Electrocarboxylation of chloroacetonitrile mediated by electrogenerated cobalt(I) phenanthroline

The electrocarboxylation of chloroacetonitrile mediated by [Co(II)(phen)(3)](2+) has been investigated. Cyclic voltammetry studies of [Co(II)(phen)3](2+) have shown that [Co(I)(phen)(3)](+), an 18 electron complex, activates chloroacetonitrile by an oxidative addition through the loss of a phenanthroline ligand to give [RCo (III)(phen)(2)Cl](+). The unstable one-electron-reduced complex underwent Co-C bond cleavage. In carbon dioxide saturated solution, CO2 insertion proceeds after reduction of the alkylcobalt complex. A catalytic current is observed which corresponds to the electrocarboxylation of chloroacetonitrile into cyanoacetic acid. Electrolyses confirmed the process and gave faradic yield of 62% in cyanoacetic acid at potentials that are about 0.3 V less cathodic than the one required for Ni(salen). (C) 2010 Elsevier B.V. All rights reserved.