Vibrational spectra, normal-coordinate analysis, r0 structure, ab initio calculations, and conformational equilibrium of 3-fluoropropene

Durig, J. R.; Zhen, Mengzhang; Heusel, H. L.; Joseph, P. Jiji Thomas; Groner, P.; Little, T. S.

doi:10.1021/j100259a034

Cited by 61 publications

(34 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our recent investigation~ have included the determination of the potential functions governing internal rotation about the ~( s p~) -~( s p ' ) bonds of the parent 3-halopropenes and some substituted derivatives (24)(25)(26)(27)(28)(29)(30)(31)(32). Ally1 fluoride (24)(25)(26), chloride (27), bromide (28,31), and iodide (32) have been determined to exist as a mixture of syn and gauche conformers, and for the fluoride we have shown that the conformer that has the halogen atom syn to the double bond is the more stable rotamer (24)(25)(26). For 3-chloropropene, the value of the energy difference (27) was inferred to be less than 100 cm-' (286 cal/mol) and the spectral data merely indicated a very slight preference for the syn conformer for the gaseous state.…”

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra, conformational stability, vibrational assignment, and ab initio calculations of cis-1,3-dichloropropene

Durig¹,

Costner²,

Little³

1993

Can. J. Chem.

View full text Add to dashboard Cite

The Raman (3200−10 cm−1) and infrared (3200−20 cm−1) spectra of gaseous and solid cis-1,3-dichloropropene, cis-ClHC=CHCH2Cl, have been recorded. Additionally, the Raman spectrum of the liquid with qualitative depolarization data has also been obtained. These spectral data have been interpreted on the basis that the molecule exists predominantly in the gauche (allylic chlorine atom oriented gauche to the double bond) conformation in all physical phases. Some bands in the infrared spectrum of the gas could be due to a second higher energy conformer but the lack of corresponding Raman bands casts doubt on such an assignment. Ab initio Hartree–Fock gradient calculations employing the RHF/6-31G* basis set are consistent with two minima that correspond to the two equivalent gauche forms for the potential surface for the internal rotation about the C—C bond. These minima occur at dihedral angles, [Formula: see text] ClCCC, of 122° and 238° (0° corresponds to the syn conformation) and the gauche to gauche barrier at the 180° transition state, which corresponds to the anti structure, is 342 cm−1. The barrier from the gauche minima to the syn (0°) structure, which is also a transition state, is 2425 cm−1. Complete equilibrium geometries for the gauche structure have been determined with the RHF/3-21G*, RHF/6-31G*, and MP2/6-31G* basis sets. A normal coordinate analysis utilizing a harmonic force field calculation with the RHF/3-21G* basis set has been carried out for the gauche conformer. The results are discussed and compared with the corresponding quantities obtained for some similar molecules.

show abstract

Section: Introductionmentioning

confidence: 99%

Raman and infrared spectra, conformational stability, vibrational assignment, and ab initio calculations of cis-1,3-dichloropropene

Durig¹,

Costner²,

Little³

1993

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…This result should be of interest to microwave, infrared, and other spectroscopists. It may be noted that in 3-fluoropropene the most stable conformer in the vapor phase also has the C-F bond lying cis to the double bond and in the plane of the molecule (17,18) and that in the liquid the stability of this conformer decreases relative to other conformers.…”

mentioning

confidence: 99%

Experimental and theoretical estimates of the internal rotational barrier of benzyl fluoride in the vapor phase

Schaefer¹,

Beaulieu²,

Sebastian³

et al. 1990

Can. J. Chem.

View full text Add to dashboard Cite

The twofold barrier to rotation about the [Formula: see text] bond in benzyl fluoride is deduced from the long-range 1H,1H; 1H,19F; and 13C,19F nuclear spin–spin coupling constants in solution. The barrier changes from 3.2(2) kJ/mol in the polar solvent, acetonitrile-d3, to 0.7(2) kJ/mol in the nonpolar environment provided by cyclohexane-d12. In all solutions the conformer of greatest stability has the C—F bond in a plane perpendicular to that of the phenyl group. Extrapolation of the barrier to the vapor phase, using a simple reaction field model, indicates that the most stable conformer for the free (unclustered) molecule is now that with the C—F bond in the phenyl plane and that the barrier to internal rotation is 1.1(7) kJ/mol. Molecular orbital calculations with the basis sets STO-3G, 4-21G, 4-31G, 6-31G, and 6-31G* all predict the latter conformer as that of lowest energy. However, they disagree significantly among themselves as to the height of the internal barrier. The complete geometries are given for both conformers, as computed with the 6-31G basis, and the side-chain geometries are tabulated for the planar and perpendicular conformers, as given by all the bases. Keywords: benzyl fluoride, internal rotational potential; 13C,19F spin–spin coupling constants in benzyl fluoride; benzyl fluoride, molecular orbital computations.

