利用理論計算探討RNCC自由基(R=H,F,C1,Br,CN,NH2,CH3)與NO之反應機制研究

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题名:	利用理論計算探討RNCC自由基(R=H,F,C1,Br,CN,NH2,CH3)與NO之反應機制研究
作者:	許惠雯
贡献者:	化學系
关键词:	密度泛函計算 DFT calculation Iminovinyliden 一氧化氮 NO 硼 B 氧化亞氮 N2O
日期:	2011
上传时间:	2012-10-11 10:16:41 (UTC+8)
摘要:	本論文主要討論NO與N2O兩種汙染氣體之分解，並將其分為兩種機構各別探討。第一部分為：探討RNCC(R = H, F, Cl, Br, CN, NH2, CH3)與NO的反應機構研究。利用不同取代基的效應，觀察是否存在快速還原氮氧化物的中間產物，並探討其是否會影響反應的活化能。本研究是使用B3LYP/6-311++G(3df,2p)的層級做結構最佳化，並計算所有結構，找出適合的路徑；在所有的路徑中，以產生P6(RNN+CCO)與P12(RNC+CNO)兩種產物為主要路徑。我們的計算結果顯示，當RNCC中的取代基為推電子基時(R = NH2 和CH3)，其斷C-C鍵的活化能會比較低；反之，當RNCC中的取代基為拉電子基時(R = H, F, Cl, Br, CN)，其斷C-C鍵的活化能會比較高。第二部分為：探討硼(B)與N2O的反應機構研究。因B為類金屬具有特殊化學性，其電子組態為1S22S22P1，有可接受電子對之空的軌域。利用理論計算的方法，找出適合的反應物來消除NOx，將NO與N2O轉變為穩定而低污染或無汙染的氣體，達到降低汙染的損害與提升空氣品質。本研究也是使用B3LYP/6-311++G(3df,2p)的層級做結構最佳化，接著用單點能量CCSD(T)/aug-cc-PVQZ//B3LYP/6-311++G(3df,2p)預測並計算所有結構，找出適合的路徑，根據計算結果，在所有的路徑中，以產生P1(N2+BO)與P2(BN+NO)兩種產物為主要路徑。 There are two major themes in this thesis. I. Computational Study of RNCC (R =H, F, Cl, Br, CN, NH2, CH3) Radicals Reaction with NO. We carried out a computational approach of radical reactions of NO + RNCC (R = H, F, Cl, Br, CN, NH2, CH3) to study how the substituted group can influence their corresponding energy barriers. The species involved have been optimized at the B3LYP/6-311++G(3df,2p) level. From our previous work of HNCC + NO reaction, our calculated results indicate that the favorable pathways are the formation of RNN + CCO (P6) and RNC + CNO (P12). Our calculated results clearly show that if the substituted RNCC are electron donating groups (for R = NH2 and CH3 cases), their corresponding barrier heights for transition states will be substantially decreased; while the electron withdrawing groups (for R = H, F, Cl, Br, CN cases), their corresponding barrier heights for transition states will be substantially increased. The possible explanations for the decreased and/or increased energy barriers of the substituted RNCC are also analyzed in this article. II. Quantum-Chemical Calculations on Reaction Mechanisms of B with N2O. The boron possesses some specific properties (metalloid non-metal element) and its electronic configuration is ns2np1, it can accept electron from another donor species. Our purpose of this study is to find the possible reactants which may react with NOx to form the stable product such as N2 which is not harmful to our environment. We used the same method with our first part, but their single-point energies are further refined by the CCSD(T)/aug-cc-PVQZ//B3LYP/6-311++G(3df,2p) method. From our calculated results, it is found that the favorable pathways are the formation of N2 + BO (P1) and BN + NO (P2).
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