Electronic Spectra of Tetraphenylporphinatoiron(III) Methoxide

Abstract

Abstract Tetraphenylporphinatoiron(III) methoxide in the high-spin state S=5⁄2 gives rise to an absorption spectrum which has been assigned to that of low-spin iron(III) porphyrins. The excited states characteristic of the spectrum of high-spin iron(III) porphyrins are the configuration-interaction admixtures of the lowest triplet and singlet porphyrin (π,π*) excited states and the low-lying “porphyrin to iron (III)” charge-transfer excited states. The charge-transfer excited states in tetraphenylporphinatoiron(III) methoxide, however, are so high that the chargetransfer excited states are not sufficiently mixed with the lowest triplet (π,π*) excited states. Thus the high-spin methoxo complex does not exhibit a spectrum characteristic of high-spin iron(III) porphyrins.