Ab initio study of the complexes of first-row transition-metal ions with CH, CH_2, and CH_3

The geometries and bonding characteristics of the complexes of the first-row transition-metal ions with CH, CH_2 and CH_3 were investigated by ab initio molecular orbital theory. MCH~ and MCH_2~ are linear and coplanar, re spectively. Both of them are with obvious treble or double bond characteristics, but these multiple bonds are mostly "im perfect". The calculated bond dissociation energies of C--M~ , C=M~ and C≡M~ are mostly close to the experi mental values, and appear in similar periodic trends from Sc to Zn.     

STUDY ON THE DYNAMICS OF H+O_2 SYSTEM AT LOW COLLISION ENERGY

In this paper, the process of the reactive collision of the atom H (~2S) with the moleculeO_2(~3∑_g~-) has been simulated on the ab initio potential surface, and the dynamics of thissystem has been studied at low collision energy, E = 0.3eV, with O_2 in quantum statesv(vibration quantum number) = 2, j(rotational quantum number) = 1, 20, 40, 60, 80, 100.The results of calculations have shown: (1) the maximum impact parameter at which thereaction occurs is 4. 5a_0, (2) the impact parameter b at which the reaction probability ismaximum decreases as j increases, (3) the reaction cross section monotonically increasesas j increases, (4) for inelastic collisions, in which b is small and j is large, both thevibration v' and rotation quantum numbers j' of the product O_2 fall down obviously, andfor reactive collisions, the products OH(~2π) are almost in vibration ground states, but theprobabilities of excited vibration states increase obviously as j increases, and the populationinversion even appears at j = 10     

H+O_2体系在低碰撞能下的动力学研究

本文用准经典轨迹理论,模拟了H(~2S)原子与O_2(~3Σ_g~-)分子在ab initio势能面上的反应碰撞过程,研究了该反应体系在低碰撞能E=0.3eV,O_2的量子态v(振动量子数)=2,j(转动量子数)=1,20,40,60,80,100时的动力学行为。计算结果表明:(1)发生反应的最大碰撞参数b_(max)为4.5a_o,(2)产生最大反应几率的碰撞参数b随j的增加而减小,(3)反应截面随j单调增加,(4)对于小b高j时的非弹性碰撞,产物O_2的振动量子数v′和转动量子数j′均明显地下降,而对于反应碰撞,产物OH(~2Π)多处于基振动态(v′=0),且随j的增加,产物OH处于振动激发态(v′>0)的几率明显增加,当j=100时,甚至出现振动态分布倒反现象。此外,还绘制了部分典型的碰撞轨迹图。     

用定量结构性质关系预测表面活性剂的Krafft点

以空间、电子、热力学等方面的微观性质作为描述符,建立了阴离子表面活性剂Krafft点与微观结构参数之间的关系。这些描述符包括:辛醇/水分配系数LogP、分子能量Energy、最高占据轨道能量HOMO、分子体积V和偶极距Dipole-z等。通过阴离子表面活性剂的Krafft点和5个结构性质参数之间的关系式,可以预测和计算阴离子和其它离子型表面活性剂的Krafft点。     

H+BrCH_3体系反应动力学的准经典轨迹研究

本文在推广LEPS势能面上用准经典轨迹理论方法计算了20000条碰撞轨迹,得到各种散射通道的几率和速度常数,讨论了振动增强、通道竞争、振动绝热性、质量组合及角动量耦合等重要动力学效应,并建立了它们与势能面性质之间的联系。据此判断该反应按直接型回弹机理进行并可满意地解释交叉分子束实验观测到的不对称性产物角分布。     

C-甲基硝酮与丙烯腈1,3-偶极环加成反应从头算研究

用从头算方法在MP2 / 6 31G(d)水平上研究了C 甲基硝酮与丙烯腈 1,3 偶极环加成反应 ,该反应可生成endo 4,exo 4,endo 5 ,exo 5四种不同的产物 ,反应势垒分别为 8.35、17.2 3、-0 .18和 4.88kJ/mol。在C 甲基硝酮与丙烯腈接近的过程中 ,首先生成 3个不同的氢键复合物 ,相对能量为 -4 7.8、-4 6 .6和 -33 .7kJ/mol。由这 3个不同的氢键复合物导致了 4个不同的过渡态而形成 4个不同的产物     

CX2（X=H,FCl）与甲基异丙基醚C—H键插入反应的理论研究

用从头计算方法在ＭＰ２／６－３１Ｇ（ｄ）水平上研究了ＣＸ２（Ｘ＝Ｈ,ＦＣＩ）与甲工异丙基醚的Ｃ－Ｈ键插入反应。ＣＣＩ２与甲基异丙基醚两个淡同的α－Ｃ的Ｃ＝Ｈ键插入势垒分别为１１７．２ｋＪ／ｍｏｌ（甲基）和２０．６ｋＪ／ｍｏｌ（异丙基）。ＣＦ２与异丙基α－Ｃ的Ｃ－Ｈ键上插入势垒为１２０．０Ｋｊ／ＭＬ,在插 Ｃ－Ｈ键时会引起Ｃ－Ｏ键的断裂。ＣＨ２的插入是不需要势垒。对ＣＸ２与二甲醚、甲乙醚、甲基异丙基     

卡宾与醚C-H键插入反应的理论研究(Ⅱ)--二氯卡宾和二氟卡宾与二甲醚的插入反应

用量子化学从头算方法在 MP2 / 6 -31 G(d)水平上研究了单重态的 CX2 (X=F,Cl)与二甲醚中 C— H键的插入反应 .两个体系的插入反应都是自发的 ,插入过程是 CX2 的亲电 -亲核过程 .CX2 与二甲醚的插入势垒分别为 1 2 5 .9k J/ mol(经零点能校正后为 1 32 .2 k J/ mol,X=Cl)和 2 5 5 .3k J/ mol(经零点能校正后为2 5 7.6 k J/ mol,X=F) .CF2 的插入反应实际上难以发生 .     

Mechanism for the addition of carbenoid CH2ClLi to formaldehyde

Ab initlo HF/6-31G* calculations have been performed for the addition mechanism of carbenoid CH2CILi with formaldehyde in tetrahydrofuran. An early complex of formaldehyde with CH2CILi is first formed with quite exothermic effect. Only a little activation energy of 14.6 kJ/mol is needed for the complex developing into the product through a transition state with coplanar bicyclic structure. In this process, the eletrophilic attack of carbonyl carbon of formaldehyde is more active than the nucleophilic attack of carbon of carbenoid. The exothermal effect of this addition process is up to 216.5 kJ/mol.