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The new polyoxomolybdovanadate, hexapotassium hexa­molybdodivanadate tetrahydrate, K6[Mo6V2O26]·4H2O, has been isolated from a solution of potassium molybdate and ammonium vanadate. The polyoxoanion, with crystallographically imposed 2/m symmetry, is built up of six MoO6 and two VO6 edge-sharing distorted octahedra.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802020536/br6067sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802020536/br6067Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](V-O) = 0.003 Å
  • R factor = 0.024
  • wR factor = 0.065
  • Data-to-parameter ratio = 27.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
ABSTM_02 Alert C The ratio of Tmax/Tmin expected RT(exp) is > 1.10 Absorption corrections should be applied. Tmin and Tmax expected: 0.508 0.567 RT(exp) = 1.115
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
1 Alert Level C = Please check

Comment top

K6[Mo6V2O26]·4H2O has been isolated from a solution of potassium molybdate and ammonium vanadate at pH = 5.90. The crystal structure is built up of [Mo6V2O26]6− anions joined together in a three-dimensional framework by electrostatic K···O linkages, as well as by hydrogen bonds. The polyoxoanion, which is isostructural with the β-octamoybdate [Mo8O26]4− anion (Lindquist, 1959), and the β-hexamolybdodivanadate [Mo6V2O26]6− anion found in the mixed potassium sodium salt K5Na[Mo6V2O26]·4H2O (Nenner, 1985), is composed of six MoO6 and two VO6 edge-sharing distorted octahedra with crystallographically imposed 2/m symmetry. Mo and V atoms are differently coordinated by the oxo ligands: Mo1 is coordinated by two terminal Ot, three double-bridging Ob, and one five-bridging O5 b atoms; Mo2 by two terminal Ot, one double-bridging Ob, two triple-bridging O3 b, and one five-bridging O5 b; and V1 by one terminal Ot, one double-bridging Ob, two triple-bridging O3 b and two five-bridging O5 b atoms. However, the metal-to-oxygen distances show the usual distribution: two short bonds, two bonds of medium values and two long bonds. The potassium ion K1, situated in special position (c) 1/2, 1/2, 1/2 of space group C2/m, occupies the same site as the sodium ion in the structure of the mixed salt K5Na[Mo6V2O26]·4H2O. However, whereas the sodium cation is surrounded by six terminal O atoms from two polyoxoanions, with Na···O distances ranging from 2.40 to 2.57 Å, the K1 cation is surrounded by eight terminal O atoms, with K1···O distances ranging from 2.600 (2) to 2.925 (2) Å. In this way, chains of polyoxoanions parallel to the [001] direction are formed in both structures. The bond-strength calculation (Brown & Altermatt, 1985) shows that the bond-valence sum around K1 is 1.69, much larger than 1.0, the theoretical value for the K atom, thus indicating that the structure cannot expand in the [001] direction to provide the ideal space required by K. The analogous value, calculated for Na ion in the structure of mixed sodium potassium salt (Nenner, 1985), is 0.92. The remaining two cations, K2 and K3, are located at the same positions as two symmetry-independent potassium ions in the structure of K5Na[Mo6V2O26]·4H2O. The cation K2, situated in a general position, is irregularly surrounded by nine O atoms, seven from the polyoxoanions and two from water molecules, K2···O distances vary from 2.796 (2) to 3.0692 (17) Å. The cation K3, located in the special position (b) 0, 1/2, 0, is surrounded by eight O atoms from four polyanions, with K3···O distances ranging from 2.8604 (16) to 3.236 (3) Å, thus forming layers of polyoxoanions parallel to the (201) plane. The bond-valence sum around cations K2 and K3 are 0.95 and 0.73, respectively. The molybdovanadate anions are additionally interconnected by O—H···O hydrogen bonds realised through water molecules. One of the H atoms, H2, is involved in a three-centred hydrogen bond between water molecules and two terminal O atoms from polyoxoanion.

Experimental top

A mixture of K2MoO4 (0.8 g) and NH4VO3 (0.12 g) was dissolved in water (15 ml) and heated on reflux for 2 h. The suspension was filtered off and pH was adjusted to 5.9 by adding 2 M HCl (5 ml). The clear yellow solution was left at room temperature. After standing for 14 d, yellow crystals were filtered off and dried in vacuo.

