Theoretical studies on electron delocalisation in selenourea

Abstract

Ab initio and density functional calculations have been performed on the different possible structures of selenourea (su), urea (u) and thiourea (tu) to understand the extent of delocalisation in selenourea in comparison to urea and thiourea. Selenourea (su-1) with C 2 symmetry has the minima on the potential energy surface at MP2(fu)/6-31+G* level. The C-N rotational barrier in selenourea is 8⋅69 kcal/mol, which is 0⋅29 and 0⋅11 kcal/mol more than that of urea and thiourea respectively at MP2(fu)/6-31+G* level. N-inversion barrier is 0⋅55 kcal/mol at MP2(fu)6-31+G* level. NBO analysis has been carried out to understand the nature of different interactions responsible for the electron delocalisation.

Anti-Thyroid Drugs and Thyroid Hormone Synthesis: Effect of Methimazole Derivatives on Peroxidase-Catalyzed Reactions

“…According to the previous studies on tautomeric rearrangements, the electron delocalization in selenourea should be larger than that in thiourea and urea. On the other hand, the lower electronegativity of Se (2.4) as compared with those of S (2.5) and O (3.5) suggests that the electron delocalization in selenourea should be less than that of thiourea and urea.…”

Pharmacophoric Features of Biguanide Derivatives: An Electronic and Structural Analysis

“…Electron Distribution in Biguanide 10. The extent of electron delocalization can be estimated in terms of (i) C−N rotations in biguanide, (ii) NBO analysis, and (iii) HOMA analysis. , The C2−N1, C2−N3, and C5−N7 bonds are expected to be single bonds with partial π character. The rotational barriers across these bonds respectively are 10.47, 11.09, and 12.39 kcal/mol through the rotational transition states 22 , 23 , 24 (Figure ).…”

Cadmium(II) Complex Formation with Selenourea and Thiourea in Solution: An XAS and 113Cd NMR Study

“…Selenourea (SeU, Scheme 1) is a resonance-stabilized selenoketone (selone) with π-conjugation between the selenocarbonyl and amino groups. 23 It is sensitive to heat, light and moisture and is easily oxidized in acidic aqueous solution forming a Se-Se bond in a diselenobis(formamidinium) cation, 24 or decomposed by atmospheric oxygen to red elemental selenium in neutral / alkaline aqueous solution, 25 and even in methanol and ethanol. 26 Hydrolytic decomposition of selenourea generates cyanamide (H 2 CN 2 ), Se 2- and HSe - , and is accelerated by increasing pH.…”

“…CdSe NPs and thin films have been prepared from mixtures of selenourea and cadmium salts in similar ways as for cadmium sulfide. Selenourea (SeU, Scheme ) is a resonance-stabilized selenoketone (selone) with π-conjugation between the selenocarbonyl and amino groups . It is sensitive to heat, light, and moisture and is easily oxidized in acidic aqueous solution, forming a Se–Se bond in a diselenobis(formamidinium) cation, or decomposed by atmospheric oxygen to red elemental selenium in neutral/alkaline aqueous solution, and even in methanol and ethanol .…”