Poly[[tetra­aqua­di-μ4-oxalato-μ2-oxalato-dineo­dymium(III)] dihydrate]

Cao, G.-J.; Rong, C.; Li, Q.; Jiang, W.-J.

doi:10.1107/S1600536812005016

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 68| Part 3| March 2012| Page m289

doi:10.1107/S1600536812005016

Open

access

Poly[[tetraaquadi-μ₄-oxalato-μ₂-oxalato-dineodymium(III)] dihydrate]

Gao-Juan Cao,^a ^* Cheng Rong,^b Qing-lu Li ^b and Wen-Jing Jiang ^b

^aCollege of Life Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, People's Republic of China, and ^bKey Laboratory of Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, People's Republic of China
^*Correspondence e-mail: 59514683@qq.com

(Received 24 November 2011; accepted 5 February 2012; online 17 February 2012)

The title compound, {[Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O}_n, was synthesized hydrothermally in the presence of bis(carboxyethylgermanium) sesquioxide. It is isostructural with the corresponding Pr compound [Yang et al. (2009). Acta Cryst. E65, m1152–m1153]. The Nd³⁺ cation is nine-coordinated and its coordination polyhedron can be described as a distorted tricapped trigonal prism. Two Nd³⁺ ions are connected by two O atoms from two oxalate ions to give a dinuclear Nd₂ unit. The unit is further linked to four others via four oxalate ions yielding a layerparallel to (0-11). The linkages between the layers by neighbouring oxalate anions lead to a three-dimensional framework with channels along the c axis. The coordinating and free water molecules are located in the channels and make contact with each other and the host framework by weak O—H⋯O hydrogen bonds.

Related literature

For the application of lanthanide compounds, see: Kido & Okamoto (2002 ). For background to lanthanide oxalates, see: Kahwa et al. (1984 ); Trombe & Jaud (2003 ); Wang et al. (2008 ). For the isostructural Pr compound, see: Yang et al. (2009 ).

Experimental

Crystal data

[Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O
M_r = 660.64
Triclinic, $[P \overline 1]$
a = 6.036 (3) Å
b = 7.603 (3) Å
c = 8.906 (4) Å
α = 98.386 (6)°
β = 99.742 (3)°
γ = 96.802 (5)°
V = 394.2 (3) Å³
Z = 1
Mo Kα radiation
μ = 6.61 mm⁻¹
T = 293 K
0.05 × 0.05 × 0.05 mm

Data collection

Rigaku SCXmini diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ) T_min = 0.758, T_max = 1.000
2997 measured reflections
1721 independent reflections
1600 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.019
wR(F²) = 0.045
S = 1.04
1721 reflections
137 parameters
9 restraints
All H-atom parameters refined
Δρ_max = 1.01 e Å⁻³
Δρ_min = −1.06 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1⋯O5ⁱ	0.84 (2)	2.00 (3)	2.681 (4)	138 (4)
O1W—H1⋯O3ⁱ	0.84 (2)	2.55 (3)	3.244 (4)	141 (4)
O1W—H2⋯O3W	0.82 (2)	2.01 (2)	2.833 (4)	175 (5)
O2W—H3⋯O3ⁱⁱ	0.83 (2)	2.20 (3)	2.919 (4)	145 (4)
O2W—H4⋯O3Wⁱⁱ	0.83 (2)	2.00 (2)	2.809 (4)	165 (4)
O3W—H5⋯O4ⁱⁱⁱ	0.82 (2)	2.04 (2)	2.827 (4)	159 (5)
O3W—H6⋯O6^iv	0.85 (2)	2.10 (4)	2.835 (4)	146 (5)
Symmetry codes: (i) x-1, y, z; (ii) -x+1, -y+2, -z+1; (iii) -x+1, -y+1, -z+1; (iv) -x, -y+1, -z+1.

Data collection: CrystalClear (Rigaku, 2007 ); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812005016/fi2122sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812005016/fi2122Isup2.hkl

checkCIF report

Comment top

The current interest in designing and making lanthanide compounds has been excitated not only by their impressive structural but also by their application in optoelectronic field (Kido & Okamoto, 2002). In our work on the preparation of lanthanide-organogermanate compounds, an unexpected lanthanide oxalate {[Nd(C₂O₄)_1.5(H₂O)₂]^.H₂O}_n, was obtained. Although the synthesis methods are different, it is isostructural with the corresponding Pr compound (Yang et al., 2009).

