Axial ligand substitution reactions of ruthenium (II) dimethylglyoxime complexes

Abstract

Kinetics of ligand substitution reactions of six-coordinated Ru(lI) macrocyclic complexes of the following type have been investigated:<br><br> (T)Ru(DMGH)₂(L)+X&rarr; (T) Ru(DMGH)₂(X) + L<br><br> where "T" and "L" are either both triphenylphosphine ligands or methylimidazole and triphenylphosphine ligands, respectively. The nucleophile "X" is either MeIm, Im, py, pip, P(OBu)₃ or Time. In all cases, with the exception of Timic as a nucleophile, the reaction mechanism is strictly dissociative (<em>D</em>)<em>. </em>The reaction proceeds through the formation of a five-coordinate intermediate which possesses little or no ability to discriminate between different nuc1eophiles.In the case of Tmic, the rate data can be fitted by a dissociative "<em>I</em>_d" or a Associative "<em>I</em>_a" interchange mechanism.