Poly[μ2-aqua-aqua­(μ3-1H-benzimidazole-5,6-dicarboxyl­ato-κ3N3:O5:O5′)manganese(II)]

Zheng-De, T.; Qian-Qian, H.; Bing, Y.

doi:10.1107/S1600536810011979

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 66| Part 5| May 2010| Page m511

https://doi.org/10.1107/S1600536810011979

Open

access

Poly[μ₂-aqua-aqua(μ₃-1H-benzimidazole-5,6-dicarboxylato-κ³N³:O⁵:O^5′)manganese(II)]

Tan Zheng-De,^a ^* Hai Qian-Qian ^a and Yi Bing ^a

^aCollege of Chemistry and Chemical Engineering, Hunan Institute of Engineering, Xiang Tan 411104, People's Republic of China
^*Correspondence e-mail: tzd0517@163.com

(Received 3 February 2010; accepted 30 March 2010; online 10 April 2010)

In the title complex, [Mn(C₉H₄N₂O₄)(H₂O)₂]_n, the Mn^II atom is in a distorted octahedral coordination completed by one N atom from one 1H-benzimidazole-5,6-dicarboxylate ligand, two O atoms from two different 1H-benzimidazole-5,6-dicarboxylate ligands, and three O atoms from three water molecules. Two bridging water molecules and two bridging carboxylate groups from a 1H-benzimidazole-5,6-dicarboxylate ligand connect two Mn^II ions into a dimeric structure. In the crystal, extensive intermolecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonding forms a three-dimensional network.

Related literature

For background to 1H-benzimidazole-5,6-dicarboxylate complexes and related structures, see: Yao et al. (2008 ); Wei et al. (2009 ); Song et al. (2009a ,b ).

Experimental

Crystal data

[Mn(C₉H₄N₂O₄)(H₂O)₂]
M_r = 295.11
Monoclinic, P 2₁ /c
a = 8.8875 (18) Å
b = 9.2079 (18) Å
c = 12.939 (3) Å
β = 97.22 (3)°
V = 1050.5 (4) Å³
Z = 4
Mo Kα radiation
μ = 1.28 mm⁻¹
T = 293 K
0.29 × 0.26 × 0.25 mm

Data collection

Rigaku/MSC Mercury CCD diffractometer
Absorption correction: multi-scan (REQAB; Jacobson, 1998 ) T_min = 0.708, T_max = 0.740
8122 measured reflections
1888 independent reflections
1792 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.036
wR(F²) = 0.098
S = 1.11
1888 reflections
163 parameters
18 restraints
H-atom parameters constrained
Δρ_max = 0.71 e Å⁻³
Δρ_min = −0.84 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O2ⁱ	0.86	1.98	2.839 (3)	174
O2W—H4W⋯O3ⁱⁱ	0.84	2.56	3.065 (3)	120
O1W—H1W⋯O2ⁱⁱ	0.84	2.10	2.819 (3)	143
O2W—H3W⋯O1Wⁱⁱⁱ	0.84	2.10	2.934 (3)	169
O1W—H2W⋯O1^iv	0.84	1.77	2.575 (3)	160
C4—H4⋯O4^v	0.93	2.48	3.216 (3)	136
Symmetry codes: (i) $[-x+2, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) x-1, y, z; (iii) -x+1, -y+1, -z+2; (iv) $[-x+2, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (v) -x+2, -y+1, -z+2.

Data collection: RAPID-AUTO (Rigaku, 1998 ); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2002 ); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536810011979/zb2004sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810011979/zb2004Isup2.hkl

checkCIF report

Comment top

1H-Benzimidazole-5,6-dicarboxylate ligand(H₂L) play an important role in coordination chemistry. They usually adopt diverse binding modes as monodentate, chelating to one metal center, bridging to two metal centers (Yao et al., 2008;Wei et al., 2009;Song et al., 2009a,b). In the present paper, we synthesized a novel colorless complex [Mn(C₉H₄N₂O₄)(H₂O)₂]_n. It is isostructural to the cobalt compound with reference of Wei et al., 2009.

