TY - JOUR
T1 - Investigation of the gas-phase structure and rotational barrier of trimethylsilyl trifluoromethanesulfonate and comparison with covalent sulfonates
AU - Defonsi Lestard, Maria E.
AU - Tuttolomondo, Maria E.
AU - Varetti, Eduardo L.
AU - Wann, Derek A.
AU - Robertson, Heather E.
AU - Rankin, David W. H.
AU - Ben Altabef, Aida
PY - 2010/12/15
Y1 - 2010/12/15
N2 - 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 lp π[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.
AB - 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 lp π[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.
KW - Gas electron diffraction
KW - ab initio calculations
KW - DFT calculations
KW - Internal barrier to rotation
KW - Fourier-type expansion
KW - Natural bond orbital analysis
UR - http://www.scopus.com/inward/record.url?scp=78649317175&partnerID=8YFLogxK
U2 - 10.1016/j.molstruc.2010.10.009
DO - 10.1016/j.molstruc.2010.10.009
M3 - Article
SN - 0022-2860
VL - 984
SP - 376
EP - 382
JO - Journal of Molecular Structure
JF - Journal of Molecular Structure
IS - 1-3
ER -