metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

Bis{μ-2,2′-[ethane-1,2-diylbis(nitrilo­methyl­­idyne)]diphenolato}dinickel(II)

aDepartment of Chemistry, Xiaogan University, Xiaogan, Hubei 432000, People's Republic of China
*Correspondence e-mail: dy9802@126.com

(Received 15 November 2007; accepted 4 December 2007; online 12 December 2007)

The asymmetric unit of the title compound, [Ni2(C16H14N2O2)2], contains an NiII cation which is coordinated by two imine N atoms and by two phenolate O atoms of the salen ligand {salen = N,N′-bis­(salicyl­idene)ethane-1,2-diamine or 2,2′-[ethane-1,2-diyl­bis(nitrilo­methyl­idyne)]diphenol}, leading to a distorted square-planar conformation. When a secondary Ni—O inter­action > 2.41 Å to the neighbouring phenolate O atom is considered, two mol­ecules are linked into a centrosymmetric dimer with an overall square-pyramidal coordination for the NiII cation. Weak ππ inter­actions with a shortest interplanar distance of 3.704 Å help to stabilize the crystal structure.

Related literature

For a review on metal–salen complexes used in catalysis, see: Cozzi (2004[Cozzi, P. G. (2004). Chem. Soc. Rev. 33, 410-421.]).

[Scheme 1]

Experimental

Crystal data
  • [Ni2(C16H14N2O2)2]

  • Mr = 650.00

  • Monoclinic, C 2/c

  • a = 26.639 (2) Å

  • b = 6.9775 (6) Å

  • c = 14.7094 (12) Å

  • β = 97.501 (1)°

  • V = 2710.7 (4) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 1.44 mm−1

  • T = 273 (2) K

  • 0.34 × 0.21 × 0.07 mm

Data collection
  • Bruker SMART CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2001[Bruker (2001). SAINT (Version 6.45), SMART (Version 5.628), SHELXTL (Version 6.12) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.641, Tmax = 0.906

  • 8437 measured reflections

  • 3090 independent reflections

  • 2607 reflections with I > 2σ(I)

  • Rint = 0.023

Refinement
  • R[F2 > 2σ(F2)] = 0.024

  • wR(F2) = 0.056

  • S = 1.03

  • 3090 reflections

  • 191 parameters

  • H-atom parameters constrained

  • Δρmax = 0.39 e Å−3

  • Δρmin = −0.18 e Å−3

Table 1
Selected geometric parameters (Å, °)

Ni1—O2 1.9115 (11)
Ni1—O1 1.9412 (10)
Ni1—N2 1.9484 (13)
Ni1—N1 1.9560 (13)
O2—Ni1—O1 91.35 (5)
O2—Ni1—N2 171.05 (5)
O1—Ni1—N2 91.21 (5)
O2—Ni1—N1 92.53 (5)
O1—Ni1—N1 170.36 (5)
N2—Ni1—N1 83.67 (6)

Data collection: SMART (Bruker, 2001[Bruker (2001). SAINT (Version 6.45), SMART (Version 5.628), SHELXTL (Version 6.12) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2001[Bruker (2001). SAINT (Version 6.45), SMART (Version 5.628), SHELXTL (Version 6.12) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997[Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.]); molecular graphics: SHELXTL ((Bruker, 2001[Bruker (2001). SAINT (Version 6.45), SMART (Version 5.628), SHELXTL (Version 6.12) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.]); software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

A review on metal-salen complexes in catalysis was given recently by Cozzi (2004). Herein, we report on synthesis and crystal structure of [Ni(salen)]2, (I).

As shown in Fig. 1, the molecular structure of (I) is made up of a centrosymmetric dimer. The NiII cation is surrounded by two N atoms and two O atoms from the salen ligands leading to a distorted square coordination with mean Ni—O distances of 1.927 Å, and somewhat longer mean Ni—N distances of 1.952 Å. Secondary Ni1—O1(-x, y, 1/2 - z) interactions of 2.4106 (11) Å of one salen ligand to the neighbouring NiII center link two molecules to a centrosymmetric dimer with an Ni1···Ni1(-x, y, 1/2 - z) separation of 3.1946 (4) Å. The resulting overall coordination sphere of the NiII cation can thus be described as a distorted square pyramid.

