An electrochemical investigation of several complexes of the type Ru(I
I)Cp(Ar) and Rh(III)Cp*(Ar) (Cp* = eta(5)-pentamethylcyclopentadienyl
, Ar = aromatic ring) has been performed. The electrochemical results,
although very complicated from a mechanistic point of view, nonethele
ss suggest a possible application of RuCp and RhCp* fragments as labe
ls of steroids for polarographic assay.