molecules in the asymmetric unit both have pentagonal-bipyramidal cages, but are related as rotational conformers about the metal–cage axis. Comparison of the molecular parameters of the three seven-vertex cages thus studied with those of analogous 12-vertex (icosahedral) systems suggests that the barrier to rotation of a metal fragment, about the axix linking it to the cage, should be less in the former
[ nido -µ 4,5- 反式-(Et 3 P)2
PT(H)}-µ 5,6 -H-2,3-Me 2 -2,3-C 2 B 4的密封管热解ħ 4 ],得到闭合碳-carbametallaborane [1,1-(ET 3 P)2 -2,3--ME 2 -1,2,3-
PTC 2乙4 ħ 4 ],结构特征在于X射线衍射。晶体是单斜晶体,空间群P 2 1 / a,Z= 4,在晶格参数为a = 15.691(6),b = 10.118(6),c = 15.949(6)Å和β= 115.76(3)°的晶胞中。使用在四圆衍射仪上以215 K收集的7 437个数据,精化收敛于R 0.067。该分子具有高度扭曲的五边形-双锥体笼,具有
PT(PEt 3)2片段的新颖(C 2 v)构象。相反,[ nido -µ 4,5- 反式-(Et 3 P)2
PT(H)}-µ 5,6 -H-2,3-C 2 B 4