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Dipotassium molybdenyl diphosphate is built up from ribbons of MoO6 octahedra linked to P2O7 groups running along the c axis. The K+ cations are located in the channels delimited by anionic (MoO2P2O7)n ribbons. The structure contains MoP2O11 units, in which each P2O7 group shares two of its apices with an MoO6 octahedron. The title compound is isotypic with (NH4)2MoO2P2O7. K2MoO2P2O7 (one-dimensional) is related structurally to Na2VOP2O7 (two-dimensional) and β-BaV2(P2O7)2 (three-dimensional), all of them being built up from MP2O11 (M = Mo, V) units.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803007001/dn6060sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536803007001/dn6060Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](P-O) = 0.004 Å
  • R factor = 0.033
  • wR factor = 0.077
  • Data-to-parameter ratio = 14.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry








Comment top

La recherche des matériaux à charpente bidimensionnelle fait l'objet de nombreuses investigations, compte tenu de leur importance en catalyse hétérogène (Nguyen & Sleight, 1996; Centi et al., 1988) ou bien en conductivité ionique (Daidouh et al., 1997; Lii & Wang, 1989). L'exploration du système K–Mo–As–O, nous a permis de caractériser les composés en couches K2MoO2As2O7 (Zid & Jouini, 1996a) et K2MoO2(MoO2As2O7)2 (Zid & Jouini, 1996b). Nous avons alors cherché à synthétiser les diphosphates équivalents afin de réaliser une étude comparative, des propriétés potentielles, entre diarséniates et diphosphates. C'est ainsi que, dans le système K–Mo–P–O, K2MoO2P2O7 a été isolé. Ce composé de formulation analogue à K2MoO2As2O7 s'avère isostructural au sel de diammonium homologue (NH4)2MoO2P2O7 (Averbuch-Pouchot, 1988), comme c'est souvent le cas pour les cations K+ et (NH4)+. La Fig. 1 montre clairement l'aspect unidimendionnel de l'enchaînement des octaèdres MoO6 et des groupements diphosphates P2O7 dans la structure de K2MoO2P2O7, mettant en évidence l'espace où logent les cation K+.

La structure de K2MoO2P2O7 est caractérisée par l'existence de l'unité cyclique MoP2O11 qui se manifeste fréquement dans les composés de formulation AMP2O7 (A = Alcalin et M = Métal trivalent) (Riou et al., 1989; Wang & Hwu, 1991; Belkouch et al., 1995) forme ici des rubans infinis (MoO2P2O7)2-, parallèles à l'axe c (Fig. 2), au moyen des liaisons mixtes Mo–O–P. Les cations situés entre les rubans assurent leur assemblage (Fig. 1). De plus si on se limite à une sphère de rayon égal à 3,06 Å [rmax(K+) = 1,64 Å e t rmax(O2-) = 1,42 Å] d'après Shannon (1976), ils sont hexacoordinés (Tableau 2). La structure présente des distances en accord avec le nombre et la nature des liaisons formées. Les calculs des forces de valence de ces liaisons d'après la formule développée par Brown (Brown & Altermatt, 1985; Brese & O'Keeffe, 1991) aboutissent aux valeurs: Mo(+6,01), P1(+4,81), P2(+4,79), K1(+1,06) e t K2(+0,88). Elles sont proches des charges des cations dans le diphosphate étudié. La comparaison de la structure de K2MoO2P2O7 avec celles des composés renfermant les mêmes types de rubans montre que ces derniers se connectent par partage des sommets entre octaèdres et tétraèdres pour former une charpente deux-dimendionnel similaire à celle rencontrée dans le matériau en couche Na2VOP2O7 (Benhamada et al., 1992), et par formation de ponts mixtes M–O–P (M = Mo, V) dans les trois directions a, b et c pour conduire à celle trois-dimendionnel de β-BaV2(P2O7)2 (Hwu et al., 1994).

