E.S.R. spectrum of 3,5-lutidine anion and comments on nitrogen hyperfine couplings

The E.S.R. spectrum of the 3,5-lutidine anion has been observed. The methyl groups prevent the dimerization which occurs for pyridine. From the observed splitting constants and those of the pyrazine negative ion an estimate is made of the relative contribution to the nitrogen hyperfine splitting of the π-orbital spin densities on the nitrogen atom and on the adjacent carbon atoms.