Electroorganic reactions. Part 55. Quinodimethane chemistry. Part 3. Transition metal complexes as inter- and intra-molecular redox catalysts for theelectrosynthesis of poly(p-xylylene) (PPX) polymers and oligomers

The role of metal complexes as redox mediators in the electrosynthesis of p oly(p-xylylenes) (PPXs) has been explored, with a view to designing metal-c ontaining precursors that can act both as mediators and starting materials for metal-containing polymers. A number of transition metal complexes [Cr(i ii), Ni(II) and Co(ii)] are efficient-redox catalysts for production of qui nodimethanes, and hence PPXs. Following encouraging results from experiment s using mediators based on anthranilic acid and salicylaldehyde ligands a m acrocyclic compound was designed, and successfully prepared by a convergent route that incorporated both a 1,4-bis(chloromethylarene) function as a pr ecursor to a quinodimethane and a Ni(II) salen unit as an intramolecular re dox catalyst. The macrocycle was successfully reduced cathodically to yield a PPX polymer with bound Ni(ii). Evidence is presented for the operation o f intramolecular redox catalysis (homomediation).