Crystal structure of disilver(I) dizinc(II) iron(III) tris­(orthovanadate) with an alluaudite-type structure

Lamsakhar, N.E.H.; Zriouil, M.; Assani, A.; Saadi, M.; El Ammari, L.

doi:10.1107/S205698901801071X

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Volume 74| Part 8| August 2018| Pages 1155-1158

https://doi.org/10.1107/S205698901801071X

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Crystal structure of disilver(I) dizinc(II) iron(III) tris(orthovanadate) with an alluaudite-type structure

Nour El Houda Lamsakhar,^a ^* Mohammed Zriouil,^a Abderrazzak Assani,^a Mohamed Saadi ^a and Lahcen El Ammari ^a

^aLaboratoire de Chimie Appliquée des Matériaux, Centre des Sciences des Matériaux, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Batouta, BP 1014, Rabat, Morocco
^*Correspondence e-mail: nlamsakhar@gmail.com

Edited by M. Weil, Vienna University of Technology, Austria (Received 5 July 2018; accepted 24 July 2018; online 27 July 2018)

The title compound, Ag₂Zn₂Fe(VO₄)₃, has been synthesized by solid-state reactions and belongs to the alluaudite structure family. In the crystal structure, four sites are positioned at special positions. One silver site is located on an inversion centre (Wyckoff position 4b), and an additional silver site, as well as one zinc and one vanadium site, on twofold rotation axes (4e). One site on a general position is statistically occupied by Fe^III and Zn^II cations that are octahedrally surrounded by O atoms. The three-dimensional framework structure of the title vanadate results from [(Zn,Fe)₂O₁₀] units of edge-sharing [(Zn,Fe)O₆] octahedra that alternate with [ZnO₆] octahedra so as to form infinite chains parallel to [10 $[\overline{1}]$ ]. These chains are linked through VO₄ tetrahedra by sharing vertices, giving rise to layers extending parallel to (010). Such layers are shared by common vanadate tetrahedra. The resulting three-dimensional framework delimits two types of channels parallel to [001] in which the silver sites are located with four- and sixfold coordination by oxygen.

Keywords: crystal structure; transition metal vanadate; solid-state reaction; alluaudite structure type.; crystal structure.

CCDC reference: 1857879

1. Chemical context

The crystal structure of the mineral alluaudite with general formula A(1)A(2)M(1)M(2)₂(XO₄)₃ was determined nearly fifty years ago by Moore (1971 ). In the structure, the two A sites can be occupied by mono- or divalent cations of medium size, and the M(1) and M(2) sites can accommodate di- or trivalent cations, which are generally transition metals and are octahedrally surrounded. The specific feature of the alluaudite structure is the existence of two channels parallel to [001] in which the A-site cations are located. As a result, alluaudite-type compounds can exhibit electronic and/or ionic conductivity (Hatert, 2008 ). In addition, alluaudite-type compounds have been reported as materials for fossil energy conversion, as sensor materials and storage energy materials (Korzenski et al., 1998 ), and as materials used in catalysis (Kacimi et al., 2005 ).

Accordingly, the synthesis and structural characterization of new alluaudite-type phosphates and vanadates within pseudo-ternary A₂O/MO/P₂O₅ or pseudo-quaternary A₂O/MO/Fe₂O₃/P₂O₅ systems using hydrothermal or solid-state reactions was the focus of our current research. Obtained phases are, for example, NaMg₃(HPO₄)₂(PO₄) (Ould Saleck et al., 2015 ), Na₂Co₂Fe(PO₄)₃ (Bouraima et al., 2015 ) or Na_1.67Zn_1.67Fe_1.33(PO₄)₃ (Khmiyas et al., 2015 ). We have also succeeded in preparing the first vanadate-based alluaudite-type phase (Na_0.70)(Na_0.70,Mn_0.30)(Fe^III,Fe^II)₂Fe^II(VO₄)₃ (Benhsina et al., 2016 ). A second alluaudite-type vanadate with composition Na₂(Fe^III/Co^II)₂Co^II(VO₄)₃ was prepared by Hadouchi et al. (2016 ) shortly afterwards.

In this context, the current exploration of A₂O/MO/Fe₂O₃/V₂O₅ systems, where A is a monovalent cation and M a divalent cation, led to another vandanate with alluaudite-type structure, namely Ag₂Zn₂Fe(VO₄)₃. Its synthesis and crystal structure are reported in this article.

