Cd₂Cu(PO₄)₂

Abstract

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)](n) chains and [Cd(2)O(10)](n) 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)](n) 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)](n) chains similar to those found in related structures. Conversely, the [Cd(2)O(10)](n) double chains, which were not found in related structures, are an exclusive feature of this structure.

Substitutional and positional disorder in Sr2.88Cu3.12(PO4)4

“…ionic conductivity, ion exchange and catalytic activity). An ongoing extensive study on the low-temperature hydrothermal synthesis, crystallography and properties of compounds in the insufficiently known AO-CuO-X 2 O 5 -H 2 O (A = Cd 2+ or Sr 2+ ; X = As 5+ or P 5+ ) system has already yielded a couple of interesting structures (Š utović et al, 2009;Ðordević et al, 2008;Stojanović et al, 2008). This contribution reports on the hydrothermal synthesis and crystal structure of the title compound, (I), and its relationship to similar structures.…”

Novel first-row transition-metal phosphates: hydrothermal synthesis and crystal structures

“…5). The correlation between the unit-cell parameters of compounds forming this family and the ionic radii of the metal cations is discussed in Stojanovic ´et al (2008).…”

[Zn3(PO4)2(H2O)0.8(NH3)1.2]

“…This work forms part of ongoing research on heteropolyhedral framework structures of divalent metal phosphates and arsenates with potentially interesting structural, physical and chemical properties Stojanović et al, 2008;Weil et al, 2009). The aim of the current study was the synthesis and characterization of new compounds in the CdO-ZnO-P 2 O 5 -NH 3 -H 2 O system.…”