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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29 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 - Dec 1995
Externally publishedYes

Bibliographical note

Funding Information:
This study was supported in part by grants from the Israel Academy of Sciences and from the Israel Atomic Energy Committee. D.M. expresses his thanks to Mrs Irene Evens for her continuous interest and support.


  • Aza-macrocyclic ligand complexes
  • Nickel complexes


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