Electronic effects at α- position of divalent five-membered ring XC4H7M (X = -NH2, -OH, -CH3 -H, -Br, -Cl, -F, -CF3 and -NO2; M = Si and Ge). Singlet and triplet energies through DFT calculation.

  • سال انتشار: 1389
  • محل انتشار: همایش منطقه ای شیمی
  • کد COI اختصاصی: MIAUCHEMISTRY01_039
  • زبان مقاله: انگلیسی
  • تعداد مشاهده: 326
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نویسندگان

F. Esmaeili

Department of Chemistry, University of Ilam and Petrochemical company, Ilam , Iran

M. Nikoorazm

Department of Chemistry, University of Ilam, Ilam, Iran

E. Vessally

Payame Noor University (PNU), Zanjan, Iran

H. Ghoudarzi Afshar

Department of Chemistry, University of Ilam, Ilam, Iran

چکیده

The stable five-membered cyclic singlet silyenes and their corresponding germylenes have been synthesized and physical properties compared with the Arduengo-type carbenes by Denk et al (1-2). Ab.Initio calculation have been carried out for determination of the stability and singlet and- triplet energy gaps five membered cyclic conjugated carbene and their heavy analogues(3). In this work, full geometry optimizations were carried out on singlet and triplet states of  substituted of divalent five membered rings XC4H7M (X = -NH2, -OH, -CH3 -H, -Br, -Cl, -F, -CF3 and -NO2; M = Si and Ge). by B3LYP method using 6-311++G** basis set. Thermal energy gaps, ΔEs–t; enthalpy gaps, ΔHs–t; Gibbs free energy gaps, ΔGs–t, between singlet (s) and triplet (t) states of above structures were calculated using the GAUSSIAN 98 program. The calculated ΔGs–t for XC4H7M indicated that when electron withdrawing and electronegative groups were placed at  position of five membered ring causes to intensify ΔGs–t, where as when electron donating groups were placed at  position of constituents lead to reduce the ΔGs–t of XC4H7M. From the calculated ΔGs-t for XC4H7 Si and XC4H7M Ge It was found that, the singlet states are more stable than triplet states. Also the relationship between all parameters (different energy types, electron energies of the frontier molecular orbital (HOMO and LUMO), chemical potential (μ), Dipole Moment (D), electrophilicity (ω), geometry parameters (Non-dihedral) and total charge on atom were carried out. The details would be presented and discussed.

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