Belogolova Elena F, Shlykov Sergey A, Eroshin Alexey V, Doronina Evgeniya P, Sidorkin Valery F
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky Street, 664033 Irkutsk, Russian Federation.
Ivanovo State University of Chemistry and Technology, Sheremetievskiy ave. 7, 153000 Ivanovo, Russian Federation.
Phys Chem Chem Phys. 2021 Feb 4;23(4):2762-2774. doi: 10.1039/d0cp05872f.
In the series of silatranes XSi(OCH2CH2)3N, 1 (X = Me, 1a; H, 1b; F, 1c) with the known gas electron diffraction (GED) structures, the problematic geometry of 1-methylsilatrane 1a has been revised. In particular, the new value of the SiN distance (dSiN) in 1a turned out to be ∼0.06 Å longer than the generally accepted one. This dSiN resolves the long-standing contradiction between the data of the structural and spectral experiments regarding the sensitivity of 1 to the medium effect. We also performed the ab initio and DFT study of the combined series of silatranes 1a-c, silylalkylamines H3Si(CH2)3NMe2 (2a) and F3SiCH2NMe2 (2b), silylhydrazines F3SiN(Me)NMe2 (2c) and F3SiN(SiMe3)NMe2 (2d), and silyloxyamines ClH2SiONMe2 (2e,f), (F3C)F2SiONMe2 (2g,h) and F3SiONMe2 (2i), in which the GED dSiN values are in a wide range of 2-3 Å. None of the involved quantum chemical methods has succeeded in reproducing all the experimental gas-phase dSiN values in 1a-c, 2a-i with an acceptable accuracy (0.01-0.03 Å). The problems of the used methods, primarily CCSD with the Pople basis sets, are caused by four molecules with the geminal SiNN and SiON fragments (2d,f-i) and dSiN < 2.3 Å. A reasonable hierarchy of computationally accessible theory levels for studying the physicochemical manifestation of the non-covalent intramolecular SiN interactions can be constructed only at dSiN > 2.3 Å: MP2 < PBE0 ∼ B3PW91 ∼ SCS-MP2 < CCSD < CCSD(T).
在具有已知气体电子衍射（GED）结构的硅氮烷系列XSi(OCH2CH2)3N，1（X = Me，1a；H，1b；F，1c）中，1-甲基硅氮烷1a存在问题的几何结构已得到修正。特别是，1a中SiN距离（dSiN）的新值比普遍接受的值长约0.06 Å。这个dSiN解决了结构和光谱实验数据之间关于1对介质效应敏感性的长期矛盾。我们还对硅氮烷1a - c、甲硅烷基烷基胺H3Si(CH2)3NMe2（2a）和F3SiCH2NMe2（2b）、甲硅烷基肼F3SiN(Me)NMe2（2c）和F3SiN(SiMe3)NMe2（2d）以及甲硅烷氧基胺ClH2SiONMe2（2e，f）、(F3C)F2SiONMe2（2g，h）和F3SiONMe2（2i）的组合系列进行了从头算和密度泛函理论（DFT）研究，其中GED的dSiN值在2 - 3 Å的宽范围内。所涉及的量子化学方法中没有一种能够以可接受的精度（0.01 - 0.03 Å）重现1a - c、2a - i中所有实验气相dSiN值。所使用方法的问题，主要是使用Pople基组的耦合簇单双激发（CCSD）方法，是由四个具有偕位SiNN和SiON片段（2d，f - i）且dSiN < 2.3 Å的分子引起的。只有在dSiN > 2.3 Å时，才能构建用于研究非共价分子内SiN相互作用物理化学表现的可计算理论水平的合理层次结构：MP2 < PBE0 ∼ B3PW91 ∼ SCS - MP2 < CCSD < CCSD(T)。
