| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1324539 | Journal of Organometallic Chemistry | 2011 | 5 Pages |
The reaction of compound Me2Si(NSiMe3)2Si(OH)Cl with Me2SiCl2 leads to the disiloxane Me2Si(NSiMe3)2Si(Cl)OSi(Me2)Cl (1). Hydrolysis of 1 in the presence of pyridine results in Me2Si(NSiMe3)2Si(OH)OSi(Me2)OH (2), which is allowed to react with SiCl4 to give cyclotrisiloxane [Me2Si(NSiMe3)2Si](OSiMe2)(OSiCl2)O (3). The treatment of 1 with (t-BuO)2Si(OH)2 forms cyclotrisiloxane [Me2Si(NSiMe3)2Si](OSiMe2)[OSi(Ot-Bu)2]O (4). Compound 3 is obtained as a crystalline solid while 4 is an oily liquid. The ring size of these new types of cyclotrisiloxanes with three different R2Si-units is confirmed by cryoscopy in benzene, 29Si NMR chemical shifts and in case of 3, additionally by a single X-ray diffraction study. The different electronegativities of the substituents in the R2Si-units lead to different bond lengths and bond angles within the Si3O3 cycle, which are discussed in detail in the molecular structure of 3.
Graphical abstractThe different electronegativities of the substituents in the R2Si-units within the Si3O3 cycle lead to different bond lengths and angles which are discussed in detail for the molecular structure of [Me2Si(NSiMe3)2Si](OSiMe2)(OSiCl2)O (3). The ring size is confirmed by cryoscopy in benzene, 29Si NMR chemical shifts and in case of 3, additionally by a single X-ray diffraction study .Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► First cyclotrisiloxanes with three different R2Si-units. ► First molecular structure of a cyclotrisiloxane with three different R2Si-units. ► Different R2Si-units cause different bond lengths and bond angles within the Si3O3 cycle. ► 29Si NMR shifts of Me2Si-units depend on neighbouring R2Si-units.
