A Density Functional Approach toward Structural Features and Properties of C20 and its Complexes with C2X4, C2X2 (X = H, F, Cl, Br) for Synthesis Application

The complexes between c20 and c2x4, c2x2 (x = h, f, cl, br) have been studied theoretically at the b3lyp/6-311g (d,p) level. the calculations include the optimized geometries, the interaction energies, aromaticity and thermodynamic. the interaction energies ranging from -60 to -101 kcal/mol and being ordered as: x = f> cl > br. natural bond orbital (nbo) analysis has been performed on all geometries. the energy and oscillator strength calculated by time-dependent density functional theory (td-dft) results, and indicate that, in all the molecules homo-1 → lumo transition has the major contribution in the most intensity electronic transition.