Computational Study of Metal鈥揇initrogen Keggin-Type Polyoxometalate Complexes [PW11O39MIIN2)]5鈥?/sup> (M = Ru, Os, Re, Ir): Bonding Nature and Dinitrog

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• 作者：Chun-Guang Liu ; Shuang Liu ; Ting Zheng
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：August 17, 2015
• 年：2015
• 卷：54
• 期：16
• 页码：7929-7935
• 全文大小：390K
• ISSN：1520-510X

文摘

Molecular geometry, electronic structure, and metal鈥揹initrogen bonding nature of a series of metal鈥揹initrogen derivatives of Keggin-type polyoxometalates (POMs) [PW₁₁O₃₉M^IIN₂)]^{5鈥?/sup> (M = Ru, Os, Re, Ir) have been studied by using a density functional theory (DFT) method with the M06L functional. Among these Keggin-type POM complexes, Os- and Re-substituted POM complexes are the most active for N₂ adsorption with considerable adsorption energy. The electronic structure analysis shows that OsII and ReII centers in their metal鈥揹initrogen POM complexes possess 蟺2_xz蟺2_yz蟺2_xy and 蟺2_xz蟺2_yz蟺1_xy configurations, respectively. DFT-M06L calculations show that the possible synthesis routes proposed in this work for the Ru鈥? Os鈥? and Re鈥揹initrogen POM complexes are thermodynamically feasible under various solvent environments. Meanwhile, the Re鈥揹initrogen POM complex was assessed for the direct cleavage of dinitrogen molecule. In the reaction mechanism, a dimeric Keggin-type POM derivative of rhenium could represent the intermediate which undergoes N鈥揘 bond scission. The calculated free energy barrier (螖G猝?/sup>) for a transition state with a zigzag conformation is 16.05 kcal mol鈥? in tetrahydrofuran, which is a moderate barrier for the cleavage of the N鈥揘 bond when compared with the literature values. In conclusion, regarding the direct cleavage of the dinitrogen molecule, the findings would be very useful to guide the search for a potential N₂ cleavage compound into totally inorganic POM fields.}