ELECTRON-SPIN RESONANCE INVESTIGATION OF SUBSTITUTED 3-NITROPYRIDINES RADICAL-ANIONS

The radical anions of 3-nitropyridine, 2-amino-3-nitropyridine, 2-amino-3-nitro-4-methylpyridine, 2-amino-3-nitro-5-methylpyridine, 2-amino-5-nitropyridine, 2-amino-3-methyl-5-nitropyridine, 2-amino-4-methyl-5-nitropyridine, 3-nitro-4-aminopyridine, 3-nitro-5-aminopyridine, 3-nitro-5-nicotinate, 3-nitro-5-methylnicotinate, 3,5-dinitropyridine, 2-methoxy-3-nitropyridine, 2-methoxy-5-nitropyridine, 2,6-dimethoxy-3-nitropyridine, and 2,6-dimethoxy-3,5-dinitropyridine have been studied by ESR spectroscopy. Cepstral and autocorrelogram analysis were applied as routine techniques to extract the hyperfine coupling constants from the experimental ESR spectra. The assignment of the hfscs to the nuclei was made through methyl substitution and quantum mechanical calculations (INDO and McLachlan methods). The Hammett equation was used to correlate ESR data; also, it is proposed as a tool to complete and to verify hfsc's assignment. © 1978 American Chemical Society.