Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study

M.E. Defonsi Lestard; M.E. Tuttolomondo; E.L. Varetti; D.A. Wann; H.E. Robertson; D.W.H. Rankin; A. Ben Altabef

doi:10.1016/j.molstruc.2010.02.046

Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study

M.E. Defonsi Lestard, M.E. Tuttolomondo, E.L. Varetti, D.A. Wann, H.E. Robertson, D.W.H. Rankin, A. Ben Altabef

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

The molecular structure of trimethylsilyl trifluoroacetate, CF 3C(O)OSi(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), 6-311G(d,p), 6-311++G(d,p) and 6-311++G(3df,3pd) basis sets. Experimental data indicate that only one conformer, with C s symmetry [dihedral angle φ(CCOSi) = 180°, and all groups staggered], is observed in the gas phase. Theoretical data indicate that both this anti conformer and a gauche conformer, created by rotating about the C(O)O bond, are possible, although the preferred conformation is the staggered anti one. The torsional energies for different values of the CCOSi and COSiC dihedral angles have been calculated using the RHF, MP2 and B3LYP methods with the 6-311++G(d,p) basis set. For rotation around the CCOSi bond, a sixfold decomposition of the rotational barrier has been performed in terms of a Fourier-type expansion, enabling us to analyze the nature of the potential function, showing that the coefficients related to electrostatic interactions and steric effects are the dominant terms. The preference for the anti conformation was studied using the total-energy scheme, comparison of dipole moments, and the natural bond orbital partition scheme. The infrared spectra for the liquid and gas phases and the Raman spectrum for the liquid phase have also been recorded and the observed bands assigned to the vibrational normal modes. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to estimate the measured frequencies with a final root-mean-square deviation of 9.7 cm-1. © 2010 Elsevier B.V. All rights reserved.

Original language	Undefined/Unknown
Pages (from-to)	114-123
Number of pages	10
Journal	JOURNAL OF MOLECULAR STRUCTURE
Volume	978
Issue number	1-3
DOIs	https://doi.org/10.1016/j.molstruc.2010.02.046
Publication status	Published - 20 Aug 2010

Bibliographical note

Cited By (since 1996):1

Export Date: 1 October 2013

Source: Scopus

CODEN: JMOSB

doi: 10.1016/j.molstruc.2010.02.046

Language of Original Document: English

Correspondence Address: Ben Altabef, A.; INQUINOA, CONICET, Universidad Nacional de Tucumán, San Lorenzo 456, T4000CAN Tucumán, Argentina; email: [email protected]

