SOLVENT EFFECTS ON THE C-13 NMR PARAMETERS (DELTA C-13 CHEMICAL-SHIFTS AND H-1-C-13 COUPLING-CONSTANTS) OF 1-METHYLPYRAZOLE AND 1-METHYLIMIDAZOLE

The C-13 chemical shifts and the 1J(H-1-C-13) coupling constants of the title compounds are relatively sensitive to solvent effects (DELTA-delta = 2-3 ppm, DELTA-J = 2-3 Hz), deuterochloroform values being near the averaged ones (11 solvents). The solvent induced shifts of the three heterocyclic carbons and those of the N-methyl groups are discussed using the Kamlet-Taft-Abboud formalism. As solvent (pure liquid) 1-methylimidazole appears as a highly dipolar-polarizable solvent