p-Cymene ruthenium thioether complexes

Abstract

Thioethers PhC2H4SMe, PhC3H6SiPr and MeSAllyl form substitutionally labile monomeric adducts (p-cymene)RuCl2(SRR′) (2a–c) upon treatment with the {(p-cymene)RuCl2}2 dimer (p-cymene = η6-MeC6H4iPr-1,4). Pure adducts were obtained by crystallization from CH2Cl2/Et2O, and 2a,c as well as the bis(thioether) complex View the MathML source (3) were studied by X-ray crystallography. The trichloro bridged diruthenium complex View the MathML source is formed as a byproduct in the preparation of 3 and was also crystallographically characterized. In solution, pure samples 2a–c equilibrate with free thioether and the dimeric starting complex 1. The amount of 1 present in these mixtures increases with increasing bulk of the thioether substituents. Attempts to thermally replace the cymene ligand by the dangling arene substituent of the thioether ligand of 2a,b failed. Complexes 2a–c as well as the dimethylsufide derivative 2d were studied by cyclic voltammetry and display a close to reversible (2a,c,d) or partially reversible (2b) oxidation near +0.85 V and an irreversible reduction at rather negative potential. New peaks observed after oxidation and reduction point to dissociation of the thioether ligand as the main decomposition pathway of the associated radical cations and anions.