Neodymium(III) molybdenum(VI) borate, NdBO₂MoO₄

Single crystals of NdBO₂MoO₄ were obtained from a molybdenum oxide–boron oxide flux under an air atmosphere. The structure features double chains of edge- and face-sharing distorted [NdO₁₀] bicapped square-anti­prisms, which are linked by rows of isolated [MoO₄] tetra­hedra and by zigzag chains of corner-sharing [BO₃] groups, all of them running along the b axis. The chains of [NdO₁₀], chains of [BO₃] and rows of [MoO₄] groups are arranged in layers parallel to the bc plane.

Related literature

A rough investigation of subsolidus phase relations in the pseudo-ternary system Nd₂O₃ – B₂O₃ – MoO₃ has been reported by Lysanova et al. (1983) and Dzhurinskii & Lysanova (1998). X-ray powder diffraction data of LnBO₂MoO₄ (Ln = La, Ce, Pr, Nd) are given by Lysanova et al. (1983). The occurrence of a structural phase transition of LaBO₂MoO₄ was reported by Becker et al. (2008). For determinations of related structures, see: Palkina et al. (1979); Zhao et al. (2008, 2009) for LaBO₂MoO₄; Zhao et al. (2008) for CeBO₂MoO₄.

Experimental

Crystal data

• NdMoBO₆

• M_r = 346.99

• Monoclinic, P 2₁ /c

• a = 10.1218 (19) Å

• b = 4.1420 (5) Å

• c = 11.896 (3) Å

• β = 116.897 (14)°

• V = 444.78 (16) ų

• Z = 4

• Mo Kα radiation

• μ = 14.30 mm⁻¹

• T = 292 K

• 0.30 × 0.20 × 0.15 mm

Data collection

• Enraf–Nonius CAD-4/MACH3 diffractometer

• Absorption correction: ψ scan (MolEN; Fair, 1990) T_min = 0.487, T_max = 0.998

• 5004 measured reflections

• 1344 independent reflections

• 1268 reflections with I > 2σ(I)

• R_int = 0.035

• 3 standard reflections every 100 reflections intensity decay: 2.1%

Refinement

• R[F² > 2σ(F²)] = 0.025

• wR(F²) = 0.063

• S = 1.22

• 1344 reflections

• 83 parameters

• Δρ_max = 2.24 e Å⁻³

• Δρ_min = −1.61 e Å⁻³

Data collection: MACH3 (Enraf–Nonius, 1993); cell refinement: MACH3; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2002); software used to prepare material for publication: publCIF (Westrip, 2010).

Supporting information

S1. Comment

In the family of lanthanide compounds LnBO₂MoO₄ the crystal structure of LaBO₂MoO₄ was first described by Palkina et al. (1979), giving the polar space group P2₁ and lattice constants a = 5.964 (1) Å, b = 4.147 (1) Å, c = 9.373 (3) Å, β = 99.28 (2)°. On the basis of X-ray powder diffraction data, Lysanova et al. (1983) claimed the isomorphism of the compounds LnBO₂MoO₄ with Ln = La, Ce, Pr, Nd. The structure of LaBO₂MoO₄ was redetermined by Zhao et al. (2008), who reported a centrosymmetric structure with space group symmetry P2₁/c with lattice constants a = 10.2968 (8) Å, b = 4.1636 (3) Å, c = 23.8587 (15) Å, β = 115.367 (3)°. These results were corroborated by Zhao et al. (2009), who, however, attributed this crystal structure to a high-temperature modification of LaBO₂MoO₄. The occurrence of a structural phase transition of LaBO₂MoO₄ was reported by Becker et al. (2008). Zhao et al. (2008) also presented the crystal structure of the related cerium compound, CeBO₂MoO₄, with space group P2₁/c and lattice constants a = 10.2404 (15) Å. b = 4.1495 (4) Å, c = 11.9286 (14) Å, β = 116.100 (9)°, and thus showed, that the presumed isomorphism of the lanthanum and the cerium compound is not correct. However, the crystal structures are closely related, with an unit cell of LaBO₂MoO₄ which is doubled with respect to the unit cell of CeBO₂MoO₄. The result of the present study shows, that also NdBO₂MoO₄ is not isomorphic to LaBO₂MoO₄, but is isomorphic to CeBO₂MoO₄.

