CO<sub>2</sub> as an Oxygen Source for Polysiloxanes – Preparation, Crystal Structure and Thermal Decomposition of Two Novel Silylcarbamates

Wiltzsch, Conny; Kraushaar, Konstantin; Schwarzer, Anke; Kroke, Edwin

doi:10.1515/znb-2011-0908

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…As the capping of tetrahedral faces trans to rather electronegative atoms X should be favorable because of N→Si lone pair donation into a lower lying σ*(Si-X) molecular orbital, the conformation 2 (as encountered with 2b) was rather expected, whereas the presence of conformer 1 in the structure of 2a was rather surprising. In dimethylsilicon carbamates Me 2 Si(-O(O=)C-NRR') 2 it is a common feature that the carbonyl O atoms are capping tetrahedral faces trans to Si-O bonds [55][56][57][58]. Therefore, we will have a closer look at the energetic differences between the conformers of compounds 2 in Section 3.2.3.…”

Section: Computational Analyses Of Isomers Of 1a and 1bmentioning

confidence: 99%

Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution

et al. 2022

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A series of pyridine-2-olates (pyO) and pyridine-2-thiolates (pyS) of silicon was studied in solid state and in solution. The crystal structures of Me3Si(pyO) (1a), Me3Si(pyS) (1b), Me2Si(pyO)2 (2a), Me2Si(pyS)2 (2b), Ph2Si(pyO)2 (3a) and Ph2Si(pyS)2 (3b) were determined by X-ray diffraction. For that purpose, crystals of the (at room temperature) liquid compounds 1a and 1b were grown in a capillary on the diffractometer. Compounds 1a, 1b, 2a, 2b and 3a feature tetracoordinate silicon atoms in the solid state, whereas 3b gave rise to a series of four crystal structures in which the Si atoms of this compound are hexacoordinate. Two isomers (3b1 with all-cis arrangement of the C2N2S2 donor atoms in P, and 3b2 with trans S-Si-S axis in P21/n) formed individual crystal batches, which allowed for their individual 29Si NMR spectroscopic study in the solid state (the determination of their chemical shift anisotropy tensors). Furthermore, the structures of a less stable modification of 3b2 (in C2/c) as well as a toluene solvate 3b2×(toluene) (in P) were determined. In CDCl3, the equimolar solutions of the corresponding pairs of pyO and pyS compounds (2a/2b and 3a/3b) showed substituent scrambling with the formation of the products Me2Si(pyO)(pyS) (2c) and Ph2Si(pyO)(pyS) (3c), respectively, as minor components in the respective substituent exchange equilibrium.

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Section: Computational Analyses Of Isomers Of 1a and 1bmentioning

confidence: 99%

Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution

et al. 2022

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“…For example, CO 2 can insert into the Si-N bond with the formation of carbamoyloxysilanes (e.g., IV) [4][5][6]. The latter are interesting starting materials for the synthesis of isocyanates and silicones in a CO 2 -consuming process [5,7,8]. The insertion of isocyanates in Si-N bonds may afford silylated urea derivatives (e.g., V) [9].…”

Section: Introductionmentioning

confidence: 99%

Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines

2023

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A series of silylated 2-aminopyrimidines Me(4−n)Si(NHpyr)n (Me = methyl, NHpyr = pyrimid-2-ylamino, n = 1, 2, 3, 4), i.e., compounds 1, 2, 3, and 4, respectively, was prepared from a series of the respective chlorosilanes Me(4−n)SiCln and 2-aminopyrimidine. Triethylamine was used as a sacrificial base. Compounds 1, 2, 3, and 4 are solid at room temperature. They were analyzed using 1H, 13C, 29Si NMR, and Raman spectroscopy, and their molecular structures were confirmed by single-crystal X-ray diffraction analyses. All structures exhibit intramolecular van der Waals contacts between the silicon atom and one nitrogen atom of the pyrimidine moiety. Thus, their Si coordination spheres can be interpreted as [4+n] coordinated capped tetrahedra. Intermolecular hydrogen bonds (N–H···N bridges between the Si-bound amino groups and the non-Si-capping pyrimidine N atoms) are a constant contributor to the solid-state structures of these compounds. Furthermore, compounds 2 and 4 exhibit N–H···N bridges which involve 50% of their Si-capping N atoms as hydrogen bridge acceptors. Consequently, 50% of the non-Si-capping pyrimidine N atoms are stabilized by C–H···N contacts. As a result of a particularly dense network of intermolecular hydrogen bridges, the melting point of Si(NHpyr)4 (compound 4) is higher than 300 °C.

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“…Another reaction is the insertion of CO 2 into the SiN bond of aminosilanes yielding carbomoyloxysilanes of the type Me 2 Si[(OCO)NR 2 ] 2 15,16. It might be possible to gain further insight into the mechanism of CO 2 insertion by using solid aminosilanes.…”

Section: Introductionmentioning

confidence: 99%

Crystalline Aminoorganosilanes – Syntheses, Structures, Spectroscopic Properties

Meinel

Günther

Schwarzer

et al. 2014

Zeitschrift anorg allge chemie

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A number of aminosilanes derived from N-methylaniline and chloroorganylsilanes were prepared and characterized. X-ray structure analysis was performed on the crystalline derivatives Ph(Cl)Si(NMePh) 2 (4a), HSi(NMePh) 3 (2b), MeSi(NMePh) 3 (3b), and Ph 2 Si(NMePh) 2 (6b). The compounds were comprehensively charac-* Dr. U. Böhme 1607 terized by 1 H, 13 C, 29 Si NMR, and IR spectroscopy. Volatile derivatives were further characterized by GC/MS. It was shown using quantum chemical methods that the planarization of the nitrogen atoms in the amino derivatives is caused by phenyl groups and silyl substituents.

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CO₂ as an Oxygen Source for Polysiloxanes – Preparation, Crystal Structure and Thermal Decomposition of Two Novel Silylcarbamates

Cited by 5 publications

References 9 publications

Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution

Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution

Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines

Crystalline Aminoorganosilanes – Syntheses, Structures, Spectroscopic Properties

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CO2 as an Oxygen Source for Polysiloxanes – Preparation, Crystal Structure and Thermal Decomposition of Two Novel Silylcarbamates

Cited by 5 publications

References 9 publications

Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution

Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution

Molecular Structures and Intermolecular Hydrogen Bonding of Silylated 2-Aminopyrimidines

Crystalline Aminoorganosilanes – Syntheses, Structures, Spectroscopic Properties

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CO₂ as an Oxygen Source for Polysiloxanes – Preparation, Crystal Structure and Thermal Decomposition of Two Novel Silylcarbamates