A new compound, 1,3-bis(1-ferrocenesulfonyl-2-benzimidazolyl)propane, has been prepared, and characterized by ¹H NMR, IR, MS and X-ray single crystal diffraction. Its crystal structure belongs to orthorhombic system, space group P_nma, with a＝1.30079(13) nm, b＝2.9627(3) nm, c＝1.01257(10) nm, V＝3.9023(7) nm³, D_c＝1.492 g/cm³, µ＝0.907 mm^－1, Z＝4, F(000)＝1816, R₁＝0.0506, wR₂＝0.1583. The crystal structure shows that the title compound is cis-configuration, and not trans-configuration. The cis-configuration and the trans-configuration of the title compound are fully optimized by B3LYP/6-31G method in Gaussian 03 package, and the optimized structures in theory are α-BFBP (cis-configuration) and β-BFBP (trans-configuration), respectively. The results show that the bond lengths and bond angles obtained by quantum chemical calculation are almost the same with those of the experiment, suggesting that the molecular geometry optimization of the structures are reliable and the calculation method used is reliable. Especially, α-BFBP is in accordance with the crystal structure in the main. The molecular total energy of α-BFBP is far lower than that of β-BFBP, indicating that the cis-configuration of the title compound is more stable than the trans-configuration from the thermodynamic point of view. The HOMO energy of α-BFBP is lower than that of β-BFBP, suggesting that antioxidative potential of α-BFBP is superior than β-BFBP. The energy gap of frontier molecular orbits of α-BFBP is bigger than that of β-BFBP, indicating that the ground state of α-BFBP has better stability. In a word, the quantum chemical calculation of the title compound provides a good testimony for the crystal structure. The cis-configuration of the title compound is attributed to terminal direction of zigzag propyl between two benzimidazolyl.

Key words: 1,3-bis(1-ferrocenesulfonyl-2-benzimidazolyl)propane, crystal structure, theoretical calculation, optimized structure, frontier molecular orbit