C – C coupling of ethyne to the carbido ligand in products from reactions with Ru5(μ5[sbnd]C)(CO)15

Abstract

The reaction of Ru5(μ5-C)(CO)15, 1 with C2H2 at 48 °C for 60 h yielded four new pentaruthenium carbonyl cluster compounds: Ru5[μ5-η5-CC(H)C(H)C(H)C(H)](CO)13(μ4-η2-HCCH), 2; Ru5[μ4-η5-CC(H)C(H)C(H)C(H)](CO)12(μ4-η2-HCCH), 3; Ru5(CO)13[μ4-η7-C(H)C(H)CC(H)C(H)C(H)C(H)], 4 and Ru4(CO)11(μ4-η2-HCCH)Ru(CO)3(μ-η1-η5-C5H4), 5. Compounds 2 and 3 were formed by opening of the Ru5 cluster of 1, the addition of three equivalents of C2H2, two of which became coupled to each other and to the carbido ligand of 1 to form bridging CC(H)C(H)C(H)C(H), pentadienyl ligands. Compounds 2 and 3 also contain a quadruply-bridging a η2-HCCH ligand. Compound 4 contains an open Ru5 cluster, in which three equivalents of C2H2 were coupled to each other and to the carbido ligand of 1 to form a quadruply-bridging heptadienyl η7-C(H)C(H)CC(H)C(H)C(H)C(H) ligand. Compound 5 contains a butterfly-tetrahedral Ru4 cluster with a quadruply-bridging a η2-HCCH ligand and a Ru(CO)3(μ-η1-η5-C5H4) grouping containing a metalated-cyclopentadienyl ligand that is linked to one of the wing-tip Ru atoms of the Ru4 cluster. The metalated-cyclopentadienyl ligand in 5 is believed to have been formed by a cyclization of the bridging, CC(H)C(H)C(H)C(H), pentadienyl ligand in compound 2. All new compounds were characterized by single-crystal X-ray diffraction analyses.