Crystal structure determination by X-ray diffraction was performed on a SCXmini-CCD diffractometer equipped with a graphite-monochromatic MoKα (λ = 0.71073 Å) radiation using an ω scan mode at 273 K. The crystallographic analysis reveals that the asymmetric unit of this compound contains one independent Nd atom, six O atoms, three C atoms and three water molecules. The Nd³⁺ cation is nine-coordinated and is described as distorted tricapped trigonal prism: six O atoms from three C₂O₄^2- ligands, one O atom from one C₂O₄^2- and two water molecules. Two Nd³⁺ ions are connected by two O atoms from two oxalates to give a dinuclear Nd₂ unit. The unit is further connected four others via four oxalates to form a layer. The linkages between the layers by oxalates lead to a three-dimensional framework with channels along a axis, as shown in Fig.2. The coordinated and free water molecules is located in the channels and contact with each other and host framework by O—H···O hydrogne bonds (Fig.3.).

Related literature top

For the application of lanthanide compounds, see: Kido & Okamoto (2002). For background to lanthanide oxalates, see: Kahwa et al. (1984); Trombe & Jaud (2003); Wang et al. (2008). For the isostructural Pr compound, see: Yang et al. (2009).

Experimental top

A mixture of H₂E₂Ge₂O₃ (bis(carboxyethylgermanium) sesquioxide) (0.085 g), Nd₂O₃ (0.090 g), H₂C₂O₄ (0.090 g) and H₂O (10 ml) was stirred for about 30 min, then sealed in a 25 ml Teflonlined bomb at 170°C for 7 days, cooled to room temperature. Pink prismatic crystals of the title compound were obtained by filtration (yield about 55% based on H₂C₂O₄), washed with distilled water, and dried in air. The H₂E₂Ge₂O₃ ligand plays a key role in the formation of the title compound although it is not present in the final product. If H₂E₂Ge₂O₃ ligand was not added, we obtained a different neodymium oxalate reported reviously (Trombe & Jaud, 2003). Elemental analysis calcd (%) for C₆H₁₂Nd₂O₁₈: C, 10.91; H, 1.83; Found: C, 10.87; H, 1.88.

Computing details top

Data collection: CrystalClear (Rigaku, 2007); cell refinement: CrystalClear (Rigaku, 2007); data reduction: CrystalClear (Rigaku, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The asymmetric unit of the title complex, together with additional O2 atom to complete the coordination of the Nd³⁺ cation. Symmetry operation (i) 1–x, 2 - y, 2–z. Displacement ellipsoids are plotted at the 50% probability level. H atoms are shown as small circles of arbitrary radii.
	Fig. 2. The three-dimensional framework of the title complex with channels viewed along the a axis.
	Fig. 3. Hydrogen bonds with dashed lines in the title compound viewed along the a axis.

Poly[[tetraaquadi-µ₄-oxalato-µ₂-oxalato-dineodymium(III)] dihydrate] top

Crystal data top

[Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O	Z = 1
M_r = 660.64	F(000) = 312
Triclinic, P1	D_x = 2.783 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.036 (3) Å	Cell parameters from 1101 reflections
b = 7.603 (3) Å	θ = 2.4–27.5°
c = 8.906 (4) Å	µ = 6.61 mm⁻¹
α = 98.386 (6)°	T = 293 K
β = 99.742 (3)°	Prism, pink
γ = 96.802 (5)°	0.05 × 0.05 × 0.05 mm
V = 394.2 (3) Å³

Data collection top

Rigaku SCXmini diffractometer	1721 independent reflections
Radiation source: fine-focus sealed tube	1600 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.019
ω scans	θ_max = 27.5°, θ_min = 3.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −7→7
T_min = 0.758, T_max = 1.000	k = −9→9
2997 measured reflections	l = −11→11

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.019	All H-atom parameters refined
wR(F²) = 0.045	w = 1/[σ²(F_o²) + (0.0267P)²] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max = 0.001
1721 reflections	Δρ_max = 1.01 e Å⁻³
137 parameters	Δρ_min = −1.06 e Å⁻³
9 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0250 (12)

