Bis{2-[(4-chloro­phen­yl)imino­meth­yl]pyrrol-1-ido-κ2N,N′}bis­(dimethyl­amido-κN)titanium(IV) toluene monosolvate

Chen, Z.; Wu, J.; Li, Y.; Hu, B.

doi:10.1107/S1600536812014961

metal-organic compounds

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ISSN: 2056-9890

Volume 68| Part 5| May 2012| Pages m596-m597

doi:10.1107/S1600536812014961

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Bis{2-[(4-chlorophenyl)iminomethyl]pyrrol-1-ido-κ²N,N′}bis(dimethylamido-κN)titanium(IV) toluene monosolvate

Zhou Chen,^a Jian Wu,^b Yahong Li ^a,^b ^* and Bin Hu ^a

^aQinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, People's Republic of China, and ^bKey Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
^*Correspondence e-mail: liyahong@suda.edu.cn

(Received 28 March 2012; accepted 5 April 2012; online 18 April 2012)

The mononuclear title compound, [Ti(C₁₁H₈ClN₂)₂(C₂H₆N)₂]·C₇H₈, was synthesized by the reaction of N-(4-chlorophenyl)-2-pyrrolylcarbaldimine with Ti(C₂H₆N)₄. The Ti^IV ion is situated on a twofold rotation axis and displays a distorted octahedral geometry defined by four N atoms from two 2-[(4-chlorophenyl)iminomethyl]pyrrol-1-ide ligands and two N atoms from two dimethylamine ligands. The Ti—N_pyrrole bond length [2.1041 (19) Å] is longer than the Ti—N_{dimethylamine} bond length [1.9013 (19) Å]; the imine N atom exhibits the longest Ti—N bond [2.3152 (17) Å]. The toluene solvent molecule is located on a twofold rotation axis running through the C atom of the methyl group. Consequently, the H atoms of the latter are rotationally disordered. The compound contains no markable hydrogen-bonding interactions.

Related literature

For the synthesis of N-(4-chlorophenyl)-2-pyrrolylcarbaldimine and its oxidovanadium(IV) complexes, see: Mozaffar et al. (2010 ). For the synthesis of titanium amido complexes and their applications in hydroamination reactions, see: Ramanathan et al. (2004 ); Cao et al. (2001 ); Bexrud et al. (2007 ); Tillack et al. (2005 ); Braunschweig & Breitling (2006 ); Zhao et al. (2012 ).

Experimental

Crystal data

[Ti(C₁₁H₈ClN₂)₂(C₂H₆N)₂]·C₇H₈
M_r = 635.48
Orthorhombic, P 2₁ 2₁ 2
a = 11.1952 (4) Å
b = 13.8545 (6) Å
c = 10.4651 (3) Å
V = 1623.18 (10) Å³
Z = 2
Mo Kα radiation
μ = 0.46 mm⁻¹
T = 296 K
0.27 × 0.25 × 0.20 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.886, T_max = 0.914
7377 measured reflections
3172 independent reflections
2855 reflections with I > 2σ(I)
R_int = 0.021

Refinement

R[F² > 2σ(F²)] = 0.035
wR(F²) = 0.103
S = 1.04
3172 reflections
191 parameters
H-atom parameters constrained
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.81 e Å⁻³
Absolute structure: Flack (1983 ), 1338 Friedel pairs
Flack parameter: 0.00 (3)

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); 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 I, global. DOI: 10.1107/S1600536812014961/wm2614sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812014961/wm2614Isup2.hkl

checkCIF report

Comment top

The ligand N-(4-chlorophenyl)-2-pyrrolylcarbaldimine can be synthesized by the reaction of 4-chloroaniline and 2-pyrrolaldehyde. The ligand has been used in the synthesis of oxidovanadium(IV) complexes (Mozaffar et al., 2010). Herein we report the synthesis and crystal structure of a titanium amido complex [Ti(C₁₁H₈N₂Cl)₂(C₂H₆N)₂](C₆H₅CH₃), (I). Such titanium amido complexes were employed as catalysts in the hydroamination of alkynes (Ramanathan et al., 2004; Cao et al., 2001; Bexrud et al., 2007; Tillack et al., 2005; Braunschweig & Breitling, 2006; Zhao et al., 2012).

