Amino-substituted cyclopentadienyl cobalt complexes

Reduction of the (η1,η5-R2NC2H4C5Me4)CoCl complexes (R=Me, R2=cyclo-C4H8), prepared by treating CoCl2 with 2-dimethylaminoethyl- or 2-pyrrolidinylethyl-tetramethylcyclopentadienyl-lithium, with active-Mg in the presence of ethylene or dienes leads to the formation of (η5-R2NC2H4C5Me4)(CH2:CH2)2Co(I) or (η5-R2NC2H4C5Me4)(diene)Co(I) complexes. These react with ethereal HBF4 with protonation of the amine followed, in the case of the diene complexes, by transfer of the proton to the diene to give (η1,η5-R2NC2H4C5Me4)(η3-allyl)Co(III)-salts.