesis, NMR and ultraviolet spectroscopy of [10] (N6,9)-6-aminopurinophane; calculation of the chemical shifts in the [n](N6,9)-6-aminopurinophane series

1995 ◽  
Vol 73 (12) ◽  
pp. 2224-2232 ◽  
Author(s):  
Alfredo Capretta ◽  
Russell A. Bell
Keyword(s):  
Chemical Shifts ◽  
Variable Temperature ◽  
Bathochromic Shift ◽  
Ultraviolet Spectroscopy ◽  
Methylene Bridge ◽  
Nmr Study ◽  
Complete Assignment ◽  
Subsequent Cyclization ◽  
Semi Empirical ◽  
Hypochromic Effect

[10](N6,9)-6-Aminopurinophane was prepared via a Mitsunobu reaction involving 6-chloropurine and 10-azido-1-decanol. Reduction of the azido moiety to an amine allowed for subsequent cyclization to the cyclophane. N6-Nonyladenine, 9-nonyladenine, and N6,9-dinonyladenine were also prepared using the established chemistry. Heating the [10](N6,9)-6-aminopurinophane to 90 °C allowed for a complete assignment of the proton and carbon spectra, while cooling the sample to −77 °C revealed additional isomers likely due to the anti–syn isomerization about the N6—C6 bond. A variable temperature proton NMR study revealed a ΔGc≠ of 59.4 ± 5.5 kJ mol−1 associated with the interchange between the two major conformers. The ultraviolet spectra of the [n](N6,9)-6-aminopurinophane series show a bathochromic shift and a hypochromic effect in the transitions as the methylene chain length decreases (i.e., n = 10 to 9 to 8). The aminopurinophanes are used to assess the relative merits of a semi-empirical model that allows for the calculation of the chemical shifts of the methylene bridge protons. Keywords: synthesis of heterocyclophanes, variable temperature NMR, cyclophane conformational analysis, ultraviolet spectroscopy, calculation of chemical shift.

scholarly journals The FT-IR, FT-Raman,1H and13C NMR study on molecular structure of sodium(I), calcium(II), lanthanum(III) and thorium(IV) cinnamates

2010 ◽  
Vol 24 (3-4) ◽  
pp. 277-281 ◽  
Author(s):  
M. Kalinowska ◽  
W. Lewandowski ◽  
R. Swislocka ◽  
E. Regulska
Keyword(s):  
Molecular Structure ◽  
Nuclear Magnetic Resonance ◽  
Electronic Structure ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
1H And13c Nmr ◽  
Nmr Study ◽  
Ft Ir ◽  
C Nmr ◽  
Ft Raman

In this work the effect of sodium(I), calcium(II), lanthanum(III) and thorium(IV) ions on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (1H,13C NMR) were used. In the series of Na(I)→ Ca(II)→ La(III)→ Th(IV) cinnamates: (1) systematic shifts of several bands in the FT-IR and FT-Raman spectra, and (2) regular chemical shifts of protons1H and13C nuclei were observed.

13C and 15N NMR study of azo-hydrazone tautomerism in azo dyes containing amino or acetamido groups

1983 ◽  
Vol 48 (11) ◽  
pp. 3104-3111 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Azo Dyes ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Study ◽  
Hydrazone Form

13C and 15N NMR spectra of ten model azo dyes containing NH2 or NHCOCH3 group in ortho- or para-position to the phenylazo group on benzene, naphthalene and anthracene skeleton were measured. A negligible content of the hydrazone form in these compounds follows from the 13C and 15N chemical shifts and from a slight temperature dependence of the 15N chemical shifts and 1J(15N15N) coupling constants. The 15N isotope effect Δδ (15N) = 0.1 ppm was observed and the values of 1J(15N15N) = 15.6 ± 0.3 Hz were found with compounds double labelled by 15N.

13C NMR study of tetrosides and their derivatives

1980 ◽  
Vol 45 (10) ◽  
pp. 2779-2783 ◽  
Author(s):  
Jiří Urban ◽  
Miroslav Marek ◽  
Jiří Jarý ◽  
Petr Sedmera
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Direct Coupling ◽  
Coupling Constants ◽  
Anomeric Configuration ◽  
Nmr Study ◽  
C Nmr

13C NMR spectra of 23 tetrose derivatives were assigned. The C(1) resonates below 103 ppm with compounds having cis-arranged substituents at C(1) and C(2) and above 106 ppm with compounds having trans-arrangement. The carbon-13 chemical shifts are mainly influenced by the 1,2-interaction. The magnitudes of direct coupling constants 1J(C(1), H) cannot be used for the determination of the anomeric configuration.

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