The molecular structure of (I) is shown in Fig. 1. The Ti^IV ion has site symmetry 2 and displays a distorted octahedral geometry. It is coordinated by four N atoms from two symmetry-related bidentate N-(4-chlorophenyl)-2-pyrrolylcarbaldimine ligands and two nitrogen atoms from two dimethylamino ions. Two pyrrolyl N atoms from two coordinating N-(4-chlorophenyl)-2-pyrrolylcarbaldimine molecules occupying trans positions in the equatorial plane. The dihedral angle between the pyrrolcarbaldiimine and chlorophenyl moieties in the bidentate ligand is 44.90 (10)° . There is a solvate toluene molecule present that is also located on a twofold rotation axis. Since the methyl group of the solvate toluene lies on a special position of higher symmetry than the molecular can possess, the H atoms of this group are rotationally disordered.

The compound contains no remarkable hydrogen bonding interactions. In the crystal packing, the complexes form channels parallel to [001] where the solvent molecules are located.

Related literature top

For the synthesis of N-(4-chlorophenyl)-2-pyrrolylcarbaldimine and its oxidovanadium(IV) complexes, see: Mozaffar et al. (2010). For the synthesis of titanium amido complexes and their applications in hydroamination reactions, see: Ramanathan et al. (2004); Cao et al. (2001); Bexrud et al. (2007); Tillack et al. (2005); Braunschweig & Breitling (2006); Zhao et al. (2012).

Experimental top

To a solution of Ti(NMe₂)₄ (0.112 g, 0.5 mmol) in THF (2 ml) was added N-(4-chlorophenyl)-2-pyrrolylcarbaldimine (0.204 g, 1 mmol) in THF (3 ml). After stirring at room temperature overnight, volatiles were removed in vacuo, resulting in an orange solid (0.246 g, 91%). Single crystals of (I) were grown from a toluene/hexane (1:1) solution at 238 K.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); 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 molecular structure of (I), with atom labels and displacement ellipsoids at the 30% probability level. [Symmetry code: A) -x + 1, -y, z.]
	Fig. 2. The packing diagram of the compound in a view down [001].

Bis{2-[(4-chlorophenyl)iminomethyl]pyrrol-1-ido- κ²N,N'}bis(dimethylamido-κN)titanium(IV) toluene monosolvate top

Crystal data top

[Ti(C₁₁H₈ClN₂)₂(C₂H₆N)₂]·C₇H₈	F(000) = 664
M_r = 635.48	D_x = 1.300 Mg m⁻³
Orthorhombic, P2₁2₁2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2 2ab	Cell parameters from 3510 reflections
a = 11.1952 (4) Å	θ = 2.7–25.3°
b = 13.8545 (6) Å	µ = 0.46 mm⁻¹
c = 10.4651 (3) Å	T = 296 K
V = 1623.18 (10) Å³	Block, red
Z = 2	0.27 × 0.25 × 0.20 mm

Data collection top

Bruker APEXII CCD diffractometer	3172 independent reflections
Radiation source: fine-focus sealed tube	2855 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.021
ϕ and ω scans	θ_max = 26.0°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −13→13
T_min = 0.886, T_max = 0.914	k = −6→17
7377 measured reflections	l = −12→12

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)] = 0.035	H-atom parameters constrained
wR(F²) = 0.103	w = 1/[σ²(F_o²) + (0.0643P)² + 0.167P] where P = (F_o² + 2F_c²)/3
S = 1.04	(Δ/σ)_max < 0.001
3172 reflections	Δρ_max = 0.24 e Å⁻³
191 parameters	Δρ_min = −0.81 e Å⁻³
0 restraints	Absolute structure: Flack (1983), 1338 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.00 (3)

Crystal data top

[Ti(C₁₁H₈ClN₂)₂(C₂H₆N)₂]·C₇H₈	V = 1623.18 (10) Å³
M_r = 635.48	Z = 2
Orthorhombic, P2₁2₁2	Mo Kα radiation
a = 11.1952 (4) Å	µ = 0.46 mm⁻¹
b = 13.8545 (6) Å	T = 296 K
c = 10.4651 (3) Å	0.27 × 0.25 × 0.20 mm

Data collection top

Bruker APEXII CCD diffractometer	3172 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	2855 reflections with I > 2σ(I)
T_min = 0.886, T_max = 0.914	R_int = 0.021
7377 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.035	H-atom parameters constrained
wR(F²) = 0.103	Δρ_max = 0.24 e Å⁻³
S = 1.04	Δρ_min = −0.81 e Å⁻³
3172 reflections	Absolute structure: Flack (1983), 1338 Friedel pairs
191 parameters	Absolute structure parameter: 0.00 (3)
0 restraints

