کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10558284 | 968974 | 2005 | 17 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Is 2-cyclopropylpropene really gauche?
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Is 2-cyclopropylpropene really gauche? Is 2-cyclopropylpropene really gauche?](/preview/png/10558284.png)
چکیده انگلیسی
Infrared spectra of gaseous and solid 2-cyclopropylpropene (2-CPP, c-C3H5C(CH3)CH2) have been recorded from 3500 to 40 cmâ1, and Raman spectra (3200-150 cmâ1) of the liquid as well as mid-infrared spectra of 2-CPP in liquid krypton solution (from â105 to â150 °C) were also obtained. Ab initio calculations, with basis sets up to 6-311 + G(2df, 2pd), were carried out for this molecule, using the restricted Hartree-Fock (RHF) approach, with full electron correlation by the perturbation method to second order (MP2(full)) and density functional theory (DFT) by the B3LYP method. The combination of the experimental and computational results (particularly with the higher basis sets) unequivocally identifies the more stable conformer of 2-CPP as the trans form, with the gauche rotamer higher in energy, but also stable. The cis structure of this compound is not observed experimentally, and is predicted by the computational approaches to be a transition state. By studying the temperature variation of two well-resolved sets of conformational doublets of 2-CPP dissolved in liquid krypton, an average enthalpy difference between conformers of 182 ± 18 cmâ1 (2.18 ± 0.22 kJ molâ1) has been determined, with the trans conformation lower in energy in the fluid states, and the sole conformer present in the polycrystalline solid phase. This enthalpy difference corresponds to an ambient temperature conformational equilibrium in the fluid phases of 2-cyclopropylpropene containing approximately 55 ± 2% of the more stable trans rotameric form. A complete vibrational assignment for the trans conformer of 2-CPP is given, and many of the bands of the gauche rotamer have also been assigned. Structural parameters, dipole moments, and rotational constants for this molecule have been calculated at the MP2(full)/6-311 + G(d,p) level, and these results-as well as the results from the experimental studies-are compared to similar quantities in related compounds.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 61, Issue 7, May 2005, Pages 1357-1373
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 61, Issue 7, May 2005, Pages 1357-1373
نویسندگان
James R. Durig, Chao Zheng, Kathleen R. Marzluf, Gerardo B. Marquez, Gamil A. Guirgis, Charles J. Wurrey, Kathleen V. Kilway,