Stojanović Jovica, Dordvić Tamara, Karanović Ljiljana
Applied Mineralogy Unit, Institute for Technology of Nuclear and Other Mineral Raw Materials, Franchet d'Esperey 86, PO Box 390, 11000 Belgrade, Republic of Serbia.
Acta Crystallogr C. 2008 Nov;64(Pt 11):i91-i94. doi: 10.1107/S0108270108032332. Epub 2008 Oct 22.
During an investigation of the insufficiently known system M1O-M2O-X(2)O(5)-H(2)O (M1 = Cd(2+), Sr(2+) and Ba(2+); M2 = Cu(2+), Ni(2+), Co(2+), Zn(2+) and Mg(2+); X = P(5+), As(5+) and V(5+)), single crystals of the novel compound dicadmium copper(II) bis[phosphate(V)], Cd(2)Cu(PO(4))(2), were obtained. This compound belongs to a small group of compounds adopting a Cu(3)(PO(4))(2)-type structure and having the general formula M1(2)M2(XO(4))(2) (M1/M2 = Cd(2+), Cu(2+), Mg(2+) and Zn(2+); X = As(5+), P(5+) and V(5+)). The crystal structure is characterized by the interconnection of infinite Cu(PO(4))(2) chains and Cd(2)O(10) double chains, both extending along the a axis. Exceptional characteristics of this structure are its novel chemical composition and the occurrence of double chains of CdO(6) polyhedra that were not found in related structures. In contrast to the isomorphous compounds, where the M1 cations are coordinated by five O atoms, the Cd atom is coordinated by six. The dissimilarity in the geometry of M1 coordination between Cd(2)Cu(PO(4))(2) and the isomorphous compounds is mostly due to the larger ionic radius of the Cd cation in comparison with the Cu, Mg and Zn cations. Sharing a common edge, two CdO(6) polyhedra form Cd(2)O(10) dimers. Each such dimer is bonded to another dimer sharing common vertices, forming Cd(2)O(10) double chains in the [100] direction. The Cu atoms, located on an inversion centre (site symmetry \overline{1}), form isolated CuO(4) squares interconnected by PO(4) tetrahedra, forming Cu(PO(4))(2) chains similar to those found in related structures. Conversely, the Cd(2)O(10) double chains, which were not found in related structures, are an exclusive feature of this structure.
在对鲜为人知的体系M1O-M2O-X(2)O(5)-H(2)O（M1 = Cd(2+)、Sr(2+)和Ba(2+)；M2 = Cu(2+)、Ni(2+)、Co(2+)、Zn(2+)和Mg(2+)；X = P(5+)、As(5+)和V(5+)）进行研究期间，获得了新型化合物二镉铜(II)双[磷酸(V)]Cd(2)Cu(PO(4))(2)的单晶。该化合物属于采用Cu(3)(PO(4))(2)型结构且通式为M1(2)M2(XO(4))(2)（M1/M2 = Cd(2+)、Cu(2+)、Mg(2+)和Zn(2+)；X = As(5+)、P(5+)和V(5+)）的一小类化合物。晶体结构的特征是无限的Cu(PO(4))(2)链和Cd(2)O(10)双链相互连接，二者均沿a轴延伸。该结构的独特之处在于其新颖的化学组成以及在相关结构中未发现的CdO(6)多面体双链的出现。与同构化合物不同，在同构化合物中M1阳离子由五个O原子配位，而Cd原子由六个O原子配位。Cd(2)Cu(PO(4))(2)与同构化合物之间M1配位几何形状的差异主要是由于Cd阳离子的离子半径比Cu、Mg和Zn阳离子的离子半径大。两个CdO(6)多面体共用一条边形成Cd(2)O(10)二聚体。每个这样的二聚体与另一个共用顶点的二聚体相连，在[100]方向上形成Cd(2)O(10)双链。位于对称中心（点群对称\overline{1}）的Cu原子形成由PO(4)四面体相互连接的孤立CuO(4)正方形，形成与相关结构中发现的类似的Cu(PO(4))(2)链。相反，在相关结构中未发现的Cd(2)O(10)双链是该结构独有的特征。
