Abstract
[CpCo2] is still unknown. The compound reported a year ago as [Cp Co2] (Angew. Chem. Int. Ed. Engl. 1991, 103, 1124) is, in fact, [CpCo2H3]. [CpCo3H4], the major component of the eluate of the chromatography after removal of a mononuclear sandwich complex, was not identified at that time.