supplementary materials


HTML versionpdf versioncif file3d viewstructure factorssupplementary materialsCIF check reportsimilar papers Open access

xu5400 scheme

Acta Cryst. (2012). E68, m21-m22    [ doi:10.1107/S1600536811051956 ]

Poly[[hexaaqua([mu]2-oxalato-[kappa]4O1,O2:O1',O2')bis([mu]3-pyridine-2,4-dicarboxylato-[kappa]4N,O1:O1':O4)dicerium(III)] monohydrate]

F. M. Shen and S. F. Lush

Abstract top

In the polymeric title compound, {[Ce2(C7H3NO4)2(C2O4)(H2O)6]·H2O}n, the Ce3+ cation is nine-coordinated in a distorted CeNO8 tricapped trigonal-prismatic geometry, formed by three pyridine-2,4-dicarboxylate anions, one oxalate anion and three water molecules. The mid-point of the oxalate anion is located on an inversion center. The oxalate and pyridine-2,4-dicarboxylate anions bridge the Ce3+ cations, forming a two-dimensional polymeric complex parallel to (010). Intermolecular classical O-H...O hydrogen bonding and weak C-H...O hydrogen bonding are present in the crystal structure and [pi]-[pi] stacking [centroid-centroid distance = 3.558 (2) Å] is observed between parallel pyridine rings of adjacent molecules. The uncoordinated water molecule shows an occupancy of 0.5.

Comment top

The pyridine-2,4-dicarboxylic acid (pdcH2) has important coordination functions to metals by either carboxylate bridges between metal centers, to form dimeric complexes or tridentate (O, N, O') chelation to metal ions. Some pydc complexes have been reported (Li et al., 2007; Wang et al., 2009; Aghabozorg et al., 2011).

The title complex is isomorphous with the La3+ complex (Shen & Lush, 2011). The CeIII is nine-coordinated in a distorted tricapped trigonal prismatic geometry formed by N and O atoms from a pydc ligand, two O atoms from two pydc ligands, two O atoms from one oxalate ligand and three O atoms from coordinated water molecules (shown as Fig. 1, Table 1). The mid-point of the oxalate anion is located on an inversion center. The oxalate and pyridinedicarboxylate anions bridge the Ce3+ cations to form the polymeric complex (Fig. 2).

The crystal structure contains O—H···O and weak C—H···O hydrogen bonds. The π-π stacking between two pyridine rings of (pydc) anion fragments with centroids distance of 3.558 (2) Å (1 - x, 1 - y, 1 - z) are observed. The uncoordinated water molecule shows half-occupation.

Related literature top

For the isotypic La3+ complex, see: Shen & Lush (2011). For related pyridine-2,4-dicarboxylate complexes, see: Aghabozorg et al. (2011); Li et al. (2007); Wang et al. (2009).

Experimental top

Ce(NO3)3.6H2O (0.1086 g, 0.25 mmole), pydridine-2,4-dicarboxylic acid (0.0418 g, 0.25 mmol) and 4,4'-dipyridine (0.0464 g, 0.25 mmol) were mixed in 10 ml of deionized water. After stirring for 30 min, the mixture was placed in a 23 ml Teflon-lined reactor which was heated under autogenous pressure to 418 K for 48 h and then allowed to cool to room temperature. The colorless transparent single crystals were obtained in 35.6% yield (based on Ce).

Refinement top

The site occupancy factor of the lattice water O10 was refined to 0.486 (15), and was set as 0.5 at the final cycles of refinement. Water H atoms were fixed in chemical sensible positions, thermal parameters were fixed as 0.08 Å2. Other H atoms were positioned geometrically with C—H = 0.93 Å (aromatic) and refined using a riding model with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. View of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level. All H atoms have been omitted for clarity. [Symmetry code: (i) x - 1, y, z; (ii) -x + 1, -y + 1, -z + 1; (iii) -x + 1, -y + 1, -z + 2.]
[Figure 2] Fig. 2. The crystal packing of (I) viewed along the c axis. Hydrogen bonds are shown as dashed lines.
Poly[[hexaaqua(µ2-oxalato- κ4O1,O2:O1',O2')bis(µ3-pyridine- 2,4-dicarboxylato- κ4N,O1:O1':O4)dicerium(III)] monohydrate] top
Crystal data top
[Ce2(C7H3NO4)2(C2O4)(H2O)6]·H2OZ = 1
Mr = 824.58F(000) = 398
Triclinic, P1Dx = 2.398 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.4160 (5) ÅCell parameters from 4490 reflections
b = 6.6486 (6) Åθ = 2.5–25.0°
c = 13.9920 (12) ŵ = 4.04 mm−1
α = 89.917 (1)°T = 294 K
β = 85.588 (1)°Columnar, colorless
γ = 73.676 (1)°0.30 × 0.10 × 0.10 mm
V = 570.98 (8) Å3
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer		2664 independent reflections
Radiation source: fine-focus sealed tube2416 reflections with I > 2σ(I)
graphiteRint = 0.030
Detector resolution: 9 pixels mm-1θmax = 27.8°, θmin = 1.5°
φ and ω scansh = −8→8
Absorption correction: multi-scan
(SADABS; Bruker, 2001)		k = −8→8
Tmin = 0.639, Tmax = 0.937l = −18→18
6072 measured reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.028H-atom parameters constrained
wR(F2) = 0.081 w = 1/[σ2(Fo2) + (0.0523P)2 + 0.4154P]
where P = (Fo2 + 2Fc2)/3
S = 1.10(Δ/σ)max = 0.019
2664 reflectionsΔρmax = 2.75 e Å−3
177 parametersΔρmin = −2.70 e Å−3
0 restraintsExtinction correction: SHELXTL (Sheldrick, 2008), FC*=KFC[1+0.001XFC2Λ3/SIN(2Θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0071 (15)
Crystal data top
[Ce2(C7H3NO4)2(C2O4)(H2O)6]·H2Oγ = 73.676 (1)°
Mr = 824.58V = 570.98 (8) Å3
Triclinic, P1Z = 1
a = 6.4160 (5) ÅMo Kα radiation
b = 6.6486 (6) ŵ = 4.04 mm−1
c = 13.9920 (12) ÅT = 294 K
α = 89.917 (1)°0.30 × 0.10 × 0.10 mm
β = 85.588 (1)°
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer		2664 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)		2416 reflections with I > 2σ(I)
Tmin = 0.639, Tmax = 0.937Rint = 0.030
6072 measured reflectionsθmax = 27.8°
Refinement top
R[F2 > 2σ(F2)] = 0.028H-atom parameters constrained
wR(F2) = 0.081Δρmax = 2.75 e Å−3
S = 1.10Δρmin = −2.70 e Å−3
2664 reflectionsAbsolute structure: ?
177 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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*/UeqOcc. (<1)
Ce0.36484 (3)0.33000 (3)0.80343 (1)0.0198 (1)
O10.7620 (6)0.3463 (6)0.2798 (2)0.0356 (11)
O21.0901 (6)0.2177 (7)0.3373 (3)0.0438 (13)
O31.0817 (5)0.2746 (6)0.7009 (2)0.0350 (10)
O40.7595 (5)0.3214 (7)0.7822 (2)0.0380 (13)
O50.5054 (7)0.2476 (5)0.9655 (2)0.0408 (13)
O60.5773 (6)0.3678 (5)1.1047 (2)0.0360 (10)
O70.0036 (8)0.5134 (8)0.8992 (4)0.0729 (14)
O80.5654 (6)−0.0533 (6)0.7844 (3)0.0419 (11)
O90.1789 (8)0.0870 (8)0.8994 (4)0.0729 (14)
N10.5723 (5)0.2600 (6)0.6274 (2)0.0208 (9)
C10.7770 (7)0.2748 (6)0.6150 (3)0.0218 (11)
C20.5683 (7)0.2406 (7)0.4556 (3)0.0248 (11)
C30.7772 (7)0.2622 (7)0.4439 (3)0.0227 (11)
C40.8836 (7)0.2747 (7)0.5250 (3)0.0251 (11)
C50.4745 (7)0.2392 (7)0.5484 (3)0.0256 (12)
C60.8875 (8)0.2745 (7)0.3451 (3)0.0275 (12)
C70.8828 (7)0.2921 (7)0.7052 (3)0.0246 (11)
C80.5247 (7)0.3884 (6)1.0201 (3)0.0237 (11)
O10−0.1094 (13)−0.0862 (13)0.9223 (7)0.050 (3)0.500
H2A0.493000.227400.402900.039 (15)*
H4A1.026300.282900.519100.0300*
H5A0.334900.222800.556000.0300*
H7A−0.078000.470600.863200.0800*
H7B−0.025000.636800.882800.0800*
H8A0.53670−0.162000.818200.0800*
H8B0.65420−0.095000.734900.0800*
H9A0.24360−0.067400.894200.0800*
H9B0.065000.090500.873000.0800*
H10A−0.219700.007900.907600.0800*0.500
H10B−0.12520−0.129600.985600.0800*0.500
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ce0.0191 (2)0.0294 (2)0.0134 (1)−0.0113 (1)−0.0006 (1)0.0005 (1)
O10.0380 (19)0.044 (2)0.0238 (16)−0.0092 (16)−0.0055 (14)0.0092 (14)
O20.0270 (18)0.064 (3)0.0303 (19)0.0011 (17)0.0068 (15)0.0078 (17)
O30.0199 (15)0.061 (2)0.0274 (17)−0.0163 (15)−0.0040 (13)−0.0028 (15)
O40.0268 (17)0.075 (3)0.0185 (15)−0.0250 (17)−0.0004 (13)−0.0012 (16)
O50.074 (3)0.0266 (17)0.0225 (16)−0.0142 (17)−0.0080 (17)−0.0003 (13)
O60.058 (2)0.0306 (17)0.0222 (16)−0.0141 (16)−0.0143 (15)0.0071 (13)
O70.055 (2)0.061 (2)0.088 (3)−0.0018 (16)0.0304 (19)0.0251 (19)
O80.048 (2)0.0333 (19)0.041 (2)−0.0115 (16)0.0176 (17)−0.0007 (15)
O90.055 (2)0.061 (2)0.088 (3)−0.0018 (16)0.0304 (19)0.0251 (19)
N10.0174 (16)0.0268 (17)0.0193 (16)−0.0077 (13)−0.0030 (13)0.0001 (13)
C10.0197 (19)0.024 (2)0.022 (2)−0.0068 (16)−0.0017 (15)0.0017 (15)
C20.028 (2)0.030 (2)0.0179 (19)−0.0099 (17)−0.0049 (16)−0.0011 (16)
C30.024 (2)0.025 (2)0.0162 (18)−0.0024 (16)−0.0005 (15)0.0042 (15)
C40.0172 (19)0.035 (2)0.022 (2)−0.0057 (17)−0.0003 (16)0.0045 (17)
C50.022 (2)0.031 (2)0.026 (2)−0.0110 (17)−0.0029 (16)0.0014 (17)
C60.033 (2)0.029 (2)0.017 (2)−0.0045 (18)0.0037 (17)−0.0004 (16)
C70.0196 (19)0.033 (2)0.025 (2)−0.0129 (17)−0.0041 (16)0.0032 (17)
C80.028 (2)0.023 (2)0.0189 (19)−0.0052 (16)−0.0027 (16)0.0009 (15)
O100.037 (4)0.042 (4)0.072 (6)−0.010 (3)−0.013 (4)0.009 (4)
Geometric parameters (Å, °) top
Ce—N12.684 (3)O8—H8B0.8600
Ce—O1i2.409 (4)O9—H9B0.8400
Ce—O3ii2.505 (3)O9—H9A0.9900
Ce—O42.511 (3)O10—H10A0.8400
Ce—O52.508 (3)O10—H10B0.9400
Ce—O6iii2.515 (3)N1—C51.338 (5)
Ce—O72.568 (5)N1—C11.343 (6)
Ce—O82.515 (4)C1—C41.386 (6)
Ce—O92.582 (5)C1—C71.498 (6)
O1—C61.268 (6)C2—C31.385 (7)
O2—C61.244 (7)C2—C51.390 (6)
O3—C71.245 (6)C3—C61.517 (6)
O4—C71.268 (5)C3—C41.383 (6)
O5—C81.248 (5)C8—C8iii1.543 (5)
O6—C81.253 (5)C2—H2A0.9300
O7—H7B0.8300C4—H4A0.9300
O7—H7A0.8600C5—H5A0.9300
O8—H8A0.9200
O4—Ce—O574.74 (12)Ce—O5—C8121.3 (3)
O4—Ce—O7142.54 (15)Ceiii—O6—C8120.9 (3)
O4—Ce—O875.62 (14)Ce—O7—H7B105.00
O4—Ce—O9130.01 (15)H7A—O7—H7B99.00
O4—Ce—N161.02 (10)Ce—O7—H7A96.00
O3ii—Ce—O4137.32 (10)Ce—O8—H8A127.00
O1i—Ce—O494.76 (13)H8A—O8—H8B113.00
O4—Ce—O6iii70.50 (13)Ce—O8—H8B119.00
O5—Ce—O784.31 (15)Ce—O9—H9A120.00
O5—Ce—O878.05 (12)H9A—O9—H9B96.00
O5—Ce—O967.22 (15)Ce—O9—H9B107.00
O5—Ce—N1130.72 (12)H10A—O10—H10B112.00
O3ii—Ce—O5141.57 (12)Ce—N1—C5123.6 (3)
O1i—Ce—O5132.71 (11)Ce—N1—C1118.7 (2)
O5—Ce—O6iii64.05 (10)C1—N1—C5117.1 (3)
O7—Ce—O8130.23 (15)N1—C1—C4122.5 (4)
O7—Ce—O964.30 (16)N1—C1—C7115.4 (4)
O7—Ce—N1144.66 (14)C4—C1—C7122.1 (4)
O3ii—Ce—O776.31 (14)C3—C2—C5118.1 (4)
O1i—Ce—O776.97 (15)C2—C3—C6121.4 (4)
O6iii—Ce—O772.47 (15)C4—C3—C6120.3 (4)
O8—Ce—O965.94 (15)C2—C3—C4118.3 (4)
O8—Ce—N171.24 (12)C1—C4—C3119.8 (4)
O3ii—Ce—O889.53 (13)N1—C5—C2124.1 (4)
O1i—Ce—O8144.86 (12)O1—C6—O2127.1 (4)
O6iii—Ce—O8134.19 (12)O2—C6—C3116.8 (4)
O9—Ce—N1127.54 (14)O1—C6—C3116.0 (4)
O3ii—Ce—O974.47 (14)O4—C7—C1116.2 (4)
O1i—Ce—O9134.92 (15)O3—C7—C1119.4 (4)
O6iii—Ce—O9116.36 (14)O3—C7—O4124.4 (4)
O3ii—Ce—N176.35 (10)O5—C8—O6126.7 (4)
O1i—Ce—N174.55 (11)O5—C8—C8iii116.7 (4)
O6iii—Ce—N1114.97 (11)O6—C8—C8iii116.6 (4)
O1i—Ce—O3ii74.72 (12)C5—C2—H2A121.00
O3ii—Ce—O6iii136.22 (12)C3—C2—H2A121.00
O1i—Ce—O6iii68.95 (11)C1—C4—H4A120.00
Cei—O1—C6138.2 (3)C3—C4—H4A120.00
Ceiv—O3—C7140.1 (3)N1—C5—H5A118.00
Ce—O4—C7127.9 (3)C2—C5—H5A118.00
O5—Ce—O4—C7158.0 (4)N1—Ce—O1i—C6i73.5 (5)
O7—Ce—O4—C7−143.7 (4)O4—Ce—O6iii—C8iii−87.9 (4)
O8—Ce—O4—C776.7 (4)O5—Ce—O6iii—C8iii−5.9 (3)
O9—Ce—O4—C7116.9 (4)O7—Ce—O6iii—C8iii86.3 (4)
N1—Ce—O4—C70.5 (4)O8—Ce—O6iii—C8iii−43.3 (4)
O3ii—Ce—O4—C73.6 (5)O9—Ce—O6iii—C8iii37.9 (4)
O1i—Ce—O4—C7−68.9 (4)N1—Ce—O6iii—C8iii−130.9 (3)
O6iii—Ce—O4—C7−134.6 (4)Cei—O1—C6—O2−76.7 (7)
O4—Ce—O5—C880.8 (4)Cei—O1—C6—C3101.7 (5)
O7—Ce—O5—C8−67.9 (4)Ceiv—O3—C7—O4−12.4 (8)
O8—Ce—O5—C8158.9 (4)Ceiv—O3—C7—C1168.6 (3)
O9—Ce—O5—C8−132.4 (4)Ce—O4—C7—O3−174.5 (3)
N1—Ce—O5—C8106.9 (4)Ce—O4—C7—C14.5 (6)
O3ii—Ce—O5—C8−127.4 (4)Ce—O5—C8—O6174.3 (4)
O1i—Ce—O5—C8−1.5 (5)Ce—O5—C8—C8iii−4.7 (6)
O6iii—Ce—O5—C85.4 (4)Ceiii—O6—C8—O5175.0 (4)
O4—Ce—N1—C1−6.1 (3)Ceiii—O6—C8—C8iii−6.0 (5)
O4—Ce—N1—C5−176.6 (4)Ce—N1—C1—C4−169.4 (3)
O5—Ce—N1—C1−35.2 (4)Ce—N1—C1—C710.5 (5)
O5—Ce—N1—C5154.3 (3)C5—N1—C1—C41.7 (6)
O7—Ce—N1—C1135.9 (3)C5—N1—C1—C7−178.4 (4)
O7—Ce—N1—C5−34.6 (5)Ce—N1—C5—C2168.0 (3)
O8—Ce—N1—C1−89.7 (3)C1—N1—C5—C2−2.7 (7)
O8—Ce—N1—C599.8 (4)N1—C1—C4—C31.0 (6)
O9—Ce—N1—C1−126.2 (3)C7—C1—C4—C3−178.8 (4)
O9—Ce—N1—C563.3 (4)N1—C1—C7—O3169.2 (4)
O3ii—Ce—N1—C1176.1 (3)N1—C1—C7—O4−9.8 (6)
O3ii—Ce—N1—C55.6 (3)C4—C1—C7—O3−11.0 (6)
O1i—Ce—N1—C198.5 (3)C4—C1—C7—O4170.0 (4)
O1i—Ce—N1—C5−72.0 (3)C5—C2—C3—C42.0 (6)
O6iii—Ce—N1—C141.2 (3)C5—C2—C3—C6−177.4 (4)
O6iii—Ce—N1—C5−129.3 (3)C3—C2—C5—N10.9 (7)
O4—Ce—O3ii—C7ii−172.6 (4)C2—C3—C4—C1−2.8 (7)
O5—Ce—O3ii—C7ii49.5 (6)C6—C3—C4—C1176.5 (4)
O7—Ce—O3ii—C7ii−12.4 (5)C2—C3—C6—O127.1 (6)
O8—Ce—O3ii—C7ii119.4 (5)C2—C3—C6—O2−154.4 (5)
O9—Ce—O3ii—C7ii54.3 (5)C4—C3—C6—O1−152.3 (4)
N1—Ce—O3ii—C7ii−169.8 (5)C4—C3—C6—O226.3 (6)
O4—Ce—O1i—C6i131.6 (5)O5—C8—C8iii—O5iii−180.0 (5)
O5—Ce—O1i—C6i−154.8 (4)O5—C8—C8iii—O6iii−0.9 (6)
O7—Ce—O1i—C6i−85.4 (5)O6—C8—C8iii—O5iii0.9 (6)
O8—Ce—O1i—C6i60.0 (6)O6—C8—C8iii—O6iii180.0 (4)
O9—Ce—O1i—C6i−54.6 (5)
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+2; (iv) x+1, y, z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O7—H7A···O4ii0.862.032.879 (6)171.00
O7—H7B···O10v0.831.842.569 (10)146.00
O8—H8A···O6vi0.922.002.910 (5)170.00
O8—H8B···O2vii0.861.842.655 (6)159.00
O9—H9A···O6vi0.992.012.987 (6)169.00
O9—H9B···O100.841.932.440 (10)118.00
O10—H10A···O5ii0.842.122.844 (9)143.00
O10—H10A···O8ii0.842.392.913 (10)121.00
O10—H10B···O9viii0.941.632.501 (11)153.00
C5—H5A···O3ii0.932.463.131 (5)129.
Symmetry codes: (ii) x−1, y, z; (v) x, y+1, z; (vi) −x+1, −y, −z+2; (vii) −x+2, −y, −z+1; (viii) −x, −y, −z+2.
Table 1
Selected geometric parameters (Å) top
Ce—N12.684 (3)Ce—O6iii2.515 (3)
Ce—O1i2.409 (4)Ce—O72.568 (5)
Ce—O3ii2.505 (3)Ce—O82.515 (4)
Ce—O42.511 (3)Ce—O92.582 (5)
Ce—O52.508 (3)
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+2.
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O7—H7A···O4ii0.862.032.879 (6)171.00
O7—H7B···O10iv0.831.842.569 (10)146.00
O8—H8A···O6v0.922.002.910 (5)170.00
O8—H8B···O2vi0.861.842.655 (6)159.00
O9—H9A···O6v0.992.012.987 (6)169.00
O9—H9B···O100.841.932.440 (10)118.00
O10—H10A···O5ii0.842.122.844 (9)143.00
O10—H10A···O8ii0.842.392.913 (10)121.00
O10—H10B···O9vii0.941.632.501 (11)153.00
C5—H5A···O3ii0.932.463.131 (5)129.
Symmetry codes: (ii) x−1, y, z; (iv) x, y+1, z; (v) −x+1, −y, −z+2; (vi) −x+2, −y, −z+1; (vii) −x, −y, −z+2.
Acknowledgements top

This work was supported financially byd Yuanpei University, Taiwan.

references
References top

Aghabozorg, H., Jafarbak, F., Mirzaei, M. & Notash, B. (2011). Acta Cryst. E67, m435–m436.

Bruker (2001). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.

Bruker (2007). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.

Li, X.-M., Niu, Y.-L., Wang, Q.-W. & Liu, B. (2007). Acta Cryst. E63, m487–m488.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Shen, F. M. & Lush, S. F. (2011). Acta Cryst. E67, m1731–m1732.

Spek, A. L. (2009). Acta Cryst. D65, 148–155.

Wang, G.-H., Li, Z.-G., Jia, H.-Q., Hu, N.-H. & Xu, J.-W. (2009). Acta Cryst. E65, m1568–m1569.