The coordination geometries of Mn centers are very close to the values observed in the [Co(C₉H₄N₂O₄)(H₂O)₂]_n compound. The Mn atoms are linked by water bridges and carboxylate groups, forming an infinite chain. The Mn···Mn distance is 3.2555 (7)Å longer than the Co···Co distance 3.114 (1) Å. In the [Co(C₉H₄N₂O₄)(H₂O)₂]_n compound, the Co—O bond lengths range between 2.0304 (18) and 2.2314 (19) Å, whereas in the title compound, the Mn—O bond lengths ranged between 2.1151 (19) and 2.3334 (19) Å. Intermolecular O—H···O , N—H···O and C—H···O hydrogen bonds form the 3D structure (Fig. 2). The hydrogen bonds are in the normal range (Table 1).

Related literature top

For background to 1H-benzimidazole-5,6-dicarboxylate complexes and related structures, see: Yao et al. (2008); Wei et al. (2009); Song et al. (2009a,b).

Experimental top

MnCl₂(0.1 mmol), H₂L(0.1 mmol), H₂O (15 ml) and a small amount NaOH for adjusting pH to 7 was placed in a 23 ml Teflon reactor,which was heated to 426 K for two days and then cooled to room temperature , and left to stand at room temperature for a few days, then the colorless block crystals were obtained.

Structure description top

For background to 1H-benzimidazole-5,6-dicarboxylate complexes and related structures, see: Yao et al. (2008); Wei et al. (2009); Song et al. (2009a,b).

Computing details top

Data collection: RAPID-AUTO (Rigaku, 1998); cell refinement: RAPID-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. A section of the structure of the title compound, showing the atomic numbering scheme with 30% probability displacement ellipsoids. [Symmetry codes: (i) 1-x, 1-y, 1-z. (ii)y, x-1, z. (iii) 2-x, 1-y,2-z.]
	Fig. 2. A view of the three-dimensional structure of the title compound along the b axis.Hydrogen bonds are shown as dashed lines.

Poly[µ₂-aqua-aqua(µ₃-1H-benzimidazole-5,6-dicarboxylato- κ³N³:O⁵:O^5')manganese(II)] top

Crystal data top

[Mn(C₉H₄N₂O₄)(H₂O)₂]	F(000) = 596
M_r = 295.11	D_x = 1.866 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 9020 reflections
a = 8.8875 (18) Å	θ = 3.2–27.5°
b = 9.2079 (18) Å	µ = 1.28 mm⁻¹
c = 12.939 (3) Å	T = 293 K
β = 97.22 (3)°	Block, colorless
V = 1050.5 (4) Å³	0.29 × 0.26 × 0.25 mm
Z = 4

Data collection top

Rigaku/MSC Mercury CCD diffractometer	1888 independent reflections
Radiation source: fine-focus sealed tube	1792 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
ω scans	θ_max = 25.2°, θ_min = 3.2°
Absorption correction: multi-scan (REQAB; Jacobson, 1998)	h = −10→10
T_min = 0.708, T_max = 0.740	k = −11→11
8122 measured reflections	l = −15→15

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.098	H-atom parameters constrained
S = 1.11	w = 1/[σ²(F_o²) + (0.0562P)² + 1.2161P] where P = (F_o² + 2F_c²)/3
1888 reflections	(Δ/σ)_max = 0.001
163 parameters	Δρ_max = 0.71 e Å⁻³
18 restraints	Δρ_min = −0.84 e Å⁻³

Crystal data top

[Mn(C₉H₄N₂O₄)(H₂O)₂]	V = 1050.5 (4) Å³
M_r = 295.11	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.8875 (18) Å	µ = 1.28 mm⁻¹
b = 9.2079 (18) Å	T = 293 K
c = 12.939 (3) Å	0.29 × 0.26 × 0.25 mm
β = 97.22 (3)°

