Magnetic circular dichroism spectra of bis(η-cyclopentadienyl)-iron and-ruthenium

Abstract

The electronic and magnetic circular dichroism (m.c.d.) spectra of the title compounds, ferrocene and ruthenocene, have been measured in solution. Perspex films, and inert-gas matrices. Extensive calculations of the m.c.d. parameters for the d–d transitions, assuming a vibronic mechanism, are reported. The results of these calculations predict that the d–d transition should be dominated by A terms with only very weak B terms. However experimentally, the m.c.d. spectra show very strong B terms with only one weak A term of the opposite sign to that expected from the calculations. The experimental results are most reasonably explained by inclusion of significant ligand character into the d orbitals.