The defect scheelite-type lanthanum(III) ortho-oxidomolybdate(VI) La0.667[MoO4]

Schustereit, T.; Schleid, T.; Hartenbach, I.

doi:10.1107/S1600536813000731

inorganic compounds

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Volume 69| Part 2| February 2013| Page i7

doi:10.1107/S1600536813000731

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The defect scheelite-type lanthanum(III) ortho-oxidomolybdate(VI) La_0.667[MoO₄]

Tanja Schustereit,^a Thomas Schleid ^a and Ingo Hartenbach ^a ^*

^aInstitut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
^*Correspondence e-mail: hartenbach@iac.uni-stuttgart.de

(Received 17 December 2012; accepted 8 January 2013; online 16 January 2013)

In scheelite-type La_0.667[MoO₄], one crystallographically unique position with site symmetry -4.. and an occupancy of 2/3 is found for the La³⁺ cation. The cation is surrounded by eight O atoms in the shape of a trigonal dodecahedron. The structure also contains one [MoO₄]²⁻ anion (site symmetry -4..), which is surrounded by eight vertex-attached La³⁺ cations. The polyhedra around the La³⁺ cations are interconnected via common edges, building up a three-dimensional network, in the tetrahedral voids of which the Mo⁶⁺ cations reside.

Related literature

For isotypic Ln_0.667[MoO₄] structures with Ln = Ce, Pr, Nd and Sm, see: Schustereit et al. (2011 ). For synthetic details, see: Liu et al. (2012 ).

Experimental

Crystal data

La_0.667[MoO₄]
M_r = 252.59
Tetragonal, I 4₁ /a
a = 5.3599 (3) Å
c = 11.9425 (7) Å
V = 343.09 (3) Å³
Z = 4
Mo Kα radiation
μ = 11.74 mm⁻¹
T = 293 K
0.11 × 0.08 × 0.06 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1995 ) T_min = 0.291, T_max = 0.480
2577 measured reflections
260 independent reflections
174 reflections with I > 2σ(I)
R_int = 0.046

Refinement

R[F² > 2σ(F²)] = 0.016
wR(F²) = 0.032
S = 0.98
260 reflections
16 parameters
Δρ_max = 0.41 e Å⁻³
Δρ_min = −0.37 e Å⁻³

Table 1
Selected bond lengths (Å)

La—Oⁱ	2.5728 (14)
La—Oⁱⁱ	2.5766 (14)
Mo—O	1.7606 (14)
Symmetry codes: (i) $[y+{\script{1\over 4}}, -x+{\script{1\over 4}}, z+{\script{1\over 4}}]$ ; (ii) $[-x+{\script{1\over 2}}, -y, z+{\script{1\over 2}}]$ .

Data collection: COLLECT (Nonius, 1998 ); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536813000731/wm2715sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813000731/wm2715Isup2.hkl

checkCIF report

Comment top

The title compound crystallizes isotypically with the already known defect scheelite-type lanthanide ortho-oxidomolybdates(VI) with general formula Ln_0.667[MoO₄] (Ln = Ce, Pr, Nd, and Sm; Schustereit et al., 2011). The crystallographically unique La³⁺ cation at Wyckoff position 4b is surrounded by eight oxide anions in the shape of a trigonal dodecahedron (Fig. 1). Besides the lanthanum cation, the structure also contains an isolated and bisphenoidally distorted tetrahedral ortho-oxidomolybdate(VI) unit [MoO₄]^2–. Its central Mo⁶⁺ cation at Wyckoff position 4a exhibits the same site symmetry (4..) as the La³⁺ cation. Hence, in order to maintain electroneutrality, the latter shows a statistically under-occupation of 2/3 on its atomic position. The [MoO₄]^2– tetrahedra share common vertices with eight [LaO₈]^13– dodecahedra to build up the scheelite-type crystal structure (Fig. 2). The cations at the sites 4a (La³⁺) and 4b (Mo⁶⁺) are thereby arranged in two interpenetrating diamond-like lattices (Schustereit et al., 2011).

