Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803001892/br6077sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536803001892/br6077Isup2.hkl |
Single crystals of Pr3MoO7 were prepared from a stoichiometric amount of Pr6O11, MoO3 and Mo. The initial mixture (ca 5 g) was cold-pressed and loaded into a molybdenum crucible, which was sealed under a low argon pressure using an arc-welding system. The charge was heated at a rate of 300 K h−1 to 1973 K, held at this temperature for 10 min, then cooled at a rate of 100 K h−1 to 1373 K and finally furnace-cooled.
Systematic absences were only consistent with the acentric space group P212121. The atomic coordinates of La, Mo and O from La3MoO7 (Greedan et al., 1997) were used as starting positions in the first stages of the refinement in the present study. Attempts to refine the structure in the space group Pbnm, as suggested by PLATON (Spek, 1998), were unsuccessful and led to an R factor of about 0.10. Refinement of the Flack (1983) parameter gave a value of 0.49 (3), indicating that the crystal studied is a racemic twin.
Data collection: COLLECT (Nonius, 1998); cell refinement: COLLECT; data reduction: DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND(Bergerhoff, 1996); software used to prepare material for publication: SHELXL97.
Fig. 1. Perspective view of Pr3MoO7 along the b axis. Displacement ellipsoids are drawn at the 97% probability level. | |
Fig. 2. Perspective view of Pr3MoO7 along the c axis. |
Pr3MoO7 | F(000) = 1100 |
Mr = 630.67 | Dx = 6.701 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71070 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 11425 reflections |
a = 7.5087 (1) Å | θ = 1–37.8° |
b = 7.6412 (2) Å | µ = 24.91 mm−1 |
c = 10.8952 (2) Å | T = 293 K |
V = 625.12 (2) Å3 | Irregular block, black |
Z = 4 | 0.09 × 0.06 × 0.05 mm |
Nonius KappaCCD diffractometer | 3345 independent reflections |
Radiation source: fine-focus sealed tube | 3222 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.058 |
ϕ scans (κ = 0) + additional ω scans | θmax = 37.8°, θmin = 3.3° |
Absorption correction: multi-scan (Blessing, 1995) | h = −12→12 |
Tmin = 0.139, Tmax = 0.225 | k = −13→12 |
16521 measured reflections | l = −16→18 |
Refinement on F2 | w = 1/[σ2(Fo2) + (0.0091P)2 + 7.1924P] where P = (Fo2 + 2Fc2)/3 |
Least-squares matrix: full | (Δ/σ)max = 0.001 |
R[F2 > 2σ(F2)] = 0.029 | Δρmax = 4.07 e Å−3 |
wR(F2) = 0.067 | Δρmin = −4.05 e Å−3 |