2. Structural commentary

The principal building units of the crystal structure of the new member of the alluaudite-type family are represented in Fig. 1. All atoms are in general positions except for four atoms that are located on special positions. Ag1 is located on an inversion centre (Wyckoff position 4b), and Ag2 as well as Zn2 and V2 are located on twofold rotation axes (4e) of space group C2/c. The M2 site is in a general position (8f) and statistically occupied by Fe1 and Zn1 atoms that are octahedrally surrounded by O atoms. Such a partial cationic disorder was also reported for the cobalt homologue Na₂(Fe^III/Co^II)₂Co^II(VO₄)₃ (Hadouchi et al., 2016).

Figure 1
The principal building units in the structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) x, −y + 1, z − $[{1\over 2}]$ ; (ii) −x + 1, −y + 1, −z + 2; (iii) −x + 1, y, −z + $[{3\over 2}]$ ; (iv) x, −y, z − $[{1\over 2}]$ ; (v) x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , z − $[{1\over 2}]$ ; (vi) −x + $[{1\over 2}]$ , y − $[{1\over 2}]$ , −z + $[{3\over 2}]$ ; (vii) x + $[{1\over 2}]$ , y − $[{1\over 2}]$ , z; (viii) −x + $[{1\over 2}]$ , −y + $[{1\over 2}]$ , −z + 1; (ix) −x + 1, y, −z + $[{1\over 2}]$ ; (x) x, y, z − 1.]

The crystal structure of Ag₂Zn₂Fe(VO₄)₃ is made up from [(Zn,Fe)1₂O₁₀] dimers, resulting from edge-sharing [(Zn,Fe)1O₆] octahedra, that are connected by a common edge to [Zn2O₆] octahedra. The linkage of alternating [(Zn,Fe)1₂O₁₀] and [Zn2O₆] units leads to infinite zigzag chains along [10 $[\overline{1}]$ ] (Fig. 2). These chains are linked via the vertices of VO₄ tetrahedra into layers parallel to (010), as shown in Fig. 3. Adjacent layers are linked by V1O₄ tetrahedra into a three-dimensional framework structure that delimits two types of channels in which the Ag^I cations reside (Fig. 4). The Ag1 site is located in one channel and is surrounded by four oxygen atoms, whereas the Ag2 site in the second channel is surrounded by six oxygen atoms.

Figure 2
Edge-sharing [(Zn,Fe)1O₆] and [Zn2O₆] octahedra forming a kinked chain running parallel to [10 $[\overline{1}]$ ].

Figure 3
A layer perpendicular to (010), resulting from the connection of chains via the vertices of VO₄ tetrahedra and [ZnO₆] octahedra.

Figure 4
Polyhedral representation of Ag₂Zn₂Fe(VO₄)₃ showing the channels running parallel to the [001] direction.

The calculated bond-valences sums (Brown & Altermatt, 1985 ) of the atoms in the structure are in the expected ranges for Ag^I, Zn^II, Fe^III and V^V and are as follows (values in valence units): Ag1 (0.83), Ag2 (1.11), Zn1 (1.95), Zn2 (2.20), Fe1 (2.67), V1 (4.98) and V2 (4.93); values of oxygen atoms range between 1.90 and 2.01 valence units.

3. Database Survey

Over the last twenty years, many synthetic alluaudite-type phosphates, arsenates, sulfates and molybdates have been reported, such as NaMnFe₂(PO₄)₃ used as the positive electrode in sodium and lithium batteries (Trad et al., 2010 ; Kim et al., 2014 ; Huang et al., 2015 ), Na_2.44Mn_1.79(SO₄)₃ used as a potential high-voltage cathode material (ca 4.4 V) for sodium batteries (Dwibedi et al., 2015 ), K_0.13Na_3.87Mg(MoO₄)₃ as a promising compound for developing new materials with high ionic conductivity (Ennajeh et al., 2015 ), or NaZn₃(AsO₄)(AsO₃OH)₂ (Đorđević et al., 2015 ).

