Trimethylamine Adducts of the Chlorosilanes

Burg, Anton B.

doi:10.1021/ja01639a021

Cited by 42 publications

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“…[1][2][3][4] Most of these chlorosilane-amine adducts are only stable in the solid state and dissociate quantitatively on melting, dissolution, or evaporation, [5] which explains why only limited information about their molecular structure is available. The adducts described in the literature mainly involve those with unsubstituted or methyl-substituted pyridines as donor molecules.…”

Section: Introductionmentioning

confidence: 99%

“…The reaction with pyrazine results in the first 1:2 adduct (2) of H 2 SiCl 2 with an electron-deficient heteroaromatic compound. Treatment of 1 d and 1 e with CHCl 3 yields the ionic complexes [SiH 2 A C H T U N G T R E N N U N G (Rpy) 4 ]Cl 2 ·6 CHCl 3 (Rpy = 4-methylpyridine (3 d) and 4-ethylpyridine (3 e)). All products are investigated by single-crystal X-ray diffraction and 29 Si CP/MAS NMR spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…Herein we report the systematic synthesis and investigation of the hexacoordinate compounds H 2 SiCl 2 A C H T U N G T R E N N U N G (Rpy) 2 , which exhibit various substitution patterns at the donor molecule. These solid adducts are stable at room temperature and are directly accessible from dichlorosilane.…”

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confidence: 99%

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Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Fester

Wagler

Brendler

et al. 2008

Chemistry A European J

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H(2)SiCl(2) and substituted pyridines (Rpy) form adducts of the type all-trans-SiH(2*)Cl(2)2 Rpy. Pyridines with substituents in the 4- (CH(3), C(2)H(5), H(2)C=CH, (CH(3))(3)C, (CH(3))(2)N) and 3-positions (Br) give the colourless solids 1 a-f. The reaction with pyrazine results in the first 1:2 adduct (2) of H(2)SiCl(2) with an electron-deficient heteroaromatic compound. Treatment of 1 d and 1 e with CHCl(3) yields the ionic complexes [SiH(2)(Rpy)(4)]Cl(2*)6 CHCl(3) (Rpy=4-methylpyridine (3 d) and 4-ethylpyridine (3 e)). All products are investigated by single-crystal X-ray diffraction and (29)Si CP/MAS NMR spectroscopy. The Si atoms are found to be situated on centres of symmetry (inversion, rotation), and the Si-N distances vary between 193.3 pm for 1 c (4-(dimethylamino)pyridine complex) and 197.3 pm for 2. Interestingly, the pyridine moieties are coplanar and nearly in an eclipsed position with respect to the SiH(2) units, except for the ethyl-substituted derivative 1 e, which shows a more staggered conformation in the solid state. Calculation of the energy profile for the rotation of one pyridine ring indicates two minima that are separated by only 1.2 kJ mol(-1) and a maximum barrier of 12.5 kJ mol(-1). The (29)Si NMR chemical shifts (delta(iso)) range from -145.2 to -152.2 ppm and correlate with the electron density at the Si atoms, in other words with the +I and +M effects of the substituents. Again, compound 1 e is an exception and shows the highest shielding. The bonding situation at the Si atoms and the (29)Si NMR tensor components are analysed by quantum chemical methods at the density functional theory level. The natural bond orbital analysis indicates polar covalent Si-H bonds and very polar Si-Cl bonds, with the highest bond polarisation being observed for the Si-N interaction, which must be considered a donor-acceptor interaction. An analysis of the topological properties of the electron distribution (AIM) suggests a Lewis structure, thereby supporting this bonding situation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Fester

Wagler

Brendler

et al. 2008

Chemistry A European J

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“…It has been shown [32,33] that the addition of acceptor molecules is directly related to their strength as acceptors. Trimethylborane and dimethylfluoroborane do not react with aminoboranes at low temperatures.…”

Section: R4mentioning

confidence: 99%

Recent Developments in the Chemistry of Aminoboranes

Niedenzu

1964

Angew. Chem. Int. Ed. Engl.

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“…Stereochemical information for the cornpounds SiC1,X.NMe3 where X = H, F, Br, or I have not previously been repo-ted although the existence of the hydride and fluoride has been known for some time (1,2). The compounds are found to be stable at -196 "C, yet completely dissociated into free halide and amine at room temperature.…”

Section: Introdt~ctionmentioning

confidence: 99%

Vibrational Spectra, Vibrational Analysis and Stereochemistries of the Pentacoordinate Molecules SiCl₃X•N(CH₃)₃ and SiCl₃X•N(CD₃)₃ where X = H, F, Br, or I

Boal¹,

Ozin²

1973

Can. J. Chem.