S = 1.05 | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
3345 reflections | Extinction coefficient: 0.0110 (3) |
101 parameters | Absolute structure: Flack (1983) |
0 restraints | Absolute structure parameter: 0.49 (3) |
Primary atom site location: isomorphous structure methods |
Pr3MoO7 | V = 625.12 (2) Å3 |
Mr = 630.67 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.5087 (1) Å | µ = 24.91 mm−1 |
b = 7.6412 (2) Å | T = 293 K |
c = 10.8952 (2) Å | 0.09 × 0.06 × 0.05 mm |
Nonius KappaCCD diffractometer | 3345 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 3222 reflections with I > 2σ(I) |
Tmin = 0.139, Tmax = 0.225 | Rint = 0.058 |
16521 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.067 | Δρmax = 4.07 e Å−3 |
S = 1.05 | Δρmin = −4.05 e Å−3 |
3345 reflections | Absolute structure: Flack (1983) |
101 parameters | Absolute structure parameter: 0.49 (3) |
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. |
x | y | z | Uiso*/Ueq | ||
Mo | 0.49773 (5) | 1.00093 (5) | 0.74955 (5) | 0.00537 (7) | |
Pr1 | 0.98074 (4) | 1.00637 (3) | 0.75374 (3) | 0.01071 (7) | |
Pr2 | 0.70257 (3) | 0.75417 (4) | 0.53386 (2) | 0.00700 (6) | |
Pr3 | 0.69200 (3) | 0.74788 (4) | −0.01812 (2) | 0.00686 (6) | |
O1 | 1.2042 (7) | 1.0298 (5) | 1.3685 (4) | 0.0126 (8) | |
O2 | 1.1372 (7) | 1.0505 (5) | 1.1117 (4) | 0.0161 (9) | |
O3 | 0.9590 (5) | 0.7487 (7) | −0.1179 (3) | 0.0092 (5) | |
O4 | 0.7888 (7) | 0.9639 (5) | 0.1292 (4) | 0.0119 (8) | |
O5 | 0.5707 (5) | 0.7473 (4) | −0.2398 (3) | 0.0095 (5) | |
O6 | 0.8275 (7) | 0.9616 (5) | 0.3754 (4) | 0.0116 (8) | |
O7 | 0.9904 (5) | 0.7577 (6) | 0.6184 (3) | 0.0088 (6) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Mo | 0.00628 (14) | 0.00418 (14) | 0.00564 (13) | 0.00035 (10) | −0.00025 (8) | −0.00016 (11) |
Pr1 | 0.01858 (13) | 0.00594 (10) | 0.00763 (10) | −0.00259 (9) | −0.00359 (9) | 0.00055 (8) |
Pr2 | 0.00728 (10) | 0.00670 (11) | 0.00702 (9) | −0.00024 (11) | −0.00112 (7) | 0.00025 (9) |
Pr3 | 0.00684 (10) | 0.00639 (11) | 0.00736 (9) | −0.00004 (11) | 0.00108 (7) | −0.00012 (9) |
O1 | 0.015 (2) | 0.0111 (16) | 0.0122 (15) | −0.0014 (15) | −0.0070 (16) | 0.0011 (13) |
O2 | 0.027 (3) | 0.0101 (16) | 0.0113 (16) | −0.0038 (15) | 0.0107 (16) | −0.0008 (13) |
O3 | 0.0061 (13) | 0.0118 (15) | 0.0099 (12) | −0.0009 (15) | −0.0013 (11) | 0.0003 (14) |
O4 | 0.017 (2) | 0.0078 (15) | 0.0107 (14) | −0.0015 (14) | −0.0037 (16) | −0.0005 (12) |