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	Occ. (<1)
Ti	0.5000	0.0000	−0.00125 (4)	0.03946 (15)
N3	0.37242 (16)	−0.00104 (15)	0.17286 (15)	0.0444 (4)
N1	0.52139 (16)	0.14665 (13)	0.04575 (18)	0.0468 (4)
C7	0.32052 (19)	0.07660 (18)	0.2402 (2)	0.0438 (5)
N2	0.37235 (18)	0.00986 (16)	−0.12037 (17)	0.0511 (4)
C8	0.25902 (18)	0.14699 (16)	0.1737 (2)	0.0458 (5)
H8	0.2554	0.1440	0.0850	0.055*
C9	0.2030 (2)	0.22161 (18)	0.2368 (2)	0.0515 (5)
H9	0.1606	0.2681	0.1915	0.062*
C2	0.5137 (3)	0.30613 (18)	0.0851 (3)	0.0651 (7)
H2	0.4953	0.3712	0.0762	0.078*
C13	0.3605 (2)	−0.08821 (17)	0.2195 (2)	0.0506 (5)
H13	0.3171	−0.0985	0.2940	0.061*
C1	0.4781 (2)	0.23225 (17)	0.0050 (2)	0.0551 (6)
H1	0.4307	0.2404	−0.0672	0.066*
C12	0.3297 (2)	0.0845 (2)	0.3729 (2)	0.0594 (7)
H12	0.3734	0.0392	0.4187	0.071*
C11	0.2741 (3)	0.1593 (2)	0.4364 (2)	0.0673 (7)
H11	0.2796	0.1642	0.5248	0.081*
C3	0.5818 (3)	0.2653 (2)	0.1808 (3)	0.0642 (7)
H3	0.6179	0.2972	0.2487	0.077*
C10	0.2107 (2)	0.22629 (19)	0.3680 (2)	0.0549 (6)
C5	0.2535 (2)	−0.0300 (2)	−0.1037 (3)	0.0651 (7)
H5A	0.1973	0.0215	−0.0914	0.098*
H5B	0.2526	−0.0716	−0.0304	0.098*
H5C	0.2318	−0.0663	−0.1784	0.098*
C4	0.5856 (2)	0.16622 (17)	0.1551 (2)	0.0505 (5)
C14	1.0000	0.0000	0.3423 (7)	0.135 (2)
C15	0.9586 (4)	0.0770 (4)	0.4130 (6)	0.1245 (18)
H15	0.9309	0.1311	0.3696	0.149*
C16	0.9561 (4)	0.0779 (4)	0.5446 (6)	0.1265 (17)
H16	0.9251	0.1304	0.5888	0.152*
C6	0.3784 (3)	0.0670 (2)	−0.2366 (3)	0.0746 (8)
H6A	0.3631	0.0264	−0.3091	0.112*
H6B	0.4565	0.0950	−0.2444	0.112*
H6C	0.3196	0.1174	−0.2332	0.112*
C17	1.0000	0.0000	0.6079 (7)	0.117 (2)
H17	1.0000	0.0000	0.6968	0.141*
Cl	0.13535 (9)	0.31837 (6)	0.44888 (7)	0.0879 (3)
C18	1.0000	0.0000	0.2026 (6)	0.135 (2)
H18A	0.9518	0.0524	0.1720	0.203*	0.50
H18B	0.9679	−0.0600	0.1720	0.203*	0.50
H18C	1.0803	0.0075	0.1720	0.203*	0.50

