Bujak Maciej, Angel Ross J
Crystallography Laboratory, Department of Geosciences, Virginia Tech, Blacksburg, Virginia 24061, USA.
J Phys Chem B. 2006 Jun 1;110(21):10322-31. doi: 10.1021/jp060652v.
The structure of N,N-dimethylethylenediammonium pentachloroantimonate(III), [(CH3)2NH(CH2)2NH3][SbCl5], NNDP, was investigated at 100 and 15 K at ambient pressure, as well as at pressures up to 4.00 GPa at room temperature in the diamond-anvil cell. The stable structure at low temperatures and low pressures consists of isolated [SbCl5]2- anions and [(CH3)2NH(CH2)2NH3]2+ cations. The inorganic anions have a distorted square pyramidal geometry. They are arranged in linear chains parallel to the c axis. In contrast to the low-temperature studies, where no phase transition was detected, pressure induces a P2(1)/c --> P2(1)/n phase transition between 0.55 and 1.00 GPa, accompanied by a doubling of the a unit-cell parameter. This solid-solid transition results from changes in the electron configuration of the Sb(III) atom and formation of the Sb-Cl bridging bonds between inorganic polyhedra to form, at approximately 1.0 GPa, isolated [Sb2Cl10]4- units consisting of [SbCl6]3- octahedra and [SbCl5]2- square pyramids connected by a common corner. The intermolecular distances continuously decrease with further increase in pressure, and at approximately 3.1 GPa, zigzag [{SbCl5}n]2n- chains containing corner-sharing [SbCl6]3- octahedra are formed. The unit-cell volume of NNDP decreases by 18.15% between room pressure and 4.00 GPa. The linear distortions of the [SbCl5]2- and [SbCl6]3- polyhedra decrease with increasing pressure and decreasing temperature and indicate a reduction in the stereochemical activity of the lone electron pair on the Sb(III) atom.
在室温下，利用金刚石对顶砧池研究了五氯锑酸（III）N，N-二甲基乙二铵盐[（CH3）2NH（CH2）2NH3][SbCl5]（NNDP）在100 K和15 K以及高达4.00 GPa压力下的结构。低温低压下的稳定结构由孤立的[SbCl5]2-阴离子和[（CH3）2NH（CH2）2NH3]2+阳离子组成。无机阴离子具有扭曲的四方锥几何结构，它们平行于c轴排列成线性链。与未检测到相变的低温研究不同，压力在0.55至1.00 GPa之间诱导了P2(1)/c→P2(1)/n相变，同时伴随着a晶胞参数加倍。这种固-固转变源于Sb(III)原子电子构型的变化以及无机多面体之间形成Sb-Cl桥键，在约1.0 GPa时形成由[SbCl6]3-八面体和[SbCl5]2-四方锥通过公共角相连的孤立[Sb2Cl10]4-单元。随着压力进一步增加，分子间距离持续减小，在约3.1 GPa时形成含有共用角的[SbCl6]3-八面体的锯齿状[{SbCl5}n]2n-链。NNDP的晶胞体积在常压和4.00 GPa之间减小了18.15%。[SbCl5]2-和[SbCl6]3-多面体的线性畸变随着压力增加和温度降低而减小，表明Sb(III)原子上孤电子对的立体化学活性降低。
