Bis(N,N-dimethyl­formamide-κO)bis­(2,4,6-trinitro­phenolato-κ2O1,O2)copper(II)

Li, B.-Y.; Tong, J.-F.; Dong, W.-K.; Yao, J.; Wu, J.-C.

doi:10.1107/S1600536808039846

metal-organic compounds

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ISSN: 2056-9890

Volume 65| Part 1| January 2009| Page m1

doi:10.1107/S1600536808039846

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Bis(N,N-dimethylformamide-κO)bis(2,4,6-trinitrophenolato-κ²O¹,O²)copper(II)

Bai-Yu Li,^a Jun-Feng Tong,^a Wen-Kui Dong,^a ^* Jian Yao ^a and Jian-Chao Wu ^a

^aSchool of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, People's Republic of China
^*Correspondence e-mail: dongwk@mail.lzjtu.cn

(Received 13 November 2008; accepted 26 November 2008; online 3 December 2008)

The molecule of the title complex, [Cu(C₆H₂N₃O₇)₂(C₃H₇NO)₂], is disposed about a crystallographic centre of symmetry. The Cu^II cation is six-coordinated by two phenolate O atoms and two ortho-nitro O atoms of two picrate units and by two carbonyl O atoms from two coordinated dimethylformamide molecules, forming a distorted octahedral geometry.

Related literature

For background to 2,4,6-trinitrophenoxides, see: Arnaud-Neu et al. (2005 ); Dong et al. (1998 , 2007a ,b ); Harrowfield et al. (1995 , 1998 ); Liu et al. (2008 ); Marchand et al. (2003 ); Muthamizhchelvan et al. (2005 ); Song et al. (2007 ); Talanova et al. (1999 ); Venkatasubramanian et al. (1985 ); Wang et al. (2003 ).

Experimental

Crystal data

[Cu(C₆H₂N₃O₇)₂(C₃H₇NO)₂]
M_r = 665.94
Triclinic, $[P \overline 1]$
a = 8.0620 (10) Å
b = 8.3361 (11) Å
c = 9.8429 (14) Å
α = 73.945 (1)°
β = 88.796 (2)°
γ = 87.968 (2)°
V = 635.25 (15) Å³
Z = 1
Mo Kα radiation
μ = 0.96 mm⁻¹
T = 298 (2) K
0.45 × 0.42 × 0.30 mm

Data collection

Siemens SMART 1000 CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.673, T_max = 0.762
3320 measured reflections
2198 independent reflections
1973 reflections with I > 2σ(I)
R_int = 0.019

Refinement

R[F² > 2σ(F²)] = 0.030
wR(F²) = 0.078
S = 1.08
2198 reflections
199 parameters
H-atom parameters constrained
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.36 e Å⁻³

Data collection: SMART (Siemens, 1996 ); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; 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 global, I. DOI: 10.1107/S1600536808039846/hg2446sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808039846/hg2446Isup2.hkl

checkCIF report

Comment top

2,4,6-Trinitrophenoxides, 'picrates', play an important role in the modern coordination chemistry (Dong et al., 1998; Dong et al., 2007a). Picrate anion with extraordinary varieties in the binding of complexes, has great potential in building coordination networks (Liu et al., 2008). They can act as the bridging mono- (Arnaud-Neu et al., 2005; Wang et al., 2003), di- (Marchand et al., 2003; Song et al., 2007), tri- (Harrowfield et al., 1995; Dong et al., 1998; Dong et al., 2007a), tetra- (Venkatasubramanian et al., 1985) or penta- (Dong et al., 2007b; Harrowfield et al., 1998) dentate ligands via the phenolic oxygen, ortho-nitro oxygen and para-nitro oxygen atoms to build coordination networks as well as interlink the one-dimensional or two-dimensional molecules into frameworks via the hydrogen bonds (Muthamizhchelvan et al., 2005) or π-π stacking interactions (Talanova et al., 1999). Here, in continuation of our previous studies on synthesis and structural characterization of transition metal complexes with salen-type bisoxime chelating ligands, a single-crystal of unexpected complex, bis(N,N-dimethylformamide-κ O)bis(2,4,6-trinitrophenolato- κ² O,O')copper(II), was obtained and structurally characterized by X-ray crystallography.