Experimental top

K2MoO2P2O7 a été préparé, sous forme de poudre polycristalline, à partir de KH2PO4 et (NH4)2Mo4O13 pris dans les proportions K:P:Mo = 2:2:1. L'échantillon initial, finement broyé, est préchauffé à l'air à 573 K en vue de l'élimination de NH3 et H2O puis porté à la fusion à 988 K pendant quatre heures. Il est ensuite soumis à un refroidissement lent à la vitesse de 2° par heure jusqu'à 968 K, pour favoriser la germination des cristaux, le mélange étant alors à l'état pâteux, il est maintenu à cette température pendant quatre jours. Un second refroidissement lent (5 K h-1) a été effectué jusqu'à 903 K, puis plus rapide à 50 K h-1 avant d'être ramené à la température ambiante. Les cristaux obtenus, de couleur jaunâtre, sont séparés du flux à l'eau bouillante.

Computing details top

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, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. Projection de la stucture de K2MoO2P2O7 selon c.
[Figure 2] Fig. 2. Projection de la stucture de K2MoO2P2O7 selon b.
Dipotassium molybdenyl diphosphate top
Crystal data top
K2MoO2P2O7F(000) = 1456
Mr = 380.1Dx = 2.962 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 25 reflections
a = 13.778 (1) Åθ = 8–15°
b = 8.0216 (9) ŵ = 2.92 mm1
c = 15.595 (1) ÅT = 293 K
β = 98.44 (1)°Prism, yellow
V = 1704.9 (3) Å30.12 × 0.10 × 0.08 mm
Z = 8
Data collection top
Enraf-Nonius CAD-4
diffractometer
1453 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.017
Graphite monochromatorθmax = 27.0°, θmin = 2.6°
ω/2θ scansh = 017
Absorption correction: ψ scan
(North et al., 1968)
k = 010
Tmin = 0.721, Tmax = 0.800l = 1919
1919 measured reflections2 standard reflections every 120 min
1843 independent reflections intensity decay: 2%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.033 w = 1/[σ2(Fo2) + (0.0099P)2 + 17.97P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.077(Δ/σ)max = 0.014
S = 1.13Δρmax = 0.60 e Å3
1843 reflectionsΔρmin = 0.65 e Å3
128 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.00044 (7)
Crystal data top
K2MoO2P2O7V = 1704.9 (3) Å3
Mr = 380.1Z = 8
Monoclinic, C2/cMo Kα radiation
a = 13.778 (1) ŵ = 2.92 mm1
b = 8.0216 (9) ÅT = 293 K
c = 15.595 (1) Å0.12 × 0.10 × 0.08 mm
β = 98.44 (1)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
1453 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.017
Tmin = 0.721, Tmax = 0.8002 standard reflections every 120 min
1919 measured reflections intensity decay: 2%
1843 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0330 restraints
wR(F2) = 0.077 w = 1/[σ2(Fo2) + (0.0099P)2 + 17.97P]
where P = (Fo2 + 2Fc2)/3
S = 1.13Δρmax = 0.60 e Å3
1843 reflectionsΔρmin = 0.65 e Å3
128 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
xyzUiso*/Ueq
Mo0.11455 (3)0.64360 (6)0.36439 (3)0.0109 (1)
K10.14457 (9)0.1634 (2)0.23762 (8)0.0213 (3)
K20.1416 (1)0.9143 (2)0.47828 (9)0.0239 (3)
P10.1293 (1)0.5808 (2)0.34432 (9)0.0116 (3)
P20.0378 (1)0.3007 (2)0.42395 (9)0.0112 (3)
O10.2230 (3)0.6669 (5)0.3785 (2)0.0171 (8)
