In the search for complexes, having sulfur‐dominated coordination spheres, that potentially bind, activate, or stabilize nitrogenase‐relevant small molecules, we have synthesized several ruthenium−sulfur complexes of the type [Ru(L)(pyS4)] starting from the labile acetonitrile complex [Ru(NCMe)(pyS4)] (2). Complex 2 was obtained from the reduction of [Ru(NO)(pyS4)]Br (1) by N2H4·H2O in the presence of MeCN. The acetonitrile ligand in 2 could be exchanged for the soft σ−π ligand CO to give [Ru(CO)(pyS4)] (3). Attempts to coordinate N2 to the pyS42− fragment of 2 gave [{Ru(pyS4)}2] (4). Complex 2 reacts also with hard σ‐ligands, such as N2H4, NH3, pyridine, and pyrazine, to afford mononuclear [Ru(N2H4)(pyS4)] (5), [Ru(NH3)(pyS4)] (6), [Ru(py)(pyS4)] (7), and [Ru(pyr)(pyS4)] (8), respectively. Reaction of 2 with NEt4N3 resulted in the formation of NEt4[Ru(N3)(pyS4)] (9). The oxidation of 2 with I2 afforded [Ru(I)(pyS4)] (10). The protonated and alkylated species [Ru(NCMe)(pyS4‐H)]BF4 (11), [Ru(NCMe)(pyS4‐Et)]BF4 (12), and [{Ru(pyS4‐Et)}2] (BF4)2 (13) were obtained from 2 by its treatment with HBF4 or Et3OBF4. The N2H4 ligand in 5 could not be oxidized to N2H2: the oxidation of the RuII center to RuIII takes place instead. Attempts to oxidize 5 using either [FeCp2]PF6 or I2 gave [{RuII/III(pyS4)}2](PF6) (14) and [RuIII(NH3)(pyS4)]X (X = PF6, I) (15, 16). The oxidation of 3 and 6 by NOBF4 gave RuIII species of [RuIII(CO)(pyS4)]BF4 (17) and [RuIII(NH3)(pyS4)]BF4 (18). The oxidation of 5 and 6 with H2O2 afforded [{RuII(pyS4−O3)}2] (19), [{RuII(pyS4−O4)}2] (20) and [RuII(NH3)(pyS4−O4)] (21). All complexes were characterized by spectroscopic methods and by elemental analysis. The molecular structures of 4, 6, 10, 14, 15, 19, and 20 were determined by X‐ray crystallographic analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