The crystal structure of NdBO₂MoO₄ consists of groups [BO₃] and [MoO₄] and tenfold coordinated neodymium atoms. The [BO₃] groups are connected via common oxygen ligands to zigzag chains [B₂O₄]_∞ along the b axis, with a periodicity of two [BO₃] groups. The planar [BO₃] groups are slightly distorted with O—B—O angles of 114.4 (4)°, 117.4 (4)° and 128.1 (4)°. They are linked by the common oxygen atom O1 with a bond angle B – O1 – B of 125.6 (3)° (see Fig. 1). The O1 ligands are connected to two boron atoms and one Nd atom, each, while the O2 ligands of the [BO₃] groups are linked to three Nd atoms and one B, each. Mo atoms are tetrahedrally coordinated by the oxygen atoms O3, O4, O5 and O6 (see Fig. 1), with Mo—O distances ranging from 1.740 (4) Å (Mo—O3) to 1.816 (3) Å (Mo—O4) and angles O—Mo—O ranging from 96.3 (2)° (O4—Mo—O3) to 117.5 (2)° (O4—Mo—O6). The [MoO₄] tetrahedra are arranged in rows that run parallel the b axis. Within a single row the [MoO₄] tetrahedra are aligned with their Mo–O3 bonding directions pointing in the same direction approximately parallel to the b axis. Rows with opposite Mo–O3 bonding direction (+b and -b) alternate along the c axis, as shown in Fig. 2. Within a row the distance of a Mo atom to the O3 ligand of the neighbouring tetrahedron amounts 2.419 (3) Å. (Note that in Zhao et al. (2008) a distorted trigonal bipyramid is preferred as description of the coordination surrounding of Mo in CeBO₂MoO₄.) The oxygen atoms O3 and O5 serve as ligands of one Mo and one Nd atom, each, while the oxygen atoms O6 and O4 act as ligands for one Mo and two Nd atoms, each. The tenfold coordination of neodymium atoms in NdBO₂MoO₄ can be described as distorted bicapped square antiprism with Nd—O bonding distances ranging between 2.364 (3) Å (Nd—O2) and 2.981 (4) Å (Nd—O6). [NdO₁₀] polyhedra are connected along the b axis by sharing three common oxygen ligands, namely O2, O6 and O4 (Fig. 1), with each neighbouring polyhedron, thus forming chains along the b axis. Two parallel chains are linked via edges (formed by two common O2 atoms) of the Nd coordination polyhedra, resulting in a double chain along b, see Fig. 2.

Related literature

A rough investigation of subsolidus phase relations in the ternary system Nd₂O₃ – B₂O₃ – MoO₃ has been reported by Lysanova et al. (1983) and Dzhurinskii & Lysanova (1998). X-ray powder diffraction data of LnBO₂MoO₄ (Ln = La, Ce, Pr, Nd) are given by Lysanova et al. (1983). The occurrence of a structural phase transition of LaBO₂MoO₄ was reported by Becker et al. (2008). For structure determinations of related structures, see: Palkina et al. (1979); Zhao et al. (2008, 2009) for LaBO₂MoO₄; Zhao et al. (2008) for CeBO₂MoO₄.

S2. Experimental

NdBO₂MoO₄ melts incongruently, therefore, single crystals of NdBO₂MoO₄ were grown from a melt with a composition differing from the crystal stoichiometry. A homogenized powder mixture of Nd₂O₃ (99.9%, Alfa Aesar), B₂O₃ (99.98%, Alfa Aesar) and MoO₃ (99,95%, Alfa Aesar) in a molar ratio of 1: 1.375: 2.625 was heated in a covered platinum crucible in air atmosphere to 1423 K and subsequently cooled at a rate of 3 K h^-1 to 1173 K. Transparent violet prismatic crystals of the title compound were separated mechanically from the surrounding flux. A suitable single-crystal was carefully selected using a polarizing microscope and mounted in a glass capillary.

S3. Refinement

The final difference maps indicate a maximum of 2.235 e Å^-3 at a distance of 0.66 Å from Nd and a minimum of -1.611 e Å^-3 at a distance of 1.06 Å of Nd.

Computing details

Data collection: MACH3 (Enraf–Nonius, 1993); cell refinement: MACH3 (Enraf–Nonius, 1993); data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ATOMS (Dowty, 2002); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

Fig. 1. The structural units in NdBO2MoO4 with atomic numbering scheme (projection approximately along the b-axis). Atoms are drawn as 50% probability ellipsoids. Symmetry codes: (i) x, y + 1, z; (ii) -x, -y + 1, -z - 1; (iii) -x, -y, -z - 1; (iv) -x + 1, -y, -z - 1; (v) -x + 1, y - 1/2, -z - 1/2; (vi) -x + 1, -y + 1, -z - 1; (vii) -x + 1, y + 1/2, -z - 1/2; (viii) x, y - 1, z; (ix) -x, y - 1/2, -z - 1/2; (x) -x, y + 1/2, -z - 1/2; (xi) x, -y + 1/2, z + 1/2; (xii) x, -y - 1/2, z - 1/2; (xiii) x, 3/2 - y, z - 1/2; (xiv) 1 - x, 1/2 + y, z - 1/2.