References: Demuth, M., Mikhail, G., George, M.V., (1981) Helv. Chim. Acta, 64, p. 2759; Fujii, N., Otaka, A., Ikemura, O., Hatano, M., Okamachi, A., Funakoshi, S., Sakurai, M., Yajima, H., (1987) Chem. Pharm. Bull. (Tokyo), 35, p. 3447; Werstiuk, N.H., Brook, M.A., Hülser, P., (1988) Can. J. Chem., 66, p. 1430; Mori, S., Okada, F., Sekiguchi, O., Fijishige, M., Koitabashi, R., Tajima, S., (1997) J. Organomet. Chem., 527, p. 277; Defonsi Lestard, M.E., Tuttolomondo, M.E., Varetti, E.L., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Mol. Struct., 917, p. 183; Defonsi Lestard, M.E., Tuttolomondo, M.E., Varetti, E.L., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Raman Spectrosc., , 10.1002/jrs.2371; Defonsi Lestard, M.E., Tuttolomondo, M.E., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2010) J. Raman Spectrosc.; Defonsi Lestard, M.E., Tuttolomondo, M.E., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Chem. Phys., 131, pp. 214303-214301; Huntley, C.M., Laurenson, G.S., Rankin, D.W.H., (1980) J. Chem. Soc. Dalton Trans., p. 954; Fleischer, H., Wann, D.A., Hinchley, S.L., Borisenko, K.B., Lewis, J.R., Mawhorter, R.J., Robertson, H.E., Rankin, D.W.H., (2005) Dalton Trans., p. 3221; Hinchley, S.L., Robertson, H.E., Borisenko, K.B., Turner, A.R., Johnston, B.F., Rankin, D.W.H., Ahmadian, M., Cowley, A.H., (2004) Dalton Trans., p. 2469; Ross, W., Fink, M., Hilderbrandt, R., (1992) International Tables for Crystallography, Vol. C, p. 245; National Service for Computational Chemistry Software (NSCCS), , http://www.nsccs.ac.uk; Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Montgomery Jr., J.A., Pople, J.A., (2004) Gaussian 03, Revision D.01, , Gaussian, Inc. Wallingford, CT; Møller, C., Plesset, M.S., (1934) Phys. Rev., 46, p. 618; Krishnan, R., Binkley, J.S., Seeger, R., Pople, J.A., (1980) J. Chem. Phys., 72, p. 650; McLean, A.D., Chandler, G.S., (1980) J. Chem. Phys., 72, p. 5639; Frisch, M.J., Pople, J.A., Binkley, J.S., (1984) J. Chem. Phys., 80, p. 3265; Hehre, W.J., Schleyer V. P, R., Pople, J.A., (1986) Ab Initio Molecular Orbital Theory, , Wiley New York; Becke, A.D., (1993) J. Chem. Phys., 98, p. 5648; Lee, C., Yang, W., Parr, R.G., (1988) Phys. Rev. B, 37, p. 785; Sipachev, V.A., (1985) J. Mol. Struct. (THEOCHEM), 121, p. 143; Sipachev, V.A., (2001) J. Mol. Struct., 567, p. 67; Glendening, E.D., Badenhoop, J.K., Reed, A.D., Carpenter, J.E., Weinhold, F.F., (1996) Theoretical Chemistry Institute, , University of Wisconsin, Madison, WI; Collier, W.B., (1992) Program FCARTP (QCPE #631), , Department of Chemistry, Oral Roberts University Tulsa, OK; Nielsen, B., Holder, A.J., (1997) GaussView, User's Reference, , Gaussian, Inc. Pittsburgh, PA; Pitzer, R.M., Lipscomb, W.N., (1963) J. Chem. Phys., 39, p. 1995; Radom, L., Pople, J.A., (1970) J. Am. Chem. Soc., 92, p. 4786; Radom, L., Hehre, W.J., Pople, J.A., (1972) J. Am. Chem. Soc., 94, p. 2371; Douglas, D., Schleyer V. P, R., (1990) J. Org. Chem., 55, p. 1003; Millefiori, S., Alparone, A., (1998) J. Chem. Soc. Faraday Trans., 94, p. 25; Reed, A.D., Weinstock, R.B., Weinhold, F., (1985) J. Chem. Phys., 83, p. 735; Blake, A.J., Brain, P.T., McNab, H., Miller, J., Morrison, C.A., Parsons, S., Rankin, D.W.H., Smart, B.A., (1996) J. Phys. Chem., 100, p. 12280; Brain, P.T., Morrison, C.A., Parsons, S., Rankin, D.W.H., (1996) J. Chem. Soc. Dalton Trans., p. 4589; Mitzel, N.W., Rankin, D.W.H., (2003) Dalton Trans., p. 3650; Robiette, A.G., Thompson, J.C., (1965) Spectrochim. Acta, 21, p. 2023; Fernández, L.E., Ben Altabef, A., Navarro, A., Gómez, M.F., Varetti, E.L., (2000) Spectrochim. Acta A, 56, p. 1101; Fernández, L.E., Ben Altabef, A., Varetti, E.L., (2000) J. Mol. Struct., 553, p. 255; Fogarasi, G., Zhou, X., Taylor, P.W., Pulay, P., (1992) J. Am. Chem. Soc., 114, p. 8191; Pulay, P., Fogarasi, G., Pongor, G., Boggs, J.E., Vargha, A., (1983) J. Am. Chem. Soc., 105, p. 7037

Keywords

Ab initio
DFT
GED
NBO
Anti conformers
Anti-conformations
B3LYP method
Basis sets
Computational studies
DFT calculation
Dihedral angles
Electron diffraction data
Electrostatic interactions
Energy schemes
Experimental data
Force constants
Fourier
Gas-phase structures
Gasphase
Gauche conformer
Infrared spectrum
Liquid and gas phasis
Liquid Phase
Natural bond orbital
Partition schemes
Potential function
Raman Spectrum
Root-mean square deviation
Rotational barriers
Scaled quantum mechanical force fields
Steric effect
Target systems
Torsional energies
Trifluoroacetates
Trimethylsilyl
Vibrational normal modes
Vibrational properties
Conformations
Liquids
Quantum theory
Raman spectroscopy
Rotation
Gases

