Investigation of the gas-phase structure and rotational barrier of trimethylsilyl trifluoromethanesulfonate and comparison with covalent sulfonates

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• 作者：Marí ; a E. Defonsi Lestard ; Marí ; a E. Tuttolomondo ; Eduardo L. Varetti ; Derek A. Wann ; Heather E. Robertson ; David W.H. Rankin ; Aida Ben Altabef
• 关键词：Gas electron diffraction ; ab initio calculations ; DFT calculations ; Internal barrier to rotation ; Fourier-type expansion ; Natural bond orbital analysis
• 刊名：Journal of Molecular Structure
• 出版年：2010
• 出版时间：15 December 2010
• 年：2010
• 卷：984
• 期：1-3
• 页码：376-382
• 全文大小：612 K

文摘

The molecular structure of trimethylsilyl trifluoromethanesulfonate, CF₃SO₂OSi(CH₃)₃, has been determined in the gas phase from electron-diffraction data supplemented by ab initio (MP2) and DFT calculations using 6-31G(d), 6-311++G(d,p) and 6-311G++(3df,3pd) basis sets. Both experimental and theoretical data indicate that only one gauche conformer is possible by rotating about the O–S bond. The anomeric effect is a fundamental stereoelectronic interaction and presents a profound influence on the electronic geometry. We have investigated the origin of the anomeric effect by means of NBO and AIM analysis. A natural bond orbital analysis showed that the lpπ[O bonded to Si)] → σ^*[C–S] hyperconjugative interaction favors the gauche conformation. In addition, comparison of the structural and stereoelectronic properties of the title molecule with those of silyl trifluoromethanesulfonate and methyl trifluoromethanesulfonate has been carried out.