Axial ligand substitution reactions of ruthenium (II) dimethylglyoxime complexes

774-778Kinetics of ligand substitution reactions of six-coordinated Ru(lI) macrocyclic complexes of the following type have been investigated: (T)Ru(DMGH)2(L)+X→ (T) Ru(DMGH)2(X) + L 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 (D). 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 "Id" or a Associative "Ia" interchange mechanism