In Situ X‐ray Absorption Spectroscopy and Nonclassical Catalytic Hydrogenation with an Iron(II) Catecholate Immobilized on a Porous Organic Polymer. Issue 22 (12th July 2013)

• Record Type: Journal Article
• Authors: Kraft, Steven J.; Hu, Bo; Zhang, Guanghui; Miller, Jeffrey T.; Hock, Adam S.
• Other Names: Lu Connie C. sponsoringEditor.; Meyer Karsten sponsoringEditor.
• Is Part Of: European journal of inorganic chemistry. Issue 22/23(2013)
• Page Start: 3972
• Page End: 3977
• Publication Date: 2013-07-12
• Subjects: Heterogeneous catalysis -- Hydrogenation -- Porous organic polymers -- Catechol -- Iron; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201300528
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The oxidation state and coordination number of immobilized iron catecholate EtO2 Fe(CAT‐POP) were determined by X‐ray absorption spectroscopy (XAS) under a variety of conditions. We find the as‐prepared material to be three‐coordinate Fe 2+ that readily oxidizes to Fe 3+ upon exposure to air but remains three‐coordinate. Both the reduced and oxidized Fe(CAT‐POP) catalyze olefin hydrogenation in batch and flow reactors. We determined the catalytic rates for both species and also observed by means of XAS that the oxidation state of the iron centers does not change in hydrogen at the reaction temperature. Therefore, we postulate that the mechanism of hydrogenation by Fe(CAT‐POP) proceeds through one of several possible nonclassical mechanisms, which are discussed. Abstract : We have characterized an iron catecholate catalyst immobilized on a 3‐dimensional porous polymer by in situ X‐ray absorption spectroscopy. The oxidation state of Fe under a dihydrogen atmosphere is +2, but it readily is oxidized to Fe 3+ upon exposure to ambient air. The Fe 2+ material in hydrogen at 150 °C catalyzes the hydrogenation of olefins. Potential mechanisms for this nonclassical catalysis are discussed.