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Acta Crystallogr Sect E Struct Rep Online. 2009 December 1; 65(Pt 12): i87.
Published online 2009 November 7. doi:  10.1107/S1600536809046297
PMCID: PMC2971751

Tricaesium dimolybdate(VI) bromide


The title compound, Cs3(Mo2O7)Br, was synthesized by the reaction of CsNO3, MoO3 and 1-ethyl-3-methyl­imidazolium bromide. Its crystal structure is isotypic with K3(Mo2O7)Br and contains (MoO4)2− tetra­hedra which share an O atom to produce a [Mo2O7]2− dimolybdate(VI) anion with a linear bridging angle and An external file that holds a picture, illustration, etc.
Object name is e-65-00i87-efi4.jpg m2 symmetry. The anions are linked by Cs atoms (site symmetry An external file that holds a picture, illustration, etc.
Object name is e-65-00i87-efi4.jpg m2), forming sheets parallel to (001). Br atoms (site symmetry An external file that holds a picture, illustration, etc.
Object name is e-65-00i87-efi4.jpg m2) are also part of this layer. Another type of Cs atom (3m site symmetry) is located in the inter­layer space and connects the layers via Cs—O and Cs—Br inter­actions into a three-dimensional array.

Related literature

For the isotypic compound K3(Mo2O7)Br, see: Becher & Fenske (1978 [triangle]). For dimolybdates with similar condensed anions made up of MoO4 tetra­hedra, see: Ce2(MoO4)2(Mo2O7) (Fallon & Gatehouse, 1982 [triangle]); Mg2Mo2O7 (Stadnicka et al., 1977 [triangle]).


Crystal data

  • Cs3(Mo2O7)Br
  • M r = 782.52
  • Hexagonal, An external file that holds a picture, illustration, etc.
Object name is e-65-00i87-efi7.jpg
  • a = 6.3993 (5) Å
  • c = 16.4870 (15) Å
  • V = 584.71 (8) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 14.77 mm−1
  • T = 293 K
  • 0.15 × 0.15 × 0.05 mm

Data collection

  • Stoe IPDS-2 diffractometer
  • Absorption correction: integration (X-RED and X-SHAPE; Stoe, 2005 [triangle]) T min = 0.153, T max = 0.532
  • 5224 measured reflections
  • 344 independent reflections
  • 338 reflections with I > 2σ(I)
  • R int = 0.044


  • R[F 2 > 2σ(F 2)] = 0.025
  • wR(F 2) = 0.062
  • S = 1.18
  • 344 reflections
  • 20 parameters
  • Δρmax = 0.60 e Å−3
  • Δρmin = −1.21 e Å−3

Data collection: X-AREA (Stoe, 2007 [triangle]); cell refinement: X-AREA; data reduction: X-RED (Stoe, 2005 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ATOMS (Dowty, 1999 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2009 [triangle]).

Table 1
Selected bond lengths (Å)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809046297/wm2275sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809046297/wm2275Isup2.hkl

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


This work was supported by a President of the Russian Federation Grant for Young Doctors of Science (to SVK, grant No. MD-407.2009.5).

supplementary crystallographic information


The structure of Cs3(Mo2O7)Br contains one symmetrically independent Mo6+ cation which is tetrahedrally coordinated by O atoms. Two (MoO4)2- tetrahedra share a common O2 atom to form a [Mo2O7]2- dimolybdate(VI) anion. The Mo—O2—Mo bond angle is linear and oriented along [001] (Fig. 1). In other dimolybdates(VI), this fragment differs from linearity and Mo—O—Mo bond angles range from 141.4° (Ce2(MoO4)2(Mo2O7); Fallon & Gatehouse, 1982) to 160.6° (Mg2Mo2O7; Stadnicka et al., 1977). The corner linkage of tetrahedra is associated with bond-length distortions: the <Mo—O1> bond length is 1.725 (4) Å, whereas the <Mo—O2> bond-length is 1.8764 (7) Å; the O—Mo—O bond angles range from 108.34 (14)° (for <O1—Mo—O1>) to 110.58 (13)° (for <O1—Mo—O2>). The structure also contains two symmetrically independent Cs atoms and one Br atom. Cs1 is coordinated by nine O atoms and one Br atom, whereas Cs2 is coordinated by six O atoms and three Br atoms. The <Cs—O> bond lengths are in the range from 3.126 (4) Å to 3.239 (4) Å. The <Cs—Br> bond lengths are 3.4268 (6) Å and 3.6946 (3) Å. The [Mo2O7]2- anions are linked by Cs2 atoms to form sheets running parallel to (001). The three-dimensional connectivity of the structure is provided by Cs1 atoms located in the interlayer (Fig. 2).