As shown in Fig. 2, there are weak π-π interactions, with plane-to-plane distances and displacement angles for the planes Cg4···Cg5 and Cg5···Cg6 of 3.704 Å and 11.85 °, and 4.022 Å and 6.72 °, respectively. The planes Cg4, Cg5 and Cg6 consist of atoms C3—O2/N1, C1—C6 and C7—C12.

Related literature top

For a review on metal–salen complexes used in catalysis, see: Cozzi (2004).

Experimental top

Compound (I) was prepared by adding Ni(Ac)2.2H2O (0.110 g, 0.5 mmol) to a solution of H2(salen) 0.122 mg (0.5 mmol) in methanol (20 mL) and DMF (20 ml). After stirring the mixture for 2 h, the solution was filtered and kept for several days at ambient temperature to evaporate. Brown block-like crystals were obtained.

Refinement top

H atoms were placed in geometrically idealized positions and were refined in the riding mode with C–H = 0.97Å and Uiso(H)=1.5Ueq(C) for C14 and C15. All other H atoms were refined with C–H = 0.93Å and Uiso(H) = 1.2Ueq(C).

Structure description top

A review on metal-salen complexes in catalysis was given recently by Cozzi (2004). Herein, we report on synthesis and crystal structure of [Ni(salen)]2, (I).

As shown in Fig. 1, the molecular structure of (I) is made up of a centrosymmetric dimer. The NiII cation is surrounded by two N atoms and two O atoms from the salen ligands leading to a distorted square coordination with mean Ni—O distances of 1.927 Å, and somewhat longer mean Ni—N distances of 1.952 Å. Secondary Ni1—O1(-x, y, 1/2 - z) interactions of 2.4106 (11) Å of one salen ligand to the neighbouring NiII center link two molecules to a centrosymmetric dimer with an Ni1···Ni1(-x, y, 1/2 - z) separation of 3.1946 (4) Å. The resulting overall coordination sphere of the NiII cation can thus be described as a distorted square pyramid.

As shown in Fig. 2, there are weak π-π interactions, with plane-to-plane distances and displacement angles for the planes Cg4···Cg5 and Cg5···Cg6 of 3.704 Å and 11.85 °, and 4.022 Å and 6.72 °, respectively. The planes Cg4, Cg5 and Cg6 consist of atoms C3—O2/N1, C1—C6 and C7—C12.

