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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Density Functional and MP2 Studies of Germylene Insertion into C-H, Si-H, N-H, P-H, O-H, S-H, F-H, and Cl-H Bonds
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Density Functional and MP2 Studies of Germylene Insertion into C-H, Si-H, N-H, P-H, O-H, S-H, F-H, and Cl-H Bonds

机译：锗插入C-H，Si-H，N-H，P-H，O-H，S-H，F-H和Cl-H键的密度泛函和MP2研究

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The potential energy surfaces for the insertion reactions of germylene into XH_n molecules have been characterized in detail using ab initio molecular orbital theory and density functional theory. The model system Ge(CH_3)_2 + XH_n (X = C, N, O, F, Si, P, S, and Cl; n = 1-4) has been chosen for the present study. All the interactions involve the initial formation of a donor-acceptor complex, followed by a high-energy transition state, and then an insertion product. The agreement between MP2 and B3LYP results indicates that the latter provides an adequate theoretical level for further investigations of molecular geometries, electronic structures, and kinetic features of the germylene reactions. The following conclusions emerge from this work: (i) the X-H insertion reactions of germylene occur in a concerted manner via a three-membered-ring transition state, and that the stereochemistry at the heteroatom X center is preserved; (ii) the stabilization energies of the germylene-XH_n complexes increase in the order NH_3 > H_2O > PH_3 > H_2S approx HF > HCl SiH_4 approx CH_4; (iii) the order of reactivity for X-H bonds toward germylene insertion is Cl > F > S > O > P > N Si > C. In other words, the greater the atomic number of heteroatom (X) in a given row, the easier the insertion reaction of XH_n hydrides and the larger the exothermicity. Moreover, the present study demonstrates that both electronic and steric effects play a major role in the course of insertion reactions of germylene into X-H bonds. This work also indicates that the chemical behavior of germylene should be more similar to that of silylene than to that of carbene species.
机译：利用从头算分子轨道理论和密度泛函理论，对亚甲基向XH_n分子插入反应的势能面进行了详细表征。本研究选择了模型系统Ge（CH_3）_2 + XH_n（X = C，N，O，F，Si，P，S和Cl; n = 1-4）。所有相互作用都涉及供体-受体复合物的最初形成，然后是高能跃迁状态，然后是插入产物。 MP2和B3LYP结果之间的一致性表明，后者为进一步研究亚甲基二甲苯反应的分子几何结构，电子结构和动力学特征提供了足够的理论水平。这项工作得出以下结论：（i）germ烯的X-H插入反应通过三元环过渡态协同发生，并且杂原子X中心的立体化学得以保留; （ii）ylene-XH_n配合物的稳定能以NH_3> H_2O> PH_3> H_2S约HF> HCl SiH_4约CH_4的顺序增加; （iii）XH键与亚甲基苯插入的反应顺序为Cl> F> S> O> P> N Si>C。换句话说，给定行中杂原子（X）的原子数越大， XH_n氢化物的插入反应越容易，放热越大。此外，本研究表明，电子和位阻作用在亚甲基向X-H键的插入反应过程中起主要作用。这项工作还表明，亚二甲苯的化学行为应与亚甲硅烷基的化学行为更相似，而不是与卡宾物种的化学行为相似。

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