The title compound was prepared by the reaction of CsNO3 (0.192 g), MoO3 (0.146 g) and the ionic-liquid salt 1-ethyl-3-methylimidazolium bromide, [emim]Br (0.451 g). The mixture was heated to 453 K for 3 days in a teflon-lined steel autoclave with an internal volume of 20 ml. The obtained crystals were washed out with distilled water and dried in air at room temperature. A suitable colorless plate-shaped single-crystal was selected for X-ray structure analysis.


Fig. 1.
View of the linear [Mo2O7]2- anion. Ellipsoids are drawn at the 50% probability level. [Symmetry codes: (iv) -y+1, x-y-1, z; (x) -x+y+2, -x, -z-1/2; (xi) -y, x-y-2, -z-1/2; (xii) x, y, -z-1/2; (xvii) -x+y+2, -x+1, z.]
Fig. 2.
The crystal structure of Cs3(Mo2O7)Br in a projection approximately on (110). Cs atoms are represented as light-purple spheres and Br atoms as green spheres; MoO4 tetrahedra are given in yellow and orange. Ellipsoids are drawn at the 50% probability level. ...

Crystal data

Cs3(Mo2O7)BrDx = 4.445 Mg m3
Mr = 782.52Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/mmcCell parameters from 5704 reflections
Hall symbol: -P 6c 2cθ = 2.5–29.5°
a = 6.3993 (5) ŵ = 14.77 mm1
c = 16.4870 (15) ÅT = 293 K
V = 584.71 (8) Å3Plate, colorless
Z = 20.15 × 0.15 × 0.05 mm
F(000) = 680

Data collection

Stoe IPDS-2 diffractometer344 independent reflections
Radiation source: fine-focus sealed tube338 reflections with I > 2σ(I)
graphiteRint = 0.044
Detector resolution: 6.67 pixels mm-1θmax = 29.2°, θmin = 2.5°
rotation method scansh = −8→8
Absorption correction: integration (X-RED and X-SHAPE; Stoe & Cie, 2007)k = −7→8
Tmin = 0.153, Tmax = 0.532l = −21→22
5224 measured reflections


Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.025w = 1/[σ2(Fo2) + (0.0295P)2 + 2.906P] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.062(Δ/σ)max < 0.001
S = 1.18Δρmax = 0.60 e Å3
344 reflectionsΔρmin = −1.21 e Å3
20 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0306 (16)

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 (Å2)

Cs11.3333−0.3333−0.04215 (3)0.0227 (2)
Cs20.6667−0.6667−0.25000.0265 (3)
Mo1.00000.0000−0.13619 (4)0.0166 (2)
O10.8543 (4)−0.2913 (7)−0.0994 (2)0.0274 (9)
O21.00000.0000−0.25000.029 (2)
Br1.3333−0.3333−0.25000.0365 (4)

Atomic displacement parameters (Å2)

Cs10.0239 (3)0.0239 (3)0.0204 (3)0.01194 (14)0.0000.000
Cs20.0274 (3)0.0274 (3)0.0246 (4)0.01372 (17)0.0000.000
Mo0.0183 (3)0.0183 (3)0.0130 (4)0.00917 (14)0.0000.000
O10.0328 (18)0.018 (2)0.0265 (18)0.0091 (10)0.0023 (7)0.0046 (15)
O20.040 (4)0.040 (4)0.008 (4)0.0200 (19)0.0000.000
Br0.0434 (6)0.0434 (6)0.0227 (7)0.0217 (3)0.0000.000

Geometric parameters (Å, °)

