Properties of monovalent nickel complexes with tetraaza-macrocyclic ligands in aqueous solutions

Israel Zilbermann, Maya Winnik, Dalia Sagiv, Amira Rotman, Haim Cohen, Dan Meyerstein

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28 Scopus citations


The effects of N-alkylation on the redox potential of the couples NiLi2+/NiLi+, L = tetraaza-14-membered-macrocyclic ligands, and on the properties of the monovalent nickel complexes in aqueous solutions are reported for 14 complexes. The spectra and lifetimes of the NiLi+ complexes are reported. The self-exchange rates for the couples NiLi2+/NiLi+ were determined. Two of the ligands were synthesized for the first time for this study. Cyclic voltammetry and pulse radiolysis were used. The results point out that: (i) N-alkylation always shifts the redox potential to a less cathodic one; this effect stems to a large degree from the decrease in the solvation energy of the complex caused by the N-alkylation of the ligand. (ii). The lifetime of the monovalent complexes is not linearly related to the redox potential of the NiLi2+/NiLi+ couples. (iii) The NiLi+ complexes exist in several isomeric forms; the rate of the isomerization depends on the structure of the ligand. (iv) Different isomers of NiLi+ may be formed when the complex NiLi2+ is reduced by different reagents; therefore, the pulse-radiolytically formed NiLi+ complexes might have different properties than those formed electrochemically.

Original languageEnglish
Pages (from-to)503-514
Number of pages12
JournalInorganica Chimica Acta
Issue number1-2
StatePublished - 1 Jan 1995
Externally publishedYes


  • Aza-macrocyclic ligand complexes
  • Nickel complexes


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