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.

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.

1H, 13C and 15N NMR Spectra of Coupling Products of Benzenediazonium Salts with Aliphatic Nitro Compounds and Study of Their E/Z Isomerism

1996 ◽  
Vol 61 (4) ◽  
pp. 589-596 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Nitro Compounds ◽  
Coupling Constants ◽  
15N Nmr ◽  
Geometrical Isomers ◽  
Sodium Salts ◽  
Aliphatic Nitro Compounds ◽  
Tautomeric Forms

The 1H, 13C and 15N NMR spectra have been measured of coupling products of benzenediazonium salts with nitromethane, nitroethane, 1-nitropropane, 2-nitroethanol and of their sodium salts, and the chemical shifts have been unambiguously assigned. The coupling products have been found to exist only in their hydrazone tautomeric forms. Stereospecific behaviour of the coupling constants 2J(15N,1H) and 2J(15N,13C) in the 15N isotopomers and NOESY have been used to differentiate between the E and Z geometrical isomers. The above-mentioned compounds exist as Z isomers in deuteriochloroform and predominantly (>95%) as E isomers in dimethyl sulfoxide, while the sodium salts are present only as E isomers in dimethyl sulfoxide.

15N-NMR-Untersuchungen an Verbindungen mit direkten N-N-Bindungen / 15N NMR Studies on Compounds with Direct N-N Bonds

1977 ◽  
Vol 32 (3) ◽  
pp. 257-264 ◽  
Author(s):  
Harald Schultheiss ◽  
Ekkehard Fluck
Keyword(s):  
Chemical Shifts ◽  
Isotopic Effect ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Studies

15N chemical shifts, the isotopic effect on chemical shifts and 1J(15N-15N) coupling constants of Na2N2O3, K2SO3N2O2, Na2[CH2(N2O2)2], [(C2H5)2NH2][(C2H5)2NN2O2] and N2O3 were measured. The discussion is based on a compilation of reported 15N-15N coupling constants.

Eine 15N-NMR-untersuchung einiger trimethylstannylhydrazine / A15N-NMR study of some trimethylstannylhydrazines

1989 ◽  
Vol 44 (6) ◽  
pp. 653-658 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Theo Gasparis-Ebeling ◽  
Heinrich Nöth
Keyword(s):  
Nmr Spectroscopy ◽  
Lone Electron Pair ◽  
Electron Pair ◽  
Relative Magnitude ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Study ◽  
Geminal Coupling ◽  
In Cis ◽  
First Time

The trimethylstannylhydrazines (Me3Sn)2N-NMe2 (1), Me3Sn(Me)N-N(Me)SnMe3 (2), (Me3Sn)2N-N(Me)SnMe3 (3), and (M e3Sn)2N-N(Ph)SnMe3 (4) have been studied by δ15N NMR at natural abundance. A correlation between δ15N of hydrazines and δI5N of corresponding am ines (replacement of one N-atom by the CH-unit) is proposed in order to estimate δI5N values and to support the non-trivial assignment of 15N resonances of hydrazines. Geminal coupling constants 2J(119SnN 15N) have been observed for the first time. Their relative magnitude is related to the probability of the N-Sn bond being in cis-position with respect to the orientation of the lone electron pair at the 15N nucleus in the 119Sn-N-15N fragment. Treatment of 4 with phenylacetylene causes non-selective cleavage of the Sn-N bonds, leading to the trim ethylstannylhydrazines 5 and 6 which have been characterized by 119Sn and 15N NMR spectroscopy in solution

13C and 15N NMR spectra of 3-methyl-1-phenylpyrazole-4,5-dione 4-(4'-substituted phenyl)hydrazones

1987 ◽  
Vol 52 (3) ◽  
pp. 727-735 ◽  
Author(s):  
Antonín Lyčka ◽  
Tibor Liptaj ◽  
Josef Jirman
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Substituent Constants ◽  
Phenyl Hydrazones

13C and 15N NMR spectra have been measured of eleven 3-methyl-1-phenylpyrazole-4,5-dione 4-(4'-substituted phenyl)hydrazones (I). The 13C chemical shifts of the non-substituted compound I have been assigned with the use of the 1J(13C, 13C) coupling constants obtained from the 1D-INADEQUATE spectrum. The greatest changes in chemical shifts of the compounds I connected with the substituent at 4'-position have been observed for the nitrogen atoms Nα, Nβ, N2 and carbon C(4). These substitution chemical shifts have been correlated with the substituent constants by means of the equations SCS = ρ1σ1 + ρRσR + const., where σR means one of the values σR0, σRBA, σR-, or σR+. The best correlations have been obtained for the combinations Nα - σRBA, Nβ - σR-, N2 - σR0, and C(4) - σR0. The 15N substituent chemical shifts of the nitrogen atoms Nα and Nβ of compounds I have been compared with the analogous values of 4-substituted trans-azobenzenes.

Some Applications of Ultrahigh Resolution 15N NMR Spectroscopy

1998 ◽  
Vol 53 (4) ◽  
pp. 411-415 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Ēriks Kupče
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Absolute Magnitude ◽  
Natural Abundance ◽  
Coupling Constants ◽  
15N Nmr ◽  
Ultrahigh Resolution ◽  
Tert Butyl ◽  
15N Nmr Spectroscopy

Abstract Ultrahigh resolution 15N NMR spectra were measured for two nitroalkanes (MeNO2 la, tBuNO2 1c), two isocyanates (tBuNCO 2c, Me3SiNCO 2d), four isothiocyanates (MeNCS 3a, EtNCS 3b, tBuNCS 3c, Me3SiNCS 3d), one carbodiimide (Me3SiNCNSiMe3 4d), one keteneimine [Me3SiNCC(SiMe3)2 5d], two sulphinyl imides (tBuNSO 6c, Me3SiNSO 6d), and N-tert-butyl-pyrrole 7c, in order to determine coupling constants J(15N ,I3C) and isotope induced chemical shifts 1∆12/13C (15N) at the natural abundance of the isotopes. The values 1∆12/13C (15N) can be separated into two groups, one dealing with NC single and another one with NC double bonds. In each group (with few exceptions), the values 1∆12/13C (15N) become more negative with a decrease in the absolute magnitude of l1J(l5N ,13C)l. The corresponding values 1∆14/15N (13C) show a sim ilar behaviour. However, N-substituted pyrroles appear to be exceptional in this respect.

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.

Application of Reverse Two-Dimensional 1H{15N} NMR Spectroscopy to the Characterization of Two Inorganic Compounds:

1987 ◽  
Vol 42 (6) ◽  
pp. 703-706 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Klaus Schamel ◽  
Karlheinz Guldner ◽  
Max Herberhold
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Inorganic Compounds ◽  
Ring System ◽  
Coupling Constants ◽  
15N Nmr ◽  
Two Dimensional ◽  
Hydrogen Atoms ◽  
15N Nmr Spectroscopy

AbstractThe inorganic ring system linked to the [Cr(CO)5] fragment [R = tBu (1), NH2 (2)], has been studied by reverse two-dimensional, 2D, 1H{15N} NMR spectroscopy. In solution, the exchange of the N-H hydrogen atoms is slow on the NMR time scale. Chemical shifts δ(1H), δ(13C), δ(31P), δ(15N) and coupling constants 1J(31P1H), 2J(31P13C), 1J(31P15N) are reported. In the case of 2, the reduced coupling constants 2K(31PN1H) and 1K(31P15N) have the same sign.

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