β-K3Fe(MoO4)2Mo2O7

Souilem, A.; Zid, M.F.; Driss, A.

doi:10.1107/S1600536814013087

inorganic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 70| Part 7| July 2014| Page i38

https://doi.org/10.1107/S1600536814013087

Open

access

β-K₃Fe(MoO₄)₂Mo₂O₇

Amira Souilem,^a ^* Mohamed Faouzi Zid ^a and Ahmed Driss ^a

^aLaboratoire de Matériaux et Cristallochimie, Faculté des Sciences de Tunis, Université de Tunis ElManar, 2092 Manar II Tunis, Tunisia
^*Correspondence e-mail: souilem_amira@yahoo.fr

(Received 9 May 2014; accepted 5 June 2014; online 11 June 2014)

The title compound, tripotassium iron(III) bis(orthomolybdate) dimolybdate, was obtained by a solid-state reaction. The main structural building units are one FeO₆ octahedron, two MoO₄ tetrahedra and one Mo₂O₇ dimolybdate group, all with point group symmetries m. These units are linked via corner-sharing to form ribbons parallel to [010]. The three K⁺ cations are located between the ribbons on mirror planes and have coordination numbers of 10 and 12. Two O atoms of one of the MoO₄ tetrahedra of the dimolybdate group are disordered over two positions in a 0.524 (11):0.476 (11) ratio. The structure of the title compound is compared briefly with that of Rb₃FeMo₄O₁₅.

CCDC reference: 1006924

Related literature

For properties of related molybdates, see: Zhang et al. (2000 ); Muessig et al. (2003 ); Bramnik et al. (2003 ); Soares & Portela (2005 ); Bowker et al. (2008 ); Otko et al. (1978 ); Klimin et al. (2003 ); Jorge et al. (2004 ); Maczka et al. (2005 ). The closely related crystal structures of α-K₃Fe(MoO₄)₂(Mo₂O₇) and Rb₃Fe(MoO₄)₂Mo₂O₇ were determined by Maczka et al. (2009 ) and Khal'baeva et al. (2010 ), respectively. For bond-valence sums, see: Brown & Altermatt (1985 ).

Experimental

Crystal data

K₃Fe(MoO₄)₂Mo₂O₇
M_r = 796.91
Monoclinic, C 2/m
a = 32.873 (2) Å
b = 5.7137 (7) Å
c = 7.9177 (9) Å
β = 91.143 (8)°
V = 1486.9 (3) Å³
Z = 4
Mo Kα radiation
μ = 5.15 mm⁻¹
T = 298 K
0.36 × 0.22 × 0.18 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ) T_min = 0.286, T_max = 0.488
3443 measured reflections
1789 independent reflections
1636 reflections with I > 2σ(I)
R_int = 0.028
2 standard reflections every 120 min intensity decay: 1.3%

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.076
S = 1.06
1789 reflections
138 parameters
Δρ_max = 1.22 e Å⁻³
Δρ_min = −1.57 e Å⁻³

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, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 1999 ); software used to prepare material for publication: WinGX (Farrugia, 2012 ).

Supporting information

CCDC reference: 1006924

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S1600536814013087/wm5025sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536814013087/wm5025Isup2.hkl

checkCIF report

Comment top

L'étude des composés appartenant à la grande famille des molybdates de fer, métaux alcalins et pseudo-alcalins qui possèdent des propriétés structurelles, catalytiques, magnétiques et ferroélastiques intéressantes (Zhang et al., 2000; Muessig et al., 2003; Bramnik et al., 2003; Soares & Portela, 2005; Bowker et al., 2008; Otko et al., 1978; Maczka et al., 2005; Klimin et al., 2003; Jorge et al., 2004) nous a encouragés à explorer les systèmes molybdates de fer à cations monovalents. Une étude bibliographique a été effectuée sur la famille de composés de formulation AFe(III)Mo₄O₁₅ où A est un cation monovalent: α-K₃Fe(MoO₄)₂(Mo₂O₇) (Maczka et al., 2009), Rb₃FeMo₄O₁₅ (Khal'baeva et al., 2010). En effet, le présent travail porte sur l'étude structurale d'un molybdate de formulation β-K₃Fe(MoO₄)₂(Mo₂O₇) obtenu par voie sèche.

