کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1232946 | 968799 | 2011 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Conformational stability, r0 structural parameters, and vibrational assignments of mono-substituted cyclobutanes: Fluorocyclobutane
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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: Conformational stability, r0 structural parameters, and vibrational assignments of mono-substituted cyclobutanes: Fluorocyclobutane Conformational stability, r0 structural parameters, and vibrational assignments of mono-substituted cyclobutanes: Fluorocyclobutane](/preview/png/1232946.png)
چکیده انگلیسی
Variable temperature (â55 to â100 °C) studies of the infrared spectra (3500-400 cmâ1) of fluorocyclobutane, c-C4H7F, dissolved in liquid xenon have been carried out as well as the infrared spectra of the gas. By utilizing eight pairs of conformers at 10 different temperatures, the enthalpy difference between the more stable equatorial conformer and the axial form has been determined to be 496 ± 40 cmâ1 (5.93 ± 0.48 kJ/mol). The percentage of the axial conformer present at ambient temperature is estimated to be 8 ± 1%. The ab initio MP2(full) average predicted energy difference from a variety of basis sets is 732 ± 47 cmâ1 (9.04 ± 0.44 kJ/mol) and the average value of 602 ± 20 cmâ1 from density functional theory predictions by the B3LYP method are significantly larger than the experimentally determined enthalpy value. By utilizing previously reported microwave rotational constants for the equatorial and axial conformers combined with ab initio MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters have been obtained. The determined heavy atom structural parameters for the equatorial [axial] conformer are: distances (Ã
) C-F = 1.383(3) [1.407(3)], Cα-Cβ = 1.543(3) [1.546(3)], Cβ-Cγ = 1.554(3) [1.554(3)] and angles (°) â CαCβCγ = 85.0(5) [89.2(5)], â CβCαCβ = 89.3(5) [89.2(5)], â F-(CβCαCβ) = 117.4(5) [109.2(5)] and a puckering angle of 37.4(5) [20.7(5)]. The conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios and vibrational frequencies have been obtained for both conformers from MP2(full)/6-31G(d) ab initio calculations and compared to experimental values where available. The results are discussed and compared to the corresponding properties of some other monosubstituted cyclobutanes with halogen and pseudo-halogen substituents.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 79, Issue 4, 15 August 2011, Pages 831-840
Journal: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy - Volume 79, Issue 4, 15 August 2011, Pages 831-840
نویسندگان
Arindam Ganguly, Joshua J. Klaassen, Gamil A. Guirgis, Todor K. Gounev, James R. Durig,