Electronic structure of ferricenium ion from absorption, MCD, and ESR studies

Abstract

The absorption and MCD spectra of the ferricenium ion have been measured at 290 and 9 °K. The data have been used, together with 20 °K ESR spectra to obtain quantitative information about the ground state of this molecule. The ground state emerges as a E‴(²E_g) state into which is mixed the E″(²E_g) state via a low symmetry perturbation. Evaluation of this from ESR and MCD data yield the values δ = 1043 cm⁻¹ at 20 °K and δ = 263 cm⁻¹ at 290 °K. The MCD strongly confirms the assignment of the electronic absorption band at 16 200 cm⁻¹ as ²E_2g → ²E_1u.