What is anionic intermediate

The spectrum is consistent with the formation of an anionic intermediate-a stable Meisenheimer complex.  (The dotted lines symbolize resonance delocalization of the negative charge.)  If you draw out the resonance structures for this ion, you will see that charge is delocalized to the carbons bearing the nitro groups, and it can also be delocalized into the nitro groups.  Though, charge is not delocalized to the other carbons.  As, the protons on these carbons do not show the smaller chemical shift that would be expected if there were high electron density on these carbons.