Access to Document

10.1016/j.molstruc.2010.02.046

http://www.scopus.com/inward/record.url?eid=2-s2.0-77956237462&partnerID=40&md5=6775ba50c5b5bddce9c7d0fc56df1dfb

Cite this

Defonsi Lestard, M. E., Tuttolomondo, M. E., Varetti, E. L., Wann, D. A., Robertson, H. E., Rankin, D. W. H., & Ben Altabef, A. (2010). Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study. JOURNAL OF MOLECULAR STRUCTURE, 978(1-3), 114-123. https://doi.org/10.1016/j.molstruc.2010.02.046

@article{a81ec6cda3d441d2a526981323c28722,

title = "Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study",

abstract = "The molecular structure of trimethylsilyl trifluoroacetate, CF 3C(O)OSi(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), 6-311G(d,p), 6-311++G(d,p) and 6-311++G(3df,3pd) basis sets. Experimental data indicate that only one conformer, with C s symmetry [dihedral angle φ(CCOSi) = 180°, and all groups staggered], is observed in the gas phase. Theoretical data indicate that both this anti conformer and a gauche conformer, created by rotating about the C(O)O bond, are possible, although the preferred conformation is the staggered anti one. The torsional energies for different values of the CCOSi and COSiC dihedral angles have been calculated using the RHF, MP2 and B3LYP methods with the 6-311++G(d,p) basis set. For rotation around the CCOSi bond, a sixfold decomposition of the rotational barrier has been performed in terms of a Fourier-type expansion, enabling us to analyze the nature of the potential function, showing that the coefficients related to electrostatic interactions and steric effects are the dominant terms. The preference for the anti conformation was studied using the total-energy scheme, comparison of dipole moments, and the natural bond orbital partition scheme. The infrared spectra for the liquid and gas phases and the Raman spectrum for the liquid phase have also been recorded and the observed bands assigned to the vibrational normal modes. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to estimate the measured frequencies with a final root-mean-square deviation of 9.7 cm-1. {\textcopyright} 2010 Elsevier B.V. All rights reserved.",

keywords = "Ab initio, DFT, GED, NBO, Anti conformers, Anti-conformations, B3LYP method, Basis sets, Computational studies, DFT calculation, Dihedral angles, Electron diffraction data, Electrostatic interactions, Energy schemes, Experimental data, Force constants, Fourier, Gas-phase structures, Gasphase, Gauche conformer, Infrared spectrum, Liquid and gas phasis, Liquid Phase, Natural bond orbital, Partition schemes, Potential function, Raman Spectrum, Root-mean square deviation, Rotational barriers, Scaled quantum mechanical force fields, Steric effect, Target systems, Torsional energies, Trifluoroacetates, Trimethylsilyl, Vibrational normal modes, Vibrational properties, Conformations, Liquids, Quantum theory, Raman spectroscopy, Rotation, Gases",

author = "{Defonsi Lestard}, M.E. and M.E. Tuttolomondo and E.L. Varetti and D.A. Wann and H.E. Robertson and D.W.H. Rankin and {Ben Altabef}, A.",

