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The new title phosphate, silver trinickel phosphate bis(hydrogenphosphate), has been synthesized by the hydro­thermal method. It has an alluaudite-like structure but shows some differences owing to the presence of the H atoms. The structure is isomorphous with the compounds of general formula AM3(XO4)(HXO4)2 (A is Na or Ag, M is Co, Zn or Mn, and X is As or P), with the Ag atom, one Ni atom and one P atom lying on twofold axes.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102003153/br1359sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270102003153/br1359Isup2.hkl
Contains datablock I

Comment top

Open-framework structures built up from MO6 octahedra and XO4 and/or X2O7 groups (M is a transition metal, X is P or As), with alkali or pseudo-alkali metals, are currently of great interest because of their potential applications in the fields of ion exchange, ionic conductivity etc. (Daidouh et al., 1997; Pintard-Scrépel et al., 1978; Winand et al., 1990; D'Yvoire et al., 1993; Couturier et al., 1991; Gueho et al., 1993; Haushalter, 1990; Piffard et al., 1985). During our recent investigation of the nickel system A2O-NiO-X2O5 (A is an alkali or pseudo-alkali metal), four compounds with mixed open frameworks were found, namely K4Ni7(AsO4)6 (Ben Smail et al., 1999), KNi3AsO4As2O7 (Ben Smail & Jouini, 2000), AgNiPO4 (Ben Smail & Jouini, 2002) and the title compound, AgNi3(PO4)(HPO4)2, which is a new open-framework phosphate. The present paper deals with the synthesis and structure determination of AgNi3(PO4)(HPO4)2.

The structure is built up from NiO6 octahedra, and PO4 and PO3(OH) tetrahedra, sharing corners and edges to form a three-dimensional framework. Two types of six-sided tunnels running along the c axis are found. One tunnel, at (1/2, 0, z), is delimited by six octahedra, where Ag atoms reside, while the other tunnel, at (0, 0, z), is delimited by four octahedra and two tetrahedra. The OH groups point into this tunnel (Fig. 1).

The extended structure can be seen as parallel sheets, oriented perpendicular to the [010] direction, linked via O5 atoms and O6—H···O1 hydrogen bonds. Each sheet consists of [Ni3O12] infinite chains of edge-sharing Ni1O6—Ni2O6—Ni2O6 octahedral units running along the [101] direction. Equivalent chains are linked together in the [101] direction by the phosphate tetrahedra (Fig. 2).

The title compound is isotypic with the following compounds: AgCo3(PO4)(HPO4)2 (Guesmi & Driss, 2001), AgCo3(AsO4)(HAsO4)2 and AgZn3(AsO4)(HAsO4)2 (Keller et al., 1981), NaCo3(AsO4)(HAsO4)2 and NaCo3(PO4)(HPO4)2 (Lii & Shih, 1994), and NaMn3(PO4)(HPO4)2 (Leroux et al., 1995). The structures of these compounds are related to the alluaudite structure type, X2X1M1M2(PO4)3 (Yakubovich et al., 1977; Moore, 1971), but there are important differences. The presence of H atoms and their need to form O—H bonds leads to a split of the (1/2, 1/2, 0) (X2) site into two H-atom positions. In addition, the X1 site is empty; it is replaced by the (0, 1/2, 1/4) position, which is occupied by monovalent Ag+ or Na+ cations.

The two Ni atoms are both octahedrally coordinated by O-atom neighbours, with average Ni—O bond distances of 2.073 (2) Å for Ni2 and 2.123 (2) Å for Ni1. The P—O bond lengths are in the range 1.533 (2)–1.578 (3) Å. The longest bond, at 1.578 (3) Å, occurs with the O6 atom, which is involved in the O6—H···O1 hydrogen bond. These values are in good agreement with those observed in other open-framework nickel phosphates (Abrahams & Eason, 1993; Jouini & Dabbabi, 1986; Erragh et al., 1998; Nord, 1983; Boudjada et al., 1978; Calvo & Faggiani, 1975; Hamanaka & Imoto, 1998).

The silver coordination in the title compound is very similar to that shown previously by arsenate (Keller et al., 1981) and phosphate (Guesmi & Driss, 2002) structures. The Ag+ cation forms a square plane, with Ag—O distances ranging from 2.364 (3) to 2.501 (3) Å.

Experimental top

Crystals of AgNi3(PO4)(HPO4)2 were grown hydrothermally using a mixture of AgNO3 (2 g; Fluka, 99%), Ni(NO3)26H2O (2.01 g; Fluka, 99%), H3PO4 (1 ml; Prolabo, 85%, density 1.70 Mg m -3) and distilled water (5 ml). The solution was heated in a sealed tube at 623 K for three weeks, followed by normal cooling to room temperature. Two types of crystals were formed, yellow-brown and green parallelepiped crystals. The green crystals were identified as AgNiPO4 by X-ray studies, the yellow-brown crystals as AgNi3(PO4)(HPO4)2.

Refinement top

The unique H atom was located from a difference Fourier map and refined isotropically.

