Abstract
The ligand substitution chemistry of the hexaruthenium cluster Ru-6(mu(6)-C)(CO)(17) (1) with several unsaturated diphosphine ligands has been investigated. Thermolysis of 1 with (Z)-Ph2PCH=CHPPh2 (dppen) furnishes the new cluster compounds Ru-5(mu(5)-C)(CO)(12)(mu(3)-dppen) (2), Ru-6(mu(6)-C)(CO)(14)(mu(3)-dppen) (3), and Ru-6(mu(6)-C)(CO)(12)(mu(3)-dppen)(mu-dppen) (4). Clusters 2 and 3 are also obtained when a mixture of 1 and dppen is treated with the oxidative-decarbonylation reagent Me3NO. Thermolysis or Me3NO activation of 1 in the presence of 4,5-bis(diphenylphosphino)-4-cyclopenten- 1,3-dione (bpcd) yields Ru-6(mu(6)-C)(CO)(14)(mu(3)-bpcd) (4) as the sole observable product. Near-UV irradiation of 4 leads to P-C bond cleavage and the formation of phosphido-bridged cluster Ru-6(mu(6)-C)(CO)(13)[mu(3)-C=C(PPh2)C(O)CH2C(O)](mu-PPh2) (6) in essentially quantitative yield. The reaction between 1 and the ligand 3,4-bis(diphenylphosphino)-5-methoxy-2(5H)-furanone (bmf) leads to the formation of Ru-6(mu(6)-C)(CO)(14)(mu(3)-bmf) (7), which exists as a single diastereomer in solution as shown by H-1 and P-31 NMR spectroscopy. The molecular structures and the binding mode of the ancillary diphosphine ligand(s) in 2-7 have all been established by X-ray diffraction analyses. The solid-state structure of 7 reveals that the chiral bmf ligand caps one of the metallic faces stereospecifically with the 5-methoxy moiety oriented distal or trans relative to the Ru-6 polyhedral core. The new substitution products are discussed relative to the products obtained from 1 and the related diphosphine ligands dppm, dppe, dppf, and dppbz.
