E. Vessally - Islamic Azad University, Miyaneh Branch, Miyaneh, Iran
M. Zargham - Payame Noor University (PNU), Zanjan, Iran

Divalent carbenes and their analogues are interesting intermediates in organic synthesis [1]. The cyclic completely conjugated species are important in the chemistry of the divalent carbene intermediates [2]. In this research work, the energy differences, ΔXS–t (∆Xs-t=X(singlet)-X(triplet)) between the singlet (s) and triplet (t) states on X2C2H4C (X=NH, PH, AsH, O, S, Se) were calculated at DFT/B3LYP/6-311++G** level of theory. The DFT calculations show that the triplet state of X2C2H4C is ground state with planar conformer respect to its corresponding nonplanar singlet state. Also, DFT calculations indicate that the heavier heteroatoms at α position decrease the stability of the singlet state. However, the light heteroatoms at α position increase the stability of the singlet state. The results will be presented and discussed.