Fig. 2. View of the crystal structure of NdBO2MoO4 along the b axis, showing chains of corner-sharing [BO3] groups (green), double-chains of face- and edge-sharing [NdO10] polyhedra (purple), and rows of isolated [MoO4] tetrahedra (orange), all of them running along the b axis. In a single row, [MoO4] tetrahedra are arranged with identical orientation, thus giving a polarity +b or -b to the row. Note the alternating polarity of the arrangement of [MoO4] tetrahedra rows along the c axis.

Neodymium(III) molybdenum(VI) borate

Crystal data

NdMoBO6	F(000) = 620
Mr = 346.99	Dx = 5.182 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 10.1218 (19) Å	θ = 12.1–21.2°
b = 4.1420 (5) Å	µ = 14.30 mm^−1
c = 11.896 (3) Å	T = 292 K
β = 116.897 (14)°	Prism, light violet
V = 444.78 (16) Å^3	0.30 × 0.20 × 0.15 mm
Z = 4

Data collection

Enraf–Nonius CAD4/MACH3 diffractometer	1268 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.035
Graphite monochromator	θmax = 30.4°, θmin = 2.3°
ω/2θ scans	h = −14→14
Absorption correction: ψ scan (MolEN; Fair, 1990)	k = −5→5
Tmin = 0.487, Tmax = 0.998	l = −16→16
5004 measured reflections	3 standard reflections every 100 reflections
1344 independent reflections	intensity decay: 2.1%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.025	w = 1/[σ^2(Fo^2) + (0.0304P)^2 + 1.8082P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.063	(Δ/σ)max < 0.001
S = 1.22	Δρmax = 2.24 e Å^−3
1344 reflections	Δρmin = −1.61 e Å^−3
83 parameters	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0428 (13)

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 is done 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 >2 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 (Ų)

	x	y	z	Uiso*/Ueq
Nd	0.19204 (2)	0.21132 (6)	−0.47183 (2)	0.00919 (11)
Mo	0.64536 (4)	0.30466 (8)	−0.31742 (3)	0.00668 (12)
B	−0.0028 (7)	0.3290 (12)	−0.3083 (5)	0.0182 (10)
O1	−0.0326 (4)	0.6580 (8)	−0.3013 (3)	0.0120 (6)
O2	−0.0035 (3)	0.2247 (7)	−0.4150 (3)	0.0099 (5)
O3	0.6616 (4)	0.7223 (8)	−0.3016 (4)	0.0173 (7)
O4	0.2605 (4)	−0.2856 (7)	−0.3501 (3)	0.0124 (6)
O5	0.4556 (4)	0.2256 (9)	−0.3956 (3)	0.0156 (6)
O6	0.7424 (4)	0.2194 (9)	−0.4084 (4)	0.0190 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nd	0.00733 (14)	0.00900 (16)	0.00992 (14)	−0.00094 (6)	0.00274 (10)	−0.00205 (7)
Mo	0.00602 (17)	0.0087 (2)	0.00546 (17)	−0.00022 (10)	0.00270 (13)	−0.00094 (10)
B	0.040 (3)	0.007 (2)	0.013 (2)	0.0020 (19)	0.017 (2)	−0.0003 (17)
O1	0.0259 (16)	0.0056 (13)	0.0050 (12)	−0.0010 (11)	0.0074 (12)	−0.0004 (10)
O2	0.0108 (13)	0.0118 (14)	0.0084 (13)	−0.0018 (10)	0.0055 (11)	−0.0021 (10)
O3	0.0203 (16)	0.0125 (15)	0.0199 (16)	0.0003 (12)	0.0099 (14)	−0.0002 (12)
O4	0.0173 (15)	0.0091 (14)	0.0067 (13)	−0.0007 (10)	0.0018 (12)	−0.0017 (10)
O5	0.0066 (12)	0.0235 (17)	0.0137 (15)	−0.0009 (11)	0.0019 (11)	−0.0008 (12)
O6	0.0271 (18)	0.0192 (17)	0.0207 (17)	−0.0024 (13)	0.0197 (15)	−0.0039 (13)

