RUTHENIUM(II) COMPLEXES WITH NS2 PYRIDINE-BASED DITHIA-CONTAINING LIGANDS - PROPOSED POSSIBLE STRUCTURAL ISOMERS AND X-RAY CONFIRMATION OF THEIR EXISTENCE

Ligands LX of the type NS2 with S-aryl and S-alkyl substituents which incorporate the unit 2,6-bis(thiomethyl)pyridine are produced. Their r eaction with [RuCl2(PPh3)(3)] and [RuCl2(DMSO)(4)] produces the first reported Ru(II)/NS2 complexes. They present the general formulas [RuCl 2(LX)L'], where L' = PPh3 or DMSO. Several isomers are possible; howev er, only two have been found in each reaction. The H-1 NMR spectra sho w that the HaHb proton atoms of the pyridine-CHaHb-thioether unit are nonisochronous. A Delta delta(HaHb) value close to 1 ppm is observed f or the cis complexes while this is smaller for the trans analogues. Th e possible distinct isomers are discussed in terms of steric effects. It is hypothesized that the trans-dl, the trans-meso, and the cis-meso -E would be the structures more favored. Those structures have been co nfirmed by X-ray diffraction analysis of trans-dl-[RuCl2(LI)(DMSO)]. 0 .5MeOH, cis-[RuCl2(LS)(PPh3)]. CH2Cl2, and trans-meso-[RuCl2(L6)(PPh3) ]. 1.5MeOH.