New silatranes possessing urea functionality: Synthesis, characterization and their structural aspects

Abstract The present work aims at the synthesis of various novel silatranes bearing substituted urea functionality. Nucleophilic addition of various amines (morpholine, aniline, ethylenediamine and 3-aminopropyltriethoxysilane) to 3-isocyanatopropyltriethoxysilane resulted in the four triethoxysilanes; N-[3-(triethoxysilyl)propyl]morpholine-4-carboxylic acid amide ( 1 ), 1-[3-(triethoxysilyl)propyl]-3-phenylurea ( 2 ), 1,2-bis{ N ′-[3-(triethoxysilyl)propyl]ureido}-ethane ( 3 ) and N-[3-(triethoxysilyl)propyl]-N′-[3-(triethoxysilyl)propyl]urea ( 4 ), respectively. In the presence of a base the resulting silanes undergo transesterification reaction with triethanolamine, thus forming the corresponding silatranes, N-(3-silatranylpropyl)morpholine-4-carboxylic acid amide ( 5 ), 1-(3-silatranylpropyl)-3-phenylurea ( 6 ), 1,2-Bis[ N ′-(3-silatranylpropyl)ureido]-ethane ( 7 ) and N-(3-silatranylpropyl)-N′-(3-silatranylpropyl)urea ( 8 ), respectively. Among these are four novel compounds ( 5 – 8 ), which were characterized by elemental analysis, IR, multinuclear ( 1 H, 13 C and 29 Si) NMR and mass spectroscopy. Structures of compounds 5 and 6 were deduced by X-ray crystallography. Single crystal X-ray studies revealed distorted trigonal bipyramidal coordination about Si in 5 and 6 with Si–N bond distance of 2.121(1) A and 2.189(2) A, respectively.