note = "Cited By (since 1996):1 Export Date: 1 October 2013 Source: Scopus CODEN: JMOSB doi: 10.1016/j.molstruc.2010.02.046 Language of Original Document: English Correspondence Address: Ben Altabef, A.; INQUINOA, CONICET, Universidad Nacional de Tucum{\'a}n, San Lorenzo 456, T4000CAN Tucum{\'a}n, Argentina; email: [email protected] References: Demuth, M., Mikhail, G., George, M.V., (1981) Helv. Chim. Acta, 64, p. 2759; Fujii, N., Otaka, A., Ikemura, O., Hatano, M., Okamachi, A., Funakoshi, S., Sakurai, M., Yajima, H., (1987) Chem. Pharm. Bull. (Tokyo), 35, p. 3447; Werstiuk, N.H., Brook, M.A., H{\"u}lser, P., (1988) Can. J. Chem., 66, p. 1430; Mori, S., Okada, F., Sekiguchi, O., Fijishige, M., Koitabashi, R., Tajima, S., (1997) J. Organomet. Chem., 527, p. 277; Defonsi Lestard, M.E., Tuttolomondo, M.E., Varetti, E.L., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Mol. Struct., 917, p. 183; Defonsi Lestard, M.E., Tuttolomondo, M.E., Varetti, E.L., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Raman Spectrosc., , 10.1002/jrs.2371; Defonsi Lestard, M.E., Tuttolomondo, M.E., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2010) J. Raman Spectrosc.; Defonsi Lestard, M.E., Tuttolomondo, M.E., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Chem. Phys., 131, pp. 214303-214301; Huntley, C.M., Laurenson, G.S., Rankin, D.W.H., (1980) J. Chem. Soc. Dalton Trans., p. 954; Fleischer, H., Wann, D.A., Hinchley, S.L., Borisenko, K.B., Lewis, J.R., Mawhorter, R.J., Robertson, H.E., Rankin, D.W.H., (2005) Dalton Trans., p. 3221; Hinchley, S.L., Robertson, H.E., Borisenko, K.B., Turner, A.R., Johnston, B.F., Rankin, D.W.H., Ahmadian, M., Cowley, A.H., (2004) Dalton Trans., p. 2469; Ross, W., Fink, M., Hilderbrandt, R., (1992) International Tables for Crystallography, Vol. C, p. 245; National Service for Computational Chemistry Software (NSCCS), , http://www.nsccs.ac.uk; Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Montgomery Jr., J.A., Pople, J.A., (2004) Gaussian 03, Revision D.01, , Gaussian, Inc. Wallingford, CT; M{\o}ller, C., Plesset, M.S., (1934) Phys. Rev., 46, p. 618; Krishnan, R., Binkley, J.S., Seeger, R., Pople, J.A., (1980) J. Chem. Phys., 72, p. 650; McLean, A.D., Chandler, G.S., (1980) J. Chem. Phys., 72, p. 5639; Frisch, M.J., Pople, J.A., Binkley, J.S., (1984) J. Chem. Phys., 80, p. 3265; Hehre, W.J., Schleyer V. P, R., Pople, J.A., (1986) Ab Initio Molecular Orbital Theory, , Wiley New York; Becke, A.D., (1993) J. Chem. Phys., 98, p. 5648; Lee, C., Yang, W., Parr, R.G., (1988) Phys. Rev. B, 37, p. 785; Sipachev, V.A., (1985) J. Mol. Struct. (THEOCHEM), 121, p. 143; Sipachev, V.A., (2001) J. Mol. Struct., 567, p. 67; Glendening, E.D., Badenhoop, J.K., Reed, A.D., Carpenter, J.E., Weinhold, F.F., (1996) Theoretical Chemistry Institute, , University of Wisconsin, Madison, WI; Collier, W.B., (1992) Program FCARTP (QCPE #631), , Department of Chemistry, Oral Roberts University Tulsa, OK; Nielsen, B., Holder, A.J., (1997) GaussView, User's Reference, , Gaussian, Inc. Pittsburgh, PA; Pitzer, R.M., Lipscomb, W.N., (1963) J. Chem. Phys., 39, p. 1995; Radom, L., Pople, J.A., (1970) J. Am. Chem. Soc., 92, p. 4786; Radom, L., Hehre, W.J., Pople, J.A., (1972) J. Am. Chem. Soc., 94, p. 2371; Douglas, D., Schleyer V. P, R., (1990) J. Org. Chem., 55, p. 1003; Millefiori, S., Alparone, A., (1998) J. Chem. Soc. Faraday Trans., 94, p. 25; Reed, A.D., Weinstock, R.B., Weinhold, F., (1985) J. Chem. Phys., 83, p. 735; Blake, A.J., Brain, P.T., McNab, H., Miller, J., Morrison, C.A., Parsons, S., Rankin, D.W.H., Smart, B.A., (1996) J. Phys. Chem., 100, p. 12280; Brain, P.T., Morrison, C.A., Parsons, S., Rankin, D.W.H., (1996) J. Chem. Soc. Dalton Trans., p. 4589; Mitzel, N.W., Rankin, D.W.H., (2003) Dalton Trans., p. 3650; Robiette, A.G., Thompson, J.C., (1965) Spectrochim. Acta, 21, p. 2023; Fern{\'a}ndez, L.E., Ben Altabef, A., Navarro, A., G{\'o}mez, M.F., Varetti, E.L., (2000) Spectrochim. Acta A, 56, p. 1101; Fern{\'a}ndez, L.E., Ben Altabef, A., Varetti, E.L., (2000) J. Mol. Struct., 553, p. 255; Fogarasi, G., Zhou, X., Taylor, P.W., Pulay, P., (1992) J. Am. Chem. Soc., 114, p. 8191; Pulay, P., Fogarasi, G., Pongor, G., Boggs, J.E., Vargha, A., (1983) J. Am. Chem. Soc., 105, p. 7037",

