Formation of Red Elemental Selenium from Seleniferous Oxyanions: Deoxygenation by a Homogeneous Iron Catalyst
Kelly L. Gullett, Courtney L. Ford, Ian J. Garvey, Tabitha J. Miller, Clare A. Leahy, Lisa N. Awaitey, Daniel Hofmann, Toby J. Woods, Alison R. Fout
Abstract
Seleniferous oxyanions are groundwater contaminants from both anthropogenic and natural sources, while pure amorphous selenium nanoparticles have a variety of industrial applications. Biology can achieve the multicomponent 6 e – /8 H + reduction of selenate to amorphous selenium using multiple metalloenzymes, like selenate and selenite reductase. Inspired by biology, we developed a new homogeneous system that can generate pure elemental selenium with no caustic waste. The stoichiometric reductions of selenate, selenite, and selenium dioxide with an iron(II) complex produced an iron(III)-oxo and red elemental selenium, the latter of which has been characterized by a variety of spectroscopic techniques. The catalytic reduction of SeO 4 2– and SeO 3 2– directly to amorphous Se and isolated as Se=PPh 3 is reported with a turnover number of 12 and 7, respectively.