3,6—二〔二甲氨基〕二苯并碘六圜氯化物的晶体和分子结构

3,6—二二甲氨基]二苯并碘六圆氯化物的晶体呈淡黄色六棱柱状。该晶体所属的空间群是P2_1/n,晶胞参数为;a=11.073(2),b=13.766(1),c=11.229(11),β=99.36(5)°,Z=4。在CAD—4四圆衍射仪上用Mo-Kα射线收录了Ⅰ≥3σ(Ⅰ)的独立衍射数据2293个。晶体结构用重原子法解出,晶体结构参数经全矩阵最小二乘方法修正,偏离因子R=0.085。 结构测定结果表明,分子中二苯环不共面,其二面交角约为133°。值得指出的是,围绕对称心成心对称的一对分子呈二聚状态。二聚体中二碘原子、二氯原子及与碘原子毗邻的四个碳原子共处于一个平面。二聚体中I—C1间距有3.074和3.102两种,围绕碘原子的四个键角值为90°左右。在二聚体中碘原子以dsp~2。杂化轨道与周围的二氯原子、二碳原子键合。

Crystal and Molecular Structures of 3,6-Di-(Dimethylamine)-Dibenzepyriodonium Chloride

The crystal and molecular structures of the title compound have been determined from three-dimensional X-ray diffraction data. The cryatal is mono-clinic with a = 11.073 (2) , b = 13.766 (1) , c = 11.229 (11) A, β= 99.36 (5)°, Z = 4, space group P21/n. The observed and calculated densities are 1.60 and 1.631g/cm3 respectively. The structure was solved by heavy atom method and refined by full-matrix least squares to a conventional R facter of 0.085 for 2293 independent intensities greater than 3σ.Two benzoic rings within one molecule are not in the same plane and the dihedral angle between them is about 133°. In the heterocycle the average value of C-I bond lengths is 2.127A and the average value of bond lengths between the carbon atom of methene and adjacent C atoms is 1.522A.. It is interesting to note that in this crystal there are dimers, one of which consists of a pair molecules around inversion center. Eight atoms (2I, 2Cl and 4C) are in the same plane and the distances between iodine and chlorine atoms are 3.074 and 3.102A shorter than the total of their Van der Waals radii(3.90A). Four bond angles around iodine atom are nearly 90°. So we are able to assume that the electronic configuration in the valence shell of iodine atoms is dsp2 with two lone electron pairs in the Z direction. The chemical forces between I and Cl atoms are ionic and partly covalent.