year = "2010",

month = aug,

day = "20",

doi = "10.1016/j.molstruc.2010.02.046",

language = "Undefined/Unknown",

volume = "978",

pages = "114--123",

journal = "JOURNAL OF MOLECULAR STRUCTURE",

issn = "0022-2860",

publisher = "Elsevier",

number = "1-3",

}

Defonsi Lestard, ME, Tuttolomondo, ME, Varetti, EL, Wann, DA, Robertson, HE, Rankin, DWH & Ben Altabef, A 2010, 'Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study', JOURNAL OF MOLECULAR STRUCTURE, vol. 978, no. 1-3, pp. 114-123. https://doi.org/10.1016/j.molstruc.2010.02.046

Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study. / Defonsi Lestard, M.E.; Tuttolomondo, M.E.; Varetti, E.L. et al.
In: JOURNAL OF MOLECULAR STRUCTURE, Vol. 978, No. 1-3, 20.08.2010, p. 114-123.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Gas-phase structure, rotational barrier and vibrational properties of trimethylsilyl trifluoroacetate CF3C(O)OSi(CH3) 3: An experimental and computational study

AU - Defonsi Lestard, M.E.

AU - Tuttolomondo, M.E.

AU - Varetti, E.L.

AU - Wann, D.A.

AU - Robertson, H.E.

AU - Rankin, D.W.H.

AU - Ben Altabef, A.

