In quest of ruthenium complexes having [RuN 3S 2] cores, a non-flexible configuration, trans-thiolate donors and exchangeable coligand L, [Ru(L)(pyN 2H 2S 2)] complexes have been synthesized [ pyN 2 H 2 S 2 2 - = 2 , 6 - bis ( 2 - mercaptophenylaminomethyl ) pyridine ( 2 - ) ] . Treatment of [RuCl 2(CH 3CN) 4] with pyN 2 H 2 S 2 2 - gave [Ru(py)(pyN 2H 2S 2)] ( 1). The pyridine coligand in 1 proved to be labile and could be substituted by either CO or DMSO under normal conditions to give [Ru(CO)(pyN 2H 2S 2)] ( 2) and [Ru(DMSO)(pyN 2H 2S 2)] ( 3), respectively. Alternatively, 2 could be obtained directly from [RuCl 2(CH 3CN) 4] and pyN 2 H 2 S 2 2 - in the presence of CO, whereas the reaction in the absence of CO gave the dinuclear [Ru(pyN 2H 2S 2)] 2 ( 8). Treatment of either 2 or 3 with NOBF 4 afforded [Ru III(CO)(pyN 2H 2S 2)]BF 4 ([ 4]BF 4) and [Ru(NO)(pyN 2H 2S 2)]BF 4 ([ 5]BF 4), respectively. Treatment of [ 5]BF 4 with either NEt 4N 3 or N 2H 4 afforded the amide [Ru(NO)(pyN 2HS 2)] ( 6) and the hydrazine [Ru(N 2H 4)(pyN 2H 2S 2)] ( 7), respectively. Treatment of the dinuclear 8 with either one or two equivalents of NOBF 4 afforded the mixed-valence diruthenium (II,III) [Ru IIIRu II(pyN 2H 2S 2) 2]BF 4 ([ 9]BF 4) and the diruthenium (III) [Ru IIIRu III(pyN 2H 2S 2) 2](BF 4) 2 {[ 10](BF 4) 2}, respectively. The diruthenium (III) complex [ 10](BF 4) 2 is diamagnetic, which can be ascribed to spin–spin pairing between the two Ru III atoms. A preliminary structure determination of [ 10](BF 4) 2 supports this observation, indicating a single bond between the two Ru III atoms. Novel diruthenium complex of this type could be synthesized more generally by treatment of [RuCl 3(MeSPh) 3] with pyN 2 H 2 S 2 2 - . All complexes were characterized by spectroscopic methods and elemental analysis. The cations [ 9] + and [ 10] 2+ were characterized by X-ray structure analysis.