La structure de K₃Fe(MoO₄)₂(Mo₂O₇) (forme-β) est de formule analogue à une autre phase déjà connue: K₃Fe(MoO₄)₂(Mo₂O₇) (forme-α; Maczka et al., 2009). Elles pésentent la même symétrie monoclinique.

La nouvelle variété β-K₃Fe(MoO₄)₂(Mo₂O₇) est formée d'un octaèdre FeO₆, de deux tétraèdres MoO₄ et d'un groupement dimolybdate Mo₂O₇ (Fig. 1). Deux unités formulaires centrosymétriques se regroupent par partage de sommets donnant lieu à un dimère de formulation (FeO₆)₂(Mo₄)₄(Mo₂O₇)₂ (Fig. 2a). Ces derniers se connectent moyennant des ponts mixtes de type Mo–O–Fe pour donner des rubans disposés selon [010] (Fig. 2b). Il en résulte une charpente unidimensionnelle possédant des espaces inter-rubans où résident les cations monovalents K⁺ (Figs. 3 et 4).

L'examen des facteurs géométriques dans la structure montre qu'ils sont en bon accord avec ceux rencontrés dans la littérature (Maczka et al., 2009; Khal'baeva et al., 2010).

D'autre part, le calcul des valences de liaisons (BVS), utilisant la formule empirique de Brown (Brown & Altermatt, 1985), conduit aux valeurs des charges des cations suivants: Fe1 (3,03), Mo1 (6,03), Mo2 (6,13), Mo3 (5,94), Mo4 (6,03), K1 (0,61), K2 (0,71) et K3 (0,59).

Une comparaison de la structure du composé étudié β-K₃Fe(MoO₄)₂(Mo₂O₇) avec celle de Rb₃Fe(MoO₄)₂Mo₂O₇ (Khal'baeva et al., 2010) montre une différence nette dans la disposition des polyèdres et en particulier des groupements dimolybdates Mo₂O₇ dans la charpente anionique (Fig. 5).

En effet, on remarque que pour le composé au rubidium, cette disposition selon la direction des rubans, permet à chaque groupement dimolybdate Mo₂O₇ de relier par partage de sommets deux octaèdres FeO₆ différents appartenant au même ruban (Fig. 6a). Par contre dans le composé étudié chaque octaèdre FeO₆ partage un sommet avec un seul groupement dimolybdate Mo₂O₇, les cinq autres sommets sont mis en commun avec respectivement cinq tétraèdres MoO₄ différents (Fig. 6b). Nous pouvant signaler que le second tétraèdre terminal du groupement Mo₂O₇ présente un atome d'oxygène délocalisé sur deux positions proches O11 et O12 donnant une forme pyramidale au tétraèdre (Fig. 6b).

Related literature top

For properties of related molybdates, see: Zhang et al. (2000); Muessig et al. (2003); Bramnik et al. (2003); Soares & Portela (2005); Bowker et al. (2008); Otko et al. (1978); Klimin et al. (2003); Jorge et al. (2004); Maczka et al. (2005). The closely related crystal structures of α-K₃Fe(MoO₄)₂(Mo₂O₇) and Rb₃Fe(MoO₄)₂Mo₂O₇ were determined by Maczka et al. (2009) and Khal'baeva et al. (2010), respectively. For bond-valence sums, see: Brown & Altermatt (1985).

