Characterization of the absorption and magnetic circular dichroism spectra from the near infrared to the near ultraviolet region of high spin Fe(III) haeme-fluoride

A description is given of the absorption and temperature dependent magnetic circular dichroism of high spin ferric haeme-fluoride, from the near infrared to the Soret region. The model used leads to functions, for the bands at 605 and 520 nm, that consist of equal amounts of π → π* and charge transfer character. This gives an explanation for the discrepancy between the assignment of the Q-band to the 520 nm band [1, 2] and to the 605 nm band [3, 4]. The calculated vibronically-induced intensity for the 0–1 components of these bands is in agreement with the observed optical density. Expressions are given for the magnetic circular dichroism of the vibronically induced bands.