Mechanistic study of the transimination of bis(N-alkylsalicylaldiminato)nickel(II) with ammonium ion in acetonitrile

Abstract

Electronic spectrophotometry has been empolyed to study the mechanism of transimination in bis(N-alkylsalicylaldiminato)nickel(II) complexes (alkyl = Me, Et, Prⁱ, Prⁿ or Buⁿ) by ammonium ion in acetonitrile. The reaction is clearly biphasic: fast addition of ammonium and slow elimination of alkylammonium ions. The addition reaction involving the two azomethine bonds of the complex occurs by two consecutive processes and a two-term rate law was found for R = Buⁿ. In the successive elimination reaction only one rate constant was observed which depends on the pK_a and steric strain of the leaving alkylammonium ions.