Universitair Centrum Antwerpen

Antwerpen, Belgium

Universitair Centrum Antwerpen

Antwerpen, Belgium
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Guirgis G.A.,College of Charleston | Sawant D.K.,University of Missouri - Kansas City | Brenner R.E.,University of Missouri - Kansas City | Deodhar B.S.,University of Missouri - Kansas City | And 6 more authors.
Journal of Physical Chemistry A | Year: 2015

The FT-microwave spectrum (6.5-26 GHz) of (chloromethyl)fluorosilane (ClCH2-SiH2F) has been recorded and 250 transitions for the parent species along with 13C, 37Cl, 29Si, and 30Si isotopologues have been assigned for trans conformer. Infrared spectra (3100 to 400 cm-1) of gas, solid, and the variable temperature (-100 to -60 °C) studies of the infrared spectra of the sample dissolved in xenon have been recorded. Additionally, the variable temperature (-153 to -133 °C) studies of the Raman spectra of the sample dissolved in krypton have been recorded. The enthalpy difference between the trans and gauche conformers in xenon solutions has been determined to be 109 ± 15 cm-1 (1.47 ± 0.16 kJ mol-1), and in krypton solution, the enthalpy difference has been determined to be 97 ± 16 cm-1 (1.16 ± 0.19 kJ mol-1) with the trans conformer as the more stable form. Approximately 46 ± 2% of the trans form is present at ambient temperature. By utilizing the microwave rotational constants of five isotopologues for trans and the structural parameters predicted from MP2(full)/6-311+G(d,p) calculations, adjusted r0 parameters have been obtained for trans conformer. The r0 structural parameter values for the trans form are for the heavy atom distances (Å): Si-F = 1.608 (3); C-Cl = 1.771 (3); Si-C = 1.884 (3); and angles (deg): ∠FSiC = 108.9 (5); ∠ClCSi = 104.9 (5). The results are discussed and compared to some related molecules. © 2015 American Chemical Society.


PubMed | College of Charleston, University of Virginia, University of Missouri - Kansas City and Universitair Centrum Antwerpen
Type: Journal Article | Journal: The journal of physical chemistry. A | Year: 2015

The FT-microwave spectrum (6.5-26 GHz) of (chloromethyl)fluorosilane (ClCH2-SiH2F) has been recorded and 250 transitions for the parent species along with (13)C, (37)Cl, (29)Si, and (30)Si isotopologues have been assigned for trans conformer. Infrared spectra (3100 to 400 cm(-1)) of gas, solid, and the variable temperature (-100 to -60 C) studies of the infrared spectra of the sample dissolved in xenon have been recorded. Additionally, the variable temperature (-153 to -133 C) studies of the Raman spectra of the sample dissolved in krypton have been recorded. The enthalpy difference between the trans and gauche conformers in xenon solutions has been determined to be 109 15 cm(-1) (1.47 0.16 kJ mol(-1)), and in krypton solution, the enthalpy difference has been determined to be 97 16 cm(-1) (1.16 0.19 kJ mol(-1)) with the trans conformer as the more stable form. Approximately 46 2% of the trans form is present at ambient temperature. By utilizing the microwave rotational constants of five isotopologues for trans and the structural parameters predicted from MP2(full)/6-311+G(d,p) calculations, adjusted r0 parameters have been obtained for trans conformer. The r0 structural parameter values for the trans form are for the heavy atom distances (): Si-F = 1.608 (3); C-Cl = 1.771 (3); Si-C = 1.884 (3); and angles (deg): FSiC = 108.9 (5); ClCSi = 104.9 (5). The results are discussed and compared to some related molecules.


Deodhar B.S.,University of Missouri - Kansas City | Brenner R.E.,University of Missouri - Kansas City | Sawant D.K.,University of Missouri - Kansas City | Guirgis G.A.,College of Charleston | And 3 more authors.
Vibrational Spectroscopy | Year: 2015