Related literature top

For isotypic Ln_0.667[MoO₄] structures with Ln = Ce, Pr, Nd and Sm, see: Schustereit et al. (2011). For synthetic details, see: Liu et al. (2012).

Experimental top

Colourless, irregular-shaped single crystals of scheelite-type La_0.667[MoO₄] were obtained as a by-product in an unsuccessful attempt to synthesize LaF[MoO₄] according to the Pecchini method (Liu et al., 2012). Aqueous solutions with stoichiometric amounts of La(NO₃)₃ and (NH₄)₆Mo₇O₂₄ (molar ratio 7 : 1) were prepared for each compound and HF was added to the latter (molar ratio HF : (NH₄)₆Mo₇O₂₄ = 7 : 1). As chelating agent, citric acid (CA) was dissolved in both solutions with a molar ratio of CA : La³⁺ = 1 : 1 and CA : Mo⁶⁺ = 2 : 1. The pH value of the La³⁺-containing solution was adjusted to 3 – 4 with an aqueous ammonia solution as well as the pH value of the CA/HF/(NH₄)₆Mo₇O₂₄ mixture, in this case to a value of 7 – 8. The two solutions were combined, stirred, and heated for about 30 minutes to obtain a transparent solution, which was then dried at 473 K for 5 hours. The residual product was thermally treated in air at 1123 K for 12 hours.

Computing details top

Data collection: COLLECT (Nonius, 1998); cell refinement: SCALEPACK (Otwinowski & Minor, 1997); data reduction: SCALEPACK and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. Trigonal dodecahedral oxygen environment of the La³⁺ cation in defect scheelite-type La_0.667[MoO₄]; ellipsoids are drawn at the 80 % probability level. [Symmetry codes: (i) x, y, z; (ii) –x+1/2, –y, z+1/2; (iii) –y+3/4, x+1/4, z+1/4; (iv) y+3/4, –x+3/4, z+3/4; (v) –x, –y, –z; (vi) x+1/2, y, –z+1/2; (vii) y+1/4, –x+3/4, –z+3/4; (viii) –y+1/4, x+1/4, –z+1/4].
	Fig. 2. View of the crystal structure of defect scheelite-type La_0.667[MoO₄] along [010]; the bisphenoidally distorted tetrahedral ortho-oxidomolybdate(VI) units [MoO₄]^2– are given in the polyhedral representation.

Lanthanum(III) ortho-tetraoxidomolybdate(VI) top

Crystal data top

La_0.667[MoO₄]	D_x = 4.890 Mg m⁻³
M_r = 252.59	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4₁/a	Cell parameters from 1769 reflections
Hall symbol: -I 4ad	θ = 0.4–30.5°
a = 5.3599 (3) Å	µ = 11.74 mm⁻¹
c = 11.9425 (7) Å	T = 293 K
V = 343.09 (3) Å³	Irregular, colourless
Z = 4	0.11 × 0.08 × 0.06 mm
F(000) = 448

Data collection top

Nonius KappaCCD diffractometer	260 independent reflections
Radiation source: fine-focus sealed tube	174 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.046
ω and ϕ scans	θ_max = 30.4°, θ_min = 4.2°
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1995)	h = −7→7
T_min = 0.291, T_max = 0.480	k = −7→7
2577 measured reflections	l = −16→16

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)] = 0.016	w = 1/[σ²(F_o²) + (0.0079P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.032	(Δ/σ)_max < 0.001
S = 0.98	Δρ_max = 0.41 e Å⁻³
260 reflections	Δρ_min = −0.37 e Å⁻³
16 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0082 (5)

Crystal data top

La_0.667[MoO₄]	Z = 4
M_r = 252.59	Mo Kα radiation
Tetragonal, I4₁/a	µ = 11.74 mm⁻¹
a = 5.3599 (3) Å	T = 293 K
c = 11.9425 (7) Å	0.11 × 0.08 × 0.06 mm
V = 343.09 (3) Å³

