15-N and 13-C NMR spectra of some ortho-substituted phenylhydrazines were measured at natural isotope abundance in DMSO-d6, solutions. The substituent present exerts a larger effect on the chemical shift of the nitrogen atom directly bound to the aromatic ring (N-1), the second one (N-2) showing an attenuated trend of similar sign. Contrary to what observed for para and meta isomers, the cross-correlation between N-1 and N-2 SCS values of ortho-substituted phenylhydrazines is not satisfactory ; on the other hand, N-1 SCSs show a reasonably good linear regression with the sigma(R-) constants. As expected, no correlation was found between N-1 and C-1 or H-1 SCS values. Correlations between 13C and 15N chemical shifts of the title compounds with those of ortho-substituted anilines and of monosubstituted benzenes are also reported. Multiparameter regression analysis carried out on a large range of ortho-substituted anilines gave satisfactory results in the TSP treatment of C-1 and C-2 chemical shifts. Onebond 15N-1H coupling constants of ortho-substituted phenylhydrazines and ortho-substituted anilines well correlate with sigma(p-) constants.
Nitrogen-15 NMR Studies on Hydrazines. 2†—Substituent Effect Analysis in ortho-Substituted Phenylhydrazines and Anilines / E.MEZZINA; D.SPINELLI; S. CHIMICHI; V.FRENNA; L.LAMARTINA. - In: MAGNETIC RESONANCE IN CHEMISTRY. - ISSN 0749-1581. - STAMPA. - 34:(1996), pp. 1019-1024.
Nitrogen-15 NMR Studies on Hydrazines. 2†—Substituent Effect Analysis in ortho-Substituted Phenylhydrazines and Anilines
CHIMICHI, STEFANO;
1996
Abstract
15-N and 13-C NMR spectra of some ortho-substituted phenylhydrazines were measured at natural isotope abundance in DMSO-d6, solutions. The substituent present exerts a larger effect on the chemical shift of the nitrogen atom directly bound to the aromatic ring (N-1), the second one (N-2) showing an attenuated trend of similar sign. Contrary to what observed for para and meta isomers, the cross-correlation between N-1 and N-2 SCS values of ortho-substituted phenylhydrazines is not satisfactory ; on the other hand, N-1 SCSs show a reasonably good linear regression with the sigma(R-) constants. As expected, no correlation was found between N-1 and C-1 or H-1 SCS values. Correlations between 13C and 15N chemical shifts of the title compounds with those of ortho-substituted anilines and of monosubstituted benzenes are also reported. Multiparameter regression analysis carried out on a large range of ortho-substituted anilines gave satisfactory results in the TSP treatment of C-1 and C-2 chemical shifts. Onebond 15N-1H coupling constants of ortho-substituted phenylhydrazines and ortho-substituted anilines well correlate with sigma(p-) constants.File | Dimensione | Formato | |
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