The interaction of aliphatic amines with transition-metal complexes of aromatic di-imines. Part 2. Concurrent nucleophilic attack at the central metal and co-ordinated ligand in the reaction between ethylenediamine and dichloro(5-nitro-1,10-phenanthroline)palladium(II) in dimethylformamide

Abstract

The complex [Pd(5NO₂-phen)Cl₂](5NO₂-phen = 5-nitro-1,10-phenanthroline) reacts with ethylenediamine (en) to give [Pd(en)₂]Cl₂ as a final product. This process, which occurs in several steps, has been investigated spectrophotometrically and conductometrically. Ethylenediamine attacks both palladium and co-ordinated phenanthroline to give respectively [Pd(5NO₂-phen)(en)]Cl₂ and a red adduct, which is presumably a Meisenheimer-type complex. These two substances then react with en to yield [Pd(en)₂]Cl₂. A reaction scheme for the overall process is proposed and kinetic and thermodynamic data for some of the steps are reported.