The infrared spectrum (3100-300 cm-1) in the gas phase and Raman spectrum (3100-150 cm-1) of the liquid of cyclobutyldichlorosilane (c-C4H7SiHCl2) have been recorded. Variable temperature (-143 °C to -123 °C) studies of the Raman spectra (3100-300 cm-1) dissolved in liquid krypton have been carried out. From these data, the experimental stabilities of the conformer have been determined to be Eq-g > Ax-t > Eq-t > Ax-g. The enthalpy difference between Eq-g and Ax-t has been determined from band pairs to be 85 ± 10 cm-1 (1.01 ± 0.11 kJ mol-1) with the Eq-g conformer the more stable form. The enthalpy difference between Eq-g and Eq-t is 116 ± 43 cm-1 (1.39 ± 0.52 kJ mol-1) and the enthalpy difference between Eq-g and Ax-g has been determined to be 138 ± 42 cm-1 (1.66 ± 0.51 kJ mol-1) with the Eq-g conformer as the more stable form. The percentage of the equatorial gauche conformer is estimated to be 47% at ambient temperature. To support the spectroscopic study, ab initio calculations by the Møller-Plesset perturbation method to second order MP2(full) and density functional theory calculations by the B3LYP method have been carried out. The infrared intensities, Raman activities, vibrational frequencies and band contours have been predicted from MP2(full)/6-31G(d) calculations and these theoretical values are compared to the experimental ones when available. The conformational stabilities have been predicted from theoretical calculations with basis sets up to 6-311+G(2d,2p) from both MP2(full) and density functional theory calculations by the B3LYP method. The results are discussed and compared to the corresponding properties of some related molecules. © 2015 Elsevier B.V. All rights reserved.


Durig J.R.,University of Missouri - Kansas City | Ganguly A.,College of Charleston | Zheng C.,University of Missouri - Kansas City | Gurigis G.A.,College of Charleston | And 3 more authors.
Journal of Molecular Structure | Year: 2010

Variable temperature (-55 to -131 °C) studies of the infrared spectra (4000-50 cm-1) of 2-fluoroethylamine, FCH2CH2NH2 dissolved in liquid xenon and the far infrared in liquid krypton have been carried out. From these data all five possible conformers have been identified and their relative stabilities obtained. The enthalpy differences have been determined among the most stable Gg′ conformer and the second stable conformer, Gt, to be 62 ± 8 cm-1 (0.74 ± 0.10 kJ/mol), the third stable conformer, Tg, to be 262 ± 26 cm-1 (3.14 ± 0.3 kJ/mol), the fourth most stable conformer, Tt, to be 289 ± 45 cm-1 (3.46 ± 0.5 kJ/mol) and the fifth most stable conformer, Gg to be 520 ± 50 cm-1 (6.24 ± 0.6 kJ/mol). The percentage of each conformer at ambient temperature is estimated to be with Gg′ (42 ± 4%), Gt (32 ± 1%), Tg (13 ± 1%), Tt (5 ± 1%) and Gg (3 ± 1%). The first indicator is the NCCF dihedral angle (G = gauche or T = trans) and the second one (g = gauche or t = trans) is the relative position of the lone pair of electrons on the nitrogen atom with respect to the fluorine atom. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug-cc-pVTZ for both MP2(full) and density functional theory calculations by the B3LYP method. By utilizing previously reported microwave rotational constants along with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters have been obtained for the two most stable conformers. The determined heavy atom structural parameters for the Gg′[Gt] conformer are: the distances (Å) C1-C2 = 1.509(3) [1.516(3)], C2-N3 = 1.466(3)[1.461(3)], C1-F4 = 1.400(3)[1.398(3)] and angles in degrees ∠N3C2C1 = 109.8(5) [115.5(5)], ∠F4C1C2 = 109.2(5)[109.3(5)], ∠H10N3H9 = 107.1(5) [107.1(5)](°) and τF4C1C2N3 = 65.3(5) [60.9(5)]. Vibrational assignments have been provided for most of the observed bands which have been supported by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force fields, frequencies, infrared intensities, Raman activities and depolarization ratios for all five conformers. The results are discussed and compared to the corresponding properties of some similar molecules. © 2010 Elsevier B.V. All rights reserved.


Durig J.R.,University of Missouri - Kansas City | Klaassen J.J.,University of Missouri - Kansas City | Deodhar B.S.,University of Missouri - Kansas City | Darkhalil I.D.,University of Missouri - Kansas City | And 5 more authors.
Journal of Molecular Structure | Year: 2013

Variable temperature (-50 to -100 °C) Raman spectra (3500-136 cm -1) were recorded of ethynylcyclopentane, c-C5H 9CCH in liquid xenon. The envelope-equatorial (Eq) conformer was determined more stable than envelope-axial (Ax) form with enthalpy difference of 94 ± 9 cm-1 (1.12 ± 0.11 kJ/mol) and 39 ± 2% Ax conformer present at ambient temperature. The conformational stabilities have been predicted from ab initio calculations with basis sets up to aug-cc-pVTZ. From previously reported microwave rotational constants and ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters are reported Eq [Ax] distances (Å) rCC = 1.211(3) [1.211(3)], rCαCC = 1.461(3) [1.467(3)], rCαC β = 1.542(3) [1.542(3)], rCβCγ = 1.541(3) [1.542(3)], rCγCγ′ = 1.556(3) [1.555(3)] and angles (°) ∠CαCC = 179.4(5) [179.9(5)], ∠CβCαCC = 113.7(5) [111.5(5)], ∠C βCαCβ′ = 102.6(5) [102.1(5)], ∠CαCβCγ = 103.7(5) [103.7(5)], ∠CβCγC γ′ = 106.0(5) [105.9(5)] and τC βCαCβ′C γ′ = 40.8(5) [41.6(5)]. Vibrational assignments are reported, supported by ab initio predictions and results are discussed. © 2012 Elsevier B.V. All rights reserved.


