Cyclopentadienide Ligand CpC– Possessing Intrinsic Helical Chirality and Its Ferrocene Analogues

The novel chiral cyclopentadiene-type ligand CpCH is accessible from dibenzosuberenone in a five-step sequence with overall yields of 64%. NMR spectroscopy as well as DFT calculations prove that the racemization of this compound is slow at room temperature. By deprotonation of CpCH and subsequent reaction with appropriate iron­(II) precursors, the novel ferrocene derivatives (CpC)2Fe and (CpC)­Fe­(4Cp) are accessible in good yields. The latter could structurally be characterized by means of single-crystal X-ray crystallography. Mössbauer spectroscopy proves the ferrocene nature of (CpC)2Fe and (CpC)­Fe­(4Cp), and electrochemical investigations carried out with (CpC)­Fe­(4Cp) show that the compound is, as expected, more easily oxidized than ferrocene.