Electrocatalytic reduction, nickel macrocyclic complexes

Electric fleld gradient, 22 214-218 Electroabsorption spectroscopy, 41 279 class II mixed-valence complexes, 41 289, 291, 294-297 [j(jl-pyz)]=+, 41 294, 296 Electrocatalytic reduction, nickel(n) macro-cyclic complexes, 44 119-121 Electrochemical interconversions, heteronuclear gold cluster compounds, 39 338-339 Electrochemical oxidation, of iron triazenide complexes, 30 21 Electrochemical properties fullerene adducts, 44 19-21, 33-34 nickeljll) macrocyclic complexes, 44 112-113... 

Fisher and Eisenberg (107) have reported on the electrocatalytic reduction of carbon dioxide using macrocycle complexes of nickel and cobalt (e.g., complex 27). An indirect electrochemical reduction of C02 was ac-... 

The electrocatalytic activity of various nickel macrocycles in aqueous solution was studied. Cyclic voltammograms indicate that 7 / S -NiHTIM2+, NiMTC2+ and NiDMC + are better catalysts than Ni(cyclam)2+ in terms of more positive potentials and/or their larger catalytic currents [26], Bulk electrolyses with 0.5 mM Ni complexes confirm that these complexes are excellent catalysts for the selective and efficient CO2 reduction to CO. The macrocycles with equatorial substituents showed increased catalytic activity over those with axial substituents. These structural factors may be important in determining their electrode adsorption and CO2 binding properties. 

Structure 5.1. Molecular structures of cobalt(ll), nickel(It) and copper(II) complexes with hexaaza-macrocyclic Ugands derived from the condensation of bipyridines. Reprinted from Figure lA M. Isaacs, J.C. Canales, M.J. Aguirre, G. Estiu, F. Caruso, G. Ferraudi and J. Costamagna, Electrocatalytic reduction of CO2 by aza-macrocycUc complexes of Ni(II), Co(II) and Cu(II). Theoretical contribution to probable mechanism, Inorganica Chimica Acta, 339 (2002) 224—232. Copyright 2002, with permission of Elsevier. 

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