New Zwitterionic Spirocyclic λ5Si-Silicates with Two Ethane-1,2-diolato(2–), Oxalato(2–), or Benzene-1,2-diolato(2–) Ligands – Synthesis, Structure, and Dynamic Behavior

✍ Scribed by Reinhold Tacke; Melanie Pülm; Ingo Richter; Brigitte Wagner; Reiner Willeke

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: German
• Weight: 244 KB
• Volume: 625
• Category: Article
• ISSN: 0372-7874
• DOI: 10.1002/(sici)1521-3749(199912)625:12<2169::aid-zaac2169>3.0.co;2-2

✦ Synopsis

The syntheses of the zwitterionic spirocyclic k 5 Sisilicates 6±9 are described. These chiral zwitterions contain a pentacoordinate (formally negatively charged) silicon atom and a tetracoordinate (formally positively charged) nitrogen atom. Compounds 6 ´1/ 2 HO(CH 2 ) 2 OH, 7, 8 ´CH 3 CN, and 9 were studied by solution-state ( 1 H, 13 C, 29 Si) and solid-state ( 29 Si CP/MAS) NMR experiments. In addition, all compounds were structurally characterized by single-crystal Xray diffraction. The dynamic behavior (Berry-type enantio-merization) of 7±9 in solution was studied by VT 1 H NMR experiments. These experimental studies were completed by ab initio investigations of the related anionic model species 10±12.