Recently, Fillol, Costas and co-workers identified a putative intermediate, [(mcp)FeIV(O)(µ–O)CeIV(H2O)] (mcp = (N,N’-dimethyl-N,N’-bis(2-pyridylmethyl)-1,2-cis-diaminocyclohexane) spectroscopically which is proposed to be relevant to water oxidation catalysis and could serve as a synthetic analogue to the oxygen evolving complex in photosystem II. We report the synthesis and spectroscopic characterization of similar heterobimetallic species (L)FeIII–O–CeIV(OH2) (L = BnTPEN, N4Py or MeN4Py) and their equilibria with [(L)FeIV=O]2+ species. The reactions of [(L)FeIV=O]2+ complexes with CeIII(NO3)3 generate (L)FeIII–O–CeIV(OH2) species have been characterized by various spectroscopic techniques including UV/Vis absorption, resonance Raman and EPR spectroscopies as well as X-ray crystallography. The existence of heterobimetallic species in the solution was further supported by XAS analysis of solutions of the complexes. The reaction of an (L)FeII precursor with cerium ammonium nitrate generates the FeIII–O–CeIV species. Upon titration with water or HClO4, the heterobimetallic species form the corresponding [(L)FeIV=O]2+ and CeIII. Taken together these results support that the [(L)FeIV=O]2+ and FeIII–O–CeIV in equilibrium and that [(L)FeIV=O]2+ and CeIII react via inner sphere electron transfer. A detailed discussion on synthesis, characterization and application of these novel intermediates will be presented in this presentation.

Reversible formation an FeIII–O–CeIV intermediate from the reaction of FeIV=O and CeIII

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.