Ubergangsmetallkomplexe mit Schwefelliganden, XXXIII*/ Transition Metal Complexes with Sulfur Ligands, XXXIII*
Abstract In order to investigate the specific properties which are associated with metal sulfur centers, the system Ru/S2C6H42- has been studied with respect to the synthesis of new complexes and their reactions as well as their structure. cis-(NBu4)(Ru(NO))(PMe4)(S2C6H4)2] reacts with an excess of PMe3 in boiling THF to give the paramagnetic (μeff = 0,96 B. M., 295 K) trans-(NBu4)(Ru(PMe4)2(S2C6H4)2) (I). A plausible intermediate in this reaction is the nitrido complex (NBu4)(Ru(N)(S2C6H4)2) (2) since 2 gives with one equivalent of PMe3 a very labile product which is probably (NBu4)(Ru(N)(PMe4)(S2C6H4)2) (3). but reacts with an excess of PMe3 even at 20 °C to give 1. The Ru(III) complex 1 is easily oxidized by O2 or PhN2BF4 to yield the diamagnetic Ru(IV) species trans-(Ru(PMe3)2(S2C6H4)2) (4). Remarkably, the transformation of 1 into 4 is achieved also by H+ ions, providing a model reaction for the coupled H+-electron transfer which has been discussed for substrate reactions at metal sulfur centers of enzymes. - The reaction of RuCl2(PMe3)4 with S2C6H42- yields [Ru(PMe3)4(S2C6H4)] (5) at 20 °C, even if an excess of S2C6H42- is applied. Upon heating in THF or EtOH, 5 looses one PMe3 ligand to give the 16e -complex [Ru(PMe4)4(S2C6H4)] (6) which rapidly coordinates CO to give [Ru(CO)(PMe4)4(S2C6H4)] (7); '1P NMR indicates a meridional coordination of PMe4 in 7, and consequently CO must be trans to S2C6H42-. 6 reacts also with LiAlH4 to yield a very sensitive hydride complex to which the tentative formula [Ru(H)2(PMe3)2(S2C6H4)] is assigned. All compounds were characterized by elemental analyses and spectroscopic means, the structures of I and 5 were determined by X-ray structure analysis.