Computing details top

Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. A projection of the structure of AgNi3(PO4)(HPO4)2 along the c axis. O3* is the sixth vertex of Ni2O6 lying behind the equatorial plane.
[Figure 2] Fig. 2. A projection of a sheet of the anionic framework of AgNi3(PO4)(HPO4)2 along the b axis, with 75% probability displacement ellipsoids.
Silver trinickel phosphate bis(hydrogenphosphate) top
Crystal data top
AgH2Ni3O12P3F(000) = 1096
Mr = 570.93Dx = 4.458 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71069 Å
Hall symbol: -C 2ycCell parameters from 25 reflections
a = 11.865 (4) Åθ = 6.6–14.9°
b = 12.117 (3) ŵ = 9.45 mm1
c = 6.467 (2) ÅT = 293 K
β = 113.82 (3)°Parallelepiped, brown-yellow
V = 850.6 (4) Å30.50 × 0.20 × 0.16 mm
Z = 4
Data collection top
Enraf-Nonius CAD-4
diffractometer
916 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.024
Graphite monochromatorθmax = 27.0°, θmin = 2.5°
ω/2θ scansh = 1513
Absorption correction: ψ scan
(North et al., 1968)
k = 015
Tmin = 0.119, Tmax = 0.221l = 08
1012 measured reflections2 standard reflections every 120 min
928 independent reflections intensity decay: 1.0%
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.020All H-atom parameters refined
wR(F2) = 0.051 w = 1/[σ2(Fo2) + (0.0174P)2 + 8.9075P]
where P = (Fo2 + 2Fc2)/3
S = 1.21(Δ/σ)max = 0.004
928 reflectionsΔρmax = 0.87 e Å3
93 parametersΔρmin = 1.07 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0112 (3)
Crystal data top
AgH2Ni3O12P3V = 850.6 (4) Å3
Mr = 570.93Z = 4
Monoclinic, C2/cMo Kα radiation
a = 11.865 (4) ŵ = 9.45 mm1
b = 12.117 (3) ÅT = 293 K
c = 6.467 (2) Å0.50 × 0.20 × 0.16 mm
β = 113.82 (3)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
916 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.024
Tmin = 0.119, Tmax = 0.2212 standard reflections every 120 min
1012 measured reflections intensity decay: 1.0%
928 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0200 restraints
wR(F2) = 0.051All H-atom parameters refined
S = 1.21Δρmax = 0.87 e Å3
928 reflectionsΔρmin = 1.07 e Å3
93 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