O5 | 0.0112 (13) | 0.0049 (12) | 0.0124 (12) | 0.0004 (11) | −0.0004 (11) | −0.0001 (16) |
O6 | 0.016 (2) | 0.0078 (15) | 0.0112 (15) | −0.0014 (13) | 0.0047 (14) | −0.0016 (12) |
O7 | 0.0086 (15) | 0.0109 (15) | 0.0070 (12) | 0.0038 (15) | 0.0002 (9) | 0.0013 (14) |
Mo—O2i | 1.854 (4) | Pr2—O7x | 2.302 (3) |
Mo—O6ii | 1.920 (5) | Pr2—O7 | 2.349 (3) |
Mo—O5iii | 1.954 (3) | Pr2—O4ii | 2.392 (4) |
Mo—O1i | 2.008 (5) | Pr2—O1xi | 2.416 (4) |
Mo—O5iv | 2.018 (3) | Pr2—O6 | 2.524 (4) |
Mo—O4ii | 2.088 (5) | Pr2—O2xii | 2.527 (4) |
Mo—Pr2 | 3.3828 (6) | Pr2—O5iv | 2.658 (3) |
Mo—Pr2v | 3.4021 (5) | Pr2—Moxiii | 3.4021 (5) |
Mo—Pr3iii | 3.4566 (6) | Pr2—Pr1i | 3.8154 (4) |
Mo—Pr3iv | 3.5034 (6) | Pr2—Pr1xii | 3.8203 (4) |
Mo—Pr1 | 3.6273 (4) | Pr3—O3 | 2.280 (4) |
Pr1—O7vi | 2.382 (4) | Pr3—O3xiv | 2.293 (4) |
Pr1—O7 | 2.406 (4) | Pr3—O4 | 2.414 (4) |
Pr1—O3vii | 2.414 (5) | Pr3—O1xii | 2.458 (4) |
Pr1—O3iv | 2.420 (5) | Pr3—O6i | 2.509 (4) |
Pr1—O4ii | 2.447 (5) | Pr3—O2x | 2.531 (4) |
Pr1—O6ii | 2.678 (5) | Pr3—O5 | 2.581 (3) |
Pr1—O1viii | 2.690 (5) | Pr3—Moxv | 3.4566 (6) |
Pr1—Pr2 | 3.7169 (4) | Pr3—Moxvi | 3.5034 (6) |
Pr1—Pr3ii | 3.7393 (4) | Pr3—Pr1i | 3.7393 (4) |
Pr1—Pr2ii | 3.8154 (4) | Pr3—Pr3xvii | 3.7752 |
Pr1—Pr3ix | 3.8194 (4) | Pr3—Pr3xiv | 3.7752 |
O2i—Mo—O6ii | 169.7 (2) | O7—Pr2—O1xi | 80.39 (16) |
O2i—Mo—O5iii | 90.94 (17) | O4ii—Pr2—O1xi | 128.12 (12) |
O6ii—Mo—O5iii | 94.31 (16) | O7x—Pr2—O6 | 77.82 (15) |
O2i—Mo—O1i | 94.9 (2) | O7—Pr2—O6 | 85.36 (15) |
O6ii—Mo—O1i | 94.2 (2) | O4ii—Pr2—O6 | 73.82 (13) |
O5iii—Mo—O1i | 87.10 (16) | O1xi—Pr2—O6 | 149.65 (13) |
O2i—Mo—O5iv | 89.50 (16) | O7x—Pr2—O2xii | 81.55 (16) |
O6ii—Mo—O5iv | 85.20 (16) | O7—Pr2—O2xii | 79.35 (16) |
O5iii—Mo—O5iv | 179.46 (6) | O4ii—Pr2—O2xii | 144.50 (17) |
O1i—Mo—O5iv | 93.18 (15) | O1xi—Pr2—O2xii | 73.79 (14) |
O2i—Mo—O4ii | 86.5 (2) | O6—Pr2—O2xii | 77.32 (13) |
O6ii—Mo—O4ii | 84.52 (18) | O7x—Pr2—O5iv | 114.20 (12) |
O5iii—Mo—O4ii | 92.49 (15) | O7—Pr2—O5iv | 88.81 (11) |
O1i—Mo—O4ii | 178.6 (2) | O4ii—Pr2—O5iv | 67.99 (12) |
O5iv—Mo—O4ii | 87.22 (15) | O1xi—Pr2—O5iv | 64.89 (12) |
O7vi—Pr1—O7 | 172.81 (4) | O6—Pr2—O5iv | 141.76 (11) |
O7vi—Pr1—O3vii | 73.92 (12) | O2xii—Pr2—O5iv | 138.38 (12) |
O7—Pr1—O3vii | 102.97 (15) | O3—Pr3—O3xiv | 168.18 (11) |
O7vi—Pr1—O3iv | 108.90 (15) | O3—Pr3—O4 | 92.88 (16) |
O7—Pr1—O3iv | 73.38 (12) | O3xiv—Pr3—O4 | 78.02 (16) |
O3vii—Pr1—O3iv | 172.36 (9) | O3—Pr3—O1xii | 92.25 (16) |
