Ag_1.49Mn_1.49^IIMn_1.51^III(AsO₄)₃

The compound Ag_1.49Mn_1.49^IIMn_1.51^III(AsO₄)₃ (silver mangan­ese arsenate) was prepared by a solid-state reaction. It crystallizes in the monoclinic system in space group C2/c. The three-dimensional network is built up from MnO₆ octahedra, sharing edges which are linked together by the arsenate groups (AsO₄). This arrangement delimits two types of hexagonal tunnels which accommodate Ag⁺ cations. The compound is isostructural with the compounds X(1)X(2)M(1)M(2)₂(PO₄)₃ of the alluaudite structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](Mn-O) = 0.009 Å
• R factor = 0.052
• wR factor = 0.156
• Data-to-parameter ratio = 11.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level A:



ABSTM_02  Alert A Crystal and compound unsuitable for non-numerical
          corrections. Product of mu and tmid > 3.0
           Value of mu given =    16.919 tmid =     0.200


 1 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 0 Alert Level C = Please check

---

S1. Comment

Ag_1.49Mn^II_1.49Mn^III_1.51(AsO₄)₃ crystallize in the monoclinic space group C2/c and is isostructural with the compounds X(1)X(2)M(1)M(2)₂(PO₄)₃ (Moore, 1971;Yakubovitch et al., 1977) of the alluaudite structure type. The framework of Ag_1.49Mn^II_1.49Mn^III_1.51(AsO₄)₃ consists of infinite chains of MnO₆ octahedra, sharing skew edge, running parallel to the [010] direction and having an Mn1–Mn2–Mn2 sequence. A projection of the structure, showing the displacement ellipsoids, is presented in Fig. 1.

In each chain, repetition of the Mn1O₆ and Mn2O₆ octahedra are ensured by c-glide and inversion centers, respectively. Atoms As2, Mn1 and Ag1 have twofold symmetry, Ag2 are on inversion centers and all other atoms are in general positions. The infinite chains are linked by As1O₄ and As2O₄ tetrahedra to form sheets parallel to (010). The As2O₄ tetrahedra share all four of their vertices with the MnO₆ octahedra two with one chain and two with an adjacent chain. The As1O₄ tetrahedron shares its four oxygen summits with four different MnO₆ octahedra belonging to three chains, two from the same chain and the two from two different chains (Fig. 2). The MnO₆ octahedra appear to be highly distorted, especially around Mn1, in which the angle subtended by two of the trans O atoms is 143.9 (2)°. This distortion probably occurs as a result of the need to accommodate to the connectivity of the AsO₄ tetrahedra, which are rather rigid entities and are responsible for holding adjacent chains together. This framework defines large tunnels running along the c direction. one tunnel along (0,0,z) and the other along (0, 1/2,z) (Fig. 3). The silver cations Ag1⁺ and Ag2⁺ partially occupy these sites in those tunnels. They exhibit two sort of coordination, Ag1⁺ [site-occupation factor = 0.870 (7)], located in the second type of tunnel, has a square-planar environment, similar to the situation observed in AgCo₃PO₄(HPO₄)₂(Guesmi & Driss, 2002) and Ag2⁺ [site-occupation factor = 0.620 (7)], located in the first type, is linked to six O atoms. For electroneutrality, it is supposed that Mn2 has the oxidation state 2.69, as indicated by the bond-valence sum (Brown & Altermatt, 1985) and based on parameters for Mn²⁺—O, then the total charge contributed by Mn1 and Mn2 is 1 × 2 + 2 × 2.69 = 7.38, which leaves a charge of 1.62 to be provided by the two tunnel sites, quite close to the vale of 1.49 provided by the X-ray refinement.

S2. Experimental

Single crystals of Ag_1.49Mn^II_1.49Mn^III_1.51(AsO₄)₃ were prepared by a conventional solid-state reaction. NH₄H₂AsO₄, MnO and AgNO₃ in the (1:2:3) ratio were ground together under acetone in an agate mortar. The mixture was heated in porcelain crucible at 673 K for 4 h, cooled to room temperature, reground, and heated at 1073 K for 24 h, then cooled slowly to room temperature at a rate of 5 K h⁻¹. The product was washed with hot water. Brown parallelepiped-shaped crystals of the title compound were extracted. Their qualitative analysis by electron microscope probe revealed them to contain Ag, As and Mn atoms.

S3. Refinement

The occupations of the Ag1 and Ag2 sites are 0.870 (7) and 0.620 (7), respectively.

