Kinetic study of ligand release promoted by ammonium ion on bis(N-alkylsalicylaldiminato)zinc(II) complexes in aprotic solvent

The reaction between ammonium ion and bis(N-alkylsalicylaldiminato)zinc(II) complexes [Zn(R-sal)2] (R-sal=anion of N-alkylsalicylaldimine; R=H, n-Bu=n-butyl, t-Bu=tert-butyl, i-Pr=iso-propyl, Et=ethyl) in dry acetonitrile, leads to the release of the ligand. The reaction was studied kinetically at different temperatures and an analysis by mean of a multi-wavelength stopped-flow technique evidences a first-order kinetic as a general rule, and a two exponential profile for the t-butyl substituted complex for the release of one of the bidentate ligands of the Zn(II) complexes. Kinetic and 1H NMR data indicate that the first step of the release reaction of the ligand is the OZn bond breaking.