HELICAL HEPTACOORDINATE COMPLEXES OF COBALT DERIVED FROM 2,2'-6',2''-6'',2'''-6''',2''''-QUINQUEPYRIDINE DERIVATIVES

We have shown1 recently that electropolymerized layers of [Co(v-terpy)2]2+exhibit properties and chemical reactivity patterns different from those of [Co(terpy)2]2+in solution and that these differences were attributed to constraints imposed by incorporation of the metal complex in a polymeric system as well as by the tridentate nature of this ligand. An especially interesting property of the electropolymerized films of [Co(v-terpy)2]2+was the electrocatalytic reduction of carbon dioxide to formic acid and of oxygen to water and hydrogen peroxide. This reactivity was attributed to the generation of vacant catalytic sites on the cobalt in its reduced state. Analogous cobalt complexes of quinquepyridine are of particular interest as they have the possibility of generating an empty coordination site with relative ease and may provide evidence for the mode of action of the polymerized [Co(v-terpy)2]2+. © 1990, American Chemical Society. All rights reserved.