The crystal structure of the title complex consists of discrete C₁₈H₁₈CuN₈O₁₆ molecules (Fig. 1), in which all bond lengths are in normal ranges. The two benzene rings in each molecule of the title complex are parallel and the distance between them is 2.115 (2)Å. The central Cu^II atom is located on a crystallographic inversion center. The carbonyl oxygens O8, O8ⁱ and the phenoxy oxygens O1, O1ⁱ(symmetry code (i) -x=1, -y+1, -z+1) coordinate to the copper atom to form a distorted square planar structure with Cu1-O2 and Cu1-O8 bond lengths of 1.9226 (15) and 1.9401 (15)Å respectively. The two ortho-nitro oxygen atoms (O2 and O2ⁱ) occupy axial positions with Cu1-O2 = 2.659 (2)Å to give a distorted octahedral coordination geometry around the copper atom.

Related literature top

For background to 2,4,6-trinitrophenoxides, see: Arnaud-Neu, Harrowfield, Michel, Skelton & White (2005); Dong et al. (1998, 2007a,b); Harrowfield et al. (1995, 1998); Liu et al. (2008); Marchand et al. (2003); Muthamizhchelvan et al. (2005); Song et al. (2007); Talanova et al. (1999); Venkatasubramanian et al. (1985); Wang et al. (2003).

Experimental top

Copper(II) picrate tetrahydrate and 5,5'-dihydroxy-2,2'-[1,1'-(propane-1,3-diyldioxydinitrilo)diethlidyne]diphenol were synthesized by an analogous method (Dong et al., 2007a). A ethyl acetate-N,N-dimethylformamide mixed solution (2 ml) of 5,5'-dihydroxy-2,2'-[1,1'-(propane-1,3-diyldioxydinitrilo)diethlidyne]diphenol (4.1 mg, 0.01 mmol) was added dropwise to a acetone solution (2 ml) of copper(II) picrate tetrahydrate (6.1 mg, 0.01 mmol) at room temperature. The brilliant yellow solution obtained was placed in n-hexane sphere and allowed to stand at room temperature for about several weeks. Along with diffusion of n-hexane into the mixed solution of the complex, Green block-like single crystals of bis(N,N-dimethylformamide-κ O)bis(2,4,6-trinitrophenolato- κ² O,O')copper(II) complex suitable for X-ray crystallographic analysis were obtained. Anal. Calc. for C₁₈H₁₈CuN₈O₁₆: C, 34,51; H, 3.48; N, 16.10; Cu, 9.13%. Found: C, 34,73; H, 3.51; N, 16.17; Cu, 9.01%.

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); 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 molecule structure of the title complex with atom numbering scheme [Symmetry codes: -x + 1,-y + 1,-z + 1]. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level.

Bis(N,N-dimethylformamide-κO)bis(2,4,6-trinitrophenolato- κ²O¹,O²)copper(II) top

Crystal data top

[Cu(C₆H₂N₃O₇)₂(C₃H₇NO)₂]	Z = 1
M_r = 665.94	F(000) = 339
Triclinic, P1	D_x = 1.741 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.062 (1) Å	Cell parameters from 2174 reflections
b = 8.3361 (11) Å	θ = 2.5–27.5°
c = 9.8429 (14) Å	µ = 0.96 mm⁻¹
α = 73.945 (1)°	T = 298 K
β = 88.796 (2)°	Block-like, green
γ = 87.968 (2)°	0.45 × 0.42 × 0.30 mm
V = 635.25 (15) Å³

Data collection top

Siemens SMART 1000 CCD area-detector diffractometer	2198 independent reflections
Radiation source: fine-focus sealed tube	1973 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.020
ϕ and ω scans	θ_max = 25.0°, θ_min = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
T_min = 0.673, T_max = 0.762	k = −9→6
3320 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)] = 0.030	H-atom parameters constrained
wR(F²) = 0.078	w = 1/[σ²(F_o²) + (0.036P)² + 0.273P] where P = (F_o² + 2F_c²)/3
S = 1.08	(Δ/σ)_max < 0.001
2198 reflections	Δρ_max = 0.22 e Å⁻³
199 parameters	Δρ_min = −0.36 e Å⁻³
0 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: 0.141 (6)

Crystal data top

[Cu(C₆H₂N₃O₇)₂(C₃H₇NO)₂]	γ = 87.968 (2)°
M_r = 665.94	V = 635.25 (15) Å³
Triclinic, P1	Z = 1
a = 8.062 (1) Å	Mo Kα radiation
b = 8.3361 (11) Å	µ = 0.96 mm⁻¹
c = 9.8429 (14) Å	T = 298 K
α = 73.945 (1)°	0.45 × 0.42 × 0.30 mm
β = 88.796 (2)°