Crystal data top

[Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O	γ = 96.802 (5)°
M_r = 660.64	V = 394.2 (3) Å³
Triclinic, P1	Z = 1
a = 6.036 (3) Å	Mo Kα radiation
b = 7.603 (3) Å	µ = 6.61 mm⁻¹
c = 8.906 (4) Å	T = 293 K
α = 98.386 (6)°	0.05 × 0.05 × 0.05 mm
β = 99.742 (3)°

Data collection top

Rigaku SCXmini diffractometer	1721 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	1600 reflections with I > 2σ(I)
T_min = 0.758, T_max = 1.000	R_int = 0.019
2997 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.019	9 restraints
wR(F²) = 0.045	All H-atom parameters refined
S = 1.04	Δρ_max = 1.01 e Å⁻³
1721 reflections	Δρ_min = −1.06 e Å⁻³
137 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

	x	y	z	U_iso*/U_eq
Nd	0.50918 (3)	0.80732 (2)	0.795455 (19)	0.01243 (9)
O1	0.3007 (4)	0.6414 (3)	0.9553 (3)	0.0197 (5)
O2	0.2687 (4)	1.0032 (3)	0.9482 (3)	0.0159 (5)
O3	0.6296 (4)	0.7244 (3)	0.5432 (3)	0.0194 (5)
O4	0.7188 (4)	0.5888 (3)	0.9155 (3)	0.0218 (5)
O5	0.9212 (4)	0.8988 (3)	0.8085 (3)	0.0210 (5)
O6	0.3574 (5)	0.4917 (3)	0.6531 (3)	0.0227 (5)
C1	0.3797 (6)	0.5159 (4)	1.0114 (4)	0.0160 (7)
C2	0.0540 (5)	0.9720 (4)	0.9295 (4)	0.0138 (6)
C3	0.5789 (6)	0.5661 (4)	0.4686 (4)	0.0163 (7)
O1W	0.1774 (4)	0.8272 (4)	0.5951 (3)	0.0303 (7)
H1	0.052 (5)	0.846 (6)	0.618 (5)	0.045*
H2	0.145 (7)	0.765 (6)	0.509 (3)	0.045*
O2W	0.5617 (5)	1.0983 (4)	0.7077 (3)	0.0283 (6)
H3	0.461 (5)	1.144 (6)	0.658 (5)	0.042*
H4	0.680 (4)	1.171 (5)	0.722 (6)	0.042*
O3W	0.0780 (5)	0.6307 (4)	0.2901 (4)	0.0390 (8)
H5	0.105 (8)	0.550 (6)	0.226 (5)	0.059*
H6	−0.065 (3)	0.620 (7)	0.277 (6)	0.059*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Nd	0.01250 (11)	0.01253 (11)	0.01129 (11)	−0.00015 (6)	0.00267 (6)	−0.00003 (6)
O1	0.0213 (13)	0.0226 (13)	0.0199 (12)	0.0078 (10)	0.0081 (10)	0.0099 (10)
O2	0.0100 (11)	0.0192 (12)	0.0172 (11)	0.0004 (9)	0.0032 (9)	−0.0006 (9)
O3	0.0231 (13)	0.0158 (12)	0.0170 (12)	−0.0022 (10)	0.0058 (10)	−0.0027 (10)
O4	0.0176 (13)	0.0249 (13)	0.0272 (13)	0.0047 (10)	0.0086 (10)	0.0123 (11)
O5	0.0137 (11)	0.0311 (14)	0.0140 (11)	−0.0038 (10)	0.0023 (9)	−0.0034 (10)
O6	0.0303 (14)	0.0191 (12)	0.0172 (12)	−0.0045 (10)	0.0128 (10)	−0.0047 (10)
C1	0.0177 (17)	0.0169 (16)	0.0125 (15)	0.0023 (13)	0.0028 (13)	−0.0001 (13)
C2	0.0131 (15)	0.0123 (14)	0.0153 (16)	0.0008 (12)	0.0025 (12)	0.0014 (13)
C3	0.0155 (16)	0.0179 (17)	0.0135 (15)	0.0021 (13)	0.0000 (12)	0.0000 (13)
O1W	0.0161 (13)	0.0518 (19)	0.0197 (13)	0.0077 (12)	0.0025 (10)	−0.0053 (13)
O2W	0.0261 (15)	0.0227 (14)	0.0342 (16)	−0.0029 (11)	−0.0005 (12)	0.0112 (12)
O3W	0.0284 (16)	0.0440 (18)	0.0356 (17)	−0.0137 (14)	0.0118 (13)	−0.0141 (14)

