13C, 15N, and 19F NMR spectra of 4-fluoro-(3´ or 4´-substituted) azobenzenes

1984 ◽  
Vol 49 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Antonín Lyčka ◽  
Jaromír Kaválek
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
19F Nmr ◽  
19F Nmr Spectra

The 13C and 19F NMR spectra of fifteen 4-fluoro-(3´ or 4´-substituted (azobenzenes have been measured. The δ(19F) values correlate with the corresponding σm,p constants (δ(19F) = 3.60σm,p-30.78). The 15N NMR spectra have been measured of six compounds, and additivity of the 15N substitution chemical shifts has been proved. The measured coupling constants are 6J(19F15N) = 2.1 Hz and 7J(19F13C) = 0.7 Hz.

scholarly journals Demystifying fluorine chemical shifts: electronic structure calculations address origins of seemingly anomalous 19F-NMR spectra of fluorohistidine isomers and analogues

2015 ◽  
Vol 17 (45) ◽  
pp. 30606-30612 ◽  
Author(s):  
Chandana Kasireddy ◽  
James G. Bann ◽  
Katie R. Mitchell-Koch
Keyword(s):  
Electronic Structure ◽  
Chemical Shift ◽  
Electron Density ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Electronic Structure Calculations ◽  
19F Nmr ◽  
19F Nmr Spectra ◽  
Structure Calculations

Understanding localization/delocalization of fluorine electron density is shown to be critical for predicting and interpreting fluorine chemical shift.

13C, 15N, and 19F NMR spectra of 2-phenylhydrazonopropanedinitriles and methyl 2-phenyl hydrazonocyanoacetates

1984 ◽  
Vol 49 (12) ◽  
pp. 2801-2806 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Nmr Spectra ◽  
Electron Pair ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Azo Coupling ◽  
19F Nmr Spectra ◽  
Mutual Comparison ◽  
Cyano Groups ◽  
Free Electron Pair

13C, 15N, and 19F NMR spectra of the azo coupling products obtained from 4-X-benzenediazonium salts (X = H, F, NO2) and propanedinitrile (I) or methyl cyanoacetate (II) and of their 15N isotopomers have been measured. The 13C chemical shifts of cyano groups have been assigned unambiguously on the basis of the 2J(15Nβ13C) coupling constants, and mutual comparison of the 15N chemical shifts in compounds I and II enabled also the assignment of the15N chemical shifts of these groups. The 13C chemical shifts of cyano groups in cis position with respect to free electron pair at Nβ nitrogen atom are shifted downfield, whereas δ(15N) of the same groups exhibit upfield shifts as compared with the cyano in trans position. The azo coupling products of benzenediazonium salts and methyl cyanoacetate contain predominantly the E isomer even after long-term standing in hexadeuteriodimethyl sulphoxide.

195Pt- und 19F-NMR-Spektren der Fluoro-Chloro-Platinate(IV), [PtFnCl6-n]2-, n = 0-6 / 195Pt and 19F NMR Spectra of the Fluoro-Chloro-Platinates(IV), [PtFnCl6-n]2-, n = 0-6

1993 ◽  
Vol 48 (9) ◽  
pp. 1169-1174 ◽  
Author(s):  
E. Parzich ◽  
G. Peters ◽  
W. Preetz
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
19F Nmr ◽  
Complex Ions ◽  
19F Nmr Spectra ◽  
Trans Influence ◽  
Wide Range ◽  
A Minor ◽  
Cl Atom

The 10 complex ions of the system [PtFnCl6-n]2-, n = 0—6, including the three pairs of stereoisomers for n = 2, 3, 4 have been characterized by 195Pt and 19F NMR spectroscopy in CD2Cl2 solution. A wide range from 4731 ([PtCl6]2-) to 11816 ppm ([PtF6]2-) is covered by the clearly separated 195Pt resonances. The chemical shift δ(195Pt) depends nearly linearly on the sum of the electronegativities of the ligands. In accordance with increasing deshielding of the 195Pt nucleus by increasing coordination with F ligands an averaged major downfield shift of 1181 ppm per substitution of Cl by F is observed, while a minor averaged value of 354 ppm downfield is found for the trans/mer isomers in comparison to the related cis/fac isomers. Coupling with 19F results in characteristic 195Pt multiplets, with 1J(PtF) coupling constants for symmetric F—Pt—F axes of averaged 1890 Hz about 31% larger than 1J(PtF•) for asymmetric F•—Pt—Cl′ axes with averaged 1296 Hz. The data reflect the trans influence of the ligands. Highly resolved and expanded 195Pt spectra reveal clearly separated isotopomer signals with intensities according to the expected statistical ratios given by the natural abundance of 35Cl and 37Cl. For [Pt35Cln37Cl6-n]2- five distinct signals related to n = 6-2 with 0,18 ppm highfield shift per 37Cl atom have been reliably assigned. Resolved isotopomer peaks have also been observed for mer-[PtF335Cl3]2-/mer-[PtF335Cl237Cl]2- with 0,21 ppm and for [PtF535Cl]2/[PtF537Cl]2- with 0,32 ppm highfield shift per 37Cl atom, respectively. The 19F resonances of symmetric axes appear at higher field, in the range from —357 to —382 ppm, than those of asymmetric axes, from —266 to —287 ppm. Under high resolution compounds with inequivalent F nuclei show multiplets originating from homonuclear 2J(FF•) couplings of about 40 Hz.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

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.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

19F NMR spectra of 1,2-dihaloperfluoropropanes

1972 ◽  
Vol 6 (2) ◽  
pp. 200-208 ◽  
Author(s):  
A De Marco ◽  
G Gatti
Keyword(s):  
Nmr Spectra ◽  
19F Nmr ◽  
19F Nmr Spectra

Automated analysis and simulation of 19F-NMR-spectra

1985 ◽  
Vol 29 (1-2) ◽  
pp. 191
Author(s):  
Gerhard Hägele ◽  
Winfried Boenigk ◽  
Michael Engelhardt
Keyword(s):  
Nmr Spectra ◽  
Automated Analysis ◽  
19F Nmr ◽  
19F Nmr Spectra
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