Experimental top

La synthèse de K₃FeMo₄O₁₅ a été effectuée par réaction à l'état solide, à partir de carbonate de potassium (Prolabo, 60109), de nitrate de fer (Fluka 44949) et de molybdate d'ammonium (Fluka, 69858) dans un rapport molaire K:Fe:Mo égal à 3:1:6 respectivement. Après un broyage poussé dans un mortier en agate, le mélange est placé dans un creuset en porcelaine, puis porté dans un premier temps à une température de 673 K pendant 4 heures, en vue d'éliminer les produits volatils. Un second traitement thermique a été effectué à la température de synthèse, 1126 K pendant 24 heures. Le résidu final est ensuite ramené à un refroidissement lent de 5 K/12 h jusqu'à 1043 K, suivi d'un autre plus rapide (50 K/24 h) jusqu'à la température ambiante. Des cristaux de couleur verdâtre sont séparés à l'eau chaude.

Structure description top

L'examen des facteurs géométriques dans la structure montre qu'ils sont en bon accord avec ceux rencontrés dans la littérature (Maczka et al., 2009; Khal'baeva et al., 2010).

For properties of related molybdates, see: Zhang et al. (2000); Muessig et al. (2003); Bramnik et al. (2003); Soares & Portela (2005); Bowker et al. (2008); Otko et al. (1978); Klimin et al. (2003); Jorge et al. (2004); Maczka et al. (2005). The closely related crystal structures of α-K₃Fe(MoO₄)₂(Mo₂O₇) and Rb₃Fe(MoO₄)₂Mo₂O₇ were determined by Maczka et al. (2009) and Khal'baeva et al. (2010), respectively. For bond-valence sums, see: Brown & Altermatt (1985).

Computing details top

Data collection: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); cell refinement: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 1999); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top

	Fig. 1. La structure de β-K₃Fe(MoO₄)₂Mo₂O₇. Les éllipsoïdes ont été définis avec 50% de probabilité. [Symmetry codes: (i) x, -y+1, z; (ii) x, y, z-1; (iii) x, -y, z; (iv) x, y-1, z; (v) x, -y+1, z-1 ; (vi) -x+3/2, -y+1/2, -z].
	Fig. 2. (a): Nouvelle unité centrosymétrique. (b): Vue, selon [010], d'un ruban dans β-K₃Fe(MoO₄)₂Mo₂O₇,
	Fig. 3. Projection de la structure de β-K₃Fe(MoO₄)₂Mo₂O₇, selon b, montrant les espaces inter-rubans où résident les cations.
	Fig. 4. Projection de la structure de β-K₃Fe(MoO₄)₂Mo₂O₇, selon c.
	Fig. 5. Projection de la structure de Rb₃Fe(MoO₄)₂Mo₂O₇ selon c.
	Fig. 6. Représentation des rubans mettant en évidence les environnements des octaèdres FeO₆ (a): Dans Rb₃Fe(MoO₄)₂Mo₂O₇; (b): Dans β-K₃Fe(MoO₄)₂Mo₂O₇.

Tripotassium iron(III) bis(orthomolybdate) dimolybdate top

Crystal data top

K₃Fe(MoO₄)₂Mo₂O₇	F(000) = 1484
M_r = 796.91	D_x = 3.560 Mg m⁻³
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 25 reflections
a = 32.873 (2) Å	θ = 11–15°
b = 5.7137 (7) Å	µ = 5.15 mm⁻¹
c = 7.9177 (9) Å	T = 298 K
β = 91.143 (8)°	Prism, green
V = 1486.9 (3) Å³	0.36 × 0.22 × 0.18 mm
Z = 4

Data collection top

Enraf–Nonius CAD-4 diffractometer	1636 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.028
Graphite monochromator	θ_max = 27.0°, θ_min = 2.5°
ω/2θ scans	h = −41→41
Absorption correction: ψ scan (North et al., 1968)	k = −1→7
T_min = 0.286, T_max = 0.488	l = −10→5
3443 measured reflections	2 standard reflections every 120 min
1789 independent reflections	intensity decay: 1.3%