The Ni and P atoms were located by the direct method; the remaining atoms were located by successive difference Fourier maps.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ag0.00000.46944 (4)0.25000.01576 (15)
Ni10.50000.27617 (5)0.25000.00488 (16)
Ni20.28914 (4)0.16290 (3)0.37743 (7)0.00391 (15)
P10.00000.18445 (10)0.25000.0031 (2)
P20.22359 (8)0.38701 (7)0.11454 (14)0.00311 (18)
O10.1079 (2)0.10763 (19)0.2648 (4)0.0063 (5)
O20.0354 (2)0.25737 (19)0.4643 (4)0.0050 (5)
O30.3430 (2)0.17260 (19)0.1127 (4)0.0052 (5)
O40.2178 (2)0.31833 (19)0.3092 (4)0.0052 (5)
O50.3362 (2)0.00011 (19)0.3945 (4)0.0069 (5)
O60.3631 (2)0.4049 (2)0.1578 (4)0.0057 (5)
H0.371 (9)0.480 (8)0.176 (17)0.10 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ag0.0063 (2)0.0284 (3)0.0109 (2)0.0000.00180 (16)0.000
Ni10.0046 (3)0.0053 (3)0.0056 (3)0.0000.0029 (2)0.000
Ni20.0041 (2)0.0036 (2)0.0048 (2)0.00018 (15)0.00269 (17)0.00007 (15)
P10.0019 (5)0.0036 (5)0.0038 (5)0.0000.0009 (4)0.000
P20.0036 (4)0.0020 (4)0.0042 (4)0.0003 (3)0.0021 (3)0.0003 (3)
O10.0031 (11)0.0039 (11)0.0126 (12)0.0006 (8)0.0037 (9)0.0011 (9)
O20.0058 (11)0.0062 (11)0.0035 (10)0.0002 (9)0.0023 (9)0.0006 (8)
O30.0061 (11)0.0069 (11)0.0042 (11)0.0015 (8)0.0037 (9)0.0011 (8)
O40.0067 (11)0.0055 (11)0.0048 (11)0.0007 (9)0.0037 (9)0.0009 (8)
O50.0063 (11)0.0040 (11)0.0108 (12)0.0004 (9)0.0039 (10)0.0003 (9)
O60.0037 (11)0.0034 (11)0.0112 (12)0.0004 (9)0.0041 (9)0.0010 (9)
Geometric parameters (Å, º) top
Ag—O5i2.364 (3)Ni2—O4i2.074 (2)
Ag—O5ii2.364 (3)Ni2—O12.083 (2)
Ag—O5iii2.501 (3)Ni2—O2i2.144 (3)
Ag—O5iv2.501 (3)P1—O21.551 (2)
Ni1—O2i2.093 (2)P1—O2vii1.551 (2)
Ni1—O2v2.093 (2)P1—O1vii1.554 (2)
Ni1—O32.121 (2)P1—O11.554 (2)
Ni1—O3vi2.121 (2)P2—O5iv1.533 (2)
Ni1—O6vi2.155 (2)P2—O41.534 (2)
Ni1—O62.155 (2)P2—O3viii1.539 (2)
Ni2—O42.039 (2)P2—O61.578 (3)
Ni2—O52.041 (2)O6—H0.9 (1)
Ni2—O32.058 (2)
O5i—Ag—O5ii162.04 (12)O4—Ni2—O4i86.18 (10)
O5i—Ag—O5iii94.07 (9)O5—Ni2—O4i99.85 (10)
O5ii—Ag—O5iii83.26 (8)O3—Ni2—O4i162.69 (10)
O5i—Ag—O5iv83.26 (8)O4—Ni2—O186.63 (10)
O5ii—Ag—O5iv94.07 (9)O5—Ni2—O185.96 (10)
O5iii—Ag—O5iv162.91 (11)O3—Ni2—O1110.55 (10)
O2i—Ni1—O2v157.61 (13)O4i—Ni2—O186.23 (10)
O2i—Ni1—O378.43 (9)O4—Ni2—O2i85.73 (10)
O2v—Ni1—O388.33 (9)O5—Ni2—O2i102.59 (10)
O2i—Ni1—O3vi88.33 (9)O3—Ni2—O2i78.67 (10)
O2v—Ni1—O3vi78.43 (9)O4i—Ni2—O2i84.14 (9)
O3—Ni1—O3vi107.44 (13)O1—Ni2—O2i168.08 (9)
O2i—Ni1—O6vi107.08 (9)O2—P1—O2vii110.57 (19)
O2v—Ni1—O6vi89.27 (9)O2—P1—O1vii108.37 (13)
O3—Ni1—O6vi168.70 (9)O2vii—P1—O1vii111.54 (13)
O3vi—Ni1—O6vi82.86 (9)O2—P1—O1111.54 (13)
O2i—Ni1—O689.27 (9)O2vii—P1—O1108.37 (13)
O2v—Ni1—O6107.08 (9)O1vii—P1—O1106.40 (19)
O3—Ni1—O682.86 (9)O5iv—P2—O4110.04 (14)
O3vi—Ni1—O6168.70 (9)O5iv—P2—O3viii109.38 (14)
O6vi—Ni1—O687.30 (13)O4—P2—O3viii110.67 (14)
O4—Ni2—O5170.12 (10)O5iv—P2—O6108.69 (14)
O4—Ni2—O390.49 (9)O4—P2—O6108.70 (14)
O5—Ni2—O385.99 (10)O3viii—P2—O6109.32 (14)
Symmetry codes: (i) x+1/2, y+1/2, z+1; (ii) x1/2, y+1/2, z1/2; (iii) x1/2, y+1/2, z; (iv) x+1/2, y+1/2, z+1/2; (v) x+1/2, y+1/2, z1/2; (vi) x+1, y, z+1/2; (vii) x, y, z+1/2; (viii) x+1/2, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O6—H···O1iv0.9 (1)1.5 (1)2.503 (3)174 (10)
Symmetry code: (iv) x+1/2, y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formulaAgH2Ni3O12P3
Mr570.93
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)11.865 (4), 12.117 (3), 6.467 (2)
β (°) 113.82 (3)
V3)850.6 (4)
Z4
Radiation typeMo Kα
µ (mm1)9.45
Crystal size (mm)0.50 × 0.20 × 0.16
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.119, 0.221
No. of measured, independent and
observed [I > 2σ(I)] reflections
1012, 928, 916
Rint0.024
(sin θ/λ)max1)0.638
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.020, 0.051, 1.21
No. of reflections928
No. of parameters93
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.87, 1.07

Computer programs: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1998), SHELXL97.

Selected bond lengths (Å) top
Ag—O5i2.364 (3)Ni2—O12.083 (2)
Ag—O5ii2.501 (3)Ni2—O2i2.144 (3)
Ni1—O2iii2.093 (2)P1—O21.551 (2)
Ni1—O32.121 (2)P1—O11.554 (2)
Ni1—O62.155 (2)P2—O5ii1.533 (2)
Ni2—O42.039 (2)P2—O41.534 (2)
Ni2—O52.041 (2)P2—O3iv1.539 (2)
Ni2—O32.058 (2)P2—O61.578 (3)
Ni2—O4i2.074 (2)
Symmetry codes: (i) x+1/2, y+1/2, z+1; (ii) x+1/2, y+1/2, z+1/2; (iii) x+1/2, y+1/2, z1/2; (iv) x+1/2, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O6—H···O1ii0.9 (1)1.5 (1)2.503 (3)174 (10)
Symmetry code: (ii) x+1/2, y+1/2, z+1/2.
 

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