International Collaboration in Chemistry: A Combined Experimetal and Theoretical Study of Redox-Active Fe4O4-Cubanes

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor Raphael G. Raptis at the University of Puerto Rico to investigate an octanuclear iron cluster, which contains an Fe4O4 cubane core surrounded by four peripheral FeIII centers and would extend studies to the 1-, 2-, 3- and 4-electron reduced analogues. The goal is to characterize each of the mixed-valent states spanning the Fe(III)8 and Fe(III) 4Fe(II)4 limits observed in the electrochemical experiment. The focus at the University of Puerto Rico will be on the synthesis of new clusters capable of supporting the more highly reduced oxidation levels and their characterization using a wide range of physicochemical techniques. Voltammetry, diffraction, in situ UV-Vis-NIR spectroelectrochemistry and XPS will be conducted in-house, while magnetochemical properties, EPR and Mossbauer spectra will be measured in the laboratories of established collaborators who are leaders in their fields. The research team at the University of Glasgow will explore the electronic structure of these compounds using broken-symmetry density functional theory. The aim is to maximize the information content of the physicochemical measurements by establishing a direct correspondence between observation and the underlying electronic structureThe Fe8 clusters described in this proposal offer a unique opportunity to study mixed valence in a discrete molecular species across an unprecedented range of oxidation states. This project will link established research programms at the University of Puerto Rico and the University of Glasgow, both of which focus on the structure of paramagnetic metal clusters. The opportunity for young researchers to exchange complementary ideas and expertise through extended stays in international laboratories is a key element of the research programs, and will help to establish long-lasting links between the two groups. This International Collaborative Chemistry research project is supported jointly by NSF and the Engineering and Physical Sciences Research Council (EPSRC) in the United Kingdom. The study is also supported by the Office of International Science and Engineering (OISE) at NSF.