On the Reaction of Pentamethylcyclopentadiene with Cobalt Atoms: A Reexamination

[Cp Co 2 ] is still unknown. The compound reported a year ago as [Cp Co 2 ] ( Angew. Chem. Int. Ed. Engl. 1991 , 103 , 1124) is, in fact, [Cp Co 2 H 3 ]. [Cp Co 3 H 4 ], the major component of the eluate of the chromatography after removal of a mononuclear sandwich complex, was not identified at that time.