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.029	w = 1/[σ²(F_o²) + (0.0306P)² + 20.6944P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.076	(Δ/σ)_max = 0.001
S = 1.06	Δρ_max = 1.22 e Å⁻³
1789 reflections	Δρ_min = −1.57 e Å⁻³
138 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.00379 (16)

Crystal data top

K₃Fe(MoO₄)₂Mo₂O₇	V = 1486.9 (3) Å³
M_r = 796.91	Z = 4
Monoclinic, C2/m	Mo Kα radiation
a = 32.873 (2) Å	µ = 5.15 mm⁻¹
b = 5.7137 (7) Å	T = 298 K
c = 7.9177 (9) Å	0.36 × 0.22 × 0.18 mm
β = 91.143 (8)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	1636 reflections with I > 2σ(I)
Absorption correction: ψ scan (North et al., 1968)	R_int = 0.028
T_min = 0.286, T_max = 0.488	2 standard reflections every 120 min
3443 measured reflections	intensity decay: 1.3%
1789 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	0 restraints
wR(F²) = 0.076	w = 1/[σ²(F_o²) + (0.0306P)² + 20.6944P] where P = (F_o² + 2F_c²)/3
S = 1.06	Δρ_max = 1.22 e Å⁻³
1789 reflections	Δρ_min = −1.57 e Å⁻³
138 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.

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

	x	y	z	U_iso*/U_eq	Occ. (<1)
Mo1	0.568576 (15)	0.5000	−0.03610 (7)	0.01354 (16)
Mo2	0.649834 (16)	0.0000	0.73776 (7)	0.01577 (16)
Mo3	0.718491 (15)	0.0000	0.18432 (7)	0.01355 (16)
Mo4	0.55700 (2)	0.5000	0.49609 (8)	0.0375 (2)
Fe1	0.68040 (3)	0.5000	−0.01846 (11)	0.0118 (2)
K1	0.51309 (5)	0.0000	0.7616 (2)	0.0253 (3)
K2	0.60638 (5)	0.0000	0.2307 (2)	0.0340 (4)
K3	0.68689 (5)	0.5000	0.4756 (2)	0.0361 (5)
O1	0.62085 (14)	0.5000	0.0211 (7)	0.0257 (11)
O2	0.73729 (17)	0.0000	0.3855 (7)	0.0373 (15)
O3	0.54601 (11)	0.7403 (7)	0.0504 (5)	0.0277 (8)
O4	0.68711 (12)	0.7469 (9)	0.1610 (6)	0.0459 (13)
O5	0.60430 (19)	0.5000	0.4216 (9)	0.053 (2)
O6	0.75919 (14)	0.0000	0.0434 (6)	0.0223 (11)
O7	0.67523 (14)	0.2575 (11)	0.8080 (7)	0.0669 (19)
O8	0.55792 (18)	0.5000	0.7337 (6)	0.0329 (13)
O9	0.64948 (18)	0.0000	0.5221 (7)	0.0346 (14)
O10	0.60110 (17)	0.0000	0.8120 (8)	0.0396 (15)
O11	0.5491 (2)	0.1696 (14)	0.4498 (9)	0.031 (2)	0.524 (11)
O12	0.5224 (3)	0.3608 (15)	0.3916 (10)	0.034 (3)	0.476 (11)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Mo1	0.0084 (3)	0.0180 (3)	0.0142 (3)	0.000	−0.00063 (19)	0.000
Mo2	0.0111 (3)	0.0210 (3)	0.0151 (3)	0.000	−0.00068 (19)	0.000
Mo3	0.0080 (2)	0.0163 (3)	0.0164 (3)	0.000	−0.00035 (19)	0.000
Mo4	0.0169 (3)	0.0820 (6)	0.0137 (3)	0.000	0.0003 (2)	0.000
Fe1	0.0092 (4)	0.0101 (4)	0.0160 (4)	0.000	−0.0006 (3)	0.000
K1	0.0184 (7)	0.0324 (9)	0.0250 (8)	0.000	−0.0022 (6)	0.000
K2	0.0195 (7)	0.0563 (12)	0.0260 (8)	0.000	−0.0046 (6)	0.000
K3	0.0226 (8)	0.0665 (14)	0.0191 (8)	0.000	−0.0004 (6)	0.000
O1	0.010 (2)	0.042 (3)	0.025 (3)	0.000	−0.0025 (19)	0.000
O2	0.023 (3)	0.065 (4)	0.023 (3)	0.000	−0.008 (2)	0.000
O3	0.0224 (17)	0.0242 (18)	0.037 (2)	0.0016 (16)	0.0069 (15)	−0.0049 (17)
O4	0.031 (2)	0.051 (3)	0.058 (3)	−0.029 (2)	0.0281 (19)	−0.040 (2)
O5	0.027 (3)	0.085 (6)	0.048 (4)	0.000	0.011 (3)	0.000
O6	0.009 (2)	0.032 (3)	0.026 (3)	0.000	0.0045 (18)	0.000
O7	0.038 (2)	0.087 (4)	0.077 (4)	−0.036 (3)	0.026 (2)	−0.068 (3)
O8	0.035 (3)	0.048 (4)	0.015 (2)	0.000	−0.006 (2)	0.000
O9	0.033 (3)	0.056 (4)	0.015 (2)	0.000	−0.004 (2)	0.000
O10	0.018 (3)	0.056 (4)	0.045 (4)	0.000	0.005 (2)	0.000
O11	0.031 (4)	0.036 (4)	0.025 (4)	0.005 (3)	0.002 (3)	−0.002 (3)
O12	0.036 (5)	0.033 (5)	0.031 (4)	−0.017 (4)	−0.003 (3)	−0.015 (4)

