کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
7808401 | 1501660 | 2018 | 14 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
On the interactions of nitriles and fluoro-substituted pyridines with silicon tetrafluoride: Computations and thin film IR spectroscopy
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: On the interactions of nitriles and fluoro-substituted pyridines with silicon tetrafluoride: Computations and thin film IR spectroscopy On the interactions of nitriles and fluoro-substituted pyridines with silicon tetrafluoride: Computations and thin film IR spectroscopy](/preview/png/7808401.png)
چکیده انگلیسی
The nature of the interactions between silicon tetrafluoride and series of nitrogen bases, including nitriles (RCN, with Râ¯>â¯CH3), pyridine, and various fluoro-substituted pyridines, has been investigated via quantum-chemical computations, low-temperature IR spectroscopy, and bulk reactivity experiments. Using (primarily) M06 with the 6-311+G(2df,2pd) basis set, we obtained equilibrium structures, binding energies, harmonic frequencies, and N-Si potentials in the gas-phase and in bulk dielectric media for an extensive series of 1:1 molecular complexes, including: C6H5CH2CN-SiF4, CH3CH2CN-SiF4, (CH3)3CCN-SiF4, C5H5N-SiF4, 4-FC5H4N-SiF4, 3,5-C5F2H3N-SiF4, 2,6-C5F2H3N-SiF4 and 3,4,5-C5F3H2N-SiF4. In addition, for the analogous 2:1 complexes of pyridine and 3,5-difluororpyridine, we obtained equilibrium structures, binding energies, and harmonic frequencies. The N-Si distances in the 1:1 nitrile complexes are fairly long, ranging from 2.84â¯Ã
to 2.88â¯Ã
, and the binding energies range from 4.0 to 4.2â¯kcal/mol (16.7-17.6â¯kJ/mol). Also, computations predict extremely anharmonic N-Si potentials, for which the inner portions of the curve are preferentially stabilized in dielectric media, which predict an enhancement of these interactions in condensed-phases. However, we see no evidence of bulk reactivity between C6H5CH2CN, CH3CH2CN, or (CH3)3CCN and SiF4, nor any significant interaction between (CH3)3CCN and SiF4 in low temperature IR spectra of solid, (CH3)3CCN/SiF4 thin films. Conversely, the interactions in four of the five 1:1, pyridine-SiF4 complexes are generally stronger; binding energies range from 5.7 to 9.6â¯kcal/mol (23.8-40.2â¯kJ/mol), and correspondingly the N-Si distances are relatively short (2.12-2.25â¯Ã
). The exception is 2,6-C5F2H3N-SiF4, for which the binding energy is only 3.6â¯kcal/mol (15.1â¯kJ/mol), and the N-Si distance is quite long (3.12â¯Ã
). In addition, both pyridine and 3,5-difluororpyridine were found to form stable reaction products with SiF4; but no analogous product was obtained with 2,6-difluororpyridine and SiF4, nor was any significant interaction indicated in low-temperature IR spectra of 2,6-difluororpyridine/SiF4 films. By contrast, low temperature spectra of pyridine/SiF4 and 3,5-difluororpyridine/SiF4 thin films are consistent with the presence of a distinct 2:1 reaction product. Moreover, the observed frequencies agree reasonably well with those predicted for the cis, octahedral coordination isomers of the 2:1 molecular complexes, in which the N-Si bonds are compressed slightly relative to those in the predicted gas-phase structures.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volume 1157, 5 April 2018, Pages 679-692
Journal: Journal of Molecular Structure - Volume 1157, 5 April 2018, Pages 679-692
نویسندگان
Nicholas J. Hora, Benjamin M. Wahl, Camilla Soares, Skylee A. Lara, John R. Lanska, James A. Phillips,