Computing details

Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS86 (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

	Fig. 1. A projection of the structure, showing displacement ellipsoids at the XX% probability level. [Please complete]
	Fig. 2. View showing the association mode between AsO4 tetrahedra (purple) and MnO6 octahedra (cyan).
	Fig. 3. Projection of the structure of Ag1.49Mn^II1.49Mn^III1.51(AsO4)3 along the [001] direction. In this presentation, the corners of the octahedra and tetrahedra are O atoms and the Mn and As atoms are at the center of each octahedron and tetrahedron, respectively. Small solid circles are Ag atoms.

(I)

Crystal data

Ag1.49Mn3(AsO4)3	F(000) = 1360
Mr = 742.29	Dx = 5.062 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 25 reflections
a = 12.262 (2) Å	θ = 10.8–13.8°
b = 12.934 (3) Å	µ = 16.92 mm^−1
c = 6.707 (1) Å	T = 293 K
β = 113.690 (2)°	Parallelepiped, brown
V = 974.1 (3) Å^3	0.44 × 0.2 × 0.03 mm
Z = 4

Data collection

Enraf-Nonius CAD-4 diffractometer	829 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.071
Graphite monochromator	θmax = 27.0°, θmin = 2.4°
ω/2θ scans	h = 0→15
Absorption correction: ψ scan (North et al., 1968)	k = 0→16
Tmin = 0.178, Tmax = 0.309	l = −8→7
1112 measured reflections	2 standard reflections every 120 min
1067 independent reflections	intensity decay: 0.4%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.052	w = 1/[σ^2(Fo^2) + (0.0825P)^2 + 48.2737P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.156	(Δ/σ)max < 0.001
S = 1.07	Δρmax = 2.61 e Å^−3
1067 reflections	Δρmin = −2.08 e Å^−3
97 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0015 (3)

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
As1	0.26356 (10)	0.38996 (9)	0.37013 (17)	0.0145 (4)
As2	0.5000	0.21390 (12)	0.2500	0.0144 (4)
Mn1	0.5000	0.23492 (19)	−0.2500	0.0160 (6)
Mn2	0.22059 (19)	0.15521 (17)	0.1344 (3)	0.0271 (5)
Ag1	0.5000	0.51173 (14)	0.7500	0.0295 (6)	0.870 (7)
Ag2	0.5000	0.0000	0.0000	0.0299 (9)	0.620 (7)
O1	0.1175 (8)	0.4045 (7)	0.3085 (17)	0.031 (2)
O2	0.4559 (7)	0.2882 (6)	0.0243 (12)	0.0191 (17)
O3	0.3344 (8)	0.5053 (7)	0.3906 (15)	0.026 (2)
O4	0.3351 (7)	0.3302 (7)	0.6127 (12)	0.0206 (18)
O5	0.2788 (8)	0.3175 (8)	0.1736 (15)	0.028 (2)
O6	0.3979 (10)	0.1304 (8)	0.2629 (16)	0.039 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
As1	0.0123 (6)	0.0174 (6)	0.0121 (6)	−0.0016 (4)	0.0031 (4)	0.0051 (4)
As2	0.0238 (9)	0.0082 (8)	0.0084 (7)	0.000	0.0035 (6)	0.000
Mn1	0.0167 (12)	0.0115 (11)	0.0225 (13)	0.000	0.0106 (10)	0.000
Mn2	0.0285 (11)	0.0301 (12)	0.0220 (10)	−0.0067 (8)	0.0095 (9)	0.0012 (8)
Ag1	0.0211 (9)	0.0406 (11)	0.0244 (9)	0.000	0.0065 (7)	0.000
Ag2	0.0458 (16)	0.0151 (12)	0.0175 (12)	−0.0011 (9)	0.0010 (10)	−0.0004 (8)
O1	0.013 (4)	0.025 (5)	0.051 (6)	0.002 (4)	0.009 (4)	0.014 (4)
O2	0.020 (4)	0.022 (4)	0.011 (4)	−0.006 (3)	0.002 (3)	0.008 (3)
O3	0.025 (5)	0.027 (5)	0.027 (5)	−0.007 (4)	0.011 (4)	0.007 (4)
O4	0.026 (5)	0.022 (4)	0.010 (4)	0.008 (4)	0.004 (3)	0.006 (3)
O5	0.028 (5)	0.038 (5)	0.019 (4)	−0.007 (4)	0.010 (4)	0.001 (4)
O6	0.050 (7)	0.026 (5)	0.032 (5)	−0.015 (5)	0.007 (5)	0.015 (4)

Geometric parameters (Å, º)

