Syntheses, Stereochemistry, and Dynamic Behavior of Chiral Zwitterionic (Ammoniomethyl)bis[glycolato(2–)-O1,O2]silicates
✍ Scribed by Reinhold Tacke; Rüdiger Bertermann; Andreas Biller; Olaf Dannappel; Melanie Pülm; Reiner Willeke
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 429 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-1948
No coin nor oath required. For personal study only.
✦ Synopsis
The syntheses of the zwitterionic (molecular) spirocyclic λ 5 Si-including VT 1 H-NMR studies of 9) and solid-state NMR spectroscopy ( 13 C CP/MAS, 29 Si CP/MAS). In addition, silicates 5-9 are described. These chiral compounds contain a pentacoordinate (formally negatively charged) silicon atom compounds 5•H 2 O, 7, 8, 9•H 2 O, and 9•2CH 3 CN were structurally characterized by single-crystal X-ray diffraction, and a tetracoordinate (formally positively charged) nitrogen atom. The stereochemistry and dynamic behavior of 5-9
and ab initio investigations of the zwitterion 8 and the related anionic model species 10 were carried out. were investigated. For this purpose, compounds 5-9 were studied by solution-state NMR spectroscopy ( 1 H, 13 C, 29 Si;
Results and Discussion
Syntheses 3, starting from the dialkoxy(phenyl)(aminomethyl)silane The zwitterionic λ 5 Si-silicates 5Ϫ9 were prepared accord-Ph(MeO) 2 SiCH 2 NMe 2 (14) and from the (ammoniomething to Scheme 1, starting from the trialkoxy(aminomethyl)tetrafluorosilicate F 4 SiCH 2 NMe 2 H (15), respectively. yl)silanes (EtO) 3 SiCH 2 NH 2 (11), (MeO) 3 SiCH 2 N(H)Me Following the strategy described for the synthesis of (12), and (MeO) 3 SiCH 2 NMe 2 (13). Compounds 8 and 9 1Ϫ4, [2e,2g] compounds 5Ϫ9 were prepared according to were synthesized alternatively according to Scheme 2 and method a by reaction of the respective silanes 11Ϫ13 with two mol equivalents of glycolic acid and 2-methyllactic [a] Institut für Anorganische Chemie, Universität Würzburg acid, respectively (Scheme 1). The reactions were performed Am Hubland,