Zwitterionic 5Si-Organofluorosilicates of the Formula Types F4SiCH2NMe2R and F
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- 作者：Reinhold Tacke ; Joachim Becht ; Olaf Dannappel ; Reinhart Ahlrichs ; Uwe Schneider ; William S. Sheldrick ; Josef Hahn ; and Frank Kiesgen
- 刊名：Organometallics
- 出版年：1996
- 出版时间：April 16, 1996
- 年：1996
- 卷：15
- 期：8
- 页码：2060 - 2077
- 全文大小：684K
- 年卷期：v.15,no.8(April 16, 1996)
- ISSN：1520-6041
文摘
The zwitterionic
fchars/lambda.gif" BORDER=0 >5Si-organofluorosilicatesF4SiCH2NMe2H(5) andF3MeSiCH2NMe2H(7;crystallographic modifications 7a and 7b) weresynthesized by reaction of the silanes(MeO)3SiCH2NMe2(11) and(MeO)2MeSiCH2NMe2(13), respectively, with HF in a mixtureof ethanol and hydrofluoric acid at 0 
f">C. The relatedzwitterionicfchars/lambda.gif" BORDER=0 >5Si-organofluorosilicatesF4SiCH2NMe3(6) andF3MeSiCH2NMe3(8) were obtained analogously by reaction of HFwith the ammonium iodides[(MeO)3SiCH2NMe3]I(12) and[(MeO)2MeSiCH2NMe3]I(14),respectively. Reaction of the silanes(MeO)3SiCH2NR2(16) and(MeO)2tBuSiCH2NR2(17)(NR2 = 2,2,6,6-tetramethylpiperidino) with HF gave thezwitterionic fchars/lambda.gif" BORDER=0 >5Si-organofluorosilicates F4SiCH2NR2H(9) andF3tBuSiCH2NR2H(10), respectively. The crystal structuresof compounds 5, 6, 7a,b,and 8-10 were determined by single-crystalX-ray diffractionstudies. Compounds 5-10 were studied bysolution-state 1H, 13C, 19F, and29Si NMRexperiments at room temperature (solvent CD3CN).These studies indicate a rapid fluorineexchange at room temperature. As shown by temperature-dependent19F NMR experimentswith 10 (solvent CD2Cl2), thisligand exchange can be reduced on cooling. According toline-shape analyses, the dynamic behavior of 10 can be describedby two different processes.For compounds 5-8 and related modelspecies ab initio studies at the SCF/SVP and MP2/TZP levels were performed. Calculated and experimental (crystalstructures) geometric datawere compared, and the influence of intermolecular interactions(packing effects) in the solidstate and intramolecular interactions between the charged centers inthe calculatedzwitterions were studied. Furthermore, the dynamic behavior of thetitle compounds wasinvestigated by ab initio studies of the related model speciesF4SiCH2NH3(19) andF3MeSiCH2NH3(20).
fchars/lambda.gif" BORDER=0 >5Si-organofluorosilicatesF4SiCH2NMe2H(5) andF3MeSiCH2NMe2H(7;crystallographic modifications 7a and 7b) weresynthesized by reaction of the silanes(MeO)3SiCH2NMe2(11) and(MeO)2MeSiCH2NMe2(13), respectively, with HF in a mixtureof ethanol and hydrofluoric acid at 0 f">C. The relatedzwitterionicfchars/lambda.gif" BORDER=0 >5Si-organofluorosilicatesF4SiCH2NMe3(6) andF3MeSiCH2NMe3(8) were obtained analogously by reaction of HFwith the ammonium iodides[(MeO)3SiCH2NMe3]I(12) and[(MeO)2MeSiCH2NMe3]I(14),respectively. Reaction of the silanes(MeO)3SiCH2NR2(16) and(MeO)2tBuSiCH2NR2(17)(NR2 = 2,2,6,6-tetramethylpiperidino) with HF gave thezwitterionic fchars/lambda.gif" BORDER=0 >5Si-organofluorosilicates F4SiCH2NR2H(9) andF3tBuSiCH2NR2H(10), respectively. The crystal structuresof compounds 5, 6, 7a,b,and 8-10 were determined by single-crystalX-ray diffractionstudies. Compounds 5-10 were studied bysolution-state 1H, 13C, 19F, and29Si NMRexperiments at room temperature (solvent CD3CN).These studies indicate a rapid fluorineexchange at room temperature. As shown by temperature-dependent19F NMR experimentswith 10 (solvent CD2Cl2), thisligand exchange can be reduced on cooling. According toline-shape analyses, the dynamic behavior of 10 can be describedby two different processes.For compounds 5-8 and related modelspecies ab initio studies at the SCF/SVP and MP2/TZP levels were performed. Calculated and experimental (crystalstructures) geometric datawere compared, and the influence of intermolecular interactions(packing effects) in the solidstate and intramolecular interactions between the charged centers inthe calculatedzwitterions were studied. Furthermore, the dynamic behavior of thetitle compounds wasinvestigated by ab initio studies of the related model speciesF4SiCH2NH3(19) andF3MeSiCH2NH3(20).