Synthesis and structural characterization of ruthenium carbonyl clusters containing acetylenic fluorene moieties derived from 9-ethynylfluoren-9-ol

Five new ruthenium fluorene clusters, [Ru3(CO)9(μ-H){μ3-η1:η2:η2-CC(C13H9)}] 1 (8%), [Ru3(CO)7(μ-CO){μ3-η1:η2:η4-(HOC13H8)CCHC(C13H8OH)CH}] 2 (15%), [Ru4(CO)10(μ-CO)(μ3-OH)(μ3-η1:η2:η2-C13H8CCH)] 3 (12%), [Ru5(CO)11(μ-H)(μ-CO)(μ3-OH)(μ5-η1:η1:η2:η2:η6-C13H7CHC)] 4 (10%) and [Ru6(CO)15(μ5-η1:η1:η2:η3:η6-C13H7CHC)] 5 (9%), have been synthesized by a reaction of 9-ethynylfluoren-9-ol with triruthenium dodecacarbonyl in tetrahydrofuran under reflux. All these compounds have been fully characterized by spectroscopic and X-ray diffraction methods. The structure of 1 consists of a fluorene ring bound to the triruthenium cluster unit via a typical μ3-( η2-⊥) co-ordination mode. Cluster 2 is based on a Ru3triangle containing a C4chain which arises from the coupling of two ligand molecules with the formation of a metallacyclopentadiene ring. An interesting structural feature observed in cluster 3 is the formation of a Ru4O square pyramidal framework in which the hydroxy group, originating from the ligand, is bound to the cluster in a triply bridging manner. The bonding modes of the organic fragments in 4 and 5 are very similar. They both interact with five ruthenium metal centres but with a novel Ru5bent chain in 4 and a spiked butterfly in 5.