A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis And Characterization
A Site-Isolated Iridium Diethylene Complex Supported on Highly Dealuminated Y Zeolite: Synthesis And Characterization
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DOI：
10.1021/jp073338p
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发表时间：
2007-09
影响因子：
3.7
通讯作者：
Alper Uzun;Vinesh A. Bhirud;Philip W. Kletnieks-;J. F. Haw;B. Gates
中科院分区：
文献类型：
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作者：
Alper Uzun;Vinesh A. Bhirud;Philip W. Kletnieks-;J. F. Haw;B. Gates
通过化学吸附Ir(C{sub 2}H{sub 4}){sub 2}(C{sub 5}H{sub 7}O{sub 2})，合成了具有活性乙烯配体的高脱铝Y沸石负载的单核铱配合物。用红外光谱（IR）和扩展x射线吸收精细结构（EXAFS）研究了产物的结构及其在He、CO、乙烯和H2中的处理。红外光谱表明，IR (C{sub 2}H{sub 4}){sub 2}（C{sub 5}H{sub 7}O{sub 2}）与沸石表面OH基团反应迅速，导致C{sub 5}H{sub 7}O{sub 2}配体去除，形成支撑的单核铱配合物，这一点在EXAFS光谱中没有IR - IR贡献。EXAFS数据表明，每个Ir原子与4个碳原子的平均距离为2.10{埃}，这与每个Ir原子存在2个乙烯配体一致，与表明{pi}键合乙烯配体的红外光谱一致。EXAFS数据还表明，每个Ir原子与沸石的两个氧原子在2.15{埃}的距离上键合。负载的铱-乙烯配合物与H{sub 2}反应生成乙烷，并在常压和294 K下催化乙烯加氢。在CO中处理样品导致形成Ir(CO){submore»2}配合物与沸石结合。V{sub CO}波段的锐度表明这些配合物在载体上的高度均匀性。在沸石载体上的铱-乙烯配合物是最接近均匀负载的金属配合物催化剂之一。结果表明，它与先前报道的在同一沸石上的铑配合物是同构的；因此，这些结果是一个类似的，结构明确的支撑金属络合催化剂家族的开始。«少
Highly dealuminated Y zeolite-supported mononuclear iridium complexes with reactive ethylene ligands were synthesized by chemisorption of Ir(C{sub 2}H{sub 4}){sub 2}(C{sub 5}H{sub 7}O{sub 2}). The resultant structure and its treatment in He, CO, ethylene, and H2 were investigated with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The IR spectra show that Ir(C{sub 2}H{sub 4}){sub 2}(C{sub 5}H{sub 7}O{sub 2}) reacted readily with surface OH groups of the zeolite, leading to the removal of C{sub 5}H{sub 7}O{sub 2} ligands and the formation of supported mononuclear iridium complexes, confirmed by the lack of Ir-Ir contributions in the EXAFS spectra. The EXAFS data show that each Ir atom was bonded to four carbon atoms at an average distance of 2.10 {angstrom}, consistent with the presence of two ethylene ligands per Ir atom and in agreement with the IR spectra indicating {pi}-bonded ethylene ligands. The EXAFS data also indicate that each Ir atom was bonded to two oxygen atoms of the zeolite at a distance of 2.15 {angstrom}. The supported iridium-ethylene complex reacted with H{sub 2} to give ethane, and it also catalyzed ethylene hydrogenation at atmospheric pressure and 294 K. Treatment of the sample in CO led to the formation of Ir(CO){submore » 2} complexes bonded to the zeolite. The sharpness of the V{sub CO} bands indicates a high degree of uniformity of these complexes on the support. The iridium-ethylene complex on the crystalline zeolite support is inferred to be one of the most nearly uniform supported metal complex catalysts. The results indicate that it is isostructural with a previously reported rhodium complex on the same zeolite; thus, the results are a start to a family of analogous, structurally well-defined supported metal complex catalysts.« less