N1 - Cited By (since 1996):1 Export Date: 1 October 2013 Source: Scopus CODEN: JMOSB doi: 10.1016/j.molstruc.2010.02.046 Language of Original Document: English Correspondence Address: Ben Altabef, A.; INQUINOA, CONICET, Universidad Nacional de Tucumán, San Lorenzo 456, T4000CAN Tucumán, Argentina; email: [email protected] References: Demuth, M., Mikhail, G., George, M.V., (1981) Helv. Chim. Acta, 64, p. 2759; Fujii, N., Otaka, A., Ikemura, O., Hatano, M., Okamachi, A., Funakoshi, S., Sakurai, M., Yajima, H., (1987) Chem. Pharm. Bull. (Tokyo), 35, p. 3447; Werstiuk, N.H., Brook, M.A., Hülser, P., (1988) Can. J. Chem., 66, p. 1430; Mori, S., Okada, F., Sekiguchi, O., Fijishige, M., Koitabashi, R., Tajima, S., (1997) J. Organomet. Chem., 527, p. 277; Defonsi Lestard, M.E., Tuttolomondo, M.E., Varetti, E.L., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Mol. Struct., 917, p. 183; Defonsi Lestard, M.E., Tuttolomondo, M.E., Varetti, E.L., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Raman Spectrosc., , 10.1002/jrs.2371; Defonsi Lestard, M.E., Tuttolomondo, M.E., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2010) J. Raman Spectrosc.; Defonsi Lestard, M.E., Tuttolomondo, M.E., Wann, D.A., Robertson, H.E., Rankin, D.W.H., Ben Altabef, A., (2009) J. Chem. Phys., 131, pp. 214303-214301; Huntley, C.M., Laurenson, G.S., Rankin, D.W.H., (1980) J. Chem. Soc. Dalton Trans., p. 954; Fleischer, H., Wann, D.A., Hinchley, S.L., Borisenko, K.B., Lewis, J.R., Mawhorter, R.J., Robertson, H.E., Rankin, D.W.H., (2005) Dalton Trans., p. 3221; Hinchley, S.L., Robertson, H.E., Borisenko, K.B., Turner, A.R., Johnston, B.F., Rankin, D.W.H., Ahmadian, M., Cowley, A.H., (2004) Dalton Trans., p. 2469; Ross, W., Fink, M., Hilderbrandt, R., (1992) International Tables for Crystallography, Vol. C, p. 245; National Service for Computational Chemistry Software (NSCCS), , http://www.nsccs.ac.uk; Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Montgomery Jr., J.A., Pople, J.A., (2004) Gaussian 03, Revision D.01, , Gaussian, Inc. Wallingford, CT; Møller, C., Plesset, M.S., (1934) Phys. Rev., 46, p. 618; Krishnan, R., Binkley, J.S., Seeger, R., Pople, J.A., (1980) J. Chem. Phys., 72, p. 650; McLean, A.D., Chandler, G.S., (1980) J. Chem. Phys., 72, p. 5639; Frisch, M.J., Pople, J.A., Binkley, J.S., (1984) J. Chem. Phys., 80, p. 3265; Hehre, W.J., Schleyer V. P, R., Pople, J.A., (1986) Ab Initio Molecular Orbital Theory, , Wiley New York; Becke, A.D., (1993) J. Chem. Phys., 98, p. 5648; Lee, C., Yang, W., Parr, R.G., (1988) Phys. Rev. B, 37, p. 785; Sipachev, V.A., (1985) J. Mol. Struct. (THEOCHEM), 121, p. 143; Sipachev, V.A., (2001) J. Mol. Struct., 567, p. 67; Glendening, E.D., Badenhoop, J.K., Reed, A.D., Carpenter, J.E., Weinhold, F.F., (1996) Theoretical Chemistry Institute, , University of Wisconsin, Madison, WI; Collier, W.B., (1992) Program FCARTP (QCPE #631), , Department of Chemistry, Oral Roberts University Tulsa, OK; Nielsen, B., Holder, A.J., (1997) GaussView, User's Reference, , Gaussian, Inc. Pittsburgh, PA; Pitzer, R.M., Lipscomb, W.N., (1963) J. Chem. Phys., 39, p. 1995; Radom, L., Pople, J.A., (1970) J. Am. Chem. Soc., 92, p. 4786; Radom, L., Hehre, W.J., Pople, J.A., (1972) J. Am. Chem. Soc., 94, p. 2371; Douglas, D., Schleyer V. P, R., (1990) J. Org. Chem., 55, p. 1003; Millefiori, S., Alparone, A., (1998) J. Chem. Soc. Faraday Trans., 94, p. 25; Reed, A.D., Weinstock, R.B., Weinhold, F., (1985) J. Chem. Phys., 83, p. 735; Blake, A.J., Brain, P.T., McNab, H., Miller, J., Morrison, C.A., Parsons, S., Rankin, D.W.H., Smart, B.A., (1996) J. Phys. Chem., 100, p. 12280; Brain, P.T., Morrison, C.A., Parsons, S., Rankin, D.W.H., (1996) J. Chem. Soc. Dalton Trans., p. 4589; Mitzel, N.W., Rankin, D.W.H., (2003) Dalton Trans., p. 3650; Robiette, A.G., Thompson, J.C., (1965) Spectrochim. Acta, 21, p. 2023; Fernández, L.E., Ben Altabef, A., Navarro, A., Gómez, M.F., Varetti, E.L., (2000) Spectrochim. Acta A, 56, p. 1101; Fernández, L.E., Ben Altabef, A., Varetti, E.L., (2000) J. Mol. Struct., 553, p. 255; Fogarasi, G., Zhou, X., Taylor, P.W., Pulay, P., (1992) J. Am. Chem. Soc., 114, p. 8191; Pulay, P., Fogarasi, G., Pongor, G., Boggs, J.E., Vargha, A., (1983) J. Am. Chem. Soc., 105, p. 7037

