Studies of the bonding in iron( II ) cyclopentadienyl and arene sandwich compounds. Part 1. An interpretation of the iron-57 Mössbauer data

A qualitative approach to the understanding of substituent effects in iron(II) sandwich compounds containing five- and six-membered rings is described. In particular, this approach highlights the differences between the symmetric, bis(arene)- and bis(cyclopentadienyl)-, and the asymmetric, mixed arene–cyclopentadienyl-iron(II) complexes. The results are discussed with respect to their chemical and physical properties and 57 Fe Mössbauer spectra.