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The thermally unstable compounds SiCI,X.N(CH,), and SiC13X.N(CD3), where X = H , F, Br, or I are studied at -196 "C by infrared a.nd Raman spectroscopy. The data are compatible with molecular five coordinate compounds having a trigonal bipyramidal stereochemistry with the ligand trimethylamine always in the axial position. Using the vibrational data and normal coordinate analyses in both the C, and C3, configurations, X is suggested to be equatorial for H and F and axial for Br and I. The factors influencing the position of X in the compounds are discussed.Les composCs thermiquement instables SiCI,X.N(CH,), et SiCI,X.N(CD,), ou X=H, F, Br, oh I ont CtB etudies a -190 "C par spectroscopie infrarouge et Raman. Les rtsultats peuvent 6tre attribuks a des composCs moleculaires de coordination cinq (5) possedant une stereochimie bipyramidale trigonale avec le coordinat trimethylamine toujours en position axiale. En utilisant les donnees vibrationnelles et les analyses en coordonnees normales pour les configurations C, et C,,, on peut supposer que X est equatorial pour H et F, axial pour Br et I. Les facteurs influen~ant la position de X dans les composes sont discutes.[Traduit par le journal]Can. J. Chem., 51. 609 (1973) Introdt~ction Stereochemical information for the cornpounds SiC1,X.NMe3 where X = H, F, Br, or I have not previously been repo-ted although the existence of the hydride and fluoride has been known for some time (1,2). The compounds are found to be stable at -196 "C, yet completely dissociated into free halide and amine at room temperature. Dissociation pressure measurements have been reported for the series SiCl,H, _,.NMe, and SiGl,F,-,.NMe, where the results indicated the influence of steric and electronegativity effects on the stability order of the molecules (3, 4). With recent improvements in low temperature infrared and Raman techniques, there has been renewed interest in vibrational and structural studies of unstable co-ordination compounds.In an attempt to study thesz complexes, ~t was assumed that the basic shape at silicon was trigonal bipyramidai, with the trimethylamine ligand lying axially. Vibrational and single crystal Raman spectra and x-ray data ( 5 , 6) for the complexes MX,.NMe, (M = Si, Ce, or Sn and X = F or CI), h4X3.2NMe, (M = Al, Ga, or In and X = H, Cl, or Br) and MX3.NMe, (M = P or As and X = Cl or Br) have been reported and the evidence IS overwhelmingly in lTo whom correspondence should be addressed.favor of the amine lying axially. Assulning this, the question is then whether the X atom will reside in the equatorial or axial position for the series SiC1,X.NMe3. An argument has been put forward (7) that for trigonal bipyramidal molecules, the most electropositive atom will lie in the equatorial plane and hence one would expect to find C1, F, C1, and Cl in the axial positions for the series X = P-f, F, Br, and I. If the trimethylamine ligand were sterically bulky enough to crowd the atoms in the equatorial plane, then one might expect to find Cl, C1, Br, and I for the same...

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Trimethylamine Adducts of the Chlorosilanes

Cited by 42 publications

References 0 publications

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Recent Developments in the Chemistry of Aminoboranes

Vibrational Spectra, Vibrational Analysis and Stereochemistries of the Pentacoordinate Molecules SiCl₃X•N(CH₃)₃ and SiCl₃X•N(CD₃)₃ where X = H, F, Br, or I

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Trimethylamine Adducts of the Chlorosilanes

Cited by 42 publications

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Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and 29Si NMR Chemical Shifts

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and 29Si NMR Chemical Shifts

Recent Developments in the Chemistry of Aminoboranes

Vibrational Spectra, Vibrational Analysis and Stereochemistries of the Pentacoordinate Molecules SiCl3X•N(CH3)3 and SiCl3X•N(CD3)3 where X = H, F, Br, or I

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Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and ²⁹Si NMR Chemical Shifts

Vibrational Spectra, Vibrational Analysis and Stereochemistries of the Pentacoordinate Molecules SiCl₃X•N(CH₃)₃ and SiCl₃X•N(CD₃)₃ where X = H, F, Br, or I