4. Synthesis and crystallization

Ag₂Zn₂Fe(VO₄)₃ was prepared by a solid-state reaction. A stoichiometric amount of silver nitrate (AgNO₃), zinc acetate (Zn(CH₃COO)₂·2H₂O), iron nitrate (Fe(NO₃)₃)·9H₂O) and vanadium oxide (V₂O₅) was employed in the molar ratio Ag: Zn:Fe:V = 2:2:1:3 and put into a platinum cruicible. After different heat treatments at lower temperatures to remove water and other voliatile gaseous products, the reaction mixture was melted at 1033 K for 30 minutes, followed by slow cooling with a 5 K h⁻¹ rate to room temperature. The resulting product contained parallelepipedic orange crystals corresponding to the studied title vanadate. In addition, small block-like crystals with poor quality and unidentified by X-ray powder diffraction were present.

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The remaining maximum and minimum electron density peaks in the final Fourier map are 0.40 Å away from Fe1 and 0.62 Å from Ag1, respectively. Due to charge neutrality, sites Zn1 and Fe2 were modelled as statistically occupied, assuming a trivalent oxidation state for the iron site.

Table 1
Experimental details

Crystal data
Chemical formula	Ag₂Zn₂Fe(VO₄)₃
M_r	747.15
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	296
a, b, c (Å)	11.8025 (2), 12.9133 (2), 6.8000 (1)
β (°)	110.759 (1)
V (Å³)	969.10 (3)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	13.09
Crystal size (mm)	0.31 × 0.26 × 0.20

Data collection
Diffractometer	Bruker X8 APEX
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.596, 0.748
No. of measured, independent and observed [I > 2σ(I)] reflections	30791, 2662, 2437
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.869

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.021, 0.048, 1.13
No. of reflections	2662
No. of parameters	95
Δρ_max, Δρ_min (e Å⁻³)	1.36, −2.41
Computer programs: APEX2 and SAINT (Bruker, 2014 ), SHELXT2014 (Sheldrick, 2015a ), SHELXL2014 (Sheldrick, 2015b ), ORTEP-3 for Windows (Farrugia, 2012 ), DIAMOND (Brandenburg, 2006 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1857879

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S205698901801071X/wm5454sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S205698901801071X/wm5454Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2014); data reduction: SAINT (Bruker, 2014); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: publCIF (Westrip, 2010).

Disilver(I) dizinc(II) iron(III) tris(orthovanadate) top

Crystal data top

Ag₂Zn₂Fe(VO₄)₃	F(000) = 1380
M_r = 747.15	D_x = 5.121 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.8025 (2) Å	Cell parameters from 2662 reflections
b = 12.9133 (2) Å	θ = 2.4–38.1°
c = 6.8000 (1) Å	µ = 13.09 mm⁻¹
β = 110.759 (1)°	T = 296 K
V = 969.10 (3) Å³	Parallelepiped, orange
Z = 4	0.31 × 0.26 × 0.20 mm

Data collection top

Bruker X8 APEX diffractometer	2662 independent reflections
Radiation source: fine-focus sealed tube	2437 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.042
φ and ω scans	θ_max = 38.1°, θ_min = 2.4°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −18→20
T_min = 0.596, T_max = 0.748	k = −22→22
30791 measured reflections	l = −11→9

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	w = 1/[σ²(F_o²) + (0.0126P)² + 4.2342P] where P = (F_o² + 2F_c²)/3
R[F² > 2σ(F²)] = 0.021	(Δ/σ)_max = 0.001
wR(F²) = 0.048	Δρ_max = 1.36 e Å⁻³
S = 1.13	Δρ_min = −2.41 e Å⁻³
2662 reflections	Extinction correction: SHELXL2016 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
95 parameters	Extinction coefficient: 0.00163 (6)