Data collection top

Rigaku/MSC Mercury CCD diffractometer	1888 independent reflections
Absorption correction: multi-scan (REQAB; Jacobson, 1998)	1792 reflections with I > 2σ(I)
T_min = 0.708, T_max = 0.740	R_int = 0.025
8122 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	18 restraints
wR(F²) = 0.098	H-atom parameters constrained
S = 1.11	Δρ_max = 0.71 e Å⁻³
1888 reflections	Δρ_min = −0.84 e Å⁻³
163 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
C1	0.6538 (3)	0.9382 (3)	0.9155 (2)	0.0248 (6)
H1	0.5552	0.9678	0.9215	0.030*
N1	0.7164 (2)	0.8221 (3)	0.96244 (19)	0.0229 (5)
O1W	0.52018 (17)	0.5378 (2)	0.88035 (12)	0.0232 (4)
Mn1	0.59756 (4)	0.64549 (4)	1.03462 (3)	0.01916 (18)
C2	0.8810 (3)	0.9343 (3)	0.8676 (2)	0.0222 (6)
N2	0.7455 (3)	1.0094 (3)	0.85830 (19)	0.0253 (5)
H2	0.7241	1.0871	0.8226	0.030*
O2	1.3361 (2)	0.7520 (2)	0.77220 (15)	0.0249 (4)
O2W	0.6154 (2)	0.74283 (19)	1.18596 (14)	0.0364 (5)
C3	0.8628 (3)	0.8183 (3)	0.9340 (2)	0.0204 (5)
O3	1.3671 (2)	0.7185 (2)	0.99961 (16)	0.0247 (4)
C4	0.9821 (3)	0.7226 (3)	0.9624 (2)	0.0229 (6)
H4	0.9724	0.6463	1.0082	0.028*
O4	1.2334 (2)	0.5175 (2)	0.95142 (17)	0.0281 (5)
C5	1.1158 (3)	0.7451 (3)	0.9201 (2)	0.0204 (6)
C6	1.1295 (3)	0.8575 (3)	0.8473 (2)	0.0208 (6)
C7	1.2657 (3)	0.8663 (3)	0.7888 (2)	0.0194 (6)
C8	1.2495 (3)	0.6528 (3)	0.9593 (2)	0.0211 (6)
C13	1.01235 (18)	0.95590 (19)	0.82118 (13)	0.0237 (6)
H13	1.0212	1.0321	0.7752	0.028*
H4W	0.5700	0.8040	1.1451	0.028*
H1W	0.4444	0.5657	0.8400	0.028*
H3W	0.5794	0.6589	1.1754	0.028*
H2W	0.5900	0.5089	0.8473	0.028*
O1	1.2983 (3)	0.9885 (2)	0.75589 (18)	0.0341 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0165 (13)	0.0247 (15)	0.0341 (15)	0.0037 (10)	0.0065 (11)	0.0005 (12)
N1	0.0160 (11)	0.0230 (12)	0.0309 (13)	0.0014 (9)	0.0079 (9)	0.0030 (10)
O1W	0.0217 (9)	0.0265 (10)	0.0230 (9)	0.0043 (8)	0.0091 (7)	0.0005 (8)
Mn1	0.0167 (3)	0.0175 (3)	0.0242 (3)	0.00077 (14)	0.00610 (17)	0.00014 (15)
C2	0.0182 (13)	0.0197 (13)	0.0291 (14)	0.0021 (10)	0.0048 (11)	0.0025 (11)
N2	0.0205 (12)	0.0214 (12)	0.0348 (13)	0.0057 (9)	0.0067 (10)	0.0086 (10)
O2	0.0248 (10)	0.0233 (10)	0.0285 (10)	0.0012 (8)	0.0102 (8)	−0.0021 (8)
O2W	0.0467 (14)	0.0317 (12)	0.0324 (12)	−0.0080 (10)	0.0109 (10)	−0.0085 (9)
C3	0.0183 (9)	0.0208 (9)	0.0225 (9)	0.0002 (8)	0.0047 (8)	0.0010 (8)
O3	0.0175 (10)	0.0255 (11)	0.0314 (10)	0.0030 (8)	0.0044 (8)	−0.0019 (8)
C4	0.0192 (13)	0.0208 (14)	0.0300 (14)	0.0011 (10)	0.0082 (11)	0.0071 (11)
O4	0.0191 (9)	0.0195 (10)	0.0470 (12)	0.0029 (7)	0.0089 (9)	0.0052 (9)
C5	0.0171 (13)	0.0184 (13)	0.0263 (14)	0.0001 (10)	0.0055 (10)	0.0010 (10)
C6	0.0182 (13)	0.0198 (14)	0.0256 (14)	−0.0015 (9)	0.0077 (11)	−0.0005 (10)
C7	0.0183 (13)	0.0180 (13)	0.0228 (13)	−0.0028 (9)	0.0068 (11)	−0.0012 (10)
C8	0.0187 (14)	0.0230 (15)	0.0239 (14)	0.0026 (10)	0.0112 (11)	0.0038 (10)
C13	0.0232 (14)	0.0189 (13)	0.0302 (14)	0.0006 (10)	0.0087 (11)	0.0066 (11)
O1	0.0359 (9)	0.0296 (9)	0.0411 (9)	−0.0028 (7)	0.0212 (7)	0.0013 (7)

