C-13 AND N-15 NMR-STUDY OF SUBSTITUTED 1,2,4-TRIAZINES

C-13 and N-15 NMR spectra of eight substituted 1,2,4-triazines were me asured and assigned. The assignments of the C-13 NMR spectra were base d on the substituent chemical shifts and (n)J(C,H) coupling constants. N-15 NMR chemical shifts generally showing well separated ranges were assigned by the proton coupled N-15 NMR spectra. N-15 NMR chemical sh ifts of N-4 in 3- and 5-methoxy or -thiomethyl-substituted 1,2,4-triaz ines were found to be related significantly (confidence level > 99%) w ith the pi-charge at N-4 calculated by a semi-empirical molecular orbi tal (AM1) procedure. For the N-15 NMR chemical shifts of N-1 and N-2, no reliable correlations with the molecular electronic properties such as AM1 pi-charges and ionization potentials (- E(HOMO)) were found.