Geometric parameters (Å, º) top

Nd—O1	2.441 (3)	O5—C2ⁱⁱⁱ	1.241 (4)
Nd—O2W	2.455 (3)	O6—C3^iv	1.248 (4)
Nd—O4	2.462 (3)	C1—O4ⁱⁱ	1.258 (5)
Nd—O5	2.480 (3)	C1—C1ⁱⁱ	1.542 (7)
Nd—O1W	2.481 (3)	C2—O5^v	1.241 (4)
Nd—O3	2.494 (3)	C2—C2^vi	1.539 (6)
Nd—O6	2.530 (3)	C3—O6^iv	1.248 (4)
Nd—O2ⁱ	2.576 (2)	C3—C3^iv	1.532 (7)
Nd—O2	2.601 (2)	O1W—H1	0.839 (19)
O1—C1	1.246 (4)	O1W—H2	0.823 (19)
O2—C2	1.267 (4)	O2W—H3	0.830 (18)
O2—Ndⁱ	2.576 (2)	O2W—H4	0.827 (19)
O3—C3	1.263 (4)	O3W—H5	0.824 (19)
O4—C1ⁱⁱ	1.258 (5)	O3W—H6	0.845 (19)

O1—Nd—O2W	142.79 (9)	O4—Nd—O2	120.99 (8)
O1—Nd—O4	66.13 (8)	O5—Nd—O2	122.26 (8)
O2W—Nd—O4	142.62 (9)	O1W—Nd—O2	76.88 (8)
O1—Nd—O5	132.18 (8)	O3—Nd—O2	146.24 (8)
O2W—Nd—O5	71.58 (9)	O6—Nd—O2	122.82 (8)
O4—Nd—O5	71.43 (9)	O2ⁱ—Nd—O2	65.42 (9)
O1—Nd—O1W	97.08 (10)	C1—O1—Nd	120.1 (2)
O2W—Nd—O1W	70.46 (10)	C2—O2—Ndⁱ	118.3 (2)
O4—Nd—O1W	142.10 (10)	C2—O2—Nd	123.74 (19)
O5—Nd—O1W	130.44 (10)	Ndⁱ—O2—Nd	114.58 (8)
O1—Nd—O3	134.13 (8)	C3—O3—Nd	121.0 (2)
O2W—Nd—O3	77.81 (9)	C1ⁱⁱ—O4—Nd	119.4 (2)
O4—Nd—O3	92.73 (9)	C2ⁱⁱⁱ—O5—Nd	123.2 (2)
O5—Nd—O3	67.13 (8)	C3^iv—O6—Nd	120.3 (2)
O1W—Nd—O3	74.66 (9)	O1—C1—O4ⁱⁱ	126.2 (3)
O1—Nd—O6	70.15 (8)	O1—C1—C1ⁱⁱ	117.3 (4)
O2W—Nd—O6	132.48 (9)	O4ⁱⁱ—C1—C1ⁱⁱ	116.5 (4)
O4—Nd—O6	69.77 (9)	O5^v—C2—O2	126.3 (3)
O5—Nd—O6	114.40 (8)	O5^v—C2—C2^vi	116.4 (4)
O1W—Nd—O6	72.59 (10)	O2—C2—C2^vi	117.2 (3)
O3—Nd—O6	64.28 (8)	O6^iv—C3—O3	125.9 (3)
O1—Nd—O2ⁱ	85.95 (9)	O6^iv—C3—C3^iv	117.0 (4)
O2W—Nd—O2ⁱ	81.77 (9)	O3—C3—C3^iv	117.1 (4)
O4—Nd—O2ⁱ	77.35 (8)	Nd—O1W—H1	122 (3)
O5—Nd—O2ⁱ	63.77 (7)	Nd—O1W—H2	124 (3)
O1W—Nd—O2ⁱ	137.60 (8)	H1—O1W—H2	105 (3)
O3—Nd—O2ⁱ	130.55 (8)	Nd—O2W—H3	126 (3)
O6—Nd—O2ⁱ	144.97 (8)	Nd—O2W—H4	128 (3)
O1—Nd—O2	67.11 (8)	H3—O2W—H4	106 (3)
O2W—Nd—O2	75.84 (10)	H5—O3W—H6	105 (3)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1···O5^v	0.84 (2)	2.00 (3)	2.681 (4)	138 (4)
O1W—H1···O3^v	0.84 (2)	2.55 (3)	3.244 (4)	141 (4)
O1W—H2···O3W	0.82 (2)	2.01 (2)	2.833 (4)	175 (5)
O2W—H3···O3^vii	0.83 (2)	2.20 (3)	2.919 (4)	145 (4)
O2W—H4···O3W^vii	0.83 (2)	2.00 (2)	2.809 (4)	165 (4)
O3W—H5···O4^iv	0.82 (2)	2.04 (2)	2.827 (4)	159 (5)
O3W—H6···O6^viii	0.85 (2)	2.10 (4)	2.835 (4)	146 (5)