Darkhalil I.D.,University of Missouri - Kansas City | Klaassen J.J.,University of Missouri - Kansas City | Nagels N.,Universitair Centrum Antwerpen | Herrebout W.A.,Universitair Centrum Antwerpen | And 4 more authors.
Journal of Raman Spectroscopy | Year: 2014

Fourier transform microwave spectrum of cyclopentylamine, c-C 5H9NH2 has been recorded, and seven transitions have been assigned for the most abundant conformer, and the rotational constants have been determined: A=4909.46(5), B=3599.01(4), and C=2932.94(4). From the determined microwave rotational constants and ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters are reported with distances (Å): rCα-C β=1.529(3), rCβ-Cγ=1.544(3), rCγ-Cγ=1.550(3), rCα-N=1. 470(3), and angles ()-CCN=108.7(5), -CβCαC β=101.4(5), and τCβCαC β-Cγ-=42.0(5). The infrared spectra (4000-220cm-1) of the gas have been recorded. Additionally, the variable temperature (-60 to -100C) Raman spectra of the sample dissolved in liquefied xenon was recorded from (3800-50cm-1). The four possible conformers have been identified, and their relative stabilities obtained with enthalpy difference relative to t-Ax of 211±21cm-1 for t-Eq≥227±22cm-1 for g-Eq≥255±25cm-1 for g-Ax. The percentage of the four conformers is estimated to be 53% for the t-Ax, 11±1% for t-Eq, 20±2% for g-Ax and 16±2% for g-Eq at ambient temperature. The conformational stabilities have been predicted from ab initio calculations by utilizing several different basis sets up to aug-cc-pVTZ from both MP2(full) and density functional theory calculations by the B3LYP method. Vibrational assignments have been provided for the observed bands for all four conformers, which are predicted by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities, and depolarization ratios for all of the conformers. The results are discussed and compared to the corresponding properties of some related molecules. Copyright © 2014 John Wiley & Sons, Ltd.


Darkhalil I.D.,University of Missouri - Kansas City | Nagels N.,Universitair Centrum Antwerpen | Herrebout W.A.,Universitair Centrum Antwerpen | Van Der Veken B.J.,Universitair Centrum Antwerpen | And 3 more authors.
Journal of Molecular Structure | Year: 2014

FT-microwave spectroscopy was carried out where the trans conformer was identified to be the most stable conformer. Variable temperature (-60 to -100 °C) studies of the Raman spectra (4000-50 cm-1) of ethylamine, CH3CH2NH2 dissolved in liquefied xenon have been carried out. From these data both conformers have been identified and their relative stabilities obtained. The enthalpy difference has been determined to be 62 ± 6 cm-1 (0.746 ± 0.072 kJ mol-1) with the trans conformer the more stable form. The percentage of the gauche conformer is estimated to be 60% at ambient temperature. The conformational stabilities have been predicted from ab initio calculations with the Møller-Plesset perturbation method to the second order (MP2(full)) and the fourth order (MP4(SDTQ)) as well as with density functional theory by the B3LYP method by utilizing a variety of basis sets. Vibrational assignments have been made for the observed bands which have been predicted by MP2(full)/6-31G(d) ab initio calculations which includes harmonic force fields, frequencies, infrared intensities, Raman activities and depolarization ratios for both conformers. The results are discussed and compared to the corresponding properties of some similar molecule. © 2014 Published by Elsevier B.V.


