p-Cymene ruthenium thioether complexes

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 [(p-cymene)RuCl(SMe2)2]+SbF6- (3) were studied by X-ray crystallography. The trichloro bridged diruthenium complex [(p-cymene)Ru}2(μ-Cl)3]+SbF6- 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.

Simple thioether complexes [(p-cymene)RuCl2(SRR′)] with methyl, allyl, and alkylaryl substituents have been prepared and studied by X-ray crystallography. Voltammetry suggests thioether dissociation as the primary degradation pathway of the associated radical cations and anions.Figure optionsDownload as PowerPoint slide