INFLUENCE OF CARBOXYLIC-ACIDS ON THE REACTIONS WITH CHLOROTETRAACETATODIRUTHENIUM(II,III) - X-RAY CRYSTAL-STRUCTURE OF [RU-2(MU-O2CC4H3S)(4)(OPPH(3))(2)]BF4-CENTER-DOT-2H(2)O

The reaction of Ru2Cl(mu-O2CCH3)(4) with indole-2-carboxylic, N-methyl-pyrrole-2-carboxylic, furane-2-carboxylic, thiophene-2-carboxylic and benzofurane-2-carboxylic acids, which contain nitrogen, oxygen or sulphur atoms in the alpha position with respect to the carboxylate group, leads to compounds of the type Ru2Cl(mu-O(2)CR)(4). In these compounds O,O-coordination of the carboxylate ligands has been found. The analogous reaction with quinoline-2-carboxylic acid (Hquin) gives a disproportionation process with formation of Ru(quin)(3) and Ru-2(quin)(4); in this case, N,O-coordination of the ligand has been observed. The indole-2-carboxylato derivative has a non-polymeric structure, whereas with the other ligands polymeric structures with chlorine atoms bridging Ru-2(5+) units are formed. Treatment of Ru2Cl(mu-O(2)CR)(4) in thf or acetone with AgBF4 gave [Ru-2(mu-O(2)CR)(4)L(2)]BF4 (L = thf, acetone; R = N-methyl-2-pyrrolyl, 2-furyl, 2-thienyl) or [Ru-2(mu-O(2)CR)(4)]BF4 (R = 2-benzofuryl). The axial positions of these compounds can be occupied by OPPh(3) to give the corresponding [Ru-2(mu-O(2)CR)(4)(OPPh(3))(2)]BF4. The compounds have been characterized by analytical, spectroscopic and magnetic data. The structure of [Ru-2(mu-O2CC4H3S)(4)(OPPh(3))(2)] BF4 . 2H(2)O has been determined by X-ray crystallography. The dinuclear cation has two ruthenium atoms linked by four bridging thiophene-2-carboxylate ligands and two OPPh(3) ligands coordinated to axial positions, with an Ru-Ru distance of 2.2747(11) Angstrom.