Data collection top

Nonius KappaCCD diffractometer	260 independent reflections
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1995)	174 reflections with I > 2σ(I)
T_min = 0.291, T_max = 0.480	R_int = 0.046
2577 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.016	16 parameters
wR(F²) = 0.032	0 restraints
S = 0.98	Δρ_max = 0.41 e Å⁻³
260 reflections	Δρ_min = −0.37 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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)
La	0.0000	0.2500	0.6250	0.01492 (18)	0.6676 (10)
Mo	0.0000	0.2500	0.1250	0.01706 (15)
O	0.1374 (3)	0.0106 (2)	0.20490 (13)	0.0313 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
La	0.0171 (2)	0.0171 (2)	0.0107 (2)	0.000	0.000	0.000
Mo	0.01534 (18)	0.01534 (18)	0.0205 (2)	0.000	0.000	0.000
O	0.0209 (8)	0.0329 (9)	0.0403 (9)	0.0048 (6)	0.0031 (9)	0.0105 (7)

Geometric parameters (Å, º) top

La—Oⁱ	2.5728 (14)	La—La^x	4.0120 (2)
La—Oⁱⁱ	2.5728 (14)	La—La^xi	4.0120 (2)
La—Oⁱⁱⁱ	2.5728 (14)	La—La^iv	4.0120 (2)
La—O^iv	2.5728 (14)	Mo—O^xii	1.7605 (14)
La—O^v	2.5766 (14)	Mo—O^xiii	1.7605 (14)
La—O^vi	2.5766 (14)	Mo—O^xiv	1.7605 (14)
La—O^vii	2.5766 (14)	Mo—O	1.7606 (14)
La—O^viii	2.5766 (14)	O—La^iv	2.5728 (14)
La—La^ix	4.0120 (2)	O—La^xv	2.5766 (14)

Oⁱ—La—Oⁱⁱ	128.57 (4)	Oⁱⁱⁱ—La—La^x	161.84 (3)
Oⁱ—La—Oⁱⁱⁱ	75.70 (7)	O^iv—La—La^x	66.64 (3)
Oⁱⁱ—La—Oⁱⁱⁱ	128.57 (4)	O^v—La—La^x	103.20 (4)
Oⁱ—La—O^iv	128.57 (4)	O^vi—La—La^x	38.79 (3)
Oⁱⁱ—La—O^iv	75.70 (7)	O^vii—La—La^x	129.62 (3)
Oⁱⁱⁱ—La—O^iv	128.57 (4)	O^viii—La—La^x	85.04 (3)
Oⁱ—La—O^v	148.98 (6)	La^ix—La—La^x	123.628 (3)
Oⁱⁱ—La—O^v	68.24 (3)	Oⁱ—La—La^xi	161.84 (3)
Oⁱⁱⁱ—La—O^v	74.21 (2)	Oⁱⁱ—La—La^xi	66.64 (3)
O^iv—La—O^v	77.64 (5)	Oⁱⁱⁱ—La—La^xi	103.00 (3)
Oⁱ—La—O^vi	74.21 (2)	O^iv—La—La^xi	38.85 (3)
Oⁱⁱ—La—O^vi	77.64 (5)	O^v—La—La^xi	38.79 (3)
Oⁱⁱⁱ—La—O^vi	148.98 (6)	O^vi—La—La^xi	103.20 (4)
O^iv—La—O^vi	68.24 (3)	O^vii—La—La^xi	85.04 (3)
O^v—La—O^vi	136.53 (7)	O^viii—La—La^xi	129.62 (3)
Oⁱ—La—O^vii	77.64 (5)	La^ix—La—La^xi	123.628 (3)
Oⁱⁱ—La—O^vii	148.98 (6)	La^x—La—La^xi	83.823 (4)
Oⁱⁱⁱ—La—O^vii	68.24 (3)	Oⁱ—La—La^iv	38.85 (3)
O^iv—La—O^vii	74.20 (2)	Oⁱⁱ—La—La^iv	161.84 (3)
O^v—La—O^vii	97.88 (2)	Oⁱⁱⁱ—La—La^iv	66.64 (3)
O^vi—La—O^vii	97.88 (2)	O^iv—La—La^iv	103.00 (3)
Oⁱ—La—O^viii	68.24 (3)	O^v—La—La^iv	129.62 (3)
Oⁱⁱ—La—O^viii	74.20 (2)	O^vi—La—La^iv	85.04 (3)
Oⁱⁱⁱ—La—O^viii	77.64 (5)	O^vii—La—La^iv	38.79 (3)
O^iv—La—O^viii	148.98 (6)	O^viii—La—La^iv	103.20 (4)
O^v—La—O^viii	97.88 (2)	La^ix—La—La^iv	83.823 (4)
O^vi—La—O^viii	97.88 (2)	La^x—La—La^iv	123.628 (3)
O^vii—La—O^viii	136.53 (7)	La^xi—La—La^iv	123.628 (3)
Oⁱ—La—La^ix	66.64 (3)	O^xii—Mo—O^xiii	107.08 (5)
Oⁱⁱ—La—La^ix	103.00 (3)	O^xii—Mo—O^xiv	114.36 (10)
Oⁱⁱⁱ—La—La^ix	38.85 (3)	O^xiii—Mo—O^xiv	107.08 (5)
O^iv—La—La^ix	161.84 (3)	O^xii—Mo—O	107.08 (5)
O^v—La—La^ix	85.04 (3)	O^xiii—Mo—O	114.36 (10)
O^vi—La—La^ix	129.62 (3)	O^xiv—Mo—O	107.08 (5)
O^vii—La—La^ix	103.20 (4)	Mo—O—La^iv	134.75 (7)
O^viii—La—La^ix	38.79 (3)	Mo—O—La^xv	120.66 (7)
Oⁱ—La—La^x	103.00 (3)	La^iv—O—La^xv	102.36 (5)
Oⁱⁱ—La—La^x	38.85 (3)