For a review on metal–salen complexes used in catalysis, see: Cozzi (2004).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL ((Bruker, 2001); software used to prepare material for publication: SHELXTL (Bruker, 2001).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing displacement ellipsoids at the 30% probability level [symmetry code: (i) -x, y, 1/2 - z].
[Figure 2] Fig. 2. The packing diagram of (I).
Bis{µ-2,2'-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}dinickel(II) top
Crystal data top
[Ni2(C16H14N2O2)2]F(000) = 1344
Mr = 650.00Dx = 1.593 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 3127 reflections
a = 26.639 (2) Åθ = 2.8–26.6°
b = 6.9775 (6) ŵ = 1.44 mm1
c = 14.7094 (12) ÅT = 273 K
β = 97.501 (1)°Block, brown
V = 2710.7 (4) Å30.34 × 0.21 × 0.07 mm
Z = 4
Data collection top
Bruker SMART CCD
diffractometer
3090 independent reflections
Radiation source: fine-focus sealed tube2607 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
φ– and ω– scansθmax = 27.5°, θmin = 2.8°
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
h = 3432
Tmin = 0.641, Tmax = 0.906k = 79
8437 measured reflectionsl = 1619
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)] = 0.024H-atom parameters constrained
wR(F2) = 0.056 w = 1/[σ2(Fo2) + (0.0243P)2 + 0.8084P]
where P = (Fo2 + 2Fc2)/3
S = 1.03(Δ/σ)max < 0.001
3090 reflectionsΔρmax = 0.39 e Å3
191 parametersΔρmin = 0.18 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.00018 (7)
Crystal data top
[Ni2(C16H14N2O2)2]V = 2710.7 (4) Å3
Mr = 650.00Z = 4
Monoclinic, C2/cMo Kα radiation
a = 26.639 (2) ŵ = 1.44 mm1
b = 6.9775 (6) ÅT = 273 K
c = 14.7094 (12) Å0.34 × 0.21 × 0.07 mm
β = 97.501 (1)°
Data collection top
Bruker SMART CCD
diffractometer
3090 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
2607 reflections with I > 2σ(I)
Tmin = 0.641, Tmax = 0.906Rint = 0.023
8437 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0240 restraints
wR(F2) = 0.056H-atom parameters constrained
S = 1.03Δρmax = 0.39 e Å3
3090 reflectionsΔρmin = 0.18 e Å3
191 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
xyzUiso*/Ueq
Ni10.267171 (7)0.20529 (3)0.402119 (12)0.02626 (7)
C10.13571 (6)0.5214 (3)0.42203 (12)0.0431 (4)
H10.15050.63160.44920.052*
O10.21557 (4)0.37606 (15)0.43757 (7)0.0331 (2)
C30.14245 (6)0.1972 (2)0.36791 (11)0.0381 (4)
C20.16650 (6)0.3629 (2)0.40947 (10)0.0333 (3)
C60.08435 (7)0.5180 (3)0.39534 (14)0.0560 (5)
H60.06500.62530.40500.067*
C40.08991 (7)0.1999 (3)0.34122 (14)0.0520 (5)
H40.07430.09140.31380.062*
C50.06105 (7)0.3565 (3)0.35422 (15)0.0611 (6)
H50.02630.35510.33580.073*
C70.36315 (6)0.3962 (2)0.39857 (10)0.0341 (4)
C120.38590 (6)0.2332 (2)0.36206 (12)0.0383 (4)
C90.44526 (7)0.5552 (3)0.40933 (14)0.0560 (5)
H90.46510.66240.42610.067*
C80.39502 (7)0.5555 (3)0.42134 (13)0.0459 (4)
H80.38150.66440.44530.055*
C110.43741 (7)0.2396 (3)0.34965 (15)0.0538 (5)
H110.45180.13310.32510.065*
N10.31197 (5)0.03112 (18)0.34648 (9)0.0342 (3)
O20.31572 (4)0.40839 (15)0.41080 (8)0.0386 (3)
N20.21745 (5)0.00240 (18)0.37265 (9)0.0360 (3)
C130.35815 (6)0.0617 (2)0.33554 (11)0.0392 (4)
H130.37500.03490.30820.047*
C140.28630 (7)0.1438 (2)0.30878 (12)0.0430 (4)
H14A0.30960.25130.31580.052*
H14B0.27470.12700.24400.052*
C150.24182 (7)0.1823 (2)0.35987 (13)0.0443 (4)
H15A0.21810.26880.32500.053*
H15B0.25320.24070.41880.053*
C100.46695 (7)0.3965 (3)0.37237 (16)0.0618 (6)
H100.50090.39740.36340.074*
C160.16935 (7)0.0228 (2)0.35544 (11)0.0402 (4)
H160.15040.08320.33320.048*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ni10.02833 (11)0.02401 (11)0.02671 (11)0.00003 (8)0.00461 (7)0.00381 (8)
C10.0403 (9)0.0467 (10)0.0431 (10)0.0081 (8)0.0082 (8)0.0044 (8)
O10.0303 (6)0.0334 (6)0.0356 (6)0.0004 (5)0.0048 (4)0.0036 (5)
C30.0359 (9)0.0435 (10)0.0343 (9)0.0052 (7)0.0030 (7)0.0054 (7)
C20.0326 (8)0.0405 (9)0.0271 (8)0.0013 (7)0.0056 (6)0.0068 (7)
C60.0404 (10)0.0672 (14)0.0615 (13)0.0172 (10)0.0112 (9)0.0118 (11)
C40.0390 (10)0.0646 (13)0.0510 (12)0.0112 (9)0.0007 (8)0.0094 (10)