O7vi—Pr1—O4ii | 108.95 (12) | O3xiv—Pr3—O1xii | 79.70 (15) |
O7—Pr1—O4ii | 76.01 (13) | O4—Pr3—O1xii | 85.83 (12) |
O3vii—Pr1—O4ii | 75.16 (13) | O3—Pr3—O6i | 80.11 (17) |
O3iv—Pr1—O4ii | 109.88 (13) | O3xiv—Pr3—O6i | 104.14 (17) |
O7vi—Pr1—O6ii | 73.48 (12) | O4—Pr3—O6i | 73.74 (13) |
O7—Pr1—O6ii | 113.66 (13) | O1xii—Pr3—O6i | 157.67 (13) |
O3vii—Pr1—O6ii | 113.30 (13) | O3—Pr3—O2x | 87.33 (17) |
O3iv—Pr1—O6ii | 74.33 (13) | O3xiv—Pr3—O2x | 98.42 (17) |
O4ii—Pr1—O6ii | 63.35 (13) | O4—Pr3—O2x | 158.83 (13) |
O7vi—Pr1—O1viii | 74.38 (13) | O1xii—Pr3—O2x | 73.01 (13) |
O7—Pr1—O1viii | 100.22 (12) | O6i—Pr3—O2x | 126.96 (12) |
O3vii—Pr1—O1viii | 101.47 (12) | O3—Pr3—O5 | 82.20 (11) |
O3iv—Pr1—O1viii | 72.98 (12) | O3xiv—Pr3—O5 | 109.59 (12) |
O4ii—Pr1—O1viii | 174.02 (15) | O4—Pr3—O5 | 136.84 (12) |
O6ii—Pr1—O1viii | 122.63 (14) | O1xii—Pr3—O5 | 136.98 (12) |
O7x—Pr2—O7 | 156.88 (10) | O6i—Pr3—O5 | 63.16 (12) |
O7x—Pr2—O4ii | 111.54 (16) | O2x—Pr3—O5 | 64.16 (12) |
O7—Pr2—O4ii | 78.14 (17) | Moxv—O5—Moxvi | 148.3 (2) |
O7x—Pr2—O1xi | 106.58 (16) |
Symmetry codes: (i) −x+3/2, −y+2, z−1/2; (ii) −x+3/2, −y+2, z+1/2; (iii) −x+1, y+1/2, −z+1/2; (iv) x, y, z+1; (v) −x+1, y+1/2, −z+3/2; (vi) −x+2, y+1/2, −z+3/2; (vii) −x+2, y+1/2, −z+1/2; (viii) −x+5/2, −y+2, z−1/2; (ix) x+1/2, −y+3/2, −z+1; (x) x−1/2, −y+3/2, −z+1; (xi) x−1/2, −y+3/2, −z+2; (xii) −x+2, y−1/2, −z+3/2; (xiii) −x+1, y−1/2, −z+3/2; (xiv) x−1/2, −y+3/2, −z; (xv) −x+1, y−1/2, −z+1/2; (xvi) x, y, z−1; (xvii) x+1/2, −y+3/2, −z. |
Experimental details
Crystal data | |
Chemical formula | Pr3MoO7 |
Mr | 630.67 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 293 |
a, b, c (Å) | 7.5087 (1), 7.6412 (2), 10.8952 (2) |
V (Å3) | 625.12 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 24.91 |
Crystal size (mm) | 0.09 × 0.06 × 0.05 |
Data collection | |
Diffractometer | Nonius KappaCCD diffractometer |
Absorption correction | Multi-scan (Blessing, 1995) |
Tmin, Tmax | 0.139, 0.225 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 16521, 3345, 3222 |
Rint | 0.058 |
(sin θ/λ)max (Å−1) | 0.862 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.067, 1.05 |
No. of reflections | 3345 |
No. of parameters | 101 |
Δρmax, Δρmin (e Å−3) | 4.07, −4.05 |
Absolute structure | Flack (1983) |
Absolute structure parameter | 0.49 (3) |
Computer programs: COLLECT (Nonius, 1998), COLLECT, DENZO and SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND(Bergerhoff, 1996), SHELXL97.
