苯并-12-冠-4分子的晶体结构和电子结构

冠醚类化合物对金属离子有特殊的络合能力,并已在分析、萃取、催化和高分子化学等方面得到广泛应用,因此有关共结构和性质的基础研究具有理论和实际意义。大量研究结果表明,冠醚分子的环孔穴大小无疑是决定其络合能力的一个重要因素。在已详细研究过的冠醚中,12-冠-4分子的孔穴最小,但它仍然能同一些金属离子形成稳定的配合物。我们在实验工作中发现,苯并-12-冠-4分子络合能力较差,为较深入地揭示其原因,测定了它的晶体结构并对共电子结构进行了量子化学近似计算。

THE CRYSTAL AND ELECTRONIC STRUCTURE OF THE BENZO-12-CROWN-4 MOLECULE

In order to get a better insight into the structural features of the benzo-12-crown-4 molecule, the determination of its crystal structure has been undertaken, while the electronic structure was calculated. The crystal belongs to monoclinic with space group p2_1/a and cell dimensions a=0.8011(2), b=3.3560(2), c=0.8435(7) nm, β=91.06(2)°, V=2.2674 nm, z=8 and D_C=1.31 g cm~(-3). Full matrix leastsquares refinement with isotropic thermal parameters for H and anisotropic for the other atoms converged at R=0.062 and R_W=0.050. There are two molecules in an asymmetric unit. In comparison with 12-crown-4, the molecule has an entirely different conformation, having the carbon atom C(110) twisted to the center of the 12-membered ring. The MINDO/3-SCF calculation has been carried out on an M-340 computer, and the geometrical and electronic structure features of the molecule were discussed.