利用理論計算方法探討HNCC自由基和NO分子之反應機制與反應動力學

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Title:	利用理論計算方法探討HNCC自由基和NO分子之反應機制與反應動力學 Computational study on reaction mechanisms and kinetics for the reaction of Iminovinylidene readical with NO molecule
Authors:	廖怡荏
Contributors:	化學系應用化學碩士班
Keywords:	HCCN自由基 iminovinylidene
Date:	2014
Issue Date:	2014-10-06 15:36:00 (UTC+8)
Abstract:	Iminovinylidene (HNCC) 自由基與一氧化氮的動力學反應機制，並探討多種可能的反應路徑,分別考慮了NO的N及O原子與HNCC的N及C原子碰撞反應的可能性。所有結構的位能和反應速率分別使用高階ab initio共軛的分子軌域與變化的TST及RRKM計算獲得。反應物、中間物、過渡狀態及產物的構型均使用B3LYP/6-311++G(3df,2p)層級計算來得到最佳化並藉由 CCSD(T)/aug-cc-PVQZ//B3LYP/6-311++G(3df,2p)方法獲得精確的單點能量。從計算結果指出HNCC + NO 最佳的反應途徑被預測為HNC+CNO (P8)產物,此產物是經由HNCC基的C原子與NO基的N原子頭對頭方式的加成反應所生成。為了更深入的探討計算結果,我們通常使用 Fukui functions與HSAB 理論尋求可能的解釋。除此之外,計算通常使用VariFlex code為反應速率常數,結果顯示當氬氣壓力為760 torr下所有速率係數,ktotal,可以用下列方程式來描述:ktotal = 6.433×10-11 T 0.100 exp(0.275 kcal mol-1/RT)且T = 298-3000 K, 單位為cm3 molecule-1 s-1。 The mechanism and kinetic for reaction of the iminovinylidene (HNCC) radical with the nitric oxide is investigated via considering the possible channels of the N and O atoms of NO attacking the N and C atoms of the HNCC based on high level ab initio molecular orbital in conjunction with variational TST and RRKM calculations. 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. The calculated results of potential energy surfaces indicated that energetically the most favorable channel for the HNCC + NO reaction was predicted to be the formation of HNC+CNO (P8) product via the addition reaction of the C atom of HNCC radical and the N atom of NO with the head to head orientation. To rationalize the scenario of the calculated results, we also employ the Fukui functions and HSAB theory to seek for the possible explanation. In addition, the reaction rate constants were calculated using VariFlex code, and the results shows total rate coefficient, ktotal, at Ar pressure 760 torr can be represented with an equation: ktotal = 6.433×10-11 T 0.100 exp(0.275 kcal mol-1/RT) at T = 298-3000 K, in units of cm3 molecule-1 s-1.
Appears in Collections:	[Department of Chemistry & Graduate Institute of Applied Chemistry ] thesis

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