Mo—O2i | 1.854 (4) | Pr2—O7 | 2.349 (3) |
Mo—O6ii | 1.920 (5) | Pr2—O4ii | 2.392 (4) |
Mo—O5iii | 1.954 (3) | Pr2—O1ix | 2.416 (4) |
Mo—O1i | 2.008 (5) | Pr2—O6 | 2.524 (4) |
Mo—O5iv | 2.018 (3) | Pr2—O2x | 2.527 (4) |
Mo—O4ii | 2.088 (5) | Pr2—O5iv | 2.658 (3) |
Pr1—O7v | 2.382 (4) | Pr3—O3 | 2.280 (4) |
Pr1—O7 | 2.406 (4) | Pr3—O3xi | 2.293 (4) |
Pr1—O3vi | 2.414 (5) | Pr3—O4 | 2.414 (4) |
Pr1—O3iv | 2.420 (5) | Pr3—O1x | 2.458 (4) |
Pr1—O4ii | 2.447 (5) | Pr3—O6i | 2.509 (4) |
Pr1—O6ii | 2.678 (5) | Pr3—O2viii | 2.531 (4) |
Pr1—O1vii | 2.690 (5) | Pr3—O5 | 2.581 (3) |
Pr2—O7viii | 2.302 (3) | ||
Moxii—O5—Moxiii | 148.3 (2) |
Symmetry codes: (i) −x+3/2, −y+2, z−1/2; (ii) −x+3/2, −y+2, z+1/2; (iii) −x+1, y+1/2, −z+1/2; (iv) x, y, z+1; (v) −x+2, y+1/2, −z+3/2; (vi) −x+2, y+1/2, −z+1/2; (vii) −x+5/2, −y+2, z−1/2; (viii) x−1/2, −y+3/2, −z+1; (ix) x−1/2, −y+3/2, −z+2; (x) −x+2, y−1/2, −z+3/2; (xi) x−1/2, −y+3/2, −z; (xii) −x+1, y−1/2, −z+1/2; (xiii) x, y, z−1. |
The Ln3MO7 compounds, where M is a pentavalent 4 d or 5 d transition element such as Nb, Mo, Ru, Ir, Os or Ta, and Ln is a rare earth, present an ordered double-fluorite structure and crystallize in various orthorhombic space groups, such as Pnma, Cmcm, C2221 or P212121. The main structural feature of the Ln3MoO7 compounds is the occurrence of zigzag chains of trans-corner-sharing MO6 octahedra that are separated by seven or eight-coordinate Ln–O polyhedra. Because of this quasi-one-dimensionality, La3RuO7, La3OsO7 (Lam et al., 2002), Ln3OsO7 (Ln = Pr, Nd, Sm; Plaisier et al., 2002), La3MoO7 (Greedan et al., 1997), Ln3RuO7 (Ln = Sm, Eu; Harada & Hinatsu, 2001) and Pr3MO7 (M = Nb, Ta; Vente et al., 1994) have been extensively studied for their physical properties.
We present here the crystal structure of Pr3MoO7. This compound was first synthesized as a powder sample by Prévost-Czeskleba (1987) and found to crystallize in the orthorhombic space group Cmcm as Nd3NbO7 (Rossel, 1979).
Our investigation on a single-crystal indicates that Pr3MoO7 crystallizes in the space group P212121 and is isostructural with La3MoO7 (Greedan et al., 1997). Perspective views of Pr3MoO7 along the b and c axes are shown in Figs. 1 and 2, respectively. The Mo—O distances within the MoO6 octahedra range from 1.854 (4) to 2.088 (5) Å [1.861 (3)–2.098 (4) Å in La3MoO7], with an average value of 1.974 Å compared to 1.981 Å in La3MoO7. The three crystallographically independent Pr3+ ions are each surrounded by seven O atoms. The oxygen environment of Pr1 can be viewed as a highly distorted cube, with one apex missing and those of Pr2 and Pr3 as distorted pentagonal bipyramids. The Pr—O distances are in the ranges 2.382 (4)–2.690 (5), 2.302 (3)–2.658 (3) and 2.280 (4)–2.581 (3) Å for the Pr1, Pr2 and Pr3 sites, respectively. As mentioned in the Experimental, the structure presents a Pbnm pseudosymmetry. The non-centrosymmetric nature of the structure arises probably from the Pr1 ion that does not reside at an inversion center as revealed by the refinement made in the space group Pbnm.