Catalytic reductive coupling of 9-bromofluorene

The reductive homocoupling of 9-bromofluorene is catalyzed by 0.1 mol % Ru 3 (CO) 12 in refluxing xylene, with a TON in excess of 3000. A stoichiometric reaction affords the novel cluster Ru 4 (μ 3 -OMe)-(μ 3 -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, Ru 4 (μ 4 -O)(μ-Br) 6 (CO) 8 , which is inactive.