Coordination of Cu+ Ions to Zeolite Frameworks Strongly Enhances Their Ability To Bind NO2. An ab Initio Density Functional Study
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- 作者：Luis Rodriguez-Santiago ; Marek Sierka ; Vicenç ; Branchadell ; Mariona Sodupe ; and Joachim Sauer
- 刊名：Journal of the American Chemical Society
- 出版年：1998
- 出版时间：February 25, 1998
- 年：1998
- 卷：120
- 期：7
- 页码：1545 - 1551
- 全文大小：158K
- 年卷期：v.120,no.7(February 25, 1998)
- ISSN：1520-5126
文摘
Comparison is made of the interaction ofNO2 with Cu+ ions in the gas phase and insidezeolitesusing density functional theory (B3LYP functional). The zeolite isrepresented by a tritetrahedra modelembedded in the periodic structure of zeolite ZSM-5 and by a free spacecluster model. Both models yieldvirtually the same results. Cu+ is coordinated totwo oxygen atoms of the zeolite framework only. Forthecomplexes with NO2, several minima and transitionstructures on the potential energy surfaces are localized.The naked Cu+ ion preferentially bindsNO2 in the 
fchars/eta.gif" BORDER=0 >1-O trans mode, while in zeolitesthe Cu+ site binds NO2in a 2fchars/eta.gif" BORDER=0 >-O,O coordination. For the2fchars/eta.gif" BORDER=0 >-O,O structure the binding is three to four timesstronger in the zeolite(43 kcal/mol) than in the gas phase which is due to a three-bodyzeolite framework-Cu+ ion-NO2interaction.d10-s1d9 promotion leads toa more favorable orbital interaction between Cu+ andNO2 in the 2A'' state and,due to reduced repulsion, to a stronger electrostatic interactionbetween Cu+ and the zeolite framework.
fchars/eta.gif" BORDER=0 >1-O trans mode, while in zeolitesthe Cu+ site binds NO2in a 2fchars/eta.gif" BORDER=0 >-O,O coordination. For the2fchars/eta.gif" BORDER=0 >-O,O structure the binding is three to four timesstronger in the zeolite(43 kcal/mol) than in the gas phase which is due to a three-bodyzeolite framework-Cu+ ion-NO2interaction.d10-s1d9 promotion leads toa more favorable orbital interaction between Cu+ andNO2 in the 2A'' state and,due to reduced repulsion, to a stronger electrostatic interactionbetween Cu+ and the zeolite framework.