O20.0373 (3)0.6790 (5)0.3552 (2)0.0141 (8)
O30.0270 (3)0.1476 (5)0.3689 (2)0.0200 (9)
O40.0534 (3)0.4096 (5)0.4174 (2)0.0158 (8)
O50.0724 (3)0.2488 (5)0.5193 (2)0.0149 (8)
O60.1279 (3)0.4102 (5)0.3988 (2)0.0172 (9)
O70.1239 (3)0.5159 (5)0.2495 (2)0.0178 (9)
O80.2245 (3)0.5729 (6)0.3882 (3)0.0216 (9)
O90.1462 (3)0.8279 (5)0.3135 (2)0.0196 (9)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mo0.0108 (2)0.0122 (2)0.0096 (2)0.0019 (2)0.0011 (2)0.0014 (2)
K10.0177 (6)0.0265 (7)0.0192 (6)0.0038 (6)0.0012 (5)0.0034 (6)
K20.0246 (7)0.0214 (7)0.0253 (7)0.0026 (6)0.0025 (5)0.0010 (6)
P10.0115 (6)0.0134 (7)0.0101 (6)0.0007 (6)0.0020 (5)0.0011 (5)
P20.0122 (6)0.0117 (7)0.0097 (6)0.0018 (5)0.0015 (5)0.0006 (5)
O10.012 (2)0.020 (2)0.019 (2)0.001 (2)0.001 (2)0.002 (2)
O20.013 (2)0.013 (2)0.017 (2)0.002 (2)0.004 (2)0.001 (2)
O30.023 (2)0.018 (2)0.017 (2)0.003 (2)0.003 (2)0.005 (2)
O40.016 (2)0.013 (2)0.019 (2)0.003 (2)0.005 (2)0.003 (2)
O50.020 (2)0.012 (2)0.012 (2)0.004 (2)0.000 (2)0.002 (2)
O60.013 (2)0.021 (2)0.018 (2)0.004 (2)0.004 (2)0.011 (2)
O70.025 (2)0.018 (2)0.011 (2)0.002 (2)0.003 (2)0.001 (2)
O80.014 (2)0.029 (2)0.023 (2)0.001 (2)0.005 (2)0.004 (2)
O90.028 (2)0.015 (2)0.016 (2)0.006 (2)0.000 (2)0.004 (2)
Geometric parameters (Å, º) top
Mo—O91.705 (4)K2—P1vii3.8797 (19)
Mo—O81.708 (4)P1—O11.491 (4)
Mo—O5i2.016 (4)P1—O21.523 (4)
Mo—O7ii2.037 (4)P1—O71.559 (4)
Mo—O22.137 (4)P1—O61.613 (4)
Mo—O42.170 (4)P1—K1x3.5977 (19)
Mo—K1iii3.6086 (14)P1—K2vii3.8797 (19)
K1—O3ii2.686 (4)P2—O31.493 (4)
K1—O1iv2.753 (4)P2—O41.521 (4)
K1—O32.794 (4)P2—O51.550 (4)
K1—O9v2.807 (4)P2—O61.616 (4)
K1—O8vi2.837 (4)P2—K1ii3.4663 (19)
K1—O72.851 (4)P2—K2xi3.466 (2)
K1—O4ii3.230 (4)P2—K2i3.537 (2)
K1—O9vi3.232 (4)O1—K2vii2.769 (4)
K1—O63.234 (4)O1—K1x2.753 (4)
K1—O7iv3.380 (4)O3—K1ii2.686 (4)
K1—P2ii3.4663 (19)O3—K2xi2.848 (4)
K1—P1iv3.5977 (19)O4—K1ii3.230 (4)
K2—O1vii2.769 (4)O4—K2i3.384 (4)
K2—O8viii2.786 (4)O5—Moi2.016 (4)
K2—O12.851 (4)O5—K2xi2.950 (4)
K2—O3ix2.848 (4)O5—K2i3.231 (4)
K2—O5ix2.950 (4)O7—Moii2.037 (4)
K2—O22.916 (4)O7—K1x3.380 (4)
K2—O5i3.231 (4)O8—K2xii2.786 (4)
K2—O4i3.384 (4)O8—K1iii2.837 (4)
K2—P13.383 (2)O9—K1xiii2.807 (4)
K2—P2ix3.466 (2)O9—K1iii3.232 (4)
K2—P2i3.537 (2)
O9—Mo—O8102.4 (2)O2—Mo—O479.1 (2)
O9—Mo—O5i93.9 (2)O1—P1—O2114.3 (2)
O8—Mo—O5i95.4 (2)O1—P1—O7114.3 (2)
O9—Mo—O7ii92.9 (2)O2—P1—O7110.7 (2)
O8—Mo—O7ii94.5 (2)O1—P1—O6106.4 (2)
O5i—Mo—O7ii166.5 (2)O2—P1—O6107.8 (2)
O9—Mo—O292.3 (2)O7—P1—O6102.3 (2)
O8—Mo—O2165.2 (2)O3—P2—O4115.0 (2)
O5i—Mo—O281.2 (2)O3—P2—O5108.7 (2)
O7ii—Mo—O286.9 (2)O4—P2—O5110.7 (2)
O9—Mo—O4170.4 (2)O3—P2—O6108.8 (2)
O8—Mo—O486.4 (2)O4—P2—O6109.1 (2)
O5i—Mo—O489.0 (2)O5—P2—O6103.9 (2)
O7ii—Mo—O482.4 (2)P1—O6—P2131.2 (2)
Symmetry codes: (i) x, y+1, z+1; (ii) x, y, z+1/2; (iii) x1/2, y+1/2, z; (iv) x+1/2, y1/2, z+1/2; (v) x, y1, z+1/2; (vi) x+1/2, y1/2, z; (vii) x+1/2, y+3/2, z+1; (viii) x+1/2, y+1/2, z; (ix) x, y+1, z; (x) x+1/2, y+1/2, z+1/2; (xi) x, y1, z; (xii) x1/2, y1/2, z; (xiii) x, y+1, z+1/2.