Computing details top

Data collection: DENZO (Otwinowski & Minor, 1997); cell refinement: DENZO; data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson,1976); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The structure of [Mo6V2O26]6− anion found in hexapotassium salt.
[Figure 2] Fig. 2. The unit-cell packing diagram and coordination of the K1 ion, viewed in the direction [001].
hexapotassium hexamolybdodivanadate tetrahydrate top
Crystal data top
K6[Mo6V2O26]·4H2OF(000) = 1320
Mr = 1400.18Dx = 3.417 Mg m3
Monoclinic, C2/mMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yCell parameters from 3364 reflections
a = 14.717 (3) Åθ = 2.4–36.3°
b = 12.813 (3) ŵ = 4.36 mm1
c = 9.251 (2) ÅT = 293 K
β = 128.73 (3)°Prism, yellow
V = 1360.9 (8) Å30.16 × 0.15 × 0.13 mm
Z = 2
Data collection top
Nonius KappaCCD
diffractometer
3267 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.013
Graphite monochromatorθmax = 36.3°, θmin = 2.4°
ϕ and ω scansh = 2424
6362 measured reflectionsk = 2120
3364 independent reflectionsl = 1515
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.024All H-atom parameters refined
wR(F2) = 0.065 w = 1/[σ2(Fo2) + (0.027P)2 + 8.9089P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max = 0.003
3364 reflectionsΔρmax = 1.53 e Å3
123 parametersΔρmin = 1.88 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: heavy-atom methodExtinction coefficient: 0.00280 (13)
Crystal data top
K6[Mo6V2O26]·4H2OV = 1360.9 (8) Å3
Mr = 1400.18Z = 2
Monoclinic, C2/mMo Kα radiation
a = 14.717 (3) ŵ = 4.36 mm1
b = 12.813 (3) ÅT = 293 K
c = 9.251 (2) Å0.16 × 0.15 × 0.13 mm
β = 128.73 (3)°
Data collection top
Nonius KappaCCD
diffractometer
3267 reflections with I > 2σ(I)
6362 measured reflectionsRint = 0.013
3364 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0240 restraints
wR(F2) = 0.065All H-atom parameters refined
S = 1.09Δρmax = 1.53 e Å3
3364 reflectionsΔρmin = 1.88 e Å3
123 parameters
Special details top

Experimental. Crystal to detector distance was 28 mm, with exposure time of 50 s per frame.