show abstract

“…Also, we have found that ab initio calculations may not give the correct conformer stability. For example ab initio calculations [3], at the MP2 level with a variety of basis sets with diffuse functions predict the gauche conformer to be the more stable form of 3-fluoropropene (allyl fluoride), CH 2 @CHCH 2 F, whereas the experimental results [4,5] clearly show the cis conformer to be the more stable rotamer. When the substituent is an asymmetric rotor such as an OH, SH, NH 2 or PH 2 group there is the possibility of five different stable conformers with cis and gauche conformations around the CAC bond and trans and gauche conformations around CAO (S,N,P) bond (Fig.…”

Section: Introductionmentioning

confidence: 99%

Conformational stability of allyl alcohol from temperature dependent infrared spectra of rare gas solutions, ab initio calculations, r0 structural parameters, and vibrational assignment

Durig

Ganguly

Defrawy

et al. 2009

Journal of Molecular Structure

View full text Add to dashboard Cite

a b s t r a c tVariable temperature (À55 to À145°C) studies of the infrared spectra (4000-50 cm À1 ) of allyl alcohol (3-hydroxypropene), CH 2 @CHCH 2 OH, dissolved in liquid krypton and/or liquid xenon have been carried out. The infrared spectra of the gas and solid have also been recorded. From these data four of the five possible stable conformers have been identified and their relative stabilities determined. The order of the conformers stabilities has been obtained experimentally where the first indicator is for the relative position of the OH group (C = cis or G = gauche) to the double bond (rotation around the CAC bond) and the second one (t = trans, g = gauche, g 0 = gauche 0 ) is the relative position of the hydroxyl rotor, i.e. rotation around the CAO bond. The enthalpy differences have been determined between the most stable Gg conformer and the second most stable rotamer, Cg, to be 135 ± 14 cm À1 (1.62 ± 0.1 kJ/mol), the third most stable conformer Ct, 260 ± 46 cm À1 (3.11 ± 0.6 kJ/mol), and the fourth most stable conformer Gt 337 ± 75 cm À1 (4.03 ± 0.9 kJ/mol). This experimentally determined order is consistent with the order of stability predicted by ab initio calculations Gg > Cg > Ct > Gt > Gg 0 . No evidence was obtained for the fifth conformer Gg 0 which is predicted by most of the ab initio calculations to be less stable by an enthalpy difference more than 500 cm À1 than the Gg form. The percentage of each conformer at ambient temperature is estimated to be Gg(54 ± 2%), Cg(28 ± 2%), Ct(8 ± 2%) and Gt(11 ± 3%). The conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios and vibrational frequencies have been obtained for all of the conformers from ab initio MP2(full)/6-31G(d) calculations. The optimized geometries and conformational stabilities have been obtained from ab initio calculations utilizing several different basis sets up to MP2(full)/aug-cc-pVTZ and from density functional theory calculations by the B3LYP method. By utilizing previously reported microwave rotational constants for the Gg and Cg conformers along with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r 0 parameters have been obtained for these two conformers. The determined heavy atom structural parameters for the Gg [Cg] conformer are: the distances(Å) C@C = 1.343(3)[1.340(5)], CAC = 1.499(3)[1.504(5)], CAO = 1.428(3)[1.419(5)] and angles( o ) \CCC = 122.8(5)[124.7(5)], \ CCO = 112.1(5)[114.9(5)] and \ CCCO = 122.7(10)[5.63 (5)]. Several of the CH distances are significantly different from the values previously reported from the earlier microwave data. The results are discussed and compared to the corresponding properties of some similar molecules.

show abstract

Vibrational spectra, normal-coordinate analysis, r0 structure, ab initio calculations, and conformational equilibrium of 3-fluoropropene

Cited by 61 publications

References 0 publications

Raman and infrared spectra, conformational stability, vibrational assignment, and ab initio calculations of cis-1,3-dichloropropene

Raman and infrared spectra, conformational stability, vibrational assignment, and ab initio calculations of cis-1,3-dichloropropene

Experimental and theoretical estimates of the internal rotational barrier of benzyl fluoride in the vapor phase

Conformational stability of allyl alcohol from temperature dependent infrared spectra of rare gas solutions, ab initio calculations, r0 structural parameters, and vibrational assignment

Contact Info

Product

Resources

About