Carbon Dioxide Coordination and Activation by Niobium Oxide Molecules

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• 作者：Mingfei Zhou ; Zijian Zhou ; Jia Zhuang ; Zhen Hua Li ; Kangnian Fan ; Yanying Zhao ; Xuming Zheng
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：December 22, 2011
• 年：2011
• 卷：115
• 期：50
• 页码：14361-14369
• 全文大小：1020K
• 年卷期：v.115,no.50(December 22, 2011)
• ISSN：1520-5215

文摘

Carbon dioxide coordination and activation by niobium oxide molecules were studied by matrix isolation infrared spectroscopy. It was found that the niobium monoxide molecule reacted with carbon dioxide to form the niobium dioxide carbonyl complex NbO₂(畏¹-CO) spontaneously on annealing in solid neon. The observation of the spontaneous reaction is consistent with theoretical predictions that this carbon dioxide activation process is both thermodynamically exothermic and kinetically facile. In contrast, four niobium dioxide鈥揷arbon dioxide complexes exhibiting three different coordination modes of CO₂ were formed from the reactions between niobium dioxide and carbon dioxide, which proceeded with the initial formation of the 畏¹-O bound NbO₂(畏¹-OCO) and NbO₂(畏¹-OCO)₂ complexes on annealing. The NbO₂(畏¹-OCO) complex rearranged to the 畏²-O,O bound NbO₂(畏²-O₂C) isomer under visible light irradiation, while the NbO₂(畏¹-OCO)₂ complex isomerized to the NbO₂(畏¹-OCO)(畏²-OC)O structure involving an 畏²-C,O ligand under IR excitation. In these niobium dioxide carbon dioxide complexes, the 畏¹-O coordinated CO₂ ligand serves as an electron donor, whereas both the 畏²-C,O and 畏²-O,O coordinated CO₂ ligands act as electron acceptors.