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ti	0.0425 (3)	0.0420 (3)	0.0339 (2)	0.0016 (2)	0.000	0.000
N3	0.0455 (9)	0.0466 (9)	0.0413 (8)	−0.0013 (10)	0.0007 (7)	0.0020 (9)
N1	0.0506 (10)	0.0436 (10)	0.0464 (9)	−0.0002 (8)	0.0061 (8)	0.0025 (8)
C7	0.0420 (10)	0.0498 (12)	0.0397 (10)	−0.0017 (10)	0.0044 (9)	0.0029 (9)
N2	0.0529 (10)	0.0574 (12)	0.0431 (8)	0.0072 (10)	−0.0077 (8)	0.0005 (9)
C8	0.0482 (12)	0.0519 (13)	0.0374 (10)	−0.0034 (10)	0.0014 (9)	0.0001 (9)
C9	0.0559 (13)	0.0489 (13)	0.0497 (13)	0.0044 (11)	−0.0017 (11)	0.0017 (10)
C2	0.0718 (17)	0.0404 (12)	0.0831 (17)	0.0009 (13)	0.0133 (15)	0.0038 (12)
C13	0.0515 (12)	0.0522 (14)	0.0482 (12)	−0.0038 (11)	0.0060 (10)	0.0076 (10)
C1	0.0579 (13)	0.0496 (13)	0.0579 (12)	0.0034 (10)	0.0104 (13)	0.0122 (11)
C12	0.0698 (15)	0.0671 (17)	0.0412 (12)	0.0118 (13)	−0.0048 (11)	0.0051 (12)
C11	0.091 (2)	0.0747 (18)	0.0364 (11)	0.0136 (16)	−0.0008 (12)	−0.0040 (12)
C3	0.0696 (16)	0.0471 (14)	0.0760 (17)	−0.0076 (12)	0.0056 (14)	−0.0090 (13)
C10	0.0634 (14)	0.0534 (14)	0.0480 (13)	0.0037 (12)	0.0050 (11)	−0.0074 (11)
C5	0.0571 (15)	0.0772 (18)	0.0611 (15)	0.0017 (13)	−0.0155 (12)	−0.0110 (12)
C4	0.0526 (12)	0.0466 (13)	0.0524 (12)	−0.0073 (11)	0.0042 (10)	−0.0051 (10)
C14	0.126 (3)	0.178 (5)	0.102 (3)	−0.114 (4)	0.000	0.000
C15	0.095 (3)	0.124 (4)	0.154 (5)	−0.039 (3)	−0.043 (3)	0.027 (3)
C16	0.094 (3)	0.144 (5)	0.141 (4)	−0.012 (3)	−0.015 (3)	−0.020 (4)
C6	0.087 (2)	0.084 (2)	0.0535 (14)	0.0153 (17)	−0.0109 (15)	0.0142 (14)
C17	0.094 (4)	0.153 (6)	0.104 (4)	0.016 (5)	0.000	0.000
Cl	0.1167 (7)	0.0798 (5)	0.0672 (4)	0.0314 (5)	0.0061 (4)	−0.0202 (4)
C18	0.126 (3)	0.178 (5)	0.102 (3)	−0.114 (4)	0.000	0.000

Geometric parameters (Å, º) top

Ti—N2ⁱ	1.9013 (19)	C12—H12	0.9300
Ti—N2	1.9013 (19)	C11—C10	1.370 (4)
Ti—N1	2.1041 (19)	C11—H11	0.9300
Ti—N1ⁱ	2.1042 (19)	C3—C4	1.399 (4)
Ti—N3ⁱ	2.3152 (17)	C3—H3	0.9300
Ti—N3	2.3152 (17)	C10—Cl	1.748 (3)
N3—C13	1.309 (3)	C5—H5A	0.9600
N3—C7	1.411 (3)	C5—H5B	0.9600
N1—C1	1.350 (3)	C5—H5C	0.9600
N1—C4	1.378 (3)	C4—C13ⁱ	1.409 (3)
C7—C8	1.382 (3)	C14—C15	1.378 (6)
C7—C12	1.397 (3)	C14—C15ⁱⁱ	1.378 (6)
N2—C5	1.452 (3)	C14—C18	1.462 (8)
N2—C6	1.453 (3)	C15—C16	1.377 (8)
C8—C9	1.378 (3)	C15—H15	0.9300
C8—H8	0.9300	C16—C17	1.359 (6)
C9—C10	1.376 (3)	C16—H16	0.9300
C9—H9	0.9300	C6—H6A	0.9600
C2—C3	1.379 (4)	C6—H6B	0.9600
C2—C1	1.382 (4)	C6—H6C	0.9600
C2—H2	0.9300	C17—C16ⁱⁱ	1.359 (6)
C13—C4ⁱ	1.409 (3)	C17—H17	0.9300
C13—H13	0.9300	C18—H18A	0.9600
C1—H1	0.9300	C18—H18B	0.9600
C12—C11	1.378 (4)	C18—H18C	0.9600