Data collection top

Siemens SMART 1000 CCD area-detector diffractometer	2198 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1973 reflections with I > 2σ(I)
T_min = 0.673, T_max = 0.762	R_int = 0.020
3320 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	0 restraints
wR(F²) = 0.078	H-atom parameters constrained
S = 1.08	Δρ_max = 0.22 e Å⁻³
2198 reflections	Δρ_min = −0.36 e Å⁻³
199 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
Cu1	0.5000	0.5000	0.5000	0.02554 (17)
N1	0.5597 (3)	0.5206 (2)	0.1667 (2)	0.0339 (5)
N2	0.8515 (3)	1.0013 (3)	−0.1186 (2)	0.0407 (5)
N3	0.5610 (3)	1.0497 (2)	0.3079 (2)	0.0341 (5)
N4	0.9697 (2)	0.3374 (2)	0.4240 (2)	0.0289 (4)
O1	0.4863 (2)	0.71913 (19)	0.36927 (16)	0.0332 (4)
O2	0.4407 (2)	0.4683 (2)	0.2441 (2)	0.0497 (5)
O3	0.6381 (3)	0.4363 (2)	0.1017 (2)	0.0496 (5)
O4	0.9214 (3)	0.9088 (3)	−0.1814 (2)	0.0587 (6)
O5	0.8672 (3)	1.1525 (3)	−0.1527 (2)	0.0639 (6)
O6	0.6713 (3)	1.1133 (3)	0.3553 (2)	0.0552 (5)
O7	0.4137 (3)	1.0653 (2)	0.3315 (2)	0.0556 (5)
O8	0.72371 (18)	0.47226 (19)	0.43167 (16)	0.0306 (4)
C1	0.5606 (3)	0.7778 (3)	0.2512 (2)	0.0255 (5)
C2	0.6088 (3)	0.6916 (3)	0.1486 (2)	0.0265 (5)
C3	0.7030 (3)	0.7633 (3)	0.0293 (2)	0.0301 (5)
H3	0.7350	0.7018	−0.0331	0.036*
C4	0.7490 (3)	0.9268 (3)	0.0041 (2)	0.0298 (5)
C5	0.7014 (3)	1.0223 (3)	0.0951 (2)	0.0287 (5)
H5	0.7312	1.1331	0.0767	0.034*
C6	0.6098 (3)	0.9480 (3)	0.2118 (2)	0.0259 (5)
C7	0.8263 (3)	0.3548 (3)	0.4840 (2)	0.0278 (5)
H7	0.7989	0.2774	0.5687	0.033*
C8	1.0134 (3)	0.4484 (4)	0.2868 (3)	0.0434 (6)
H8A	0.9757	0.4034	0.2134	0.065*
H8B	1.1317	0.4587	0.2795	0.065*
H8C	0.9615	0.5564	0.2768	0.065*
C9	1.0878 (3)	0.2028 (3)	0.4895 (3)	0.0402 (6)
H9A	1.0476	0.1441	0.5817	0.060*
H9B	1.1933	0.2489	0.4979	0.060*
H9C	1.1001	0.1270	0.4320	0.060*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0244 (2)	0.0238 (2)	0.0255 (2)	−0.00033 (15)	0.00563 (15)	−0.00252 (15)
N1	0.0396 (12)	0.0273 (11)	0.0347 (11)	−0.0003 (9)	−0.0077 (9)	−0.0081 (9)
N2	0.0390 (12)	0.0539 (15)	0.0278 (11)	−0.0100 (11)	0.0067 (9)	−0.0084 (10)
N3	0.0480 (13)	0.0224 (10)	0.0299 (10)	0.0035 (9)	0.0070 (9)	−0.0051 (8)
N4	0.0255 (10)	0.0290 (10)	0.0325 (10)	0.0012 (8)	0.0019 (8)	−0.0097 (8)
O1	0.0358 (9)	0.0260 (8)	0.0316 (9)	0.0026 (7)	0.0142 (7)	0.0011 (7)
O2	0.0463 (11)	0.0393 (10)	0.0610 (12)	−0.0169 (9)	0.0065 (9)	−0.0085 (9)
O3	0.0708 (14)	0.0310 (10)	0.0510 (12)	0.0033 (9)	−0.0010 (10)	−0.0187 (9)
O4	0.0601 (13)	0.0758 (15)	0.0440 (12)	−0.0094 (11)	0.0237 (10)	−0.0236 (11)
O5	0.0878 (17)	0.0495 (13)	0.0479 (12)	−0.0253 (12)	0.0274 (11)	−0.0019 (10)
O6	0.0705 (14)	0.0512 (12)	0.0538 (12)	−0.0025 (11)	−0.0067 (10)	−0.0306 (10)
O7	0.0498 (13)	0.0475 (12)	0.0714 (14)	0.0092 (9)	0.0224 (10)	−0.0225 (10)
O8	0.0249 (8)	0.0303 (9)	0.0318 (9)	0.0019 (7)	0.0065 (6)	−0.0015 (7)
C1	0.0218 (11)	0.0253 (11)	0.0256 (11)	0.0035 (9)	−0.0002 (9)	−0.0013 (9)
C2	0.0273 (12)	0.0235 (11)	0.0274 (11)	0.0003 (9)	−0.0013 (9)	−0.0047 (9)
C3	0.0316 (12)	0.0328 (13)	0.0262 (12)	0.0031 (10)	0.0000 (9)	−0.0088 (9)
C4	0.0286 (12)	0.0348 (13)	0.0226 (11)	−0.0015 (10)	0.0024 (9)	−0.0026 (9)
C5	0.0300 (12)	0.0239 (11)	0.0292 (12)	−0.0041 (9)	0.0008 (9)	−0.0020 (9)
C6	0.0268 (11)	0.0247 (11)	0.0259 (11)	0.0031 (9)	0.0010 (9)	−0.0069 (9)
C7	0.0284 (12)	0.0273 (12)	0.0267 (11)	−0.0027 (9)	0.0025 (9)	−0.0060 (9)
C8	0.0360 (14)	0.0516 (16)	0.0381 (14)	−0.0010 (12)	0.0132 (11)	−0.0059 (12)
C9	0.0323 (13)	0.0369 (14)	0.0517 (16)	0.0065 (11)	−0.0001 (11)	−0.0135 (12)

