RATES AND MECHANISM OF SUBSTITUTION REACTIONS OF STERICALLY HINDERED PALLADIUM(2) COMPLEXES

The preparation and characterization of the complexes Pd(dien)SO3, Pd(Et4dien)SO3, Pd(Et4dien)S2O3, Pd(MeEt4dien)-S2O3, Pd(Mesdien)S2O3, [Pt(Et4dien)NH3] [PtCl4] -H2O, and [Pt(Et4dien)NH3]Cl21 are described, as well as the in situ preparation of [Pd(Et4dien)H2O] (ClO4)2. In these complexes, the amine is tridentate and the other ligand is unidentate. The kinetics of the reaction of sulfite ion with [Pd(Et4dien)Br]Br and of thiosulfate ion with [Pd(Et4dien)Br] Br, [Pd(Me5dien)-C1]PF6, and [Pd(MeEt4dien)Cl]Cl were investigated. The sulfite ion reaction follows the same first-order path as found previously for other ligands with this substrate, yet the thiosulfate ion reactions are described by both a ligand-dependent and a ligand-independent path. The kinetics of the reaction of [Pd(Et4dien)H2O] (ClO4)2 with a series of nucleophiles was studied by the stopped-flow method; all reactions were fast and were first order in both substrate and reagent. © 1968, American Chemical Society. All rights reserved.