Syntheses and Characterization of Ruthenium Complexes Containing a Doubly Linked Dicyclopentadienyl Ligand and Acetonitrile Ligands

The reaction of a mixture of isomers of 4,4,8,8-tetramethyl-tetrahydro-s-indacene (1) with Ru3(CO)12 afforded cis-{(η5-C5H3)2(CMe2)2}Ru2(CO)4, (2) in 68% yield. Reaction of 2 with Br2 gave cis-{(η5-C5H3)2(CMe2)2}Ru2(CO)4Br2 (3) in 88% yield. Reaction of 3 with AgOTf yields cis-[{(η5-C5H3)2(CMe2)2}Ru2(CO)4(μ-Br)][OTf] (4), while reaction of 3 with Me3NO and AgOTf yields cis-[{(η5-C5H3)2(CMe2)2}Ru2(CO)2(MeCN)2(μ-Br)][OTf] (5). Reaction of 3 under more forcing conditions with AgOTf in MeCN gave cis-[{(η5-C5H3)2(CMe2)2}Ru2(CO)2(MeCN)4][OTf]2 (6), while a MeCN/C6H6 solvent combination afforded cis-[{(η5-C5H3)2(CMe2)2}Ru2(η6-C6H6)2][OTf]2 (7) in a 64% yield. Removal of the benzene ligands in 7 can be accomplished by first adding H− to the coordinated benzene ligands to afford cis-{(η5-C5H3)2(CMe2)2}Ru2(η5-C6H7)2 (10). Subsequent protonation of 10 in MeCN afforded [cis-{(η5-C5H3)2(CMe2)2}Ru2(MeCN)6][OTf]2 (8) in 88% yield. Structural data for 4, 5, 7, and 10 are reported.