Symmetry codes: (i) y+1/4, −x+1/4, z+1/4; (ii) x, y+1/2, −z+1; (iii) −y−1/4, x+1/4, z+1/4; (iv) −x, −y, −z+1; (v) x−1/2, y+1/2, z+1/2; (vi) −x+1/2, −y, z+1/2; (vii) −y−1/4, x−1/4, −z+3/4; (viii) y+1/4, −x+3/4, −z+3/4; (ix) −x, −y+1, −z+1; (x) −x+1/2, −y+1/2, −z+3/2; (xi) −x−1/2, −y+1/2, −z+3/2; (xii) y−1/4, −x+1/4, −z+1/4; (xiii) −x, −y+1/2, z; (xiv) −y+1/4, x+1/4, −z+1/4; (xv) x+1/2, y−1/2, z−1/2.

Experimental details

Crystal data
Chemical formula	La_0.667[MoO₄]
M_r	252.59
Crystal system, space group	Tetragonal, I4₁/a
Temperature (K)	293
a, c (Å)	5.3599 (3), 11.9425 (7)
V (Å³)	343.09 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	11.74
Crystal size (mm)	0.11 × 0.08 × 0.06

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	Numerical (X-SHAPE; Stoe & Cie, 1995)
T_min, T_max	0.291, 0.480
No. of measured, independent and observed [I > 2σ(I)] reflections	2577, 260, 174
R_int	0.046
(sin θ/λ)_max (Å⁻¹)	0.712

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.016, 0.032, 0.98
No. of reflections	260
No. of parameters	16
Δρ_max, Δρ_min (e Å⁻³)	0.41, −0.37

Computer programs: COLLECT (Nonius, 1998), SCALEPACK (Otwinowski & Minor, 1997), SCALEPACK and DENZO (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006).

Selected bond lengths (Å) top

La—Oⁱ	2.5728 (14)	Mo—O	1.7606 (14)
La—Oⁱⁱ	2.5766 (14)

Symmetry codes: (i) y+1/4, −x+1/4, z+1/4; (ii) −x+1/2, −y, z+1/2.

Acknowledgements

This work was supported by the State of Baden-Württemberg (Stuttgart) and the Deutsche Forschungsgemeinschaft (DFG, Frankfurt/Main) within the funding program Open Access Publishing.

References

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