Computational benchmark for calculation of silane and siloxane thermochemistry
Computational benchmark for calculation of silane and siloxane thermochemistry
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硅烷和硅氧烷热化学计算的计算基准
DOI：
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发表时间：
2016
影响因子：
2.2
通讯作者：
Bartłomiej Gostyński
中科院分区：
文献类型：
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作者：
M. Cypryk;Bartłomiej Gostyński
模型氯硅烷，R3 SiCl，硅烷醇，R3 SiOH，和二硅氧烷，（R3 Si）2 O，R = H，Me，以及涉及这些物种的反应的热化学的几何形状进行了建模，使用11个常见的密度泛函结合5个基组，以检查在有机硅化学的各种理论方法的准确性和适用性。作为模型反应，考虑了硅烷醇和硅氧烷的质子亲合性，氯硅烷的水解和硅烷醇缩合成硅氧烷。作为参考值，实验的键合参数和反应谱被使用在任何可用的地方。如果没有实验数据，则使用W1和CBS-QB 3值。对于气相条件，观察到理论CBS-QB 3和W1与实验热化学值之间的极好的一致性。所有DFT方法也给出了可接受的值，并且所使用的各种泛函的精度相当。新的更先进的功能比“经典”B3 LYP和PBEPE的没有显着的优势。当使用三重zeta基组而不是双zeta基组进行能量计算时，结果的准确性显著提高。在SCRF模型内的水溶液中的反应的计算的准确性是较差的气相相比。然而，通过仔细估计对H+和HCl的ΔHsolv和ΔGsolv的修正，可以获得所讨论的反应的热力学量的合理值。
Geometries of model chlorosilanes, R3SiCl, silanols, R3SiOH, and disiloxanes, (R3Si)2O, R = H, Me, as well as the thermochemistry of the reactions involving these species were modeled using 11 common density functionals in combination with five basis sets to examine the accuracy and applicability of various theoretical methods in organosilicon chemistry. As the model reactions, the proton affinities of silanols and siloxanes, hydrolysis of chlorosilanes and condensation of silanols to siloxanes were considered. As the reference values, experimental bonding parameters and reaction enthalpies were used wherever available. Where there are no experimental data, W1 and CBS-QB3 values were used instead. For the gas phase conditions, excellent agreement between theoretical CBS-QB3 and W1 and experimental thermochemical values was observed. All DFT methods also give acceptable values and the precision of various functionals used was comparable. No significant advantage of newer more advanced functionals over ‘classical’ B3LYP and PBEPBE ones was noted. The accuracy of the results was improved significantly when triple-zeta basis sets were used for energy calculations, instead of double-zeta ones. The accuracy of calculations for the reactions in water solution within the SCRF model was inferior compared to the gas phase. However, by careful estimation of corrections to the ΔHsolv and ΔGsolv of H+ and HCl, reasonable values of thermodynamic quantities for the discussed reactions can be obtained.