Experimental details

Crystal data
Chemical formulaK2MoO2P2O7
Mr380.1
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)13.778 (1), 8.0216 (9), 15.595 (1)
β (°) 98.44 (1)
V3)1704.9 (3)
Z8
Radiation typeMo Kα
µ (mm1)2.92
Crystal size (mm)0.12 × 0.10 × 0.08
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.721, 0.800
No. of measured, independent and
observed [I > 2σ(I)] reflections
1919, 1843, 1453
Rint0.017
(sin θ/λ)max1)0.638
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.033, 0.077, 1.13
No. of reflections1843
No. of parameters128
w = 1/[σ2(Fo2) + (0.0099P)2 + 17.97P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)0.60, 0.65

Computer programs: CAD-4 EXPRESS (Duisenberg, 1992; Macíček & Yordanov, 1992), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg, 1998), SHELXL97.

Selected geometric parameters (Å, º) top
Mo—O91.705 (4)K2—O8vii2.786 (4)
Mo—O81.708 (4)K2—O12.851 (4)
Mo—O5i2.016 (4)K2—O3viii2.848 (4)
Mo—O7ii2.037 (4)K2—O5viii2.950 (4)
Mo—O22.137 (4)K2—O22.916 (4)
Mo—O42.170 (4)P1—O11.491 (4)
K1—O3ii2.686 (4)P1—O21.523 (4)
K1—O1iii2.753 (4)P1—O71.559 (4)
K1—O32.794 (4)P1—O61.613 (4)
K1—O9iv2.807 (4)P2—O31.493 (4)
K1—O8v2.837 (4)P2—O41.521 (4)
K1—O72.851 (4)P2—O51.550 (4)
K2—O1vi2.769 (4)P2—O61.616 (4)
O9—Mo—O8102.4 (2)O2—Mo—O479.1 (2)
O9—Mo—O5i93.9 (2)O1—P1—O2114.3 (2)
O8—Mo—O5i95.4 (2)O1—P1—O7114.3 (2)
O9—Mo—O7ii92.9 (2)O2—P1—O7110.7 (2)
O8—Mo—O7ii94.5 (2)O1—P1—O6106.4 (2)
O5i—Mo—O7ii166.5 (2)O2—P1—O6107.8 (2)
O9—Mo—O292.3 (2)O7—P1—O6102.3 (2)
O8—Mo—O2165.2 (2)O3—P2—O4115.0 (2)
O5i—Mo—O281.2 (2)O3—P2—O5108.7 (2)
O7ii—Mo—O286.9 (2)O4—P2—O5110.7 (2)
O9—Mo—O4170.4 (2)O3—P2—O6108.8 (2)
O8—Mo—O486.4 (2)O4—P2—O6109.1 (2)
O5i—Mo—O489.0 (2)O5—P2—O6103.9 (2)
O7ii—Mo—O482.4 (2)P1—O6—P2131.2 (2)
Symmetry codes: (i) x, y+1, z+1; (ii) x, y, z+1/2; (iii) x+1/2, y1/2, z+1/2; (iv) x, y1, z+1/2; (v) x+1/2, y1/2, z; (vi) x+1/2, y+3/2, z+1; (vii) x+1/2, y+1/2, z; (viii) x, y+1, z.
 

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