N-15 NMR-STUDIES ON HYDRAZINES .2. SUBSTITUENT EFFECT ANALYSIS IN ORTHO-SUBSTITUTED PHENYLHYDRAZINES AND ANILINES

N-15 and C-13 NMR spectra of some ortho-substituted phenylhydrazines w ere measured at natural isotope abundance in DMSO-d(6) solutions. The substituent present exerts a larger effect on the chemical shift of th e nitrogen atom directly bound to the aromatic ring (N-1), the second one (N-2) showing an attenuated trend of similar sign, Contrary to wha t observed for par a and meta isomers, the cross-correlation between N -1 and N-2 SCS values of ortho-substituted phenylhydrazines is not sat isfactory; on the other hand, N-1 SCSs show a reasonably good linear r egression with the sigma(R)(-) constants, As expected, no correlation was found between N-1 and C-1 or H-1 SCS values, Correlations between C-13 and N-15 chemical shifts of the title compounds with those of ort ho-substituted anilines and of monosubstituted benzenes are also repor ted, Multiparameter regression analysis carried out on a large range o f ortho-substituted anilines gave satisfactory results in the TSP trea tment of C-1 and C-2 chemical shifts, One-bond N-15-H-1 coupling const ants of ortho-substituted phenylhydrazines and ortho-substituted anili nes well correlate with sigma(p)(-) constants.