کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5160746 | 1501683 | 2017 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
2,2â²,2â³-Thiotris(acetic acid) betaine, S(CH2COOH)2(CH2COO), and 2,2â²,2â³-selenotris(acetic acid) betaine, Se(CH2COOH)2(CH2COO)
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آلی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The title compounds, X(CH2COOH)2(CH2COO), X = S, 1, and X = Se, 2, have been characterised by FTIR, NMR and MS and by their crystal structures at 123(2) K. The FTIR spectra show two major peaks, at 1396 and 1731 cmâ1 in 1 and at 1390 and 1721 cmâ1 in 2. The 77Se NMR signal of 2 at 325.5 ppm is 83.4 ppm downfield from the signal of Se(CH2COOH)2 indicating a substantial selenonium character of 2. The two compounds are isostructural and have a pyramidal configuration. The C-X-C bond angles range from 99.29 to 103.14° in 1 and from 97.56 to 99.87° in 2. The XCCO torsion angles for the three substituents are most different; one of the carboxylic acid groups attains the anti-conformation with rather short Sâ¯O(H) and Seâ¯O(H) distances, 2.744 and 2.750 Ã
, the other acid group is synclinal and with longer Sâ¯OC and Seâ¯OC distances, 3.063 and 3.090 Ã
, whereas the carboxylate group is in the XCC plane with Xâ¯OC distances of 2.869 and 2.908 Ã
in 1 and 2. The presence of these strong Xâ¯O interactions is suggested to be the cause for the very low Bronsted basicity of this class of betaines preventing salts of the corresponding acids, the presently unknown [X(CH2COOH)3]+ - cations, to be isolated. The molecules are linked together with two fairly strong but different hydrogen bonds to the carboxylate oxygen atoms with Oâ¯O distances of 2.493 and 2.580 Ã
in 1 and 2.489 and 2.581Â Ã
in 2 and with one Xâ¯OC contact, 3.244 Ã
in 1 and 3.209Â Ã
in 2. The carbonyl oxygen atoms do not participate significantly in intermolecular hydrogen bonding and there are no contacts between the heteroatoms.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volume 1134, 15 April 2017, Pages 611-616
Journal: Journal of Molecular Structure - Volume 1134, 15 April 2017, Pages 611-616
نویسندگان
Khalid Doudin, Karl W. Törnroos,