Special details top

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ag1	0.500000	0.49090 (3)	0.750000	0.02736 (7)
Ag2	0.500000	0.000000	0.500000	0.02115 (6)
Zn2	0.500000	0.23529 (2)	0.250000	0.00945 (6)
Zn1	0.29222 (2)	0.34062 (2)	0.38041 (3)	0.00652 (5)	0.5
Fe1	0.29222 (2)	0.34062 (2)	0.38041 (3)	0.00652 (5)	0.5
V1	0.27045 (3)	0.38683 (2)	0.88206 (4)	0.00612 (5)
V2	0.500000	0.20643 (3)	0.750000	0.00602 (6)
O1	0.12116 (12)	0.39616 (11)	0.8338 (2)	0.0128 (2)
O2	0.28524 (13)	0.31700 (11)	0.6746 (2)	0.0124 (2)
O3	0.33803 (14)	0.50767 (11)	0.8997 (2)	0.0139 (2)
O4	0.33926 (12)	0.32576 (11)	1.1233 (2)	0.0112 (2)
O5	0.46319 (12)	0.27705 (11)	0.5152 (2)	0.0099 (2)
O6	0.38484 (12)	0.12416 (10)	0.7343 (2)	0.0115 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ag1	0.01209 (9)	0.05204 (18)	0.01674 (11)	0.000	0.00362 (8)	0.000
Ag2	0.03519 (13)	0.01557 (9)	0.01224 (9)	−0.01110 (8)	0.00786 (9)	−0.00296 (7)
Zn2	0.00905 (11)	0.01104 (12)	0.00942 (12)	0.000	0.00472 (9)	0.000
Zn1	0.00607 (8)	0.00863 (9)	0.00535 (9)	0.00074 (6)	0.00264 (6)	0.00062 (6)
Fe1	0.00607 (8)	0.00863 (9)	0.00535 (9)	0.00074 (6)	0.00264 (6)	0.00062 (6)
V1	0.00655 (10)	0.00709 (10)	0.00474 (10)	0.00040 (8)	0.00202 (8)	0.00021 (8)
V2	0.00649 (14)	0.00644 (14)	0.00448 (14)	0.000	0.00112 (11)	0.000
O1	0.0095 (5)	0.0130 (5)	0.0160 (6)	0.0017 (4)	0.0045 (5)	0.0008 (5)
O2	0.0140 (6)	0.0155 (6)	0.0082 (5)	0.0017 (5)	0.0046 (4)	−0.0004 (4)
O3	0.0149 (6)	0.0116 (5)	0.0158 (6)	−0.0010 (4)	0.0061 (5)	0.0017 (5)
O4	0.0123 (5)	0.0133 (5)	0.0078 (5)	0.0037 (4)	0.0034 (4)	0.0019 (4)
O5	0.0090 (5)	0.0135 (5)	0.0075 (5)	0.0019 (4)	0.0035 (4)	0.0027 (4)
O6	0.0087 (5)	0.0103 (5)	0.0136 (6)	−0.0007 (4)	0.0019 (4)	0.0016 (4)

Geometric parameters (Å, º) top

Ag1—O3ⁱ	2.4699 (15)	Zn2—O1^v	2.1619 (15)
Ag1—O3ⁱⁱ	2.4699 (16)	Zn1—O6^viii	2.0068 (14)
Ag1—O3ⁱⁱⁱ	2.4734 (16)	Zn1—O4^x	2.0222 (14)
Ag1—O3	2.4734 (16)	Zn1—O3ⁱ	2.0241 (15)
Ag2—O6^iv	2.4374 (14)	Zn1—O2	2.0540 (14)
Ag2—O6ⁱⁱⁱ	2.4374 (14)	Zn1—O5	2.0675 (13)
Ag2—O1^v	2.5032 (15)	Zn1—O2^viii	2.2082 (15)
Ag2—O1^vi	2.5032 (15)	V1—O1	1.6784 (14)
Ag2—O1^vii	2.5873 (14)	V1—O2	1.7343 (14)
Ag2—O1^viii	2.5873 (14)	V1—O3	1.7372 (15)
Zn2—O5^ix	2.0704 (14)	V1—O4	1.7402 (13)
Zn2—O5	2.0705 (14)	V2—O6	1.6984 (14)
Zn2—O4ⁱⁱⁱ	2.1325 (13)	V2—O6ⁱⁱⁱ	1.6984 (14)
Zn2—O4^x	2.1325 (13)	V2—O5ⁱⁱⁱ	1.7544 (13)
Zn2—O1^viii	2.1619 (15)	V2—O5	1.7544 (13)

