1,3-Diazolyl functionalized organopropylsilatranes: Synthesis and structural characterization

• 1,3-Diazolyl substituted carbofunctional silatranes were synthesized.
• Silatranes were characterized by elemental analysis, IR, 1H, 13C NMR, spectroscopy and mass spectrometry.
• Single crystal X-ray structure of silatrane 5 was elucidated.
• Molecules of 5 interact with each other via the C–H⋯O interactions forming a layered structure.
• The thermal stability of silatranes was investigated by thermogravimetric technique.

This work aims at the synthesis of unsubstituted and 3,7,10-trimethylsubstituted organopropylsilatranes by the reaction of 1,3-diazoles, viz. benzimidazole and 2-isopropylimidazole with 3-chloropropyltriethoxysilane which results in the triethoxysilanes: N-(3-triethoxysilylpropyl)benzimidazole (3) and N-(3-triethoxysilylpropyl)-2-isopropylimidazole (4). In the presence of a base, these silanes undergo transesterification reaction with triethanolamine (1) and tris(isopropanol)amine (2) thus forming the corresponding silatranes, N-(3-silatranylpropyl)benzimidazole (5), N-[3-(3,7,10-trimethylsilatranyl)propyl]benzimidazole (6), N-(3-silatranylpropyl)-2-isopropylimidazole (7), N-[3-(3,7,10-trimethylsilatranyl)propyl]-2-isopropylimidazole (8). Among these novel silatranes, which have been characterized by elemental analysis, IR, 1H, 13C NMR spectroscopy, mass spectrometry and thermogravimetric analysis, the structure of silatrane (5) has been deduced by single crystal X-ray diffraction analysis.

A synthetic methodology for the synthesis of 1,3-diazolyl substituted silatranes derived from triethanolamine and tris(isopropanol)amine has been described. The molecular structure of silatrane, N-(3-silatranylpropyl)benzimidazole was obtained from single crystal X-ray diffraction studies with N → Si bond length of 2.15 Å.Figure optionsDownload as PowerPoint slide