C50.0288 (9)0.0842 (16)0.0691 (14)0.0010 (10)0.0019 (9)0.0164 (12)
C70.0328 (8)0.0386 (9)0.0309 (8)0.0011 (7)0.0037 (7)0.0026 (7)
C120.0357 (9)0.0395 (9)0.0403 (10)0.0041 (7)0.0066 (7)0.0034 (7)
C90.0434 (11)0.0600 (13)0.0637 (13)0.0162 (9)0.0043 (9)0.0022 (10)
C80.0433 (10)0.0445 (10)0.0505 (11)0.0054 (8)0.0082 (8)0.0047 (8)
C110.0390 (10)0.0576 (12)0.0667 (13)0.0083 (9)0.0143 (9)0.0018 (10)
N10.0396 (7)0.0309 (7)0.0323 (7)0.0024 (6)0.0052 (6)0.0032 (6)
O20.0349 (6)0.0327 (6)0.0499 (7)0.0017 (5)0.0119 (5)0.0051 (5)
N20.0425 (8)0.0318 (7)0.0342 (7)0.0048 (6)0.0071 (6)0.0026 (6)
C130.0438 (10)0.0365 (9)0.0387 (9)0.0109 (7)0.0110 (7)0.0005 (7)
C140.0542 (11)0.0333 (9)0.0419 (10)0.0018 (8)0.0083 (8)0.0087 (7)
C150.0583 (12)0.0301 (9)0.0455 (10)0.0035 (8)0.0102 (9)0.0035 (7)
C100.0330 (10)0.0720 (14)0.0817 (16)0.0024 (10)0.0124 (10)0.0065 (12)
C160.0447 (10)0.0394 (9)0.0361 (9)0.0142 (8)0.0037 (7)0.0004 (7)
Geometric parameters (Å, º) top
Ni1—O21.9115 (11)C12—C131.433 (2)
Ni1—O11.9412 (10)C9—C81.373 (3)
Ni1—N21.9484 (13)C9—C101.392 (3)
Ni1—N11.9560 (13)C9—H90.9300
C1—C61.373 (2)C8—H80.9300
C1—C21.403 (2)C11—C101.364 (3)
C1—H10.9300C11—H110.9300
O1—C21.3217 (18)N1—C131.279 (2)
C3—C41.403 (2)N1—C141.472 (2)
C3—C21.421 (2)N2—C161.281 (2)
C3—C161.436 (2)N2—C151.466 (2)
C6—C51.387 (3)C13—H130.9300
C6—H60.9300C14—C151.508 (3)
C4—C51.364 (3)C14—H14A0.9700
C4—H40.9300C14—H14B0.9700
C5—H50.9300C15—H15A0.9700
C7—O21.3021 (18)C15—H15B0.9700
C7—C81.412 (2)C10—H100.9300
C7—C121.426 (2)C16—H160.9300
C12—C111.409 (2)
O2—Ni1—O191.35 (5)C9—C8—C7122.30 (18)
O2—Ni1—N2171.05 (5)C9—C8—H8118.9
O1—Ni1—N291.21 (5)C7—C8—H8118.9
O2—Ni1—N192.53 (5)C10—C11—C12122.30 (19)
O1—Ni1—N1170.36 (5)C10—C11—H11118.8
N2—Ni1—N183.67 (6)C12—C11—H11118.8
C6—C1—C2121.78 (18)C13—N1—C14119.87 (14)
C6—C1—H1119.1C13—N1—Ni1126.75 (11)
C2—C1—H1119.1C14—N1—Ni1113.21 (10)
C2—O1—Ni1125.41 (10)C7—O2—Ni1127.05 (10)
C4—C3—C2119.15 (16)C16—N2—C15121.38 (14)
C4—C3—C16118.13 (16)C16—N2—Ni1126.61 (12)
C2—C3—C16122.67 (15)C15—N2—Ni1111.57 (11)
O1—C2—C1118.39 (15)N1—C13—C12125.11 (15)
O1—C2—C3124.28 (15)N1—C13—H13117.4
C1—C2—C3117.33 (15)C12—C13—H13117.4
C1—C6—C5120.74 (18)N1—C14—C15108.46 (14)
C1—C6—H6119.6N1—C14—H14A110.0
C5—C6—H6119.6C15—C14—H14A110.0
C5—C4—C3122.08 (19)N1—C14—H14B110.0
C5—C4—H4119.0C15—C14—H14B110.0
C3—C4—H4119.0H14A—C14—H14B108.4
C4—C5—C6118.93 (17)N2—C15—C14107.30 (13)
C4—C5—H5120.5N2—C15—H15A110.3
C6—C5—H5120.5C14—C15—H15A110.3
O2—C7—C8118.69 (15)N2—C15—H15B110.3
O2—C7—C12124.88 (15)C14—C15—H15B110.3
C8—C7—C12116.43 (15)H15A—C15—H15B108.5
C11—C12—C7119.51 (16)C11—C10—C9118.58 (18)
C11—C12—C13117.88 (16)C11—C10—H10120.7
C7—C12—C13122.60 (15)C9—C10—H10120.7
C8—C9—C10120.87 (19)N2—C16—C3124.89 (15)
C8—C9—H9119.6N2—C16—H16117.6
C10—C9—H9119.6C3—C16—H16117.6
O2—Ni1—O1—C2148.07 (12)O1—Ni1—N1—C1454.8 (3)
N2—Ni1—O1—C223.36 (12)N2—Ni1—N1—C143.41 (11)
N1—Ni1—O1—C234.3 (4)C8—C7—O2—Ni1170.58 (11)
Ni1—O1—C2—C1164.26 (11)C12—C7—O2—Ni110.4 (2)
Ni1—O1—C2—C316.4 (2)O1—Ni1—O2—C7177.25 (13)
C6—C1—C2—O1179.44 (16)N2—Ni1—O2—C776.1 (4)
C6—C1—C2—C30.1 (3)N1—Ni1—O2—C711.58 (13)
C4—C3—C2—O1179.69 (15)O2—Ni1—N2—C1686.3 (4)
C16—C3—C2—O12.5 (3)O1—Ni1—N2—C1620.29 (14)
C4—C3—C2—C10.4 (2)N1—Ni1—N2—C16151.53 (15)
C16—C3—C2—C1176.84 (15)O2—Ni1—N2—C1586.0 (3)
C2—C1—C6—C50.4 (3)O1—Ni1—N2—C15167.35 (11)
C2—C3—C4—C50.3 (3)N1—Ni1—N2—C1520.84 (11)
C16—C3—C4—C5177.11 (18)C14—N1—C13—C12174.47 (15)
C3—C4—C5—C60.2 (3)Ni1—N1—C13—C120.4 (2)
C1—C6—C5—C40.5 (3)C11—C12—C13—N1176.60 (17)
O2—C7—C12—C11178.16 (16)C7—C12—C13—N14.5 (3)
C8—C7—C12—C110.8 (2)C13—N1—C14—C15158.62 (15)
O2—C7—C12—C130.7 (3)Ni1—N1—C14—C1525.82 (17)
C8—C7—C12—C13179.72 (15)C16—N2—C15—C14133.16 (16)
C10—C9—C8—C71.0 (3)Ni1—N2—C15—C1439.67 (16)
O2—C7—C8—C9179.08 (17)N1—C14—C15—N241.36 (18)
C12—C7—C8—C90.0 (3)C12—C11—C10—C90.2 (3)
C7—C12—C11—C100.8 (3)C8—C9—C10—C111.1 (3)
C13—C12—C11—C10179.71 (19)C15—N2—C16—C3178.62 (15)
O2—Ni1—N1—C136.72 (14)Ni1—N2—C16—C39.7 (2)
O1—Ni1—N1—C13120.4 (3)C4—C3—C16—N2176.60 (17)
N2—Ni1—N1—C13178.60 (14)C2—C3—C16—N26.1 (3)
O2—Ni1—N1—C14168.47 (11)