As1—O1	1.680 (9)	Mn2—O3^vi	2.038 (9)
As1—O5	1.688 (9)	Mn2—O4^vii	2.076 (8)
As1—O4	1.693 (8)	Mn2—O5^iv	2.098 (9)
As1—O3	1.703 (9)	Mn2—O2^iv	2.121 (9)
As2—O6	1.682 (10)	Mn2—O5	2.198 (10)
As2—O6^i	1.682 (10)	Ag1—O3^viii	2.451 (9)
As2—O2^i	1.688 (7)	Ag1—O3	2.451 (9)
As2—O2	1.688 (7)	Ag1—O3^ix	2.569 (9)
Mn1—O2^ii	2.226 (9)	Ag1—O3^x	2.569 (9)
Mn1—O2	2.226 (9)	Ag2—O6^i	2.311 (10)
Mn1—O4^i	2.227 (8)	Ag2—O6^xi	2.311 (10)
Mn1—O4^iii	2.227 (8)	Ag2—O1^xii	2.342 (9)
Mn1—O1^iv	2.242 (9)	Ag2—O1^iv	2.342 (9)
Mn1—O1^v	2.242 (9)	Ag2—O1^v	2.595 (10)
Mn2—O6	2.016 (12)	Ag2—O1^vi	2.595 (10)
O1—As1—O5	108.2 (5)	O4^vii—Mn2—O5^iv	157.1 (4)
O1—As1—O4	112.1 (5)	O6—Mn2—O2^iv	167.5 (3)
O5—As1—O4	108.6 (4)	O3^vi—Mn2—O2^iv	92.9 (3)
O1—As1—O3	112.4 (5)	O4^vii—Mn2—O2^iv	77.0 (3)
O5—As1—O3	109.6 (4)	O5^iv—Mn2—O2^iv	81.6 (3)
O4—As1—O3	105.8 (4)	O6—Mn2—O5	81.8 (4)
O6—As2—O6^i	100.1 (8)	O3^vi—Mn2—O5	177.7 (4)
O6—As2—O2^i	107.2 (5)	O4^vii—Mn2—O5	90.7 (3)
O6^i—As2—O2^i	115.7 (4)	O5^iv—Mn2—O5	80.1 (4)
O6—As2—O2	115.7 (4)	O2^iv—Mn2—O5	87.0 (3)
O6^i—As2—O2	107.2 (5)	O3^viii—Ag1—O3	176.1 (4)
O2^i—As2—O2	110.6 (6)	O3^viii—Ag1—O3^ix	83.9 (3)
O2^ii—Mn1—O2	143.9 (4)	O3—Ag1—O3^ix	95.8 (3)
O2^ii—Mn1—O4^i	71.9 (3)	O3^viii—Ag1—O3^x	95.8 (3)
O2—Mn1—O4^i	88.2 (3)	O3—Ag1—O3^x	83.9 (3)
O2^ii—Mn1—O4^iii	88.2 (3)	O3^ix—Ag1—O3^x	170.2 (4)
O2—Mn1—O4^iii	71.9 (3)	O6^i—Ag2—O6^xi	180.0 (5)
O4^i—Mn1—O4^iii	112.8 (5)	O6^i—Ag2—O1^xii	78.8 (4)
O2^ii—Mn1—O1^iv	117.2 (4)	O6^xi—Ag2—O1^xii	101.2 (4)
O2—Mn1—O1^iv	92.4 (3)	O6^i—Ag2—O1^iv	101.2 (4)
O4^i—Mn1—O1^iv	158.5 (3)	O6^xi—Ag2—O1^iv	78.8 (4)
O4^iii—Mn1—O1^iv	87.7 (3)	O1^xii—Ag2—O1^iv	180.0 (4)
O2^ii—Mn1—O1^v	92.4 (3)	O6^i—Ag2—O1^v	74.8 (4)
O2—Mn1—O1^v	117.2 (4)	O6^xi—Ag2—O1^v	105.2 (4)
O4^i—Mn1—O1^v	87.7 (3)	O1^xii—Ag2—O1^v	114.9 (4)
O4^iii—Mn1—O1^v	158.5 (3)	O1^iv—Ag2—O1^v	65.1 (4)
O1^iv—Mn1—O1^v	72.9 (5)	O6^i—Ag2—O1^vi	105.2 (4)
O6—Mn2—O3^vi	98.5 (4)	O6^xi—Ag2—O1^vi	74.8 (4)
O6—Mn2—O4^vii	108.5 (4)	O1^xii—Ag2—O1^vi	65.1 (4)
O3^vi—Mn2—O4^vii	87.0 (4)	O1^iv—Ag2—O1^vi	114.9 (4)
O6—Mn2—O5^iv	91.0 (4)	O1^v—Ag2—O1^vi	180.0 (3)
O3^vi—Mn2—O5^iv	102.2 (4)

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