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 H-1 NMR data indicate that the first step of the release reaction of the ligand is the O-Zn bond breaking. (C) 2000 Elsevier Science S.A. All rights reserved.