Geometric parameters (Å, º) top

Cu1—O1ⁱ	1.9226 (15)	O1—C1	1.275 (3)
Cu1—O1	1.9226 (15)	O8—C7	1.261 (3)
Cu1—O8	1.9401 (15)	C1—C6	1.431 (3)
Cu1—O8ⁱ	1.9401 (15)	C1—C2	1.432 (3)
Cu1—O2	2.659 (2)	C2—C3	1.385 (3)
N1—O3	1.226 (3)	C3—C4	1.379 (3)
N1—O2	1.228 (3)	C3—H3	0.9300
N1—C2	1.455 (3)	C4—C5	1.393 (3)
N2—O5	1.222 (3)	C5—C6	1.361 (3)
N2—O4	1.230 (3)	C5—H5	0.9300
N2—C4	1.452 (3)	C7—H7	0.9300
N3—O6	1.215 (3)	C8—H8A	0.9600
N3—O7	1.215 (3)	C8—H8B	0.9600
N3—C6	1.474 (3)	C8—H8C	0.9600
N4—C7	1.310 (3)	C9—H9A	0.9600
N4—C8	1.455 (3)	C9—H9B	0.9600
N4—C9	1.459 (3)	C9—H9C	0.9600

O1ⁱ—Cu1—O1	180.0	C3—C2—N1	116.6 (2)
O1ⁱ—Cu1—O8	90.87 (6)	C1—C2—N1	120.38 (19)
O1—Cu1—O8	89.13 (6)	C4—C3—C2	119.3 (2)
O1ⁱ—Cu1—O8ⁱ	89.13 (6)	C4—C3—H3	120.4
O1—Cu1—O8ⁱ	90.87 (6)	C2—C3—H3	120.4
O8—Cu1—O8ⁱ	180.000 (1)	C3—C4—C5	121.5 (2)
O1ⁱ—Cu1—O2	108.49 (7)	C3—C4—N2	119.6 (2)
O1—Cu1—O2	71.51 (7)	C5—C4—N2	118.9 (2)
O8—Cu1—O2	78.81 (6)	C6—C5—C4	117.8 (2)
O8ⁱ—Cu1—O2	101.19 (6)	C6—C5—H5	121.1
O3—N1—O2	123.1 (2)	C4—C5—H5	121.1
O3—N1—C2	118.1 (2)	C5—C6—C1	125.5 (2)
O2—N1—C2	118.8 (2)	C5—C6—N3	117.3 (2)
O5—N2—O4	123.1 (2)	C1—C6—N3	117.15 (18)
O5—N2—C4	118.4 (2)	O8—C7—N4	122.7 (2)
O4—N2—C4	118.5 (2)	O8—C7—H7	118.7
O6—N3—O7	125.3 (2)	N4—C7—H7	118.7
O6—N3—C6	117.4 (2)	N4—C8—H8A	109.5
O7—N3—C6	117.3 (2)	N4—C8—H8B	109.5
C7—N4—C8	120.7 (2)	H8A—C8—H8B	109.5
C7—N4—C9	121.3 (2)	N4—C8—H8C	109.5
C8—N4—C9	117.95 (19)	H8A—C8—H8C	109.5
C1—O1—Cu1	130.29 (14)	H8B—C8—H8C	109.5
N1—O2—Cu1	108.53 (14)	N4—C9—H9A	109.5
C7—O8—Cu1	126.60 (14)	N4—C9—H9B	109.5
O1—C1—C6	119.4 (2)	H9A—C9—H9B	109.5
O1—C1—C2	127.7 (2)	N4—C9—H9C	109.5
C6—C1—C2	112.79 (19)	H9A—C9—H9C	109.5
C3—C2—C1	123.0 (2)	H9B—C9—H9C	109.5