PY - 2010/8/20

Y1 - 2010/8/20

N2 - The molecular structure of trimethylsilyl trifluoroacetate, CF 3C(O)OSi(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), 6-311G(d,p), 6-311++G(d,p) and 6-311++G(3df,3pd) basis sets. Experimental data indicate that only one conformer, with C s symmetry [dihedral angle φ(CCOSi) = 180°, and all groups staggered], is observed in the gas phase. Theoretical data indicate that both this anti conformer and a gauche conformer, created by rotating about the C(O)O bond, are possible, although the preferred conformation is the staggered anti one. The torsional energies for different values of the CCOSi and COSiC dihedral angles have been calculated using the RHF, MP2 and B3LYP methods with the 6-311++G(d,p) basis set. For rotation around the CCOSi bond, a sixfold decomposition of the rotational barrier has been performed in terms of a Fourier-type expansion, enabling us to analyze the nature of the potential function, showing that the coefficients related to electrostatic interactions and steric effects are the dominant terms. The preference for the anti conformation was studied using the total-energy scheme, comparison of dipole moments, and the natural bond orbital partition scheme. The infrared spectra for the liquid and gas phases and the Raman spectrum for the liquid phase have also been recorded and the observed bands assigned to the vibrational normal modes. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to estimate the measured frequencies with a final root-mean-square deviation of 9.7 cm-1. © 2010 Elsevier B.V. All rights reserved.

AB - The molecular structure of trimethylsilyl trifluoroacetate, CF 3C(O)OSi(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), 6-311G(d,p), 6-311++G(d,p) and 6-311++G(3df,3pd) basis sets. Experimental data indicate that only one conformer, with C s symmetry [dihedral angle φ(CCOSi) = 180°, and all groups staggered], is observed in the gas phase. Theoretical data indicate that both this anti conformer and a gauche conformer, created by rotating about the C(O)O bond, are possible, although the preferred conformation is the staggered anti one. The torsional energies for different values of the CCOSi and COSiC dihedral angles have been calculated using the RHF, MP2 and B3LYP methods with the 6-311++G(d,p) basis set. For rotation around the CCOSi bond, a sixfold decomposition of the rotational barrier has been performed in terms of a Fourier-type expansion, enabling us to analyze the nature of the potential function, showing that the coefficients related to electrostatic interactions and steric effects are the dominant terms. The preference for the anti conformation was studied using the total-energy scheme, comparison of dipole moments, and the natural bond orbital partition scheme. The infrared spectra for the liquid and gas phases and the Raman spectrum for the liquid phase have also been recorded and the observed bands assigned to the vibrational normal modes. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to estimate the measured frequencies with a final root-mean-square deviation of 9.7 cm-1. © 2010 Elsevier B.V. All rights reserved.

KW - Ab initio

KW - DFT

KW - GED

KW - NBO

KW - Anti conformers

KW - Anti-conformations

KW - B3LYP method

KW - Basis sets

KW - Computational studies

KW - DFT calculation

KW - Dihedral angles

KW - Electron diffraction data

KW - Electrostatic interactions

KW - Energy schemes

KW - Experimental data

KW - Force constants

KW - Fourier

KW - Gas-phase structures

KW - Gasphase

KW - Gauche conformer

KW - Infrared spectrum

KW - Liquid and gas phasis

KW - Liquid Phase

KW - Natural bond orbital

KW - Partition schemes

KW - Potential function

KW - Raman Spectrum

KW - Root-mean square deviation

KW - Rotational barriers

KW - Scaled quantum mechanical force fields

KW - Steric effect

KW - Target systems

KW - Torsional energies

KW - Trifluoroacetates

KW - Trimethylsilyl

KW - Vibrational normal modes

KW - Vibrational properties

KW - Conformations

KW - Liquids

KW - Quantum theory

KW - Raman spectroscopy

KW - Rotation

KW - Gases

U2 - 10.1016/j.molstruc.2010.02.046

DO - 10.1016/j.molstruc.2010.02.046

M3 - Article

SN - 0022-2860

VL - 978

SP - 114

EP - 123

JO - JOURNAL OF MOLECULAR STRUCTURE

JF - JOURNAL OF MOLECULAR STRUCTURE

IS - 1-3

ER -