Mechanistic and synthetic aspects of a novel route to poly-p-xylylene (PPX)via nickel complex catalysed electropolymerisation of 1,4-bis(chloromethyl)benzene

Abstract

It is shown that in the presence of catalytic amounts of Ni^II Cl₂L₂(L₂= dppe or dppp) 1,4-bis(chloromethyl)benzene is electrochemically reduced to poly-p-xylylene (PPX). Cyclic voltammetric examination of this reaction, and of the analogous conversion of benzyl chloride into bibenzyl, is combined with the construction of reactant/product vs. charge profiles to develop a detailed mechanistic description. There is compelling evidence that, in contrast with the established cathodic formation of PPX from 1,4-bis(halomethyl)benzene via electrogenerated quinodimethane (xylylene), the Ni complex catalysed route involves oxidative addition of the halide derivative to Ni⁰L₂.