O3ⁱ—Ag1—O3ⁱⁱ	179.15 (7)	O5—Zn2—O1^v	107.36 (5)
O3ⁱ—Ag1—O3ⁱⁱⁱ	92.83 (5)	O4ⁱⁱⁱ—Zn2—O1^v	85.01 (5)
O3ⁱⁱ—Ag1—O3ⁱⁱⁱ	87.10 (5)	O4^x—Zn2—O1^v	161.31 (5)
O3ⁱ—Ag1—O3	87.10 (5)	O1^viii—Zn2—O1^v	76.52 (7)
O3ⁱⁱ—Ag1—O3	92.83 (5)	O6^viii—Zn1—O4^x	104.63 (6)
O3ⁱⁱⁱ—Ag1—O3	169.95 (7)	O6^viii—Zn1—O3ⁱ	91.33 (6)
O6^iv—Ag2—O6ⁱⁱⁱ	180.00 (6)	O4^x—Zn1—O3ⁱ	89.94 (6)
O6^iv—Ag2—O1^v	105.99 (5)	O6^viii—Zn1—O2	90.95 (6)
O6ⁱⁱⁱ—Ag2—O1^v	74.01 (5)	O4^x—Zn1—O2	161.09 (6)
O6^iv—Ag2—O1^vi	74.01 (5)	O3ⁱ—Zn1—O2	100.52 (6)
O6ⁱⁱⁱ—Ag2—O1^vi	105.99 (5)	O6^viii—Zn1—O5	168.70 (6)
O1^v—Ag2—O1^vi	180.00 (6)	O4^x—Zn1—O5	79.73 (5)
O6^iv—Ag2—O1^vii	107.39 (5)	O3ⁱ—Zn1—O5	99.16 (6)
O6ⁱⁱⁱ—Ag2—O1^vii	72.61 (5)	O2—Zn1—O5	83.05 (5)
O1^v—Ag2—O1^vii	116.56 (6)	O6^viii—Zn1—O2^viii	80.30 (5)
O1^vi—Ag2—O1^vii	63.44 (6)	O4^x—Zn1—O2^viii	89.43 (5)
O6^iv—Ag2—O1^viii	72.61 (5)	O3ⁱ—Zn1—O2^viii	171.16 (6)
O6ⁱⁱⁱ—Ag2—O1^viii	107.39 (5)	O2—Zn1—O2^viii	82.59 (6)
O1^v—Ag2—O1^viii	63.44 (6)	O5—Zn1—O2^viii	89.40 (5)
O1^vi—Ag2—O1^viii	116.56 (6)	O1—V1—O2	106.24 (7)
O1^vii—Ag2—O1^viii	180.0	O1—V1—O3	111.93 (7)
O5^ix—Zn2—O5	149.81 (8)	O2—V1—O3	110.32 (7)
O5^ix—Zn2—O4ⁱⁱⁱ	77.17 (5)	O1—V1—O4	108.88 (7)
O5—Zn2—O4ⁱⁱⁱ	86.37 (5)	O2—V1—O4	112.54 (7)
O5^ix—Zn2—O4^x	86.37 (5)	O3—V1—O4	107.01 (7)
O5—Zn2—O4^x	77.17 (5)	O6—V2—O6ⁱⁱⁱ	102.56 (10)
O4ⁱⁱⁱ—Zn2—O4^x	113.56 (8)	O6—V2—O5ⁱⁱⁱ	108.46 (7)
O5^ix—Zn2—O1^viii	107.36 (5)	O6ⁱⁱⁱ—V2—O5ⁱⁱⁱ	109.48 (6)
O5—Zn2—O1^viii	96.35 (6)	O6—V2—O5	109.48 (6)
O4ⁱⁱⁱ—Zn2—O1^viii	161.31 (5)	O6ⁱⁱⁱ—V2—O5	108.47 (7)
O4^x—Zn2—O1^viii	85.01 (5)	O5ⁱⁱⁱ—V2—O5	117.36 (9)
O5^ix—Zn2—O1^v	96.35 (6)

Symmetry codes: (i) x, −y+1, z−1/2; (ii) −x+1, −y+1, −z+2; (iii) −x+1, y, −z+3/2; (iv) x, −y, z−1/2; (v) x+1/2, −y+1/2, z−1/2; (vi) −x+1/2, y−1/2, −z+3/2; (vii) x+1/2, y−1/2, z; (viii) −x+1/2, −y+1/2, −z+1; (ix) −x+1, y, −z+1/2; (x) x, y, z−1.

Acknowledgements

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

Funding information

The authors thank Mohammed V University, Rabat, Morocco, for financial support.

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