N2ⁱ—Ti—N2	98.06 (12)	C7—C12—H12	119.8
N2ⁱ—Ti—N1	97.88 (8)	C10—C11—C12	119.4 (2)
N2—Ti—N1	99.75 (8)	C10—C11—H11	120.3
N2ⁱ—Ti—N1ⁱ	99.76 (8)	C12—C11—H11	120.3
N2—Ti—N1ⁱ	97.88 (8)	C2—C3—C4	106.3 (3)
N1—Ti—N1ⁱ	152.96 (10)	C2—C3—H3	126.9
N2ⁱ—Ti—N3ⁱ	93.02 (7)	C4—C3—H3	126.9
N2—Ti—N3ⁱ	168.31 (8)	C11—C10—C9	121.4 (2)
N1—Ti—N3ⁱ	74.92 (8)	C11—C10—Cl	119.41 (19)
N1ⁱ—Ti—N3ⁱ	83.81 (7)	C9—C10—Cl	119.1 (2)
N2ⁱ—Ti—N3	168.31 (8)	N2—C5—H5A	109.5
N2—Ti—N3	93.02 (7)	N2—C5—H5B	109.5
N1—Ti—N3	83.81 (7)	H5A—C5—H5B	109.5
N1ⁱ—Ti—N3	74.92 (8)	N2—C5—H5C	109.5
N3ⁱ—Ti—N3	76.19 (8)	H5A—C5—H5C	109.5
C13—N3—C7	118.36 (19)	H5B—C5—H5C	109.5
C13—N3—Ti	111.21 (16)	N1—C4—C3	109.6 (2)
C7—N3—Ti	129.97 (15)	N1—C4—C13ⁱ	118.0 (2)
C1—N1—C4	106.1 (2)	C3—C4—C13ⁱ	132.4 (2)
C1—N1—Ti	137.17 (17)	C15—C14—C15ⁱⁱ	115.0 (7)
C4—N1—Ti	116.32 (15)	C15—C14—C18	122.5 (3)
C8—C7—C12	118.8 (2)	C15ⁱⁱ—C14—C18	122.5 (3)
C8—C7—N3	119.42 (19)	C16—C15—C14	123.4 (6)
C12—C7—N3	121.8 (2)	C16—C15—H15	118.3
C5—N2—C6	110.5 (2)	C14—C15—H15	118.3
C5—N2—Ti	125.68 (17)	C17—C16—C15	118.2 (6)
C6—N2—Ti	123.6 (2)	C17—C16—H16	120.9
C9—C8—C7	121.0 (2)	C15—C16—H16	120.9
C9—C8—H8	119.5	N2—C6—H6A	109.5
C7—C8—H8	119.5	N2—C6—H6B	109.5
C10—C9—C8	119.0 (2)	H6A—C6—H6B	109.5
C10—C9—H9	120.5	N2—C6—H6C	109.5
C8—C9—H9	120.5	H6A—C6—H6C	109.5
C3—C2—C1	107.2 (2)	H6B—C6—H6C	109.5
C3—C2—H2	126.4	C16ⁱⁱ—C17—C16	121.6 (7)
C1—C2—H2	126.4	C16ⁱⁱ—C17—H17	119.2
N3—C13—C4ⁱ	119.1 (2)	C16—C17—H17	119.2
N3—C13—H13	120.5	C14—C18—H18A	109.5
C4ⁱ—C13—H13	120.5	C14—C18—H18B	109.5
N1—C1—C2	110.8 (2)	H18A—C18—H18B	109.5
N1—C1—H1	124.6	C14—C18—H18C	109.5
C2—C1—H1	124.6	H18A—C18—H18C	109.5
C11—C12—C7	120.3 (2)	H18B—C18—H18C	109.5
C11—C12—H12	119.8

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

Experimental details

Crystal data
Chemical formula	[Ti(C₁₁H₈ClN₂)₂(C₂H₆N)₂]·C₇H₈
M_r	635.48
Crystal system, space group	Orthorhombic, P2₁2₁2
Temperature (K)	296
a, b, c (Å)	11.1952 (4), 13.8545 (6), 10.4651 (3)
V (Å³)	1623.18 (10)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.46
Crystal size (mm)	0.27 × 0.25 × 0.20

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.886, 0.914
No. of measured, independent and observed [I > 2σ(I)] reflections	7377, 3172, 2855
R_int	0.021
(sin θ/λ)_max (Å⁻¹)	0.616

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.035, 0.103, 1.04
No. of reflections	3172
No. of parameters	191
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.81
Absolute structure	Flack (1983), 1338 Friedel pairs
Absolute structure parameter	0.00 (3)

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

The authors appreciate financial support from the Hundreds of Talents Program (2005012) of the CAS, the Natural Science Foundation of China (20872105), the Qinglan Project of Jiangsu Province (Bu109805) and the Open Project of the Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education of Lanzhou University (LZUMMM2010003).

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