Mixed-valent diruthenium half-sandwich complex containing two chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligands: Reactivity toward (cyclo-C6H10)(OH)Ctriple bond; length of mdashCH and PhC(O)Ctriple bond; length of mdashCH

The reaction of (p-cymene)Ru2(μ-S2)(S2C2B10H10)2 (1) with (cyclo-C6H10)(OH)Ctriple bond; length of mdashCH at ambient temperature leads to the alkyne addition complexes, (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(R1Cdouble bond; length as m-dashCR2) (R1 = (cyclo-C6H10)(OH), R2 = H (2); R1 = H, R2 = (cyclo-C6H10)(OH) (3)). In boiling chloroform the added alkynes in both 2 and 3 spontaneously lose water to generate two geometrical isomers (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(R3Cdouble bond; length as m-dashCR4) (R3 = cyclo-C6H9, R4 = H (4); R3 = H, R4 = cyclo-C6H9 (5)), respectively. In boiling toluene, 4 and 5 could be interconverted. In contrast, the reaction of 1 with PhC(O)Ctriple bond; length of mdashCH gives rise to (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(R5Cdouble bond; length as m-dashCR6) (R5 = PhCO, R6 = H (6); R5 = H, R6 = PhCO (7)) and (p-cymene)Ru2(μ-S2)(S2C2B10H10)2(PhC(O)Cdouble bond; length as m-dashCH) (CHdouble bond; length as m-dashCHC(O)Ph) (8). In 2–7 alkyne addition occurs at the sulfur atoms of the two individual chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligands that leads to a change of the 16e Ru(IV) center in 1 to the 18e Ru(II) center. In 8 one additional reduced alkyne is added to the other sulfur atom of one 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand that leads to the central 19e Ru(I). All the new complexes were characterized by elemental analysis, mass, and NMR spectroscopy. X-ray structural analyses were performed on 2–4 and 8.