The electrochemical reduction mechanism of Ni(II)(salophen), Ni(L), in DMF has been investigated by cyclic voltammetry and controlled potential electrolysis. The complex exhibits several redox processes. The first electron uptake, a ligand-based one-electron transfer at E° = -1.39 V vs sce, leads to the formation of a nickel(II) radical anion, [Ni(II)(L)]-, which rapidly dimerizes, giving rise to a product containing two Ni(L) units joined through a C-C bond. The dimer [Ni(II)(L)]2(2-) undergoes a nickel-centred reversible reduction process occurring at E° = -2.25 V vs sce to give [Ni(I)(L)]2(4-). The dianion dimer can also be oxidized irreversibly at ca -0.8 V to regenerate the original Ni(L) complex. At the highest sweep rates dimerization is hampered thus allowing the reversible reduction of the primary radical anion to [Ni(I)(L)]2- to be observed.
A STUDY OF THE ELECTROCHEMICAL REDUCTION-MECHANISM OF NI(SALOPHEN) IN DMF
AHMED ISSE, ABDIRISAK;GENNARO, ARMANDO;VIANELLO, ELIO
1992
Abstract
The electrochemical reduction mechanism of Ni(II)(salophen), Ni(L), in DMF has been investigated by cyclic voltammetry and controlled potential electrolysis. The complex exhibits several redox processes. The first electron uptake, a ligand-based one-electron transfer at E° = -1.39 V vs sce, leads to the formation of a nickel(II) radical anion, [Ni(II)(L)]-, which rapidly dimerizes, giving rise to a product containing two Ni(L) units joined through a C-C bond. The dimer [Ni(II)(L)]2(2-) undergoes a nickel-centred reversible reduction process occurring at E° = -2.25 V vs sce to give [Ni(I)(L)]2(4-). The dianion dimer can also be oxidized irreversibly at ca -0.8 V to regenerate the original Ni(L) complex. At the highest sweep rates dimerization is hampered thus allowing the reversible reduction of the primary radical anion to [Ni(I)(L)]2- to be observed.
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