Deactivators: what's resonance got to do with it?

[SaintJude]

---

Members don't see this ad.

Wiki: "Nitro group" are strongly deactivating because of their resonance structures.

What do they mean? What's resonance got to do with this?

Thanks

 

[chiddler]

if i remember the mechanism correctly

they are deactivating because the resonance structures of NO2 groups can suck in electrons from the aromatic ring. So with less electron availability, there is less reactivity since additions to an aromatic ring are with an electrophile, right?

see a mechanism example here.