Cs1—O1i3.126 (4)Cs2—O2xv3.6946 (3)
Cs1—O1ii3.126 (4)Cs2—O2xiv3.6946 (3)
Cs1—O1iii3.126 (4)Cs2—O23.6946 (3)
Cs1—O1iv3.3441 (12)Cs2—Brxvi3.6946 (3)
Cs1—O1v3.3441 (12)Mo—O1iv1.725 (4)
Cs1—O13.3441 (12)Mo—O1xvii1.725 (4)
Cs1—O1vi3.3441 (12)Mo—O11.725 (4)
Cs1—O1vii3.3441 (12)Mo—O21.8764 (7)
Cs1—O1viii3.3441 (12)Mo—Cs1xviii4.0067 (4)
Cs1—Br3.4268 (6)Mo—Cs1xvi4.0067 (4)
Cs1—Cs1ix3.9475 (5)Mo—Cs2xviii4.1438 (4)
Cs1—Cs1iii3.9475 (5)Mo—Cs2xix4.1438 (4)
Cs2—O1x3.239 (4)O1—Cs1iii3.126 (4)
Cs2—O1v3.239 (4)O1—Cs1xvi3.3441 (12)
Cs2—O1xi3.239 (4)O2—Moxii1.8764 (7)
Cs2—O13.239 (4)O2—Cs2xviii3.6946 (3)
Cs2—O1xii3.239 (4)O2—Cs2xix3.6946 (3)
Cs2—O1xiii3.239 (4)Br—Cs1xii3.4268 (6)
Cs2—Brxiv3.6946 (3)Br—Cs2xix3.6946 (3)
Cs2—Br3.6946 (3)Br—Cs2vi3.6946 (3)
O1i—Cs1—O1ii70.37 (12)O1v—Cs2—O2xv50.04 (7)
O1i—Cs1—O1iii70.37 (12)O1xi—Cs2—O2xv108.73 (3)
O1ii—Cs1—O1iii70.37 (12)O1—Cs2—O2xv108.73 (3)
O1i—Cs1—O1iv68.67 (13)O1xii—Cs2—O2xv108.73 (3)
O1ii—Cs1—O1iv104.90 (6)O1xiii—Cs2—O2xv108.73 (3)
O1iii—Cs1—O1iv137.64 (3)Brxiv—Cs2—O2xv60.0
O1i—Cs1—O1v104.90 (6)Br—Cs2—O2xv60.0
O1ii—Cs1—O1v137.64 (3)O1x—Cs2—O2xiv108.73 (3)
O1iii—Cs1—O1v68.67 (13)O1v—Cs2—O2xiv108.73 (3)
O1iv—Cs1—O1v112.36 (6)O1xi—Cs2—O2xiv50.04 (7)
O1i—Cs1—O168.67 (13)O1—Cs2—O2xiv108.73 (3)
O1ii—Cs1—O1137.64 (3)O1xii—Cs2—O2xiv108.73 (3)
O1iii—Cs1—O1104.90 (6)O1xiii—Cs2—O2xiv50.04 (7)
O1iv—Cs1—O149.43 (14)Brxiv—Cs2—O2xiv60.0
O1v—Cs1—O165.19 (14)Br—Cs2—O2xiv180.0
O1i—Cs1—O1vi137.64 (3)O2xv—Cs2—O2xiv120.0
O1ii—Cs1—O1vi68.67 (13)O1x—Cs2—O2108.73 (3)
O1iii—Cs1—O1vi104.90 (6)O1v—Cs2—O2108.73 (3)
O1iv—Cs1—O1vi112.36 (6)O1xi—Cs2—O2108.73 (3)
O1v—Cs1—O1vi112.36 (6)O1—Cs2—O250.04 (7)
O1—Cs1—O1vi146.20 (13)O1xii—Cs2—O250.04 (7)
O1i—Cs1—O1vii104.90 (6)O1xiii—Cs2—O2108.73 (3)
O1ii—Cs1—O1vii68.67 (13)Brxiv—Cs2—O2180.0
O1iii—Cs1—O1vii137.64 (3)Br—Cs2—O260.0
O1iv—Cs1—O1vii65.19 (14)O2xv—Cs2—O2120.0
O1v—Cs1—O1vii146.20 (13)O2xiv—Cs2—O2120.0
O1—Cs1—O1vii112.36 (6)O1x—Cs2—Brxvi129.96 (7)
O1vi—Cs1—O1vii49.43 (14)O1v—Cs2—Brxvi129.96 (7)
O1i—Cs1—O1viii137.64 (3)O1xi—Cs2—Brxvi71.27 (3)
O1ii—Cs1—O1viii104.90 (6)O1—Cs2—Brxvi71.27 (3)