Geometric parameters (Å, º) top

C1—N1	1.317 (4)	N2—H2	0.8600
C1—N2	1.339 (4)	O2—C7	1.257 (3)
C1—H1	0.9300	O2W—H4W	0.8407
N1—C3	1.396 (3)	O2W—H3W	0.8411
N1—Mn1	2.209 (2)	C3—C4	1.392 (4)
O1W—Mn1	2.2572 (18)	O3—C8	1.262 (4)
O1W—Mn1ⁱ	2.3334 (19)	O3—Mn1^iv	2.1495 (19)
O1W—H1W	0.8386	C4—C5	1.384 (4)
O1W—H2W	0.8401	C4—H4	0.9300
Mn1—O4ⁱⁱ	2.115 (2)	O4—C8	1.256 (3)
Mn1—O2W	2.141 (2)	O4—Mn1ⁱⁱ	2.115 (2)
Mn1—O3ⁱⁱⁱ	2.1496 (19)	C5—C6	1.414 (4)
Mn1—O1Wⁱ	2.3334 (19)	C5—C8	1.497 (4)
Mn1—H4W	2.0785	C6—C13	1.390 (3)
Mn1—H3W	1.8533	C6—C7	1.508 (4)
C2—N2	1.381 (3)	C7—O1	1.250 (3)
C2—C3	1.392 (4)	C13—H13	0.9300
C2—C13	1.393 (3)

N1—C1—N2	113.6 (2)	N1—Mn1—H3W	118.2
N1—C1—H1	123.2	O1W—Mn1—H3W	147.6
N2—C1—H1	123.2	O1Wⁱ—Mn1—H3W	59.0
C1—N1—C3	104.6 (2)	H4W—Mn1—H3W	41.0
C1—N1—Mn1	126.53 (18)	N2—C2—C3	105.7 (2)
C3—N1—Mn1	127.15 (18)	N2—C2—C13	131.3 (2)
Mn1—O1W—Mn1ⁱ	90.32 (6)	C3—C2—C13	123.0 (2)
Mn1—O1W—H1W	123.2	C1—N2—C2	107.0 (2)
Mn1ⁱ—O1W—H1W	98.2	C1—N2—H2	126.5
Mn1—O1W—H2W	115.3	C2—N2—H2	126.5
Mn1ⁱ—O1W—H2W	114.5	Mn1—O2W—H4W	74.3
H1W—O1W—H2W	111.5	Mn1—O2W—H3W	58.9
O4ⁱⁱ—Mn1—O2W	104.41 (8)	H4W—O2W—H3W	111.8
O4ⁱⁱ—Mn1—O3ⁱⁱⁱ	152.59 (8)	C2—C3—C4	120.3 (2)
O2W—Mn1—O3ⁱⁱⁱ	91.19 (8)	C2—C3—N1	109.1 (2)
O4ⁱⁱ—Mn1—N1	100.75 (8)	C4—C3—N1	130.6 (3)
O2W—Mn1—N1	95.40 (9)	C8—O3—Mn1^iv	130.88 (18)
O3ⁱⁱⁱ—Mn1—N1	100.03 (8)	C5—C4—C3	117.6 (3)
O4ⁱⁱ—Mn1—O1W	84.15 (8)	C5—C4—H4	121.2
O2W—Mn1—O1W	166.37 (7)	C3—C4—H4	121.2
O3ⁱⁱⁱ—Mn1—O1W	76.97 (7)	C8—O4—Mn1ⁱⁱ	128.63 (18)
N1—Mn1—O1W	93.33 (8)	C4—C5—C6	121.5 (2)
O4ⁱⁱ—Mn1—O1Wⁱ	78.58 (7)	C4—C5—C8	117.7 (2)
O2W—Mn1—O1Wⁱ	81.81 (7)	C6—C5—C8	120.6 (2)
O3ⁱⁱⁱ—Mn1—O1Wⁱ	81.59 (7)	C13—C6—C5	121.0 (2)
N1—Mn1—O1Wⁱ	176.83 (8)	C13—C6—C7	117.8 (2)
O1W—Mn1—O1Wⁱ	89.68 (6)	C5—C6—C7	121.0 (2)
O4ⁱⁱ—Mn1—H4W	125.7	O1—C7—O2	123.6 (3)
O2W—Mn1—H4W	22.9	O1—C7—C6	117.1 (2)
O3ⁱⁱⁱ—Mn1—H4W	74.5	O2—C7—C6	119.3 (2)
N1—Mn1—H4W	83.0	O4—C8—O3	126.1 (3)
O1W—Mn1—H4W	150.1	O4—C8—C5	117.2 (2)
O1Wⁱ—Mn1—H4W	94.9	O3—C8—C5	116.7 (2)
O4ⁱⁱ—Mn1—H3W	96.4	C6—C13—C2	116.4 (2)
O2W—Mn1—H3W	22.9	C6—C13—H13	121.8
O3ⁱⁱⁱ—Mn1—H3W	89.3	C2—C13—H13	121.8