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
xyzUiso*/Ueq
Mo10.269588 (18)0.00000.46554 (3)0.00584 (5)
Mo20.067755 (12)0.175610 (12)0.22648 (2)0.00516 (5)
V10.11872 (3)0.00000.00147 (5)0.00301 (7)
O10.25531 (16)0.00000.2146 (3)0.0069 (3)
O20.14901 (18)0.00000.1400 (3)0.0089 (3)
O30.03695 (13)0.17245 (11)0.3781 (2)0.0094 (2)
O40.08808 (11)0.14558 (11)0.00235 (18)0.0060 (2)
O50.23583 (19)0.00000.6151 (3)0.0106 (3)
O60.22998 (11)0.14291 (11)0.38772 (18)0.0072 (2)
O70.06443 (17)0.00000.1947 (3)0.0068 (3)
O80.41828 (17)0.00000.6071 (3)0.0108 (3)
O90.07877 (12)0.30576 (11)0.1953 (2)0.0086 (2)
OW0.36789 (15)0.13693 (15)0.1403 (3)0.0205 (3)
H10.345 (4)0.084 (3)0.183 (6)0.030 (11)*
H20.456 (6)0.130 (5)0.232 (8)0.076 (19)*
K10.50000.50000.50000.01135 (13)
K20.28723 (4)0.30373 (4)0.23213 (7)0.01832 (9)
K30.00000.50000.00000.0337 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mo10.00540 (9)0.00542 (9)0.00475 (9)0.0000.00222 (7)0.000
Mo20.00529 (7)0.00458 (7)0.00481 (7)0.00002 (4)0.00277 (5)0.00040 (4)
V10.00240 (14)0.00289 (14)0.00342 (14)0.0000.00166 (12)0.000
O10.0052 (7)0.0077 (7)0.0064 (7)0.0000.0029 (6)0.000
O20.0081 (7)0.0113 (8)0.0079 (7)0.0000.0053 (6)0.000
O30.0108 (6)0.0112 (6)0.0085 (5)0.0005 (4)0.0071 (5)0.0006 (4)
O40.0055 (5)0.0056 (5)0.0059 (5)0.0003 (4)0.0030 (4)0.0003 (4)
O50.0143 (8)0.0101 (8)0.0095 (8)0.0000.0084 (7)0.000
O60.0057 (5)0.0058 (5)0.0071 (5)0.0004 (4)0.0026 (4)0.0001 (4)
O70.0073 (7)0.0049 (7)0.0082 (7)0.0000.0048 (6)0.000
O80.0052 (7)0.0109 (8)0.0094 (8)0.0000.0013 (6)0.000
O90.0093 (5)0.0057 (5)0.0089 (5)0.0000 (4)0.0047 (5)0.0002 (4)
OW0.0115 (6)0.0186 (8)0.0252 (8)0.0023 (6)0.0084 (6)0.0075 (7)
K10.0138 (3)0.0103 (3)0.0092 (3)0.0000.0068 (3)0.000
K20.01600 (19)0.0204 (2)0.0177 (2)0.00066 (16)0.01012 (17)0.00029 (17)
K30.0533 (8)0.0131 (4)0.0179 (5)0.0000.0140 (5)0.000
Geometric parameters (Å, º) top
Mo1—O81.708 (2)Mo2—O72.2658 (6)
Mo1—O51.738 (2)Mo2—O42.3050 (14)
Mo1—O6i1.9198 (14)V1—O21.625 (2)
Mo1—O61.9198 (14)V1—O11.723 (2)
Mo1—O12.196 (2)V1—O41.9202 (14)
Mo1—O72.435 (2)V1—O4i1.9202 (14)
Mo2—O91.7172 (15)V1—O7iii2.107 (2)
Mo2—O31.7235 (15)V1—O72.371 (2)
Mo2—O61.9090 (16)V1—Mo2iii3.1305 (9)
Mo2—O4ii1.9530 (17)V1—Mo2ii3.1305 (9)
K1···O2iv2.600 (2)K2···O2iv2.9885 (13)
K1···O2v2.600 (2)K2···O5ix3.0061 (14)
K1···O3vi2.6864 (15)K2···O3vi3.0352 (18)
K1···O3vii2.6864 (15)K2···O43.0692 (17)
K1···O3viii2.6864 (15)K3···O9ii2.8604 (15)
K1···O3ix2.6864 (15)K3···O9x2.8604 (16)
K1···O5viii2.925 (2)K3···O92.8604 (16)
K1···O5ix2.925 (2)K3···O9xi2.8604 (16)
K2···OWiv2.796 (2)K3···O8xii3.031 (2)
K2···OW2.821 (2)K3···O8ix3.031 (2)
K2···O3ix2.849 (2)K3···O5xii3.236 (3)
K2···O92.8674 (17)K3···O5ix3.236 (3)
K2···O62.9234 (15)
O8—Mo1—O5104.89 (11)O2—V1—O4100.77 (4)
O8—Mo1—O6i103.31 (4)O1—V1—O495.98 (4)
O5—Mo1—O6i97.33 (5)O2—V1—O4i100.77 (4)
O8—Mo1—O6103.31 (4)O1—V1—O4i95.98 (4)
O5—Mo1—O697.33 (5)O4—V1—O4i152.52 (8)
O6i—Mo1—O6145.02 (8)O2—V1—O7iii98.87 (9)
O8—Mo1—O192.27 (10)O1—V1—O7iii159.01 (9)
O5—Mo1—O1162.84 (9)O4—V1—O7iii80.00 (4)
O6i—Mo1—O178.33 (4)O4i—V1—O7iii80.00 (4)
O6—Mo1—O178.33 (4)O2—V1—O7177.11 (9)
O8—Mo1—O7163.32 (9)O1—V1—O780.77 (8)
O5—Mo1—O791.79 (9)O4—V1—O778.81 (4)
O6i—Mo1—O773.98 (4)O4i—V1—O778.81 (4)
O6—Mo1—O773.98 (4)O7iii—V1—O778.24 (8)
O1—Mo1—O771.05 (7)V1—O1—Mo1118.76 (10)
O9—Mo2—O3105.07 (7)V1—O4—Mo2ii107.85 (6)
O9—Mo2—O698.11 (6)V1—O4—Mo2109.21 (6)
O3—Mo2—O6101.31 (7)Mo2ii—O4—Mo2102.53 (6)
O9—Mo2—O4ii100.34 (6)Mo2—O6—Mo1116.12 (7)
O3—Mo2—O4ii98.57 (7)V1iii—O7—Mo291.37 (5)
O6—Mo2—O4ii148.22 (6)V1iii—O7—Mo2i91.37 (5)
O9—Mo2—O7159.92 (7)Mo2—O7—Mo2i166.49 (10)
O3—Mo2—O794.99 (7)V1iii—O7—V1101.76 (8)
O6—Mo2—O778.37 (7)Mo2—O7—V196.19 (5)
O4ii—Mo2—O775.42 (6)Mo2i—O7—V196.19 (5)
O9—Mo2—O486.11 (6)V1iii—O7—Mo1168.81 (10)
O3—Mo2—O4167.54 (6)Mo2—O7—Mo187.38 (5)
O6—Mo2—O482.15 (6)Mo2i—O7—Mo187.38 (5)
O4ii—Mo2—O473.58 (6)V1—O7—Mo189.43 (7)
O7—Mo2—O473.85 (6)H1—OW—H2101 (4)
O2—V1—O1102.12 (10)
Symmetry codes: (i) x, y, z; (ii) x, y, z; (iii) x, y, z; (iv) x+1/2, y+1/2, z; (v) x+1/2, y+1/2, z+1; (vi) x+1/2, y+1/2, z; (vii) x+1/2, y+1/2, z+1; (viii) x+1/2, y+1/2, z; (ix) x+1/2, y+1/2, z+1; (x) x, y+1, z; (xi) x, y+1, z; (xii) x1/2, y+1/2, z1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
OW—H1···O10.94 (4)1.87 (4)2.779 (2)162 (4)
OW—H2···O9vi1.02 (6)2.20 (7)2.908 (2)125 (5)
OW—H2···O8xiii1.02 (6)2.23 (6)3.040 (3)136 (5)
Symmetry codes: (vi) x+1/2, y+1/2, z; (xiii) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaK6[Mo6V2O26]·4H2O
Mr1400.18
Crystal system, space groupMonoclinic, C2/m
Temperature (K)293
a, b, c (Å)14.717 (3), 12.813 (3), 9.251 (2)
β (°) 128.73 (3)
V3)1360.9 (8)
Z2
Radiation typeMo Kα
µ (mm1)4.36
Crystal size (mm)0.16 × 0.15 × 0.13
Data collection
DiffractometerNonius KappaCCD
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
6362, 3364, 3267
Rint0.013
(sin θ/λ)max1)0.832
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.065, 1.09
No. of reflections3364
No. of parameters123
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)1.53, 1.88

