NMR studies of pyridazine- N-oxide. Determination of spectroscopic parameters from the [ 15N]- and parent species

Abstract

Pyridazine- N-oxide and [ 15Npyridazine- N-oxide have been investigated by NMR spectroscopy. 1H and 13C spectra have been obtained and analyzed, in terms of chemical shifts and spin-spin coupling constants. Relaxation times have been measured for 13C and have been used to determine the correlation time π c under the assumption of isotropic molecular diffusion. From 1H, 15N INDOR experiments the lineshape of N(2) is determined; analysis of the lineshape yields 1 J NN and TqN(1). On the basis of experimental data and observed linewidth variations, the N(1) nitrogen quadrupole coupling constant has been evaluated. The experimental data are correlated with semiempirical calculations within the azine series.