The crystal structure of magnesium copper(II) bis[orthophosphate(V)] monohydrate is formed by three types of cationic sites and by two unique (PO4)3− anions. One site is occupied by Cu2+, the second site by Mg2+and the third site by a mixture of the two cations with an Mg2+:Cu2+ occupancy ratio of 0.657 (3):0.343 (3).
Single crystals of sodium copper(II) indium bis[phosphate(V)], NaCuIn(PO4)2, were grown from the melt under atmospheric conditions. The title phosphate crystallizes in the space group P21/n and is isotypic with KCuFe(PO4)2. In the crystal, two [CuO5] trigonal bipyramids share an edge to form a dimer [Cu2O8] that is connected to two PO4 tetrahedra. The obtained [Cu2P2O12] units are interconnected through vertices to form sheets that are sandwiched between undulating layers resulting from the junction of PO4 tetrahedra and [InO6] octahedra. The two types of layers are alternately stacked along [101] and are joined into a three-dimensional framework through vertex- and edge-sharing, leaving channels parallel to the stacking direction. The channels host the sodium cations that are surrounded by four oxygen atoms in form of a distorted disphenoid.
The transition-metal orthophosphate Na1.67Zn1.67Fe1.33(PO4)3 cristallizes in an alluaudite-type structure. The chains characterizing the alluaudite structure are then built up from [M
2O10] (M = Fe/Zn) units alternating with [ZnO6] octahedra. This structure is characterized by a cationic disorder in one tunnel and in the general position.
Key indicators: single-crystal X-ray study; T = 296 K; mean (P-O) = 0.001 Å; R factor = 0.019; wR factor = 0.045; data-to-parameter ratio = 27.3.The title compound, Sr 2 Mn 3 (HPO 4 ) 2 (PO 4 ) 2 , was synthesized under hydrothermal conditions. In the structure, one of two Mn atoms is located on an inversion centre, whereas all others atoms are located in general positions. The framework structure is built up from two types of MnO 6 octahedra (one almost undistorted, one considerably distorted), one PO 3 OH and one PO 4 tetrahedron. The centrosymmetric MnO 6 octahedron is linked to two other MnO 6 octahedra by edgesharing, forming infinite zigzag chains parallel to [010]. The PO 3 OH and PO 4 tetrahedra connect these chains through common vertices or edges, resulting in the formation of sheets parallel to (100). The Sr 2+ cation is located in the interlayer space and is bonded to nine O atoms in form of a distorted polyhedron and enhances the cohesion of the layers. Additional stabilization is achieved by a strong interlayer O-HÁ Á ÁO hydrogen bond between the PO 3 OH and PO 4 units. The structure of the title phosphate is isotypic to that of Pb 2 Mn 3 (HPO 4 ) 2 (PO 4 ) 2 .
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ExperimentalCrystal data
Crystals of the new compound, AgSr4Cu4.5(PO4)6, were grown successfully by the hydrothermal process. The asymmetric unit of the crystal structure of the title compound contains 40 independent atoms (4 Sr, 4.5 Cu, 1 Ag, 6 P and 24 O), which are all in general positions except for one Cu atom, which is located on an inversion centre. The Cu atoms are arranged in CuO
n
(n = 4 or 5) polyhedra, linked through common oxygen corners to build a rigid three-dimensional motif. The connection of these copper units is assured by PO4 tetrahedra. This arrangement allows the construction of layers extending parallel to the (100) plane and hosts suitable cavities in which Ag+ and Sr2+ cations are located. The crystal-structure cohesion is ensured by ionic bonds between the silver and strontium cations and the oxygen anions belonging to two adjacent sheets. Charge-distribution analysis and bond-valence-sum calculations were used to validate the structural model.
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