Mechanistic features of SNAr reactions of neutral and cationic metal-complexed halogenobenzenes with methoxide

Abstract

Rate studies have shown that the activation of halogenobenzenes towards replacement of halide by methoxide in methanol increases through the series of π-attached residues (OC)₃Cr < (OC)₃Mo < < (η⁵-C₅H₅)Fe⁺ < (OC)₃Mn⁺, with the fluorobenzene complexes more reactive than the chlorobenzene analogues; evidence has been obtained that the cationic complexes readily form ion-pairs with methoxide, resulting in a reduction in their reactivity towards nucleophilic substitution.