O1iii—Cs1—O1viii68.67 (13)O1xii—Cs2—Brxvi71.27 (3)
O1iv—Cs1—O1viii146.20 (13)O1xiii—Cs2—Brxvi71.27 (3)
O1v—Cs1—O1viii49.43 (14)Brxiv—Cs2—Brxvi120.0
O1—Cs1—O1viii112.36 (6)Br—Cs2—Brxvi120.0
O1vi—Cs1—O1viii65.19 (14)O2xv—Cs2—Brxvi180.0
O1vii—Cs1—O1viii112.36 (6)O2xiv—Cs2—Brxvi60.0
O1i—Cs1—Br138.29 (8)O2—Cs2—Brxvi60.0
O1ii—Cs1—Br138.29 (8)O1iv—Mo—O1xvii108.34 (14)
O1iii—Cs1—Br138.29 (8)O1iv—Mo—O1108.34 (14)
O1iv—Cs1—Br73.60 (6)O1xvii—Mo—O1108.34 (14)
O1v—Cs1—Br73.60 (6)O1iv—Mo—O2110.58 (13)
O1—Cs1—Br73.60 (6)O1xvii—Mo—O2110.58 (13)
O1vi—Cs1—Br73.60 (6)O1—Mo—O2110.58 (13)
O1vii—Cs1—Br73.60 (6)Mo—O1—Cs1iii152.3 (2)
O1viii—Cs1—Br73.60 (6)Mo—O1—Cs2109.37 (16)
O1x—Cs2—O1v100.09 (14)Cs1iii—O1—Cs298.33 (11)
O1x—Cs2—O1xi67.58 (11)Mo—O1—Cs199.46 (8)
O1v—Cs2—O1xi142.54 (6)Cs1iii—O1—Cs175.10 (6)
O1x—Cs2—O1142.54 (6)Cs2—O1—Cs199.88 (7)
O1v—Cs2—O167.58 (11)Mo—O1—Cs1xvi99.46 (8)
O1xi—Cs2—O1142.54 (6)Cs1iii—O1—Cs1xvi75.10 (6)
O1x—Cs2—O1xii67.58 (11)Cs2—O1—Cs1xvi99.88 (7)
O1v—Cs2—O1xii142.54 (6)Cs1—O1—Cs1xvi146.20 (13)
O1xi—Cs2—O1xii67.58 (11)Moxii—O2—Mo180.0
O1—Cs2—O1xii100.09 (14)Moxii—O2—Cs2xviii90.0
O1x—Cs2—O1xiii142.54 (6)Mo—O2—Cs2xviii90.0
O1v—Cs2—O1xiii67.58 (11)Moxii—O2—Cs290.0
O1xi—Cs2—O1xiii100.09 (14)Mo—O2—Cs290.0
O1—Cs2—O1xiii67.58 (11)Cs2xviii—O2—Cs2120.0
O1xii—Cs2—O1xiii142.54 (6)Moxii—O2—Cs2xix90.0
O1x—Cs2—Brxiv71.27 (3)Mo—O2—Cs2xix90.0
O1v—Cs2—Brxiv71.27 (3)Cs2xviii—O2—Cs2xix120.0
O1xi—Cs2—Brxiv71.27 (3)Cs2—O2—Cs2xix120.0
O1—Cs2—Brxiv129.96 (7)Cs1xii—Br—Cs1180.0
O1xii—Cs2—Brxiv129.96 (7)Cs1xii—Br—Cs2xix90.0
O1xiii—Cs2—Brxiv71.27 (3)Cs1—Br—Cs2xix90.0
O1x—Cs2—Br71.27 (3)Cs1xii—Br—Cs290.0
O1v—Cs2—Br71.27 (3)Cs1—Br—Cs290.0
O1xi—Cs2—Br129.96 (7)Cs2xix—Br—Cs2120.0
O1—Cs2—Br71.27 (3)Cs1xii—Br—Cs2vi90.0
O1xii—Cs2—Br71.27 (3)Cs1—Br—Cs2vi90.0
O1xiii—Cs2—Br129.96 (7)Cs2xix—Br—Cs2vi120.0
O1x—Cs2—O2xv50.04 (7)

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


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2275).


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  • Westrip, S. P. (2009). publCIF. In preparation.

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