Nature of the Metal-cyclopentadienyl Bonding in Some Organometallic Molecules

Abstract

SINCE the discovery of ferrocene, bis-π-cyclopentadienyl-iron, the cyclopentadienyl ligand has been used in the preparation of a large number of organometallic compounds. Its π-bonded complexes have often been described by fairly sophisticated theories, although one difficulty in assessing the value of the various structural models has been the lack of precise values of molecular parameters; even in ferrocene, disorder in the crystal¹ makes an accurate determination of carbon–carbon bond lengths somewhat difficult. Recently we have investigated the molecular structures of a number of organo-metallic compounds, and details of the molecular geometries, as we require them for the present discussion, are shown in Fig. 1.