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O2^v	0.86	1.98	2.839 (3)	174
O2W—H4W···O3ⁱⁱⁱ	0.84	2.56	3.065 (3)	120
O1W—H1W···O2ⁱⁱⁱ	0.84	2.10	2.819 (3)	143
O2W—H3W···O1Wⁱ	0.84	2.10	2.934 (3)	169
O1W—H2W···O1^vi	0.84	1.77	2.575 (3)	160
C4—H4···O4ⁱⁱ	0.93	2.48	3.216 (3)	136

Symmetry codes: (i) −x+1, −y+1, −z+2; (ii) −x+2, −y+1, −z+2; (iii) x−1, y, z; (v) −x+2, y+1/2, −z+3/2; (vi) −x+2, y−1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	[Mn(C₉H₄N₂O₄)(H₂O)₂]
M_r	295.11
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	293
a, b, c (Å)	8.8875 (18), 9.2079 (18), 12.939 (3)
β (°)	97.22 (3)
V (Å³)	1050.5 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	1.28
Crystal size (mm)	0.29 × 0.26 × 0.25

Data collection
Diffractometer	Rigaku/MSC Mercury CCD
Absorption correction	Multi-scan (REQAB; Jacobson, 1998)
T_min, T_max	0.708, 0.740
No. of measured, independent and observed [I > 2σ(I)] reflections	8122, 1888, 1792
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.599

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.098, 1.11
No. of reflections	1888
No. of parameters	163
No. of restraints	18
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.71, −0.84

Computer programs: RAPID-AUTO (Rigaku, 1998), CrystalStructure (Rigaku/MSC, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEPII (Johnson, 1976).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2···O2ⁱ	0.86	1.98	2.839 (3)	173.6
O2W—H4W···O3ⁱⁱ	0.84	2.56	3.065 (3)	119.7
O1W—H1W···O2ⁱⁱ	0.84	2.10	2.819 (3)	143.0
O2W—H3W···O1Wⁱⁱⁱ	0.84	2.10	2.934 (3)	169.1
O1W—H2W···O1^iv	0.84	1.77	2.575 (3)	159.6
C4—H4···O4^v	0.93	2.48	3.216 (3)	136

Symmetry codes: (i) −x+2, y+1/2, −z+3/2; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+2; (iv) −x+2, y−1/2, −z+3/2; (v) −x+2, −y+1, −z+2.

Acknowledgements

The authors acknowledge the Scientific Research Project of Hunan Department of Education (No. 09c259) for supporting this work.

References

Jacobson, R. (1998). REQAB. Molecular Structure Corporation, The Woodlands, Texas, USA. Google Scholar
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA. Google Scholar
Rigaku (1998). RAPID-AUTO. Rigaku Corporation, Tokyo, Japan. Google Scholar
Rigaku/MSC (2002). CrystalStructure. Rigaku/MSC, The Woodlands, Texas, USA. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Song, W.-D., Wang, H., Hu, S.-W., Qin, P.-W. & Li, S.-J. (2009b). Acta Cryst. E65, m701. Web of Science CSD CrossRef IUCr Journals Google Scholar
Song, W.-D., Wang, H., Li, S.-J., Qin, P.-W. & Hu, S.-W. (2009a). Acta Cryst. E65, m702. Web of Science CSD CrossRef IUCr Journals Google Scholar
Wei, Y. Q., Yu, Y. F., Sa, R. J., Li, Q. H. & Wu, K. C. (2009). CrystEngComm, 11,1054–1060. Web of Science CSD CrossRef CAS Google Scholar
Yao, Y. L., Che, Y. X. & Zheng, J. M. (2008). Cryst. Growth Des. 8, 2299–2306. Web of Science CSD CrossRef CAS Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.