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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Gas Phase Reactions between SiH_4 and B_2H_6: A Theoretical Study
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Gas Phase Reactions between SiH_4 and B_2H_6: A Theoretical Study

机译：SiH_4与B_2H_6之间的气相反应：理论研究

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Gas-phase reactions of silane (SiH_4) and diborane (B_2H_6) are investigated using ab initio calculations at the MP2/6-311 ++g~(**) level. Initially SiH_4 and B_2H_6 are only weakly attracted to each other. Under thermal activation, the two molecules can overcome an energy barrier of 33.87 kcal/mol to associate into a complex SiH_4-BH_3-BH_3 with a hydrogen-bridged Si-H-B bond. Upon bonding, one of the two hydrogen-bridged bonds B-H-B in B_2H_6 is broken and the other becomes polarized. Started from the SiH_4-BH_3-BH_3 complex, three comparable fragmentation pathways involving BH_3 and H_2 elimination produce several silaboranes with various silicon-boron-hydrogen ratios. A much higher barrier exists between the initial loosely bonded SiH_4-B_2H_6 system and a direct H_2 elimination product SiH_3-B_2H_5 with C_s symmetry. The bonding nature in the species are further elucidated through topological analysis of electron density using the AIM theory. These intermediate silaboranes are possible precursors for chemical vapor deposition in fabricating boron doped silicon films. Their composition and polarity may determine their tendency of surface adsorption and the properties of the relevant solid. The proposed mechanisms can help to understand and control the initial gas-phase reactions in practice. Calculated IR spectra, dipole moment, and rotational constants of the species are provided to facilitate experimental investigations.
机译：使用从头算在MP2 / 6-311 ++ g〜（**）的水平上研究了硅烷（SiH_4）和乙硼烷（B_2H_6）的气相反应。最初，SiH_4和B_2H_6仅被弱力吸引。在热激活下，这两个分子可以克服33.87 kcal / mol的能垒，从而缔合具有氢桥Si-H-B键的复合SiH_4-BH_3-BH_3。在键合时，B_2H_6中的两个氢桥键B-H-B之一断裂，而另一个变为极化。从SiH_4-BH_3-BH_3络合物开始，涉及BH_3和H_2消除的三个可比的断裂途径可产生具有不同硅-硼-氢比率的几种硅硼烷。最初的松散键合SiH_4-B_2H_6系统与具有C_s对称性的直接H_2消除产物SiH_3-B_2H_5之间存在更高的势垒。通过使用AIM理论对电子密度进行拓扑分析，进一步阐明了物种中的键合性质。这些中间硅硼烷是制造硼掺杂的硅膜时化学气相沉积的可能前体。它们的组成和极性可能决定其表面吸附的趋势以及相关固体的性质。所提出的机制可以在实践中帮助理解和控制初始气相反应。提供了物种的红外光谱，偶极矩和旋转常数，以方便实验研究。

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