Ligand Effects in Dinitrogen Hydrogenation of Binuclear Zirconium Complexes

作     者：LIU Cai-Ping WU Ke-Chen 

作者机构：State Key Laboratory of Structural Chemistry Fujian Institute of Research on theStructure of Matter The Chinese Academy of Sciences Fuzhou Fujian 350002 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China 

出 版 物：《Chinese Journal of Structural Chemistry》 (结构化学（英文）)

年 卷 期：2008年第27卷第2期

页      面：238-244页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学] 070301[理学-无机化学] 

基　　金：Supported by the National Natural Science Foundation of China (No. 20573114) MOST Project of 2006DFA43020 and 2007CB815307 

主　　题：density functional theory binuclear zirconium complexes electronic structure vibrational properties dinitrogen hydrogenation 

摘      要：In this work, we report a theoretical exploration of the ground-state electronic structures and molecular vibrational properties of a series of binuclear zirconium complexes in the framework of density functional theory （DFT） employing the B3LYP hybrid functional. The calculated results reveal that the electronic structure of the complex [（η^5-C5Me5）2Zr]2（μ^2, η^2, η^2-N2） is unfavorable for hydrogenation due to the exclusion of side-on dinitrogen in the LUMO＋ 1 molecular orbital as compared with the reactant 1 [（η^5-C5Me4H）2Zr]2（μ2,η^2,η^2-N2）. Besides, the structural feature of the hypothetical intermediate 1′, [（η^5C5Me4H）2Zr]2（μ2,η^2, η^2-N2）-n2, clearly implies the possibility of further hydrogenation. In addition, the distinguishing of vibrational modes of experimental intermediate 2, [（η^5-C5Me4H）2ZrH]2（μ2,η^2,η^2-N2H2）, indicates that the asymmetric stretching of Zr-N and Zr-H leads to dissociation. Moreover, the vibrational intensity of Zr-H is stronger than that of Zr-N. Therefore, it can be predicted that excess hydrogen atmosphere is necessary to ensure the dissociation of Zr-N bonds.