Geometric parameters (Å, º)

Nd—O2	2.364 (3)	B—O2	1.338 (6)
Nd—O5	2.399 (3)	B—O1^ix	1.381 (6)
Nd—O4	2.431 (3)	B—O1	1.406 (6)
Nd—O4^i	2.452 (3)	B—Nd^ii	3.099 (6)
Nd—O1^ii	2.498 (3)	B—Nd^iii	3.315 (6)
Nd—O2^iii	2.528 (3)	O1—B^x	1.381 (6)
Nd—O6^iv	2.551 (3)	O1—Nd^ii	2.498 (3)
Nd—O3^v	2.901 (4)	O2—Nd^iii	2.528 (3)
Nd—O2^ii	2.930 (3)	O2—Nd^ii	2.930 (3)
Nd—O6^vi	2.981 (4)	O3—Mo^i	2.419 (3)
Mo—O3	1.740 (4)	O3—Nd^vii	2.901 (4)
Mo—O5	1.745 (3)	O4—Mo^v	1.816 (3)
Mo—O6	1.795 (3)	O4—Nd^viii	2.452 (3)
Mo—O4^vii	1.816 (3)	O6—Nd^iv	2.551 (3)
Mo—O3^viii	2.419 (3)	O6—Nd^vi	2.981 (4)
Mo—Nd^vii	3.5017 (8)
O2—Nd—O5	145.40 (12)	O4^vii—Mo—Nd^vi	128.02 (11)
O2—Nd—O4	84.21 (11)	O3^viii—Mo—Nd^vi	120.27 (9)
O5—Nd—O4	80.04 (12)	Nd^vii—Mo—Nd^vi	103.052 (17)
O2—Nd—O4^i	81.98 (11)	Nd^v—Mo—Nd^vi	135.816 (15)
O5—Nd—O4^i	77.71 (12)	O3—Mo—Nd	99.98 (12)
O4—Nd—O4^i	116.06 (13)	O5—Mo—Nd	7.61 (12)
O2—Nd—O1^ii	95.08 (11)	O6—Mo—Nd	121.06 (13)
O5—Nd—O1^ii	117.89 (12)	O4^vii—Mo—Nd	113.32 (11)
O4—Nd—O1^ii	134.27 (11)	O3^viii—Mo—Nd	87.93 (9)
O4^i—Nd—O1^ii	109.02 (10)	Nd^vii—Mo—Nd	114.650 (15)
O2—Nd—O2^iii	68.97 (12)	Nd^v—Mo—Nd	105.813 (15)
O5—Nd—O2^iii	131.40 (11)	Nd^vi—Mo—Nd	116.653 (16)
O4—Nd—O2^iii	69.84 (11)	O3—Mo—Nd^iv	122.17 (12)
O4^i—Nd—O2^iii	149.91 (11)	O5—Mo—Nd^iv	102.87 (12)
O1^ii—Nd—O2^iii	67.44 (11)	O6—Mo—Nd^iv	20.25 (12)
O2—Nd—O6^iv	129.71 (11)	O4^vii—Mo—Nd^iv	113.64 (11)
O5—Nd—O6^iv	72.70 (12)	O3^viii—Mo—Nd^iv	60.20 (9)
O4—Nd—O6^iv	70.40 (12)	Nd^vii—Mo—Nd^iv	134.533 (16)
O4^i—Nd—O6^iv	148.09 (12)	Nd^v—Mo—Nd^iv	94.773 (16)
O1^ii—Nd—O6^iv	75.67 (12)	Nd^vi—Mo—Nd^iv	60.259 (12)
O2^iii—Nd—O6^iv	61.79 (10)	Nd—Mo—Nd^iv	110.359 (15)
O2—Nd—O3^v	75.40 (11)	O2—B—O1^ix	128.1 (4)
O5—Nd—O3^v	70.07 (11)	O2—B—O1	117.4 (4)
O4—Nd—O3^v	58.78 (10)	O1^ix—B—Nd^ii	155.4 (4)
O4^i—Nd—O3^v	57.31 (10)	O1^ix—B—Nd^iii	102.0 (3)
O1^ii—Nd—O3^v	163.84 (10)	O1—B—Nd^iii	129.6 (4)
O2^iii—Nd—O3^v	119.20 (10)	Nd^ii—B—Nd^iii	80.37 (14)
O6^iv—Nd—O3^v	120.47 (11)	O1^ix—B—Nd	120.0 (3)
O2—Nd—O2^ii	69.96 (11)	O1—B—Nd	111.8 (3)