Symmetry codes: (iv) −x+1, −y+1, −z+1; (v) x−1, y, z; (vii) −x+1, −y+2, −z+1; (viii) −x, −y+1, −z+1.

Experimental details

Crystal data
Chemical formula	[Nd₂(C₂O₄)₃(H₂O)₄]·2H₂O
M_r	660.64
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	6.036 (3), 7.603 (3), 8.906 (4)
α, β, γ (°)	98.386 (6), 99.742 (3), 96.802 (5)
V (Å³)	394.2 (3)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	6.61
Crystal size (mm)	0.05 × 0.05 × 0.05

Data collection
Diffractometer	Rigaku SCXmini diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2004)
T_min, T_max	0.758, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	2997, 1721, 1600
R_int	0.019
(sin θ/λ)_max (Å⁻¹)	0.649

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.019, 0.045, 1.04
No. of reflections	1721
No. of parameters	137
No. of restraints	9
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	1.01, −1.06

Computer programs: CrystalClear (Rigaku, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1···O5ⁱ	0.839 (19)	2.00 (3)	2.681 (4)	138 (4)
O1W—H1···O3ⁱ	0.839 (19)	2.55 (3)	3.244 (4)	141 (4)
O1W—H2···O3W	0.823 (19)	2.012 (19)	2.833 (4)	175 (5)
O2W—H3···O3ⁱⁱ	0.830 (18)	2.20 (3)	2.919 (4)	145 (4)
O2W—H4···O3Wⁱⁱ	0.827 (19)	2.00 (2)	2.809 (4)	165 (4)
O3W—H5···O4ⁱⁱⁱ	0.824 (19)	2.04 (2)	2.827 (4)	159 (5)
O3W—H6···O6^iv	0.845 (19)	2.10 (4)	2.835 (4)	146 (5)

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

Acknowledgements

This work was supported financially by the Natural Science Fund for Young Scholars of Fujian Province (grant No. 2011 J05018) and the Fund for Young Scholars from Fujian Agriculture and Forestry University (grant No. 2011xjj06).

References

Kahwa, I. A., Fronczek, F. R. & Selbin, J. (1984). Inorg. Chim. Acta, 82, 161–166. CSD CrossRef CAS Web of Science Google Scholar
Kido, J. & Okamoto, Y. (2002). Chem. Rev. 102, 2357–2368. Web of Science CrossRef PubMed CAS Google Scholar
Rigaku (2007). CrystalClear. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sheldrick, G. M. (2004). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Trombe, J. C. & Jaud, J. (2003). J. Chem. Crystallogr. 33, 19–26. Web of Science CSD CrossRef CAS Google Scholar
Wang, C.-M., Wu, Y.-Y., Chang, Y.-W. & Lii, K.-H. (2008). Chem. Mater. 20, 2857–2859. Web of Science CSD CrossRef CAS Google Scholar
Yang, T.-H., Chen, Q., Zhuang, W., Wang, Z. & Yue, B.-Y. (2009). Acta Cryst. E65, m1152–m1153. Web of Science CSD CrossRef IUCr Journals Google Scholar