Geometric parameters (Å, º) top

Mo1—O3	1.710 (4)	K1—O3^x	2.882 (4)
Mo1—O3ⁱ	1.710 (4)	K1—O10	2.913 (6)
Mo1—O1	1.768 (5)	K1—O3^xi	2.916 (4)
Mo1—O8ⁱⁱ	1.849 (5)	K1—O3^xii	2.916 (4)
Mo2—O9	1.708 (5)	K1—O11ⁱⁱⁱ	2.924 (7)
Mo2—O10	1.717 (6)	K1—O11	2.924 (7)
Mo2—O7	1.776 (5)	K1—O8^iv	3.224 (3)
Mo2—O7ⁱⁱⁱ	1.776 (5)	K2—O9	2.683 (6)
Mo3—O2	1.697 (5)	K2—O11	2.762 (7)
Mo3—O6	1.759 (5)	K2—O11ⁱⁱⁱ	2.762 (7)
Mo3—O4^iv	1.784 (4)	K2—O3^iv	2.841 (4)
Mo3—O4ⁱ	1.784 (4)	K2—O3ⁱ	2.841 (4)
Mo4—O12	1.605 (7)	K2—O4ⁱ	3.082 (5)
Mo4—O12ⁱ	1.605 (7)	K2—O4^iv	3.082 (5)
Mo4—O5	1.674 (6)	K2—O5	3.233 (3)
Mo4—O8	1.881 (5)	K2—O5^iv	3.233 (3)
Mo4—O11	1.940 (8)	K2—O10ⁱⁱ	3.317 (7)
Mo4—O11ⁱ	1.940 (8)	K2—O1^iv	3.343 (3)
Fe1—O7ⁱⁱ	1.956 (4)	K2—O1	3.343 (3)
Fe1—O7^v	1.956 (4)	K3—O2^xiii	2.704 (6)
Fe1—O1	1.989 (5)	K3—O5	2.740 (7)
Fe1—O6^vi	2.000 (5)	K3—O4ⁱ	2.863 (5)
Fe1—O4	2.011 (4)	K3—O4	2.863 (5)
Fe1—O4ⁱ	2.011 (4)	K3—O7ⁱ	3.005 (7)
K1—O12^vii	2.650 (8)	K3—O7	3.005 (7)
K1—O12^viii	2.650 (8)	K3—O9	3.135 (3)
K1—O11^vii	2.789 (8)	K3—O9^xiv	3.135 (3)
K1—O11^viii	2.789 (8)	K3—O2^xiv	3.386 (3)
K1—O3^ix	2.882 (4)	K3—O2	3.386 (3)

