Catalytic Reductive Coupling of 9-Bromofluorene

The reductive homocoupling of 9-bromofluorene is catalyzed by 0.1 mol % Ru₃(CO)₁₂ in refluxing xylene, with a TON in excess of 3000. A stoichiometric reaction affords the novel cluster Ru₄(μ₃-OMe)(μ₃-OH)(μ-Br)₂(CO)₁₀, which is found to be even more catalytically active. Further reaction of this cluster with bromofluorene gives another novel cluster, Ru₄(μ₄-O)(μ-Br)₆(CO)₈, which is inactive.