Tetravalent Nickel : Molecular Design, Chemistry and Cyclic Voltammetry

Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, U. P, India

The possibility of obtaining stable octahedral nickel(IV) species using appropriate ligand design is explored. Studied with the help of an indigenously built cyclic voltammeter, the oxidation-reduction reactions of of such species have revealed ; (i) the occurrence of coupled electron and proton transfer reactions, (ii) the formation of nickel(lll) intermediates under certain conditions and (iii) the occurrence of irreversible decomposition after reversible electron transfer. The various electrode processes have been characterized thermodynamically. The rate of the decomposition reaction is also determined. The oximato group plays the dual role of stabilizing high oxidation states and of providing a pathway for facile electron transfer.