<b>Electronic effects at α-position of divalent five-membered ring carbenes: singlet-triplet
Thermal energy gaps, ΔE<sub>s–t</sub>; enthalpy gaps, ΔH<sub>s–t</sub>; Gibbs free energy gaps, ΔG<sub>s–t</sub>, between singlet (s) and triplet (t) states of G–C<sub>4</sub>H<sub>3</sub>C (G = –NH<sub>2</sub>, –OH, –CH<sub&...
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| Format: | Article |
| Language: | English |
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Chemical Society of Ethiopia
2009-04-01
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| Series: | Bulletin of the Chemical Society of Ethiopia |
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| Online Access: | http://www.ajol.info/index.php/bcse/article/view/21314 |
| Summary: | Thermal energy gaps, ΔE<sub>s–t</sub>; enthalpy gaps, ΔH<sub>s–t</sub>; Gibbs free energy gaps, ΔG<sub>s–t</sub>, between singlet (s) and triplet (t) states of G–C<sub>4</sub>H<sub>3</sub>C (G = –NH<sub>2</sub>, –OH, –CH<sub>3</sub>, –F, –Cl, –Br, –H, –CF<sub>3</sub>, –NO<sub>2</sub>) were calculated at B3LYP/6-311++G** level of theory. DFT calculations indicated that electron donating substituents (G = –NH<sub>2</sub>, –OH and –CH<sub>3</sub>) at α position cause to decrease ΔG<sub>s–t</sub> and electron withdrawing substituents (G = –F, –Cl, –Br, –CF<sub>3</sub> and –NO<sub>2</sub>) lead to increase the ΔG<sub>s–t</sub> of G-C<sub>4</sub>H<sub>3</sub>C. Nuclear independent chemical shifts (NICS) calculations were carried out to determine the aromatic character. |
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| ISSN: | 1011-3924 1726-801X |