Computer programs: DENZO (Otwinowski & Minor, 1997), DENZO, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPII (Johnson,1976), SHELXL97.

Selected bond lengths (Å) top
Mo1—O81.708 (2)Mo2—O72.2658 (6)
Mo1—O51.738 (2)Mo2—O42.3050 (14)
Mo1—O6i1.9198 (14)V1—O21.625 (2)
Mo1—O61.9198 (14)V1—O11.723 (2)
Mo1—O12.196 (2)V1—O41.9202 (14)
Mo1—O72.435 (2)V1—O4i1.9202 (14)
Mo2—O91.7172 (15)V1—O7iii2.107 (2)
Mo2—O31.7235 (15)V1—O72.371 (2)
Mo2—O61.9090 (16)V1—Mo2iii3.1305 (9)
Mo2—O4ii1.9530 (17)V1—Mo2ii3.1305 (9)
Symmetry codes: (i) x, y, z; (ii) x, y, z; (iii) x, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
OW—H1···O10.94 (4)1.87 (4)2.779 (2)162 (4)
OW—H2···O9iv1.02 (6)2.20 (7)2.908 (2)125 (5)
OW—H2···O8v1.02 (6)2.23 (6)3.040 (3)136 (5)
Symmetry codes: (iv) x+1/2, y+1/2, z; (v) x+1, y, z+1.
 

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