Grignard reaction on electron-poor benzyl bromides I am trying to prepare a Grignard reagent from 4-nitrobenzyl bromide



but the reaction just doesn't work. My conditions are:


10 mL of THF (anhydrous);
7.04 mmol of 4-nitrobenzyl bromide;
7.04 mmol of Mg;
Argon atmosphere.


Water is not a problem since I left all my glassware in the oven overnight and flame-dried the round bottom flask + stir bar before adding Mg and the bromide. I also did everything under argon. I know the reaction is not proceeding because virtually all of the Mg turnings I added are still there and the solution is still clear. I tried adding two crystals of iodine but it didn't help either.

Is there something about this particular bromide that prevents/slows down the formation of the Grignard? I was wondering if the fact that the nitro group is electron withdrawing could make it more difficult to form the carbanion-like structure of the Grignard.
This question has aged a bit with no other answers, so here I go.

The same nitro group that can oxidize Grignard reagents could be oxidizing the magnesium too, thus keeping it passivated.  What you need is not so much a milder EWG but one with less oxidizing potential.  Try your reaction with nonoxidizing EWGs like acetyl (watch for side reactions), a $\ce{CF3}$ group, or a chlorine atom attached to the aryl group.