Ligand substitution behavior of Ru6(μ6-C)(CO)17 with unsaturated diphosphines: facile capping of a polyhedral face and photochemically promoted P–C bond cleavage in the clusterRu6(μ6-C)(CO)14(μ3-bpcd)

Abstract

The ligand substitution chemistry of the hexaruthenium cluster Ru(6)(mu(6)-C)(CO)(17) () with several unsaturated diphosphine ligands has been investigated. Thermolysis of with (Z)-Ph(2)PCH[double bond, length as m-dash]CHPPh(2) (dppen) furnishes the new cluster compounds Ru(5)(mu(5)-C)(CO)(12)(mu(3)-dppen) (), Ru(6)(mu(6)-C)(CO)(14)(mu(3)-dppen) (), and Ru(6)(mu(6)-C)(CO)(12)(mu(3)-dppen)(mu-dppen) (). Clusters and are also obtained when a mixture of and dppen is treated with the oxidative-decarbonylation reagent Me(3)NO. Thermolysis or Me(3)NO activation of 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) () as the sole observable product. Near-UV irradiation of leads to P-C bond cleavage and the formation of phosphido-bridged cluster Ru(6)(mu(6)-C)(CO)(13)[mu(3)-C[double bond, length as m-dash]C(PPh(2))C(O)CH(2)C(O)](mu-PPh(2)) () in essentially quantitative yield. The reaction between 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) (), which exists as a single diastereomer in solution as shown by (1)H and (31)P NMR spectroscopy. The molecular structures and the binding mode of the ancillary diphosphine ligand(s) in have all been established by X-ray diffraction analyses. The solid-state structure of 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 and the related diphosphine ligands dppm, dppe, dppf, and dppbz.