二正丙基胂酸合六聚钼酸四胍盐(CN3H6)4[(n-C3H7As)2Mo6O24]的晶体和分子结构

一种新型有机胂合聚钼酸盐(CN_3H_6)_4(n-C_3H_7As)_2Mo_6O_(24)]的晶体属于正交晶系, 空间群为Cmca, 晶胞参数为: a=1.3938(1), b=1.6350(2), c=1.6173(2) nm直接法得出所有钼、砷原子的位置, 再由差值Fourier合成得到全部其他非氢原子位置。采用全矩阵最小二乘法精修, 最后的R因子为0.047。在该结构中, 阴离子呈笼状结构并具有较高的C_(2h)的对称性。键长数值在正常的范围内, 配位氧与钼原子的键角呈有规律的变化。氢键联结阴、阳离子并纵横于整个空间的各个方向, 形成网状分布, 对晶体的稳定起着重要的作用。

CRYSTAL AND MOLECULE STRUCTURE OF GUANIDINIUM HEXAMOLYBDO-BIS(n-PROPYLARSONATE), (CN3H6)4(n-C3H7As)2Mo6O24

The crystal structure of the title compound was determined by single crystal X-ray diffraction analysis. The intensity data were collected on an Enraf-Nonius CAD_4 diffractometer with MoK_a radiation, The space group is Cmca with a= 1.3938(1), b=1.6350(2), c=1.61 nm, Z=4, D_c=2.588 g/cm~3, μ=38.115 cm~(-1). The positions of all Mo and As atoms were determined by direct method.The others of the non-H atoms were revealed by difference Fourier synthe- sis. The structure was refined by full-matrix least squares procedure to a final R value of 0.047.The molecule of the title compound consists of anion, (n-C_3H_7As)_2Mo_6O_(24)~(4-), and four caions CN_3H_6~+. In the anion, six distorted octahedra MoO_6 join together to form a six membered ring, which is capped, top and bottom, by the C_3H_7As groups as a cage. The center of anionis at a special position of symmetry 2/m. The bond angles of O—Mo—O change regularly with different coordinated O atoms. There are many hydrogen bonds betweem the cations and anions throughout the whole crystal. Thus, each anion relates twelve neighbouring ones.