Theoretical investigation of the chalcogeno-ureas structures

الملخص EN

Theoretically predicted structural parameters and geometry of a series of compounds named chalcogeno-ureas (IXIV), R = CH3 of urea I, thio-urea II, seleno-urea III and teller-urea lV and compared these data with those.

Determined from X-ray diffraction studies and some theoretical late..

Compounds used in this study are of particular interest as a urea formed bv the conversion of (i..1I) ie electron-rich olefin =CNR (CH2) : (NR)2.These compounds were chosen to compare the K": 22 jEsp —X and Csp —N bond distances where X is O, S, Se and Te in order to understand the I '^localization in tailor-urea in compression with the others.

It was noticed that there is a partial .

—" X double bond only for X is O, S, and Se whereas for X = Te is largely single bond, the P*-X bond distances increase in the sequence X = O (l.22oA).

X = S(1.652A).

X = S l6A) and X =Te (2.126A) with CNj framework is a double bond.

The sum of the angles jjjnd the central carbon atom is 360 so the geometry is planar.

The five member ring of the Toluidine is planar except for Urea is twisted.