Experimental details

Crystal data
Chemical formula[Ni2(C16H14N2O2)2]
Mr650.00
Crystal system, space groupMonoclinic, C2/c
Temperature (K)273
a, b, c (Å)26.639 (2), 6.9775 (6), 14.7094 (12)
β (°) 97.501 (1)
V3)2710.7 (4)
Z4
Radiation typeMo Kα
µ (mm1)1.44
Crystal size (mm)0.34 × 0.21 × 0.07
Data collection
DiffractometerBruker SMART CCD
Absorption correctionMulti-scan
(SADABS; Bruker, 2001)
Tmin, Tmax0.641, 0.906
No. of measured, independent and
observed [I > 2σ(I)] reflections
8437, 3090, 2607
Rint0.023
(sin θ/λ)max1)0.650
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.056, 1.03
No. of reflections3090
No. of parameters191
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.39, 0.18

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL ((Bruker, 2001), SHELXTL (Bruker, 2001).

Selected geometric parameters (Å, º) top
Ni1—O21.9115 (11)Ni1—N21.9484 (13)
Ni1—O11.9412 (10)Ni1—N11.9560 (13)
O2—Ni1—O191.35 (5)O2—Ni1—N192.53 (5)
O2—Ni1—N2171.05 (5)O1—Ni1—N1170.36 (5)
O1—Ni1—N291.21 (5)N2—Ni1—N183.67 (6)
 

Acknowledgements

This work was supported by the Natural Science Foundation of Xiaogan University (Z2008012).

References

First citationBruker (2001). SAINT (Version 6.45), SMART (Version 5.628), SHELXTL (Version 6.12) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCozzi, P. G. (2004). Chem. Soc. Rev. 33, 410–421.  Web of Science CrossRef PubMed CAS Google Scholar
First citationSheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.  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.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds