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Theoretical Investigation of the Chalcogeno-Ureas Structures | ||
| JOURNAL OF THI-QAR SCIENCE | ||
| Article 1, Volume 2, Issue 3, 2011, Pages 127-134 | ||
| Author | ||
| Hatam A. Jasim | ||
| Abstract | ||
| Abstract Theoretically predicted structural parameters and geometry of a series of compounds named chalcogeno-ureas)I)-(IV(, R═CH3 of urea I, thio-urea II, seleno-urea III and telluro-urea IV and compared these data with those determined from X-ray diffraction studies and some theoretical data. Compounds used in this study are of particular interest as a urea formed by the conversion of the electron-rich olefin ( CNR(CH2)2NR)2. These compounds were chosen to compare the Csp2─X and Csp2─N bond distances where X is O, S, Se and Te in order to understand the delocalization in telluro-urea in compression with the others. It was noticed that there is a partial Csp2─X double bond only for X is O, S, and Se whereas for X=Te is largely single bond, the Csp2─X bond distances increase in the sequence X═ O (1.220Ǻ), X═ S)1.652Ǻ), X═ Se (1.796Ǻ) and X═ Te (2.126Ǻ) with CN2 framework is a double bond. The sum of the angles around the central carbon atom is 360° so the geometry is planar. The five member ring of the imidazolidine is planar except for Urea is twisted.Key words: chalcogenoureas, imidazolidine, theoretical calculation, density functional studies. | ||
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