Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3)

Hagemann M, Mix A, Berger R, Pape T, Mitzel NW (2008)
INORGANIC CHEMISTRY 47(22): 10554-10564.

Zeitschriftenaufsatz | Veröffentlicht | Englisch
 
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Abstract / Bemerkung
The compounds Cl3SiOCH2CH2NMe2 (1) and Cl2HSiOCH2CH2NMe2 (2) were prepared by reactions of lithium 2-(dimethylamino)ethanolate with SiCl4 and HSO3. The analogous reaction with H2SiCl2 gave ClH2SiOCH2CH2NMe2 (3), but only in a mixture with Cl2HSiOCH2CH2NMe2 (2), from which it could not be separated. All compounds were characterized by IR and NMR (1(H), C-13, Si-29) spectroscopy, 1 and 2 by elemental analyses and by determination of their crystal structures. Cl3SiOCH2CH2NMe2 (1) and Cl2HSiOCH2CH2NMe2 (2) crystallize as monomeric ring compounds with pentacoordinate silicon atoms participating in intramolecular Si-N bonds [2.060(2) angstrom (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 H-1, Si-29-HMBC-NMR experiments by detection of the scalar coupling between the 29Si and the protons of the NCH2 and NCH3 groups. A function describing the chemical shift delta Si-29(exp) 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 . mol(-1) for 1 and Delta G = -22.3 +/- 0.4 kJ . 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 Si-29 MAS NMR spectrum. Quantumchemical calculations (up to MP2/TZVPP) gave largely differing geometries for 1 (with a Si...N distance of 3.072 angstrom), 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.
Erscheinungsjahr
2008
Zeitschriftentitel
INORGANIC CHEMISTRY
Band
47
Ausgabe
22
Seite(n)
10554-10564
ISSN
0020-1669
eISSN
1520-510X
Page URI
https://pub.uni-bielefeld.de/record/1636677

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Hagemann M, Mix A, Berger R, Pape T, Mitzel NW. Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3). INORGANIC CHEMISTRY. 2008;47(22):10554-10564.
Hagemann, M., Mix, A., Berger, R., Pape, T., & Mitzel, N. W. (2008). Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3). INORGANIC CHEMISTRY, 47(22), 10554-10564. doi:10.1021/ic801205q
Hagemann, M., Mix, A., Berger, R., Pape, T., and Mitzel, N. W. (2008). Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3). INORGANIC CHEMISTRY 47, 10554-10564.
Hagemann, M., et al., 2008. Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3). INORGANIC CHEMISTRY, 47(22), p 10554-10564.
M. Hagemann, et al., “Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3)”, INORGANIC CHEMISTRY, vol. 47, 2008, pp. 10554-10564.
Hagemann, M., Mix, A., Berger, R., Pape, T., Mitzel, N.W.: Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3). INORGANIC CHEMISTRY. 47, 10554-10564 (2008).
Hagemann, Michael, Mix, Andreas, Berger, Raphael, Pape, Tania, and Mitzel, Norbert W. “Strong Intramolecular Si-N Interactions in the Chlorosilanes Cl3-nHnSiOCH2CH2NMe2 (n=1-3)”. INORGANIC CHEMISTRY 47.22 (2008): 10554-10564.

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