Kinetics and Mechanism of the Ligand Exchange Reaction Between Tetradentate Schiff Base N,N’-ethylen-bis (salicylaldimine) and Ni(N,N’-propylen-bis(salicylaldimine))

  • R Vafazadeh
  • M Bagheri
Keywords: Kinetic, mechanism, Schiff base, Ni complexes, ligand exchange.

Abstract

Visible spectrophotometry is used to study the kinetics of ligand exchange in the system Ni(salpn)/H2salen with or without triethylamine (NEt3) and H2O in dimethylformamide (DMF) solvent at 25 ± 0.1 °C and 0.01M NaNO3 [H2salen and H2salpn are N,N’-ethylen-bis(salicylaldimine) and N,N’-propylen-bis(salicylaldimine), respectively]. It was found that the reaction rate is of the first-order with respect to Ni(salpn). In addition, the effect of NEt3 andH2O on the rate of the reaction was examined. The rate of the ligand exchange reaction was accelerated by adding NEt3 to the reaction mixture. However, the ligand exchange rate was not changed by adding H2O to the mixture reaction. The effects of NEt3 and H2O on the ligand exchange rate show that deprotonation/protonation of the H2salen ligand and anionic form of H2salen is important. On the basis of these results, the reaction mechanism is discussed.

KEYWORDS Kinetic, mechanism, Schiff base, Ni complexes, ligand exchange.

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