利用理論計算方法探討HNCN自由基解離之反應機制以及RCCN取代基(R = H, F, Cl, Br, CN, NH2, CH3)與NO之反應機制

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Title:	利用理論計算方法探討HNCN自由基解離之反應機制以及RCCN取代基(R = H, F, Cl, Br, CN, NH2, CH3)與NO之反應機制
Authors:	潘孟青
Contributors:	化學系
Keywords:	初始法
Date:	2010
Issue Date:	2011-10-27 16:05:39 (UTC+8)
Abstract:	我們使用高層級的初始法（Ab initio）分別去研究：(1) HNCN (Cyanomidyl radical )自解離的反應機構與產物，以及(2)RCCN(R=H、F、Cl、Br、CN、NH2、CH3)與NO的反應機構。我們使用B3LYP/6-311 ++G(3df,2p)做結構最佳化，單點能量則使用CCSD(T)/aug-cc-PVQZ// B3LYP/6-311++G(3df,2p) 去計算。在第一部份中我們預測並計算所有的結構並找出最適當的路徑，得知產生P5(CH+N2)為主要路徑，其中doublet HNCN兩條路徑：HNCN→TS1→IM4→TS4→IM2→TS8 →CH+N2以及HNCN→TS3→IM1→TS2→IM2→TS8→CH+N2皆可以產生N2產物。而quartet HNCN產生N2 的路徑：R→TS4→IM5→TS5→ IM2→TS7→IM3→TS12→CH+N2 、R→TS9→IM4→TS13→IM1→TS11 →IM3→TS12→CH+N2以及R→TS4→IM5→TS10→IM1→TS11→IM3 →TS12→CH +N2。經由Fukui functions以及硬軟酸鹼理論（HSAB）所計算得出的數據可以合理地解釋我們所計算出來的結果，其N2為最穩定之產物。 RCCN (R=H, F, Cl, Br, CN, NH2, and CH3)與NO之反應機制中，經過我們的計算結果明確的表示，如果取代基為推電子基時(R= F, NH2, and CH3)，其相對應的TS能障較低，藉此來解釋並分析能障增加或減少的原因。 The reaction mechanisms of (1) the decomposition reaction of cyanomidyl radical (HNCN), and (2) the reaction of RCCN (R=H, F, Cl, Br, CN, NH2, and CH3) radicals with the NO have been investigated by the highlevel ab initio molecular orbital method. The species involved have been optimized at the B3LYP/6-311++G (3df,2p) level and their singlepoint energies are refined by the CCSD(T)/aug-cc- PVQZ//B3LYP /6-311+G(3df,2p) method. For the HNCN decomposition reaction system with two different configurations (doublet and quartet states), our calculated results indicate that there exists two and three favorable paths for the formations of CH + N2. For doublet state case, these two paths are HNCN→TS1→IM4→TS4→ IM2→TS8→CH+N2, and HNCN→TS3→ IM1→TS2→IM2→TS8→CH+N2, respectively. For quartet state case, these three paths are R→TS4→IM5→TS5→IM2→TS7→IM3→TS12→ CH+N2, R→TS9→IM4→TS13→IM1→TS11→IM3→TS12→CH+N2, and R→TS4→IM5→TS10→IM1→TS11→ IM3→TS12 →CH+N2, respectively. In addition, employing the Fukui functions and HSAB theory we are able to rationalize the scenario of these calculated outcomes. For the reaction of RCCN (R=H, F, Cl, Br, CN, NH2, and CH3) radicals with the NO system, our calculated results clearly show that if the substituted RCCN are electron donating groups (for R = F, NH2 and CH3 cases), their corresponding barrier heights for transition states will be slightly decreased. The possible explanations for the decreased and/or increased energy barriers of the substituted RCCN are also analyzed in this part.
Appears in Collections:	[Department of Chemistry & Graduate Institute of Applied Chemistry ] thesis

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