O3—Mo1—O3ⁱ	106.8 (3)	O12—Mo4—O11	47.9 (4)
O3—Mo1—O1	108.94 (15)	O12ⁱ—Mo4—O11	107.1 (4)
O3ⁱ—Mo1—O1	108.94 (15)	O5—Mo4—O11	93.2 (2)
O3—Mo1—O8ⁱⁱ	108.63 (16)	O8—Mo4—O11	100.9 (2)
O3ⁱ—Mo1—O8ⁱⁱ	108.63 (16)	O12—Mo4—O11ⁱ	107.1 (4)
O1—Mo1—O8ⁱⁱ	114.6 (2)	O12ⁱ—Mo4—O11ⁱ	47.9 (4)
O9—Mo2—O10	110.8 (3)	O5—Mo4—O11ⁱ	93.2 (2)
O9—Mo2—O7	107.9 (2)	O8—Mo4—O11ⁱ	100.9 (2)
O10—Mo2—O7	109.20 (18)	O11—Mo4—O11ⁱ	153.4 (4)
O9—Mo2—O7ⁱⁱⁱ	107.9 (2)	O7ⁱⁱ—Fe1—O7^v	90.2 (4)
O10—Mo2—O7ⁱⁱⁱ	109.20 (18)	O7ⁱⁱ—Fe1—O1	92.22 (17)
O7—Mo2—O7ⁱⁱⁱ	111.9 (4)	O7^v—Fe1—O1	92.22 (17)
O2—Mo3—O6	109.2 (3)	O7ⁱⁱ—Fe1—O6^vi	90.18 (17)
O2—Mo3—O4^iv	107.2 (2)	O7^v—Fe1—O6^vi	90.18 (17)
O6—Mo3—O4^iv	112.33 (14)	O1—Fe1—O6^vi	176.6 (2)
O2—Mo3—O4ⁱ	107.2 (2)	O7ⁱⁱ—Fe1—O4	178.6 (2)
O6—Mo3—O4ⁱ	112.33 (14)	O7^v—Fe1—O4	90.4 (3)
O4^iv—Mo3—O4ⁱ	108.3 (3)	O1—Fe1—O4	89.03 (15)
O12—Mo4—O12ⁱ	59.4 (7)	O6^vi—Fe1—O4	88.54 (16)
O12—Mo4—O5	118.2 (4)	O7ⁱⁱ—Fe1—O4ⁱ	90.4 (3)
O12ⁱ—Mo4—O5	118.2 (4)	O7^v—Fe1—O4ⁱ	178.6 (2)
O12—Mo4—O8	120.8 (3)	O1—Fe1—O4ⁱ	89.03 (15)
O12ⁱ—Mo4—O8	120.8 (3)	O6^vi—Fe1—O4ⁱ	88.54 (16)
O5—Mo4—O8	110.9 (3)	O4—Fe1—O4ⁱ	89.1 (3)

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

Experimental details

Crystal data
Chemical formula	K₃Fe(MoO₄)₂Mo₂O₇
M_r	796.91
Crystal system, space group	Monoclinic, C2/m
Temperature (K)	298
a, b, c (Å)	32.873 (2), 5.7137 (7), 7.9177 (9)
β (°)	91.143 (8)
V (Å³)	1486.9 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	5.15
Crystal size (mm)	0.36 × 0.22 × 0.18

Data collection
Diffractometer	Enraf–Nonius CAD-4
Absorption correction	ψ scan (North et al., 1968)
T_min, T_max	0.286, 0.488
No. of measured, independent and observed [I > 2σ(I)] reflections	3443, 1789, 1636
R_int	0.028
(sin θ/λ)_max (Å⁻¹)	0.638

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.076, 1.06
No. of reflections	1789
No. of parameters	138
	w = 1/[σ²(F_o²) + (0.0306P)² + 20.6944P] where P = (F_o² + 2F_c²)/3
Δρ_max, Δρ_min (e Å⁻³)	1.22, −1.57

Computer programs: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 1999), WinGX (Farrugia, 2012).