O5—Nd—O2^ii	122.40 (10)	Nd^ii—B—Nd	84.34 (13)
O4—Nd—O2^ii	154.13 (10)	Nd^iii—B—Nd	74.17 (11)
O4^i—Nd—O2^ii	62.95 (10)	O2—B—Nd^xi	144.1 (4)
O1^ii—Nd—O2^ii	50.40 (10)	O1—B—Nd^xi	90.2 (3)
O2^iii—Nd—O2^ii	98.46 (10)	Nd^ii—B—Nd^xi	142.25 (16)
O6^iv—Nd—O2^ii	125.50 (11)	Nd^iii—B—Nd^xi	132.90 (16)
O3^v—Nd—O2^ii	113.50 (9)	Nd—B—Nd^xi	117.93 (18)
O2—Nd—O6^vi	120.96 (10)	B^x—O1—B	125.6 (3)
O5—Nd—O6^vi	73.22 (11)	B^x—O1—Nd^ii	132.3 (3)
O4—Nd—O6^vi	152.84 (11)	B—O1—Nd^ii	101.4 (3)
O4^i—Nd—O6^vi	62.98 (10)	B^x—O1—Nd^xi	57.4 (2)
O1^ii—Nd—O6^vi	59.13 (11)	B—O1—Nd^xi	68.4 (3)
O2^iii—Nd—O6^vi	126.02 (10)	Nd^ii—O1—Nd^xi	169.04 (12)
O6^iv—Nd—O6^vi	96.66 (11)	B^x—O1—Nd	137.1 (3)
O3^v—Nd—O6^vi	114.35 (10)	B—O1—Nd	49.7 (3)
O2^ii—Nd—O6^vi	52.35 (9)	Nd^ii—O1—Nd	78.20 (8)
O3—Mo—O5	105.76 (17)	Nd^xi—O1—Nd	96.89 (8)
O3—Mo—O6	102.12 (17)	B—O2—Nd	129.3 (3)
O5—Mo—O6	114.36 (17)	B—O2—Nd^iii	114.5 (3)
O3—Mo—O4^vii	96.26 (16)	Nd—O2—Nd^iii	111.03 (12)
O5—Mo—O4^vii	116.79 (16)	B—O2—Nd^ii	84.3 (3)
O6—Mo—O4^vii	117.52 (17)	Nd—O2—Nd^ii	110.04 (11)
O3—Mo—O3^viii	169.5 (2)	Nd^iii—O2—Nd^ii	98.46 (10)
O5—Mo—O3^viii	82.75 (15)	Mo—O3—Mo^i	169.5 (2)
O6—Mo—O3^viii	79.30 (15)	Mo—O3—Nd^vii	94.65 (15)
O4^vii—Mo—O3^viii	74.10 (13)	Mo^i—O3—Nd^vii	94.88 (12)
O3—Mo—Nd^vii	55.67 (13)	Mo—O3—Nd^vi	92.60 (14)
O5—Mo—Nd^vii	121.91 (12)	Mo^i—O3—Nd^vi	84.42 (10)
O6—Mo—Nd^vii	123.02 (13)	Nd^vii—O3—Nd^vi	131.41 (12)
O4^vii—Mo—Nd^vii	40.63 (10)	Mo^v—O4—Nd	110.25 (14)
O3^viii—Mo—Nd^vii	114.71 (9)	Mo^v—O4—Nd^viii	133.69 (16)
O3—Mo—Nd^v	123.03 (13)	Nd—O4—Nd^viii	116.06 (13)
O5—Mo—Nd^v	105.84 (12)	Mo^v—O4—Nd^iii	117.45 (14)
O6—Mo—Nd^v	106.15 (13)	Nd—O4—Nd^iii	71.19 (8)
O4^vii—Mo—Nd^v	26.80 (10)	Nd^viii—O4—Nd^iii	78.89 (8)
O3^viii—Mo—Nd^v	47.32 (9)	Mo—O5—Nd	166.9 (2)
Nd^vii—Mo—Nd^v	67.430 (16)	Mo—O6—Nd^iv	145.65 (19)
O3—Mo—Nd^vi	62.27 (12)	Mo—O6—Nd^vi	115.69 (16)
O5—Mo—Nd^vi	114.60 (12)	Nd^iv—O6—Nd^vi	96.66 (11)
O6—Mo—Nd^vi	41.02 (12)

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