Liang Ann J, Bhirud Vinesh A, Ehresmann Justin O, Kletnieks Philip W, Haw James F, Gates Bruce C
Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616, USA.
J Phys Chem B. 2005 Dec 29;109(51):24236-43. doi: 10.1021/jp054623g.
The reaction of Rh(C2H4)2(acac) with the partially dehydroxylated surface of dealuminated zeolite Y (calcined at 773 K) and treatments of the resultant surface species in various atmospheres (He, CO, H2, and D2) were investigated with infrared (IR), extended X-ray absorption fine structure (EXAFS), and 13C NMR spectroscopies. The IR spectra show that Rh(C2H4)2(acac) reacted readily with surface OH groups of the zeolite, leading to loss of acac ligands from the Rh(C2H4)2(acac) and formation of supported mononuclear rhodium complexes, confirmed by the lack of Rh-Rh contributions in the EXAFS spectra; each Rh atom was bonded on average to two oxygen atoms of the zeolite surface with a Rh-O distance of 2.19 A. IR, EXAFS, and 13C NMR spectra show that the ethylene ligands remained bonded to the Rh center in the supported complex. Treatment of the sample in CO led to the formation of site-isolated Rh(CO)2 complexes bonded to the zeolite. The sharpness of the nu(CO) bands in the IR spectrum gives evidence of a nearly uniform supported Rh(CO)2 complex and, by inference, the near uniformity of the mononuclear rhodium complex with ethylene ligands from which it was formed. The supported complex with ethylene ligands reacted with H2 to give ethane, and it also catalyzed ethylene hydrogenation at 294 K.
采用红外光谱（IR）、扩展X射线吸收精细结构（EXAFS）和13C核磁共振光谱（NMR）研究了Rh(C2H4)2(acac)与脱铝Y型沸石部分脱羟基表面（在773K下煅烧）的反应，以及所得表面物种在各种气氛（He、CO、H2和D2）中的处理情况。红外光谱表明，Rh(C2H4)2(acac)与沸石的表面羟基容易反应，导致Rh(C2H4)2(acac)中的acac配体损失，并形成负载型单核铑配合物，EXAFS光谱中缺乏Rh-Rh贡献证实了这一点；每个Rh原子平均与沸石表面的两个氧原子键合，Rh-O距离为2.19 Å。红外光谱、EXAFS光谱和13C NMR光谱表明，乙烯配体在负载型配合物中仍与Rh中心键合。样品在CO中处理导致形成与沸石键合的位点隔离的Rh(CO)2配合物。红外光谱中ν(CO)带的尖锐程度证明了负载型Rh(CO)2配合物几乎是均匀的，由此推断，形成它的带有乙烯配体的单核铑配合物也几乎是均匀的。带有乙烯配体的负载型配合物与H2反应生成乙烷，并且它在294K时也催化乙烯加氢反应。