References

Bowker, M., Holroyd, R., House, M., Bracey, R., Bamroongwongdee, C., Shannon, M. & Carley, A. (2008). Top. Catal. 48, 158–165. Web of Science CrossRef CAS Google Scholar
Bramnik, K. G., Muessig, E. & Ehrenberg, H. (2003). J. Solid State Chem. 176, 192–197. Web of Science CrossRef CAS Google Scholar
Brandenburg, K. & Putz, H. (1999). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Brown, I. D. & Altermatt, D. (1985). Acta Cryst. B41, 244–247. CrossRef CAS Web of Science IUCr Journals Google Scholar
Duisenberg, A. J. M. (1992). J. Appl. Cryst. 25, 92–96. CrossRef CAS Web of Science IUCr Journals Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany. Google Scholar
Jorge, G. A., Capan, C., Ronning, F., Jaime, M., Kenzelmann, M., Gasparovic, G., Broholm, C., Shapiro, A. & Demianets, Y. (2004). Physica B, 354, 297–299. Web of Science CrossRef CAS Google Scholar
Khal'baeva, K. M., Solodovnikov, S. F., Khaikina, E. G., Kadyrova, Y. M., Solodovnikova, Z. A. & Basovich, O. M. (2010). J. Solid State Chem. 183, 712–719. CAS Google Scholar
Klimin, S. A., Popova, M. N., Mavrin, B. N., Van Loosdrecht, P. H. M., Svistov, L. E., Smirnov, A. I., Prozorova, L. A., Krug van Nidda, H. A., Seidov, Z. & Loidl, A. (2003). Phys. Rev. B68, 174408–174412. Web of Science CrossRef Google Scholar
Macíček, J. & Yordanov, A. (1992). J. Appl. Cryst. 25, 73–80. CrossRef Web of Science IUCr Journals Google Scholar
Maczka, M., Pietraszko, A., Paraguassu, W., Souza Filho, A. G., Freire, P. T. C., Mendes Filho, J. & Hanuza, J. (2009). J. Phys. Condens. Matter, 21, 095402, 1–8. Google Scholar
Maczka, M., Pietraszko, A., Saraiva, G. D., Souza Filho, A. G., Paraguassu, W., Lemos, V., Perottoni, C. A., Gallas, M. R., Freire, P. T. C., Tomaszewski, P. E., Melo, F. E. A., Mendes Filho, J. & Hanuza, J. (2005). J. Phys. Condens. Matter, 17, 6285–6300. Web of Science CrossRef CAS Google Scholar
Muessig, E., Bramnik, K. G. & Ehrenberg, H. (2003). Acta Cryst. B59, 611–616. Web of Science CrossRef CAS IUCr Journals Google Scholar
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359. CrossRef IUCr Journals Web of Science Google Scholar
Otko, A. I., Nesterenko, N. M. & Povstyanyi, L. V. (1978). Phys. Status Solidi A, 46, 577–587. CrossRef CAS Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Soares, A. P. V. & Portela, M. F. (2005). Catal. Rev. 47, 125–174. Web of Science CrossRef CAS Google Scholar
Zhang, L. J., Zhou, Y. S., Zuo, J. L., Yu, Z., Fun, H. K., Abdul, I. & You, X. Z. (2000). Inorg. Chem. Commun. 3, 697–699. Web of Science CrossRef CAS Google Scholar