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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >A Theoretical Investigation of teh Tripelt Carobn Atom C(~3P) + Vinyl Radical C_2H_3(~2A') Reaction and Thermochemistry of C_3H_n ( n = 1-4) Species
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A Theoretical Investigation of teh Tripelt Carobn Atom C(~3P) + Vinyl Radical C_2H_3(~2A') Reaction and Thermochemistry of C_3H_n ( n = 1-4) Species

机译：Tripelt Carobn原子C（〜3P）+乙烯基自由基C_2H_3（〜2A'）反应和C_3H_n（n = 1-4）物种热化学的理论研究

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摘要

The mechanism for the C(3P)+ C_2H_3 reaction has been studied via ab initio calculations to investigate possible formations ofC_3H_2 and C_3H isomers in an extraterrestrial environment, combustion processes, and CVD. The C(3p) + C_2H_3 reaction, which produces C3H3 radical intermediates on the ground-state potential energy surface (PES), is studied employing the B3L YP/6-311o(d,p)and RCCSD(T)/6-311 +G(3df,2p) levels of theory. Initially formed C_3H_3 intermediates have enough energy to undergo unimolecular rearrangements. Further, H or H2 eliminations then lead to C3H2 orC3H fragments. The most energetically favorable channel is found to be the formation of ground-state singletcyclopropenylidene (c-C3H2, 1 A1) by splitting H from cycloprop-2- enyl (c-C3H3, 2A'). The other reaction mechanisms leading to H_2CCCrA1) + H, HCCCH(3B) +H, and H2 + HCCCrII)exhibit barriers only .1-5 kcaVmol higher than those to produce H + c-C3H2. Detailed RRKM calculations will be needed to predict the product branching ratios under various reaction conditions. The C(3P) +C2H3 reaction channel, yielding intermediate C3H3 radicals on the first excited doublet state PES, is also studied by utilizing the CASSCF(11,11)/6-3l1+o(d.p) and MRCI+D(7,8)/ANO(2+) levels of theory. Three local minima and six transition states are located on the excited-state C_3H_3 PES. Various Hand H21oss channels are studied as well. The C-H fission of H2CCCH(12A") leading to HCCCH(11A") + H is the most energetically favorable channel. Finally, thermochemical parameters for the C3Hn (n = 1-4) species are determined by employing the 03 theory and the CCSD(T)/6-311 +0(3df,2p) method. The differences between the calculated results and available literature data do not normally exceed 1-2 kcaVmol. On the basis of the present calculations and previous theoretical and experimental data, ~HfO298(H2CCCH) = 84.5 +- 1 kcaVmol, ~HfO298(C-C3H3) = 114.5 +- 2 kcaVmol, AHfo298(H_3CCC) = 124 +- 2 kcaVmol, AHfo298(C-C_3H_2) = 118.0+- 1 kcaVmol, AHfo298(H2CCC) = 133+- 1 kcaVmol, AHfo298[HCCCH(3B)] = 132.5+- 1 kcaVmol, AHfo298[HCCCH- (IAu] =.144+- 1 kcaVmol, AHfo298[HCCCrII)] = 173+- 2 kcal/mol, and~HfO298(c-C3H) = 170+- 2 kcal/ mol are recommended.
机译：通过从头算来研究C（3P）+ C_2H_3反应的机理，以研究在地球外环境，燃烧过程和CVD中C_3H_2和C_3H异构体的可能形成。使用B3L YP / 6-311o（d，p）和RCCSD（T）/ 6-311研究了在基态势能表面（PES）上产生C3H3自由基中间体的C（3p）+ C_2H_3反应+ G（3df，2p）的理论水平。最初形成的C_3H_3中间体具有足够的能量以进行单分子重排。此外，H或H 2的消除随后导致C 3 H 2或C 3 H片段。发现从能量上最有利的通道是通过将H从环丙-2-烯基（c-C3H3，2A'）拆分而形成基态单环环丙烯基（c-C3H2，1 A1）。导致H_2CCCrA1）+ H，HCCCH（3B）+ H和H2 + HCCCrII）的其他反应机理所显示的壁垒仅比产生H + c-C3H2的壁垒高.1-5 kcaVmol。需要使用详细的RRKM计算来预测各种反应条件下的产物支化比。还利用CASSCF（11,11）/ 6-3l1 + o（dp）和MRCI + D（7，C，（3P）+ C2H3反应通道，在第一个激发的双峰态PES上产生中间C3H3自由基。 8）/ ANO（2+）理论水平。三个局部最小值和六个过渡态位于激发态C_3H_3 PES上。还研究了Hand H21oss的各种通道。 H2CCCH（12A“）的C-H裂变导致HCCCH（11A”）+ H是能量最有利的通道。最后，采用03理论和CCSD（T）/ 6-311 +0（3df，2p）方法确定C3Hn（n = 1-4）物种的热化学参数。计算结果与可用文献数据之间的差异通常不超过1-2 kcaVmol。根据目前的计算和先前的理论和实验数据，〜HfO298（H2CCCH）= 84.5 +-1 kcaVmol，〜HfO298（C-C3H3）= 114.5 +-2 kcaVmol，AHfo298（H_3CCC）= 124 +-2 kcaVmol ，AHfo298（C-C_3H_2）= 118.0±1 kcaVmol，AHfo298（H2CCC）= 133±1 kcaVmol，AHfo298 [HCCCH（3B）] = 132.5±-1 kcaVmol，AHfo298 [HCCCH-（IAu] = .144 +建议-1 kcaVmol，AHfo298 [HCCCrII]] = 173±2 kcal / mol，〜HfO298（c-C3H）= 170±2 kcal / mol。

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