Poison or Promoter? Investigating the Dual-Role of Carbon Monoxide in Pincer-Iridium-Based Alkane Dehydrogenation Systems via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy
Poison or Promoter? Investigating the Dual-Role of Carbon Monoxide in Pincer-Iridium-Based Alkane Dehydrogenation Systems via Operando Diffuse Reflectance Infrared Fourier Transform Spectroscopy
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毒药还是促进剂？
DOI：
10.1021/acscatal.0c02406
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发表时间：
2020
期刊：
影响因子：
12.9
通讯作者：
Celik, Fuat E.
中科院分区：
文献类型：
--
作者：
Sheludko, Boris;Castro, Cristina F.;Goldman, Alan S.;Celik, Fuat E.
[(R4PCP)IrL]形式的螯合铱配合物（R4PCP = κ3-C6H3-2,6-(XPR2)2）；X = ch2, 0；R =tBu,iPr)先前已被证明在二氧化硅上负载时能进行无受体烷烃脱氢。催化后固态核磁共振观察到硅系[(≡SiO-tBu4POCOP)Ir(C2H4)] （3-C2H4）在300℃下完全转化为[(≡SiO-tBu4POCOP)Ir(CO)] （3-CO）。在这项工作中，在远离丁烷和丁烯平衡的脱氢反应条件下（在300°C时接近平衡q /Keq= 0.3），使用operando漫反射红外傅立叶变换光谱（DRIFTS）进行了物种表征，以显示从3- c2h4到3- co的物种转化动力学。进一步发现[(≡SiO-tBu4POCOP)IrHCl] （3-HCl）被认为是烷烃脱氢的预催化剂，也完全转化为3- co。提出了一种涉及表面硅醇基团的分解机制，而一氧化碳通过促进其还原消除并维持络合物处于I氧化态来作为催化剂的“稳定剂”。
Pincer-ligated iridium complexes of the form [(R4PCP)IrL] (R4PCP = κ3-C6H3-2,6-(XPR2)2; X = CH2, O; R =tBu,iPr) have previously been shown competent for acceptorless alkane dehydrogenation when supported on silica. It was observed by postcatalysis solid-state NMR that silica-tethered [(≡SiO-tBu4POCOP)Ir(C2H4)] (3-C2H4) was converted fully to [(≡SiO-tBu4POCOP)Ir(CO)] (3-CO) at 300 °C. In this work, the characterization of species under dehydrogenation reaction conditions far from equilibrium between butane and butenes (approach to equilibriumQ/Keq= 0.3 at 300 °C) is performed with operando Diffuse Reflectance Infrared Fourier–Transform Spectroscopy (DRIFTS) to show the kinetics of species conversion from3-C2H4to3-CO. It is further found that [(≡SiO-tBu4POCOP)IrHCl] (3-HCl), a species considered to be a precatalyst for alkane dehydrogenation, is also fully converted to3-CO. A mechanism of decomposition is proposed that implicates surface silanol groups, while carbon monoxide acts as a “stabilizer” for the catalyst by promoting their reductive elimination and maintaining the complex in the I oxidation state.
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影响因子：
15
作者：
Göttker-Schnetmann, I;White, P;Brookhart, M
通讯作者：
Brookhart, M
影响因子：
5.4
作者：
Ito, Jun-ichi;Shiomi, Takushi;Nishiyama, Hisao
通讯作者：
Nishiyama, Hisao
三苯基膦对含铱、铑、铂多相催化剂饱和烃脱氢活性的影响
影响因子：
2.3
作者：
I. K. Böhmer;H. Alt
通讯作者：
H. Alt
影响因子：
2.8
作者：
Riache, Nassima;Dery, Alexandre;Basset, Jean-Marie
通讯作者：
Basset, Jean-Marie
Heck 催化过程中束缚钯 (II) 钳配合物稳定性的研究
影响因子：
2.8
作者：
W. Sommer;Kunquan Yu;J. Sears;Yaying Ji;Xiaolai Zheng;R. Davis;C. Sherrill;†‡ and Christopher W. Jones;M. Weck
通讯作者：
M. Weck