ESR of biradicals of dipyridyl mononegative ions and alkali ions

It is shown that the biradical species, observed in frozen solutions of dipyridyl mononegative ions and alkali metal ions, has the composition M⁻Me⁺M⁻. The independence of the zero field splitting parameter D of the type of solvent used, shows that the associate is of the contact type, in which the lone pair electrons of the nitrogen atoms are involved in the bond with the alkali metal ion.