Petrícek Václav, Dusek Michal, Cernák Juraj
Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague, Czech Republic.
Acta Crystallogr B. 2005 Jun;61(Pt 3):280-6. doi: 10.1107/S0108768105012632. Epub 2005 May 13.
The crystal structure of [Cd(NH(3))(3)Ni(CN)(4)] has been solved and refined as an incommensurate structure in four-dimensional superspace. The Xcalibur point-detector diffractometer was used for data collection up to the third-order satellites. The structure was refined from 3496 observed reflections to a final R value of 0.0371. The modulation strongly affects all the atoms of the structure. The dominating feature of the modulation is the incommensurate alternation between octahedrally and tetrahedrally coordinated Cd atoms in the electroneutral chains -Cd(NH(3))(n)-NC-Ni(CN)(2)-CN- (n alternates between 2 and 4). The chain is propagated along the a axis, in which the Cd(NH(3))(n) cations are linked by square Ni(CN)(4) anions. The atomic positional modulations, having mainly a transversal character in the c-direction, exhibit a switching character that can be described by the crenel and sawtooth functions. The effectively pentagonal coordinated cadmium positions were detected in the intermediate regions.
[Cd(NH₃)₃Ni(CN)₄]的晶体结构已作为四维超空间中的非公度结构得以解析和精修。使用Xcalibur点探测器衍射仪收集直至三阶卫星峰的数据。该结构从3496个观测反射进行精修，最终R值为0.0371。这种调制强烈影响结构中的所有原子。调制的主要特征是在电中性链[-Cd(NH₃)ₙ-NC-Ni(CN)₂-CN-]∞（n在2和4之间交替）中，八面体和四面体配位的Cd原子之间的非公度交替。该链沿a轴延伸，其中[Cd(NH₃)ₙ]²⁺阳离子通过方形[Ni(CN)₄]²⁻阴离子相连。主要在c方向具有横向特征的原子位置调制表现出一种可由城垛函数和锯齿函数描述的切换特征。在中间区域检测到了有效五配位的镉位置。
