Silver trimagnesium phosphate bis­(hydrogenphosphate), AgMg3(PO4)(HPO4)2, with an alluaudite-like structure

Abderrazzak Assani; Mohamed Saadi; Mohammed Zriouil; Lahcen El Ammari

doi:10.1107/S1600536810053304

. 2010 Dec 24;67(Pt 1):i5. doi: 10.1107/S1600536810053304

Silver trimagnesium phosphate bis(hydrogenphosphate), AgMg₃(PO₄)(HPO₄)₂, with an alluaudite-like structure

Abderrazzak Assani ^a,^*, Mohamed Saadi ^a, Mohammed Zriouil ^a, Lahcen El Ammari ^a

PMCID: PMC3050206 PMID: 21522513

Abstract

The title compound, AgMg₃(PO₄)(HPO₄)₂, which has been synthesized by the hydrothermal method, has an alluaudite-like structure which is formed by edge-sharing MgO₆ octahedra (one of which has symmetry 2), resulting in chains linked together by phosphate groups and hydrogen bonds. The three-dimensional framework leads to two different channels along the c axis, one of which is occupied by Ag⁺ ions with a square-planar coordination. The Ag⁺ ions are disordered over two sites in a 0.89 (3):0.11 (3) ratio. The OH groups, which point into the other type of channel, are involved in strong O—H⋯O hydrogen bonds. The title compound is isotypic with the compounds AM ₃H₂(XO₄)(HXO₄)₂ (A = Na or Ag, M = Mn, Co or Ni, and X = P or As) of the alluaudite structure type.

Related literature

For applications of related compounds, see: Kacimi et al. (2005 ▶); Korzenski et al. (1998 ▶); Trad et al. (2010 ▶). For compounds with the same structure type, see: Moore (1971 ▶); Hatert (2008 ▶); Hatert et al. (2000 ▶); Assani et al. (2010 ▶); Guesmi & Driss (2002 ▶); Ben Smail & Jouini (2002 ▶); Stock & Bein (2003 ▶); Leroux et al. (1995 ▶).

Experimental

Crystal data

AgMg₃(PO₄)(HPO₄)₂
M _r = 467.73
Monoclinic,
a = 11.9126 (5) Å
b = 12.1197 (6) Å
c = 6.4780 (3) Å
β = 113.812 (2)°
V = 855.66 (7) Å³
Z = 4
Mo Kα radiation
μ = 3.21 mm⁻¹
T = 296 K
0.31 × 0.16 × 0.12 mm

Data collection

Bruker X8 APEX diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.545, T _max = 0.680
10680 measured reflections
2330 independent reflections
1998 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.026
wR(F ²) = 0.075
S = 1.08
2330 reflections
91 parameters
H-atom parameters constrained
Δρ_max = 0.63 e Å⁻³
Δρ_min = −1.28 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810053304/fj2371sup1.cif

e-67-000i5-sup1.cif^{(23KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810053304/fj2371Isup2.hkl

e-67-000i5-Isup2.hkl^{(114.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O6—H6⋯O1ⁱ	0.86	1.68	2.5266 (17)	168

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.

supplementary crystallographic information

Comment

Compounds belonging to the large structural family of alluaudite derivatives (Moore (1971); Hatert et al. (2000)) have been of continuing interest due to their structural properties, such as their open-framework architecture and their physical properties. Accordingly, the alluaudite structure exhibit an appropriate frameworks for a variety of applications, such as corrosion inhibition, passivation of metal surfaces, and catalysis (Hatert (2008); Korzenski et al. (1998); Kacimi et al. (2005)).

In addition, the accommodation of the monovalent cations in the one-dimensional channels of the alluaudite-like structures is strongly required for conductivity properties and have offered a great field of application as positive electrode in the lithium and sodium batteries (Trad et al. 2010)

By means of the powerful hydrothermal technique, our attempts to synthesize new monovalent divalent cations phosphate with alluaudite –like structure have successfully allowed to obtain a new silver magnesium phosphate phase. The present paper aims to report detailed hydrothermal synthesis and structural characterization of the title compound.

The structure is built up from MgO₆ octahedra, PO₄ and PO₃(OH) tetrahedra, sharing corners and edges to form a three-dimensional framework as schown in Fig.1 and Fig.2. The three-dimensional network delimits two types of hexagonal channels which accommodate Ag+ cations and OH groups (see Fig.2). In the channels, each silver atoms is surrounded by four O atoms with Ag–O bond length varies between 2.3621 and 2.5150 Å. The same Ag⁺coordination sphere is observed in γ-AgZnPO₄ (Assani et al. (2010)). Moreover the OH groups, pointing into one type of channel, are involved in strong hydrogen bonds. The silver trimagnesium phosphate bis-(hydrogenphosphate): AgMg₃(PO₄)(HPO₄)₂, is isostructural with the compounds AM₃H₂(XO₄)₃ (A = Na or Ag, M = Mn, Co or Ni, and X = P or As) of the alluaudite structure type (Guesmi & Driss (2002); Ben Smail & Jouini (2002); Stock & Bein (2003).

Experimental

The crystals of the title compound has been hydrothermally synthesized starting from a mixture of magnesium oxide (0,0605 g), silver nitrate (0,1699 g), 85 wt % phosphoric acid (0,10 ml), and 12 ml of water. The hydrothermal synthesis was carried out in 23 ml Teflon-lined autoclave under autogeneous pressure at 468 K during 24 h. The product was filtered off, washed with deionized water and air dried. The reaction product consists yellow powder besides a colorless parallelepipedic crystals of the title compound.