共查询到18条相似文献,搜索用时 93 毫秒
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计算了气相反应C60+O3=C6O(C2v)+O2的热力学函数.得到了该反应Gibbs自由能的具体数值,结果表明在所研究的温度范围内Gibbs自由能为负值,从热力学角度来说,该反应可以自发进行,在计算该气相反应热力学函数的基础上,给出了气相C6O(C2v)的标准热力学函数 相似文献
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采用统计热力学方法计算了气相C76(D2)的标准热力学函数,在此基础上计算了不同温度下气相反应76/70C70=C76(D2)的热力学函数,讨论了C70与C76(D2)之间相互转化的热力学条件.结果表明,气相中温度低于536K时C70转化为C76(D2),温度高于536K时气相中C76(D2)转化为C70。 相似文献
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1985年,在质谱实验中发现了碳存在的第三种形态──碳原子簇[1],其中以C60最为引人注目.这是一个具有划时代意义的发现,它结束了几个世纪以来人们对碳元素的某种观念──仅有两种存在形式:石墨和金刚石,C60的一个显著特点是中空球状分子,其直径达7,足以包容进原子和小分子并与它们无须键联.将原子或分子包容在另一分子中是一个全新的化学概念及领域,这一课题引起了许多科学家的关注.目前有证据表明某些金属原子M已进入C60笼[2-5],对这种内嵌复合物的性质已有不少理论研究[6-13].但M是怎样进入C60笼的,除了(M@C6… 相似文献
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计算了不同温度下气相反应84/70C70(D5h)=C84(D2)的热力学函数,讨论了C70(D5h)与C84(D2)之间相互转化的热力学条件;结果表明,温度低于2392K时C84(D2)比C70(D5h)稳定,温度高于2392K时气相中C70(D5h)比C84(D2)稳定;同时给出了气相C84(D2)的标准热力学函数。 相似文献
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INDO方法研究了C70R2(R=OH,CH3)4种异构体的结构和稳定性,表明1,9-C70(OH)2比7,8-C70(OH)2稳定,两者能量差为38.5kJ/mol,而7,8-C70(CH3)2比1,9-C70(CH3)2能量低23.0kJ/mol.以优化构型为基础,对C70R2(R=OH,CH3)的电子光谱进行了理论预测. 相似文献
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C60O结构和电子光谱的理论研究 总被引:1,自引:0,他引:1
用INDO系列方法研究C60O的两种结构:一是桥氧加在2个六元环之间的键上为C2v构型;另一个是桥氧加在1个五元环和1个六元环之间的键上为Cs构型。计算表明,从总能量、HOMO-LUMO能级差和光谱性质看,C60O的稳定构型都应是C2v构型,该C2v异构体具有环氧结构(桥C15-C30键长为0.1518nm,键序为0.8744),其电子光谱计算结果与实验值较好地符合。 相似文献
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用INDO系列方法对C602-与CH3反应的中间体C60(CH3)-进行理论研究,得到具有Cs对称性的构型。结果表明,CH3加成到C15上,将使与其相邻的双键碳(C30)的电荷密度和自旋密度达极大值,故加成反应部位在C30处;另外,C15的对位C12(或C27)也较其它部位易于反应,且有两个反应场所,因而产物C60(CH3)2可能为六元环上的1,2-加成和1,4-加成两种异构体的混合物。同时对两种加成产物的结构和电子光谱进行了理论研究,指认其电子跃迁,并讨论了其光谱红移的原因。 相似文献
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用量子化学密度泛函理论和QCISD(Quadratic configuration interaction calculation)方法,对0(^3P)与CH2CHCl的反应进行了理论研究.在UB3LYP/6—311 G(d,p),UB3LYP/6—31 (3df,3pd)计算水平上,优化了反应物、产物、中间体和过渡态的几何构型,并在UQCISD(T)/6—311 G(2df,2pO)水平上计算了单点能量.为了确证过渡态的真实性,在UB3LYP/6—311 G(3df,3pd)水平上进行了内禀坐标(IRC)计算和频率分析,并确定了反应机理.研究结果表明,反应主要产物为CH2CHO和Cl. 相似文献
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The complex doublet potential energy surface of the CH(2)NO(2) system is investigated at the B3LYP/6-31G(d,p) and QCISD(T)/6-311G(d,p) (single-point) levels to explore the possible reaction mechanism of the triplet CH(2) radical with NO(2). Forty minimum isomers and 92 transition states are located. For the most relevant reaction pathways, the high-level QCISD(T)/6-311 + G(2df,2p) calculations are performed at the B3LYP/6-31G(d,p) geometries to accurately determine the energetics. It is found that the top attack of the (3)CH(2) radical at the N-atom of NO(2) first forms the branched open-chain H(2)CNO(2) a with no barrier followed by ring