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NH···S and SH···N intramolecular hydrogen bond in β‐thioaminoacrolein: A quantum chemical study
Author(s) -
Nowroozi A.,
Roohi H.,
Poorsargol M.,
Jahani P. Mohammadzadeh,
Hajiabadi H.,
Raissi H.
Publication year - 2011
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22615
Subject(s) - intramolecular force , natural bond orbital , chemistry , tautomer , conformational isomerism , ab initio , computational chemistry , hydrogen bond , basis set , charge (physics) , delocalized electron , molecule , stereochemistry , density functional theory , physics , quantum mechanics , organic chemistry
The conformational study of β‐thioaminoacrolein was performed at various theoretical levels, HF, B3LYP, and MP2 with 6‐311++G(d,p) basis set, and the equilibrium conformations were determined. To have more reliable energies, the total energies of all conformers were recomputed at high‐level ab initio methods, G2MP2, G3, and CBS‐QB3. According to these calculations, the intramolecular hydrogen bond is accepted as the origin of conformational preference in thialamine (TAA) and thiolimine groups. The hydrogen bond strength in various resonance‐assisted hydrogen bond systems was evaluated by HB energy, geometrical parameters, topological parameters, and charge transfers corresponding to orbital interactions. Furthermore, our results reveal that the TAA tautomer has extra stability with respect to the other tautomers. The population analyses of the possible conformations by NBO predict that the origin of this preference is mainly due to the π‐electron delocalization in framework of TAA forms, especially usual π CC → π* CS and Lp (N) → π* CC charge transfers. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011