O8—Cu1—O1—C1	27.0 (2)	N1—C2—C3—C4	178.0 (2)
O8ⁱ—Cu1—O1—C1	−153.0 (2)	C2—C3—C4—C5	−0.7 (3)
O2—Cu1—O1—C1	−51.52 (19)	C2—C3—C4—N2	178.4 (2)
O3—N1—O2—Cu1	123.9 (2)	O5—N2—C4—C3	167.6 (2)
C2—N1—O2—Cu1	−57.3 (2)	O4—N2—C4—C3	−14.0 (3)
O1ⁱ—Cu1—O2—N1	−115.98 (15)	O5—N2—C4—C5	−13.3 (3)
O1—Cu1—O2—N1	64.02 (15)	O4—N2—C4—C5	165.1 (2)
O8—Cu1—O2—N1	−28.83 (15)	C3—C4—C5—C6	1.1 (3)
O8ⁱ—Cu1—O2—N1	151.17 (15)	N2—C4—C5—C6	−177.9 (2)
O1ⁱ—Cu1—O8—C7	−8.81 (18)	C4—C5—C6—C1	1.4 (3)
O1—Cu1—O8—C7	171.19 (18)	C4—C5—C6—N3	179.6 (2)
O2—Cu1—O8—C7	−117.49 (19)	O1—C1—C6—C5	174.3 (2)
Cu1—O1—C1—C6	−144.15 (17)	C2—C1—C6—C5	−3.9 (3)
Cu1—O1—C1—C2	33.8 (3)	O1—C1—C6—N3	−3.9 (3)
O1—C1—C2—C3	−173.8 (2)	C2—C1—C6—N3	177.93 (19)
C6—C1—C2—C3	4.3 (3)	O6—N3—C6—C5	−56.1 (3)
O1—C1—C2—N1	5.9 (3)	O7—N3—C6—C5	122.8 (2)
C6—C1—C2—N1	−176.03 (19)	O6—N3—C6—C1	122.2 (2)
O3—N1—C2—C3	19.5 (3)	O7—N3—C6—C1	−58.9 (3)
O2—N1—C2—C3	−159.3 (2)	Cu1—O8—C7—N4	173.74 (16)
O3—N1—C2—C1	−160.2 (2)	C8—N4—C7—O8	−4.3 (3)
O2—N1—C2—C1	21.0 (3)	C9—N4—C7—O8	178.2 (2)
C1—C2—C3—C4	−2.2 (3)

Symmetry code: (i) −x+1, −y+1, −z+1.

Experimental details

Crystal data
Chemical formula	[Cu(C₆H₂N₃O₇)₂(C₃H₇NO)₂]
M_r	665.94
Crystal system, space group	Triclinic, P1
Temperature (K)	298
a, b, c (Å)	8.062 (1), 8.3361 (11), 9.8429 (14)
α, β, γ (°)	73.945 (1), 88.796 (2), 87.968 (2)
V (Å³)	635.25 (15)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	0.96
Crystal size (mm)	0.45 × 0.42 × 0.30

Data collection
Diffractometer	Siemens SMART 1000 CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.673, 0.762
No. of measured, independent and observed [I > 2σ(I)] reflections	3320, 2198, 1973
R_int	0.020
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.078, 1.08
No. of reflections	2198
No. of parameters	199
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.22, −0.36

Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

This work was supported by the Foundation of the Education Department of Gansu Province (No. 0604–01) and the `Qing Lan' Talent Engineering Funds of Lanzhou Jiaotong University (No. QL-05-19 A), which are gratefully acknowledged.

References

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