SYNTHESIS AND ELECTROCHEMICAL PROPERTIES OF P-CYMENE-RUTHENIUM(II) COMPLEXES WITH (EPPH2)(2)CHR (E=S, SE - R=H, ME) AND THEIR ANIONIC DERIVATIVES AS LIGANDS - CRYSTAL-STRUCTURE OF A(6)-MEC6H4PRI)RU(ETA(3)-(SPPH2)(2)CME-C,S,S')]PF6

The synthesis and properties of cationic complexes of general formula (6)-MeC6H4Pri)RuCl{eta(2)-(EPPh2)(2)CHR-E,E'})]BF4 (R = H, E = S (1), Se (2); R = Me, E = S (5)) are described. The methylene proton of the coordinated dichalcogenide ligand reacts with strong bases such as KOH in methanol or TIPz in dichloromethane solutions, to give new cationi c complexes in which the anionic ligand is acting as tridentate chelat e with a C,E,E'-donor set, eta(6)-MeC6H4Pri)Ru{eta(3)-(EPPh2)(2)CR-C,E ,E'})]A (R = H, A = BF4-, E = S (3), Se (4); R = Me, A = PF6-, E = S ( 6)). The complexes have been characterised by elemental analyses, mola r conductivities and IR and NMR spectroscopy. The structure of the tit le complex was established by X-ray crystallography. The crystals are tetragonal; at 293 degrees C a = 15.120(2), c = 16.090(3) Angstrom, sp ace group P4(3), Z = 4. The complex contains a tridentate C,S,S'-bonde d ligand occupying three coordination positions of a distorted octahed ral ruthenium centre, with an eta(6)-MeC6H4Pri group completing the co ordination sphere. Cyclic voltammetry shows that under argon the acidi c protons of the coordinated neutral disulfide ligands (1, 5) are redu ced to hydrogen yielding the complexes with the anionic ligand coordin ated in their tridentate form (3, 6). These compounds are irreversibly reduced in a one-electron process to give Ru(I) species, followed by chemical decomposition.