Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616, USA.
Langmuir. 2010 Nov 2;26(21):16368-74. doi: 10.1021/la101344t.
Supported rhenium complexes were prepared from CH(3)Re(CO)(5) and dealuminated HY zeolite or NaY zeolite, each with a Si/Al atomic ratio of 30. The samples were characterized with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies. EXAFS data characterizing the sample formed by the reaction of CH(3)Re(CO)(5) with dealuminated HY zeolite show that the rhenium complexes were bonded to the zeolite frame, incorporating, on average, three carbonyl ligands per Re atom (as shown by Re-C and multiple-scattering Re-O EXAFS contributions). The IR spectra, consistent with this result, show that the supported rhenium carbonyls were bonded near aluminum sites of the zeolite, as shown by the decrease in intensity of the IR bands characterizing the acidic silanol groups resulting from the reaction of the rhenium carbonyl with the zeolite. This supported metal complex was characterized by narrow peaks in the ν(CO) region of the IR spectrum, indicating highly uniform species. In contrast, the species formed from CH(3)Re(CO)(5) on NaY zeolite lost fewer carbonyl ligands than those formed on HY zeolite and were significantly less uniform, as indicated by the greater breadth of the ν(CO) bands in the IR spectra. The results show the importance of zeolite H(+) sites for the formation of uniform supported rhenium carbonyls from CH(3)Re(CO)(5); the formation of such uniform complexes did not occur on the NaY zeolite.
支持铼配合物由 CH(3)Re(CO)(5)和脱铝 HY 沸石或 NaY 沸石制备，Si/Al 原子比均为 30。用红外（IR）和扩展 X 射线吸收精细结构（EXAFS）光谱对样品进行了表征。EXAFS 数据表征了由 CH(3)Re(CO)(5)与脱铝 HY 沸石反应形成的样品，表明铼配合物与沸石骨架键合，每个 Re 原子平均结合三个羰基配体（如 Re-C 和多重散射 Re-O EXAFS 贡献所示）。与这一结果一致的 IR 光谱表明，负载的铼羰基键合在沸石的铝位附近，这是由铼羰基与沸石反应导致酸性硅醇基团的 IR 带强度降低所表明的。这种负载金属配合物的特征是 IR 光谱中 ν(CO)区域的峰很窄，表明其物种非常均匀。相比之下，由 CH(3)Re(CO)(5)在 NaY 沸石上形成的物种比在 HY 沸石上形成的物种失去的羰基配体更少，并且物种的均匀性明显较差，这是由 IR 光谱中 ν(CO)带的较宽所表明的。结果表明沸石 H(+)位对于从 CH(3)Re(CO)(5)形成均匀的负载铼羰基的重要性；在 NaY 沸石上没有形成这样的均匀配合物。