Durig J.R.,University of Missouri - Kansas City | Darkhalil I.D.,University of Missouri - Kansas City | Klaassen J.J.,University of Missouri - Kansas City | Nagels N.,Universitair Centrum Antwerpen | And 2 more authors.
Journal of Molecular Structure | Year: 2013

Variable temperature (-60 to -100 °C) studies of the Raman spectra (4000-300 cm-1) of 2,2,2 trifluoroethylamine, F3CCH 2NH2 dissolved in liquid xenon have been carried out. From these data both conformers have been identified and their relative stabilities obtained. The enthalpy difference has been determined to be 267 ± 27 cm-1 (3.19 ± 0.32 kJ mol-1) with the trans conformer the more stable form. The percentage of the gauche conformer is estimated to be 35 ± 3% at ambient temperature. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug-cc-pVTZ for both MP2(full) and density functional theory calculations by the B3LYP method. By utilizing previously reported microwave rotational constants along with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters have been obtained for the trans conformer. The determined heavy atom structural parameters are for the distances (Å): C1-C2 = 1.513(3), C2-N3 = 1.447(3), C1-F4 = 1.344(3), C1-F5,F6 = 1.347(3) and angles in degrees (°) ∠N3C2C1 = 115.2(5), ∠F4C1C2 = 111.4(5), ∠C 2C1F5, F6 = 111.6(5), ∠F 4C1F5 = 107.6(5), and ∠F51F 6 = 106.9(5). Vibrational assignments have been provided for the observed bands which have been supported by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force fields, frequencies, infrared intensities, Raman activities and depolarization ratios for both conformers. The results are discussed and compared to the corresponding properties of some similar molecules. © 2012 Elsevier B.V. All rights reserved.


Durig J.R.,University of Missouri - Kansas City | Darkhalil I.D.,University of Missouri - Kansas City | Klaassen J.J.,University of Missouri - Kansas City | Herrebout W.A.,Universitair Centrum Antwerpen | And 2 more authors.
Journal of Raman Spectroscopy | Year: 2012

The Raman and infrared spectra (4000 to 50 cm -1) of the gas, liquid or solution, and solid have been recorded of n-propylamine, CH3CH2CH2NH2. Variable temperature (-60 to -100 °C) studies of the Raman (1175 to 625 cm -1) and far infrared (600 to 10cm -1) spectra dissolved in liquid xenonwere carried out. From these data, the five possible conformers were identified and their relative stabilities obtained with enthalpy difference relative to trans-trans (Tt) for trans-gauche (Tg) of 79±9cm -1 (0.9±0.1 kJ/mol); for Gg of 91±26cm -1 (1.08±0.3 kJ/mol); for Gg? of 135±21 cm -1 (1.61±0.2 kJ/mol); for Gt of 143±11cm -1 (1.71±0.1 kJ/mol). The percentage of the five conformers is estimated to be 18% for the Tt, 24±1% for Tg, 23±3% for Gg, 18±1% for Gg? and 18±1% for Gt at ambient temperature. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug-cc-pVTZ from both second-order Moller-Plesset (MP2, full) and density functional theory calculations by the Becke, three-parameter, Lee-Yang-Parr method. Vibrational assignments were provided for the observed bands for all five conformers, which are supported by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities and depolarization ratios for both conformers. Estimated r0 structural parameters were obtained from adjusted MP2(full)/6-311+G(d,p) calculations. The results are discussed and compared with the corresponding properties of some related molecules. ©2012 John Wiley & Sons, Ltd.


Durig J.R.,University of Missouri - Kansas City | Klaassen J.J.,University of Missouri - Kansas City | Darkhalil I.D.,University of Missouri - Kansas City | Herrebout W.A.,Universitair Centrum Antwerpen | And 2 more authors.
Journal of Molecular Structure | Year: 2012

The Raman and infrared spectra (4000-50 cm -1) of the gas, liquid or solution, and solid have been recorded of isopropylamine, (CH 3) 2CHNH 2. Variable temperature (-50 to -100 °C) studies of the Raman spectra (3500-100 cm -1) dissolved in liquid xenon have been carried out. From these data, both the trans and gauche conformers have been identified and their relative stability obtained. The enthalpy difference has been determined to be 113 ± 11 cm -1 (1.35 ± 0.13 kJ mol -1) with the trans conformer the more stable form. The percentage of the gauche conformer is estimated to be 54 ± 1% at ambient temperature. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug-cc-pVTZ from both MP2(full) and density functional theory calculations by the B3LYP method. By utilizing previously reported microwave rotational constants along with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r 0 parameters have been obtained for the trans conformer. The determined heavy atom and NH 2 distances are () C-C = 1.530(3), C-N = 1.465(3), N-H = 1.019(3) and angles in degrees (°) ∠NCC = 108.9(5), ∠CCC = 111.0(5), ∠HNC = 110.3(5). The structural parameters for the gauche conformer were estimated by using the same adjustment differences to the gauche form as those obtained for the corresponding trans parameters. Vibrational assignments have been provided for the observed bands for both conformers which are supported by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities and depolarization ratios for both conformers. The results are discussed and compared to the corresponding properties of some related molecules. © 2011 Elsevier B.V. All rights reserved.

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