کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9770060 | 1501939 | 2005 | 4 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
An ab initio study of the electronic and vibrational properties of pyrazineâ¯HX and XHâ¯pyrazineâ¯HX hydrogen-bonded complexes (X=F, NC, Cl, CN and CCH)
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: An ab initio study of the electronic and vibrational properties of pyrazineâ¯HX and XHâ¯pyrazineâ¯HX hydrogen-bonded complexes (X=F, NC, Cl, CN and CCH) An ab initio study of the electronic and vibrational properties of pyrazineâ¯HX and XHâ¯pyrazineâ¯HX hydrogen-bonded complexes (X=F, NC, Cl, CN and CCH)](/preview/png/9770060.png)
چکیده انگلیسی
Ab initio molecular orbital calculations have been performed at the MP2/6-31++G** theoretical level in order to obtain molecular properties of hydrogen-bonded complexes involving pyrazine and the HX linear acids with, X=F, NC, Cl, CN, and CCH. Both the 1:1 and 1:2 adducts have been investigated, i.e., Pyzâ¯HX and XHâ¯Pyzâ¯HX. The H-bond strength for these complexes can be interpreted in terms of the H-X stretching frequency downward displacement. This latter shows a good linear correlation with the intermolecular charge transfer and follows the order: X=F>X=NC>X=Cl>X=CN>X=CCH. As expected, the H-X stretching intensity is much enhanced upon H-bond formation. Here these effects on the HX infrared spectra are much more pronounced than those previously found in complexes with unsaturated hydrocarbons as proton acceptors. On the other hand, no important change has been verified in pyrazine, except the inhibition of the lone-pair trans effect from the lone-pair of nitrogen to the Ï* antibonding orbital of the CC chemical bond in pyrazine. The new vibrational modes arising from complexation show several interesting features, specially the bending modes of the proton-donor molecule and the intermolecular stretching mode.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volumes 744â747, 3 June 2005, Pages 217-220
Journal: Journal of Molecular Structure - Volumes 744â747, 3 June 2005, Pages 217-220
نویسندگان
João Bosco P. da Silva, Mário R. Silva Júnior, Mozart N. Ramos, Sérgio E. Galembeck,