closure to give the three-membered ring isomer cC(H(2))ON-O b that will almost barrierlessly dissociate to product P(1) H(2)CO + NO. The lesser followed competitive channel is the 1,3-H-shift of a to isomer HCN(O)OH c, which will take subsequent cis-trans conversion and dissociation to P(2) OH + HCNO. The direct O-extrusion of a to product P(3) (3)O + H(2)CNO is even much less feasible. Because the intermediates and transition states involved in the above three channels are all lower than the reactants in energy, the title reaction is expected to be rapid, as is consistent with the measured large rate constant at room temperature. Formation of the other very low-lying dissociation products such as NH(2) + CO(2), OH + HNCO and H(2)O + NCO seems unlikely due to kinetic hindrance. Moreover, the (3)CH(2) attack at the end-O of NO(2) is a barrier-consumed process, and thus may only be of significance at very high temperatures. The reaction of the singlet CH(2) with NO(2) is also briefly discussed. Our calculated results may assist in future laboratory identification of the products of the title reaction. 相似文献
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Lü Ling-Ling 《结构化学》2008,27(9):1039-1044
The insertion reaction mechanism of CF2 with CH2O was investigated at the B3LYP/6-311G(d)//MP2/6-311G(d) level. The geometric conformations at each stationary point in reaction potential surface were fully optimized and the transition states were verified by intrinsic reaction coordinate (IRC) and frequency analysis. The energies of all reactants were calculated with CCSD(T)/6-311G(d)//G2MP2 methods. Results indicated that the P1 reaction route with difuoroaldehyde as product is the dominant reaction pathway, which exhibits nucleophilic character. According to NBO analysis, the starting point of insertion reaction is the interaction between carbene LP(C3) and formaldehyde π(Cl-O2). Besides, the thermodynamic and dynamic properties of dominated reaction (1) at different temperature were studied with statistic thermodynamic method and Eyring transition state theory adjusted by Wigner means, from which the proper temperature (500- 1200 K) of reaction (1) could be estimated. Finally, the thermo- dynamic and dynamic properties of insertion reaction mechanisms (CF2, CX2 (X = Cl, Br) with CH2O) were compared and discussed. 相似文献
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C60CH2结构和电子光谱的理论研究 总被引:1,自引:1,他引:1
用INDO系列方法研究C60CH2的两种结构,CH2加在两个六元环之间的键上为C20构型,CH2加在一个五元环和一个六元环之间的键上为C5构型,计算表明,从总能量和LUMO-HOMO能级差看,C60CH2的稳定结构应是C20构型,该C20异构体有类环丙结构(C15-C30桥键键长为0.1556nm,键序等于0.8663),其电子光谱计算结果与实验值符合较好。 相似文献
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在密度泛函理论B3LYP/6-311G^*水平下,研究了NH2与CH4的反应机理。通过振动频率和内禀反应坐标(IRC)分析,对反应过渡态进行了确认。在QCISD(T)/6-311G^*水平下进行了单点能计算,并进行了零点能校正,结果表明,反应NH2+CH4→N3+CH3是主要的反应通道。 相似文献