Facile and Reversible Formation of Iron(III)-Oxo-Cerium(IV) Adducts from Nonheme Oxoiron(IV) Complexes and Cerium(III).

ABSTRACT: Ceric ammonium nitrate (CAN) or CeIV (NH4 )2 (NO3 )6 is often used in artificial water oxidation and generally considered to be an outer-sphere oxidant. Herein we report the spectroscopic and crystallographic characterization of [(N4Py)FeIII -O-CeIV (OH2 )(NO3 )4 ]+ (3), a complex obtained from the reaction of [(N4Py)FeII (NCMe)]2+ with 2?equiv CAN or [(N4Py)FeIV =O]2+ (2) with CeIII (NO3 )3 in MeCN. Surprisingly, the formation of 3 is reversible, the position of the equilibrium being dependent on the MeCN/water ratio of the solvent. These results suggest that the FeIV and CeIV centers have comparable reduction potentials. Moreover, the equilibrium entails a change in iron spin state, from S=1 FeIV in 2 to S=5/2 in 3, which is found to be facile despite the formal spin-forbidden nature of this process. This observation suggests that FeIV =O complexes may avail of reaction pathways involving multiple spin states having little or no barrier.

SUBMITTER: Draksharapu A 

PROVIDER: S-EPMC5598155 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature