{6,6′-Dibromo-4,4′-dichloro-2,2′-[o-phenyl­enebis(nitrilo­methyl­idyne)]diphenolato}nickel(II)

Ali, A.; Abdullah, N.; Maah, M.J.; Lo, K.M.

doi:10.1107/S1600536810010949

metal-organic compounds

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ISSN: 2056-9890

Volume 66| Part 4| April 2010| Page m458

doi:10.1107/S1600536810010949

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{6,6′-Dibromo-4,4′-dichloro-2,2′-[o-phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II)

Abdulaziz Ali,^a Norbani Abdullah,^a Mohd Jamil Maah ^a and Kong Mun Lo ^a ^*

^aDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
^*Correspondence e-mail: kmlo@um.edu.my

(Received 8 March 2010; accepted 23 March 2010; online 27 March 2010)

In the title complex, [Ni(C₂₀H₁₀Br₂Cl₂N₂O₂)], the Ni^II ion is coordinated by two phenoxy O atoms and two imino N atoms of the tetradentate ligand, forming a slightly distorted square-planar environment. The molecule is essentially planar, with an r.m.s. deviation of 0.088 Å for the mean plane defined by all non-H atoms in the molecule.

Related literature

For applications of nickel(II) complexes containing nitrogen and oxygen donor ligands, see: Chang et al. (2008 ). For related structures, see: Wang et al. (2003 ); Niu et al. (2009 ); Azevedo et al. (1994 ).

Experimental

Crystal data

[Ni(C₂₀H₁₀Br₂Cl₂N₂O₂)]
M_r = 599.73
Monoclinic, P 2₁ /c
a = 10.4289 (2) Å
b = 9.2712 (2) Å
c = 20.6731 (4) Å
β = 102.101 (1)°
V = 1954.43 (7) Å³
Z = 4
Mo Kα radiation
μ = 5.38 mm⁻¹
T = 296 K
0.40 × 0.10 × 0.10 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.222, T_max = 0.616
18381 measured reflections
4487 independent reflections
2921 reflections with I > 2σ(I)
R_int = 0.060

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.085
S = 0.99
4487 reflections
302 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.62 e Å⁻³
Δρ_min = −0.46 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810010949/lh5011sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810010949/lh5011Isup2.hkl

checkCIF report

Comment top

Many low-spin square-planar nickel(II) complexes and high-spin octahedral nickel(II) complexes containing nitrogen and oxygen donor ligands have been reported due to their potential industrial applications (e.g. Chang et al., 2008). In continuation of our study on the optical properties of nickel(II) Schiff base complexes, we report here the molecular structure of the title nickel(II) complex.

The molecular structure of the title complex is shown in Fig .1. The the Ni^II ion is coordinated by two phenoxy oxygen atoms and two imino nitrogen atoms in a slightly distorted square-planar geometry. The molecule is essentially planar with an rms deviation of 0.088Å for the mean plane defined by all non-hydrogen atoms in the molecule. The Ni—O bond distances [1.836 (2), 1.838 (2) Å] and Ni—N bond distances [1.853 (3), 1.858 (3) Å] are similar to those reported for related structures [1.841 (5), 1.847 (5) Å and 1.859 (6), 1.856 (6) Å, respectively, Azevedo et al., 1994; Ni-O 1.840 (5) and Ni-N 1.863 (5), 1.858 (5)Å, Wang et al., 2003; Ni-O 1.839 (2) A and Ni-N 1.825 (2) Å, Niu et al., 2009].

Related literature top

For applications of nickel(II) complexes containing nitrogen and oxygen donor ligands, see: Chang et al. (2008). For related structures, see: Wang et al. (2003); Niu et al. (2009); Azevedo et al. (1994).

Experimental top

The Schiff base, o-phenylenebis(3-bromo-5-chlorosalicylidenaminate was prepared by the condensation reaction between o-phenylenediamine and 3-bromo-5-chlorosalicylaldehyde in ethanol. 0.1 g (0.183 mmol) of the Schiff base ligand and 0.04 g (0.183 mmol) of nickel(II) acetate tetrahydrate were dissolved in 100 ml of absolute ethanol. A few drops of triethylamine were added and the mixture was refluxed for 3 hours. After filtering, a red colored solid was obtained upon slow evaporation of the filtrate. It was recrystalised from DMF to obtain the red crystals suitable for X-ray analysis.

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

Fig. 1. Thermal ellipsoid plot (Barbour, 2001) at the 70% probability level. Hydrogen atoms are drawn as spheres of arbitrary radius.

{6,6'-Dibromo-4,4'-dichloro-2,2'-[o- phenylenebis(nitrilomethylidyne)]diphenolato}nickel(II) top

Crystal data top

[Ni(C₂₀H₁₀Br₂Cl₂N₂O₂)]	F(000) = 1168
M_r = 599.73	D_x = 2.038 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2542 reflections
a = 10.4289 (2) Å	θ = 2.5–22.8°
b = 9.2712 (2) Å	µ = 5.38 mm⁻¹
c = 20.6731 (4) Å	T = 296 K
β = 102.101 (1)°	Tube, red
V = 1954.43 (7) Å³	0.40 × 0.10 × 0.10 mm
Z = 4

Data collection top

Bruker APEXII CCD area-detector diffractometer	4487 independent reflections
Radiation source: fine-focus sealed tube	2921 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.060
ω scans	θ_max = 27.5°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −13→13
T_min = 0.222, T_max = 0.616	k = −12→12
18381 measured reflections	l = −26→25

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)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.085	H atoms treated by a mixture of independent and constrained refinement
S = 0.99	w = 1/[σ²(F_o²) + (0.0337P)²] where P = (F_o² + 2F_c²)/3
4487 reflections	(Δ/σ)_max < 0.001
302 parameters	Δρ_max = 0.62 e Å⁻³
0 restraints	Δρ_min = −0.46 e Å⁻³

Crystal data top

[Ni(C₂₀H₁₀Br₂Cl₂N₂O₂)]	V = 1954.43 (7) Å³
M_r = 599.73	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 10.4289 (2) Å	µ = 5.38 mm⁻¹
b = 9.2712 (2) Å	T = 296 K
c = 20.6731 (4) Å	0.40 × 0.10 × 0.10 mm
β = 102.101 (1)°

Data collection top

Bruker APEXII CCD area-detector diffractometer	4487 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	2921 reflections with I > 2σ(I)
T_min = 0.222, T_max = 0.616	R_int = 0.060
18381 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	0 restraints
wR(F²) = 0.085	H atoms treated by a mixture of independent and constrained refinement
S = 0.99	Δρ_max = 0.62 e Å⁻³
4487 reflections	Δρ_min = −0.46 e Å⁻³
302 parameters

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 > 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
Ni1	0.42858 (4)	0.82303 (5)	0.00079 (2)	0.03697 (13)
Br2	0.81519 (4)	0.64578 (5)	0.13971 (2)	0.05814 (14)
Br1	0.53750 (4)	0.96193 (5)	0.22642 (2)	0.06178 (15)
Cl2	0.88192 (10)	0.28706 (11)	−0.06471 (6)	0.0600 (3)
Cl1	0.13100 (12)	1.35240 (12)	0.17562 (7)	0.0714 (3)
C15	0.6015 (3)	0.5754 (4)	−0.05020 (18)	0.0378 (8)
O2	0.4438 (2)	0.9051 (3)	0.08286 (12)	0.0459 (6)
C16	0.6762 (4)	0.4667 (4)	−0.0737 (2)	0.0447 (9)
N1	0.2791 (3)	0.9255 (3)	−0.03805 (15)	0.0394 (7)
C14	0.4875 (4)	0.6290 (4)	−0.0939 (2)	0.0429 (9)
C20	0.6425 (3)	0.6305 (4)	0.01441 (18)	0.0382 (8)
C17	0.7884 (4)	0.4177 (4)	−0.0343 (2)	0.0442 (9)
C1	0.3679 (4)	1.0010 (4)	0.10100 (19)	0.0418 (9)
O1	0.5802 (2)	0.7289 (3)	0.03987 (12)	0.0418 (6)
N2	0.4122 (3)	0.7309 (3)	−0.08005 (14)	0.0372 (7)
C5	0.1859 (4)	1.1734 (4)	0.0825 (2)	0.0493 (10)
C19	0.7597 (3)	0.5726 (4)	0.05273 (18)	0.0409 (9)
C2	0.3932 (4)	1.0453 (4)	0.16778 (19)	0.0434 (9)
C13	0.3023 (4)	0.7792 (4)	−0.12826 (18)	0.0424 (9)
C11	0.1575 (5)	0.7925 (5)	−0.2344 (2)	0.0615 (13)
C9	0.1218 (4)	0.9484 (5)	−0.1469 (2)	0.0548 (11)
C10	0.0866 (5)	0.9001 (5)	−0.2110 (2)	0.0617 (12)
C8	0.2305 (4)	0.8878 (4)	−0.10542 (18)	0.0435 (9)
C18	0.8314 (4)	0.4705 (4)	0.0289 (2)	0.0451 (10)
C7	0.2236 (4)	1.0247 (4)	−0.0091 (2)	0.0446 (10)
C3	0.3200 (4)	1.1484 (4)	0.1905 (2)	0.0479 (10)
C4	0.2165 (4)	1.2134 (4)	0.1466 (2)	0.0511 (10)
C6	0.2602 (3)	1.0669 (4)	0.05861 (19)	0.0418 (9)
C12	0.2644 (4)	0.7316 (5)	−0.1927 (2)	0.0559 (11)
H14	0.471 (3)	0.581 (3)	−0.1363 (16)	0.028 (8)*
H3	0.341 (3)	1.177 (4)	0.2365 (19)	0.052 (11)*
H16	0.643 (3)	0.431 (4)	−0.1153 (19)	0.045 (11)*
H18	0.901 (4)	0.432 (4)	0.0531 (19)	0.049 (12)*
H7	0.155 (3)	1.070 (4)	−0.0322 (17)	0.039 (10)*
H11	0.125 (5)	0.765 (5)	−0.279 (3)	0.097 (17)*
H10	0.023 (4)	0.947 (4)	−0.239 (2)	0.057 (12)*
H5	0.120 (3)	1.212 (4)	0.0547 (19)	0.044 (11)*
H9	0.066 (4)	1.023 (4)	−0.132 (2)	0.069 (13)*
H12	0.310 (4)	0.651 (5)	−0.210 (2)	0.085 (16)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ni1	0.0367 (3)	0.0410 (3)	0.0324 (3)	−0.0011 (2)	0.0056 (2)	0.0021 (2)
Br2	0.0541 (3)	0.0737 (3)	0.0418 (3)	0.0081 (2)	−0.00089 (19)	−0.0011 (2)
Br1	0.0653 (3)	0.0779 (3)	0.0398 (3)	0.0091 (2)	0.0058 (2)	0.0018 (2)
Cl2	0.0570 (7)	0.0536 (6)	0.0746 (8)	0.0071 (5)	0.0256 (6)	−0.0057 (5)
Cl1	0.0824 (8)	0.0545 (7)	0.0866 (9)	0.0122 (6)	0.0392 (7)	−0.0079 (6)
C15	0.039 (2)	0.040 (2)	0.035 (2)	−0.0059 (16)	0.0088 (17)	0.0009 (16)
O2	0.0452 (15)	0.0519 (16)	0.0387 (15)	0.0094 (12)	0.0044 (12)	−0.0038 (12)
C16	0.043 (2)	0.048 (2)	0.044 (3)	−0.0076 (18)	0.010 (2)	−0.0020 (19)
N1	0.0404 (17)	0.0384 (17)	0.0381 (18)	−0.0021 (14)	0.0051 (14)	0.0054 (14)
C14	0.048 (2)	0.050 (2)	0.032 (2)	−0.0087 (19)	0.0099 (18)	−0.0027 (18)
C20	0.035 (2)	0.042 (2)	0.039 (2)	−0.0052 (16)	0.0125 (17)	0.0050 (17)
C17	0.047 (2)	0.040 (2)	0.051 (3)	−0.0036 (17)	0.023 (2)	0.0005 (18)
C1	0.046 (2)	0.036 (2)	0.046 (2)	−0.0070 (17)	0.0151 (19)	0.0036 (17)
O1	0.0373 (14)	0.0513 (15)	0.0356 (15)	0.0052 (11)	0.0048 (11)	−0.0009 (12)
N2	0.0344 (17)	0.0429 (17)	0.0332 (17)	−0.0024 (13)	0.0049 (13)	0.0026 (13)
C5	0.046 (3)	0.043 (2)	0.058 (3)	0.0019 (19)	0.010 (2)	0.006 (2)
C19	0.038 (2)	0.044 (2)	0.042 (2)	−0.0051 (17)	0.0102 (17)	0.0042 (17)
C2	0.048 (2)	0.046 (2)	0.039 (2)	−0.0016 (17)	0.0152 (18)	0.0053 (18)
C13	0.044 (2)	0.049 (2)	0.033 (2)	−0.0080 (17)	0.0054 (17)	0.0059 (17)
C11	0.067 (3)	0.076 (3)	0.034 (3)	−0.010 (2)	−0.007 (2)	0.003 (2)
C9	0.055 (3)	0.055 (3)	0.047 (3)	0.000 (2)	−0.005 (2)	0.007 (2)
C10	0.060 (3)	0.064 (3)	0.051 (3)	−0.006 (2)	−0.010 (2)	0.011 (2)
C8	0.045 (2)	0.047 (2)	0.037 (2)	−0.0087 (17)	0.0019 (18)	0.0066 (17)
C18	0.036 (2)	0.047 (2)	0.053 (3)	0.0006 (18)	0.009 (2)	0.007 (2)
C7	0.040 (2)	0.041 (2)	0.050 (3)	0.0021 (18)	0.002 (2)	0.0094 (19)
C3	0.055 (3)	0.049 (2)	0.043 (3)	−0.009 (2)	0.019 (2)	−0.004 (2)
C4	0.056 (3)	0.042 (2)	0.062 (3)	−0.0010 (18)	0.028 (2)	−0.003 (2)
C6	0.039 (2)	0.039 (2)	0.047 (2)	−0.0020 (16)	0.0074 (18)	0.0003 (17)
C12	0.059 (3)	0.065 (3)	0.041 (3)	−0.003 (2)	0.004 (2)	−0.003 (2)

Geometric parameters (Å, º) top

Ni1—O2	1.836 (2)	C1—C2	1.411 (5)
Ni1—O1	1.838 (2)	N2—C13	1.424 (4)
Ni1—N2	1.853 (3)	C5—C4	1.349 (6)
Ni1—N1	1.858 (3)	C5—C6	1.407 (5)
Br2—C19	1.895 (4)	C5—H5	0.87 (3)
Br1—C2	1.888 (4)	C19—C18	1.362 (5)
Cl2—C17	1.752 (4)	C2—C3	1.367 (5)
Cl1—C4	1.744 (4)	C13—C12	1.381 (5)
C15—C20	1.410 (5)	C13—C8	1.394 (5)
C15—C16	1.420 (5)	C11—C12	1.379 (6)
C15—C14	1.424 (5)	C11—C10	1.388 (7)
O2—C1	1.297 (4)	C11—H11	0.95 (5)
C16—C17	1.356 (5)	C9—C10	1.372 (6)
C16—H16	0.92 (4)	C9—C8	1.389 (5)
N1—C7	1.297 (5)	C9—H9	0.99 (4)
N1—C8	1.422 (5)	C10—H10	0.89 (4)
C14—N2	1.298 (5)	C18—H18	0.87 (4)
C14—H14	0.97 (3)	C7—C6	1.426 (5)
C20—O1	1.294 (4)	C7—H7	0.87 (3)
C20—C19	1.416 (5)	C3—C4	1.393 (6)
C17—C18	1.379 (5)	C3—H3	0.97 (4)
C1—C6	1.411 (5)	C12—H12	0.99 (4)

O2—Ni1—O1	83.74 (11)	C20—C19—Br2	116.8 (3)
O2—Ni1—N2	176.99 (12)	C3—C2—C1	122.4 (4)
O1—Ni1—N2	94.91 (12)	C3—C2—Br1	119.5 (3)
O2—Ni1—N1	95.14 (12)	C1—C2—Br1	118.0 (3)
O1—Ni1—N1	177.58 (12)	C12—C13—C8	119.5 (4)
N2—Ni1—N1	86.31 (13)	C12—C13—N2	126.9 (4)
C20—C15—C16	120.1 (3)	C8—C13—N2	113.6 (3)
C20—C15—C14	121.4 (3)	C12—C11—C10	119.7 (4)
C16—C15—C14	118.4 (3)	C12—C11—H11	125 (3)
C1—O2—Ni1	127.7 (2)	C10—C11—H11	115 (3)
C17—C16—C15	119.9 (4)	C10—C9—C8	118.8 (4)
C17—C16—H16	123 (2)	C10—C9—H9	118 (3)
C15—C16—H16	117 (2)	C8—C9—H9	123 (3)
C7—N1—C8	121.6 (3)	C9—C10—C11	121.1 (5)
C7—N1—Ni1	125.3 (3)	C9—C10—H10	118 (3)
C8—N1—Ni1	113.1 (2)	C11—C10—H10	120 (3)
N2—C14—C15	125.2 (4)	C9—C8—C13	120.6 (4)
N2—C14—H14	122.3 (18)	C9—C8—N1	125.6 (4)
C15—C14—H14	112.5 (18)	C13—C8—N1	113.7 (3)
O1—C20—C15	124.2 (3)	C19—C18—C17	119.7 (4)
O1—C20—C19	119.2 (3)	C19—C18—H18	122 (3)
C15—C20—C19	116.6 (3)	C17—C18—H18	118 (3)
C16—C17—C18	121.2 (4)	N1—C7—C6	126.4 (4)
C16—C17—Cl2	119.4 (3)	N1—C7—H7	118 (2)
C18—C17—Cl2	119.4 (3)	C6—C7—H7	115 (2)
O2—C1—C6	124.9 (4)	C2—C3—C4	119.4 (4)
O2—C1—C2	118.8 (3)	C2—C3—H3	120 (2)
C6—C1—C2	116.3 (3)	C4—C3—H3	120 (2)
C20—O1—Ni1	127.9 (2)	C5—C4—C3	120.9 (4)
C14—N2—C13	120.6 (3)	C5—C4—Cl1	120.5 (3)
C14—N2—Ni1	126.1 (3)	C3—C4—Cl1	118.6 (3)
C13—N2—Ni1	113.2 (2)	C5—C6—C1	120.7 (4)
C4—C5—C6	120.2 (4)	C5—C6—C7	118.9 (4)
C4—C5—H5	122 (2)	C1—C6—C7	120.3 (3)
C6—C5—H5	118 (2)	C11—C12—C13	120.2 (4)
C18—C19—C20	122.4 (4)	C11—C12—H12	118 (3)
C18—C19—Br2	120.7 (3)	C13—C12—H12	122 (3)

Experimental details

Crystal data
Chemical formula	[Ni(C₂₀H₁₀Br₂Cl₂N₂O₂)]
M_r	599.73
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	10.4289 (2), 9.2712 (2), 20.6731 (4)
β (°)	102.101 (1)
V (Å³)	1954.43 (7)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	5.38
Crystal size (mm)	0.40 × 0.10 × 0.10

Data collection
Diffractometer	Bruker APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.222, 0.616
No. of measured, independent and observed [I > 2σ(I)] reflections	18381, 4487, 2921
R_int	0.060
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.085, 0.99
No. of reflections	4487
No. of parameters	302
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.62, −0.46

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2010).

Acknowledgements

We thank the University of Malaya (grant Nos. PS320/2008 C and RG020/09AFR) for supporting this study.

References

Azevedo, F., Carrondo, M. A. A. F. de C. T., de Castro, B., Convery, M., Domingues, D., Freire, C., Duarte, M. T., Nielsen, K. & Santos, I. C. (1994). Inorg. Chim. Acta, 219, 43–45. CSD CrossRef CAS Web of Science Google Scholar
Barbour, L. J. (2001). J. Supramol. Chem. 1, 189–191. CrossRef CAS Google Scholar
Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chang, J., Shannon, E. D. & William, C. S. (2008). J. Electroanal. Chem. 622, 15–21. Google Scholar
Niu, M., Liu, G., Wang, D. & Dou, J. (2009). Acta Cryst. E65, m1357. Web of Science CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (1996). 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
Wang, J., Bei, F.-L., Xu, X. Y., Yang, X. J. & Wang, X. (2003). J. Chem. Crystallogr. 33, 845–849. Web of Science CSD CrossRef CAS Google Scholar
Westrip, S. P. (2010). publCIF. In preparation. Google Scholar

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