[zeoblade]

There is this question about why diazonium substituent cannot direct nucleophiles to the meta-position.

A diazonium substituted benzene cannot direct a nucleophile to the meta-position because the nucleophile substitutes with the diazonium substituent only as the nucleophile attacks the positive charge left behind when N₂ leaves. Is this correct to say?

So it cannot ortho/para-direct either, and only substitutes with that 'ipso-' position?

[zeoblade]

Also, if you want to halogenate using diazonium substituents you should use HBr or HCl if you want Br or Cl substitution respectively, right?

For Iodo, KI is added. When the diazonium salt is p-toluene-N⁺NCl^-, how come it can iodonate and give KCl rather than a mixture?

I is a better leaving group than Cl, so is it something to do with KCl more favourable in forming?