The homonuclear cobalt cluster [(η5-Cp*)Co]3H4 2 reacts with various organic and inorganic substrates with complete degradation of the cluster core to afford mainly mononuclear organometallic cobalt compounds. Thus, whereas reaction of the cluster with CO, NO or alkynes results in the retention of the Co3 ring, the cluster reacts with Br2, I2, I2/CO , I2/ P(C 2H5)3, CCl4, HCI3, (CH2)2Br2, Hacac, CH2Br2, (C6H5CO)OOC(CH3)3, HBF4, and BrCN to give mononuclear complexes or bridged dinuclear complexes without a metal-metal bond. In all cases formal oxidation of the metal center is observed. The crystal structures of six organocobalt complexes have been determined by X-ray crystallography.