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(mu(3)-OMe)(mu(3)-OH)(mu-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(mu(4)-O)(mu-Br)(6)(CO)(8), which is inactive.