Strong intramolecular Si-N interactions in the chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n = 1-3).
Strong intramolecular Si-N interactions in the chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n = 1-3).
复制标题
氯硅烷 Cl3-nHnSiOCH2CH2NMe2 (n = 1-3) 中存在强分子内 Si-N 相互作用。
DOI：
10.1021/ic801205q
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发表时间：
2008
影响因子：
4.6
通讯作者：
N. Mitzel
中科院分区：
文献类型：
--
作者：
M. Hagemann;A. Mix;R. J. Berger;T. Pape;N. Mitzel
用2-（二甲氨基）乙醇锂与SiCl 4和HSiCl 3反应合成了化合物Cl 3SiOCH 2CH 2NMe 2（1）和Cl 2 HSiOCH 2CH 2NMe 2（2）。与H2 SiCl 2进行类似的反应，得到ClH 2 SiOCH 2 CH 2 NMe 2（3），但只是与Cl 2 HSiOCH 2 CH 2 NMe 2（2）的混合物，不能分离。所有化合物均经IR和NMR（（1）H，（13）C，（29）Si）谱表征，1和2经元素分析和晶体结构测定表征。Cl 3SiOCH 2CH 2NMe 2（1）和Cl 2 HSiOCH 2CH 2NMe 2（2）结晶为五配位硅原子参与分子内Si-N键的单体环化合物[2.060（2）A（1），2.037（2）A（2）]。在（1）H，（29）Si HMBC NMR实验中，通过检测（29）Si与NCH 2和NCH 3基团质子之间的标量耦合，证明了在低温下硅和氮原子之间的配价键1和2也存在于溶液中。计算出描述化学位移Δ exp（29）Si依赖于各个平衡组分的化学位移、温度和反应自由焓的函数，并将其拟合到1和2的实验VT-NMR数据。这提供了对于1的Δ G = -28.8 +/- 3.9 kJ x mol（-1）和对于2的Δ G = -22.3 +/- 0.4 kJ x mol（-1）的自由反应速率值，以及对于1的开链（指数o）和环构象体（指数r）的化学位移的估计值，Δ r = -94 +/- 2 ppm和Δ o =-22.3 +/-0.4 kJ x mol（-1）。36 +/- 5 ppm，并且对于Δ r = -82 +/-lppm和Δ o = -33 +/-4ppm中的2个。1的Δ r值非常接近从固态（29）Si MAS NMR谱获得的值。量子化学计算（MP2/TZVPP）给出了很大程度上不同的几何1（与Si…N的距离为3.072 A），但很好地再现了几何2。这些差异是由于Cl…H和Cl…C排斥和固态效应，这可以通过类似导体的屏蔽模型计算来建模，也可以根据电子密度的拓扑结构来合理化，这是根据分子中原子的量子理论来分析的。
The compounds Cl 3SiOCH 2CH 2NMe 2 ( 1) and Cl 2HSiOCH 2CH 2NMe 2 ( 2) were prepared by reactions of lithium 2-(dimethylamino)ethanolate with SiCl 4 and HSiCl 3. The analogous reaction with H 2SiCl 2 gave ClH 2SiOCH 2CH 2NMe 2 ( 3), but only in a mixture with Cl 2HSiOCH 2CH 2NMe 2 ( 2), from which it could not be separated. All compounds were characterized by IR and NMR ( (1)H, (13)C, (29)Si) spectroscopy, 1 and 2 by elemental analyses and by determination of their crystal structures. Cl 3SiOCH 2CH 2NMe 2 ( 1) and Cl 2HSiOCH 2CH 2NMe 2 ( 2) crystallize as monomeric ring compounds with pentacoordinate silicon atoms participating in intramolecular Si-N bonds [2.060(2) A ( 1), 2.037(2) A ( 2)]. The dative bonds in 1 and 2 between the silicon and nitrogen atoms could also be proven to exist at low temperatures in solution in (1)H, (29)Si-HMBC-NMR experiments by detection of the scalar coupling between the (29)Si and the protons of the NCH 2 and NCH 3 groups. A function describing the chemical shift delta exp (29)Si dependent on the chemical shifts of the individual equilibrium components, the temperature, and the free enthalpy of reaction was worked out and fitted to the experimental VT-NMR data of 1 and 2. This provided values of the free reaction enthalpies of Delta G = -28.8 +/- 3.9 kJ x mol (-1) for 1 and Delta G = -22.3 +/- 0.4 kJ x mol (-1) for 2 and estimates for the chemical shifts of open-chain (index o) and ring conformers (index r) for 1 of delta r = -94 +/- 2 ppm and delta o = -36 +/- 5 ppm and for 2 of delta r = -82 +/- 1 ppm and delta o = -33 +/- 4 ppm. The value of delta r for 1 is very close to that obtained from a solid-state (29)Si MAS NMR spectrum. Quantumchemical calculations (up to MP2/TZVPP) gave largely differing geometries for 1 (with a Si...N distance of 3.072 A), but well reproduced the geometry of 2. These differences are due to Cl...H and Cl...C repulsions and solid state effects, which can be modeled by conductor-like screening model calculations and also rationalized in terms of the topology of the electron density, which was analyzed in terms of the quantum theory of atoms in molecules.