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

Abstract

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 Ru₃ triangle containing a C₄ chain 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 Ru₅ bent chain in 4 and a spiked butterfly in 5.