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Acta Cryst. (2007). E63, m2043    [ doi:10.1107/S1600536807031716 ]

Dibromidobis(quinoxaline-[kappa]N)zinc(II)

B. M. E. Markowitz, M. M. Turnbull and F. F. Awwadi

Abstract top

In the title complex, [ZnBr2(C8H6N2)2], the quinoxaline ligands are monocoordinated to the ZnII atom and, with the bromide ions, form a distorted tetrahedral geometry. The combination of [pi]-stacking interactions between inversion-related quinoxaline ligands and the bridging Zn creates layers parallel to the bc plane [distances range from 3.250 (1) to 3.51 (1) Å].

Comment top

We are interested in the study of low-dimensional coordination polymers and their magnetic properties. Our previous work on two copper(II) complexes of quinoxaline (quinox) showed that Cu(quinox)X2 complexes (X = Cl, Br) form structural and magnetic ladders. The rungs of the ladder are formed by bridging halide ions and the rails formed by bridging quinoxaline molecules (Lindroos and Lumme, 1990; Landee et al., 2003). A diamagnetic analogue of these materials would be useful for related experiments and we previously prepared the chloride analogue of (I) (Markowitz et al., 2006). It resulted in a tetrahedral complex which was not a suitable analogue so the bromo complex was prepared and is reported here. Reaction of ZnBr2 with quinoxaline gave Zn(quinox)Br2, even in the presence of excess ZnBr2.

The ZnII complex (I, Fig. 1) is a distorted tetrahedron with a mean angle at Zn of 120.6 (2)° (Turnbull et al., 2005). The Br1—Zn—Br2 and N1—Zn1—N11 angles are both expanded and correspond with the chloride complex, unlike the pyridine and quinoline analogues (Markowitz et al. 2006 and references therein). The two quinoxaline ligands are nearly planar. The mean deviation from planarity for the N1 containing quinoxaline is 0.013 (12) Å and the angle between the normals to the two component rings is 1.0 (1)°; the comparable values for the N11 ring are 0.019 (17) Å and 1.4 (1)°; both are identical with the chloride complex, within experimental error. The bond lengths and angles within the quinoxaline rings are the same within experimental error and agree with those values seen in chloride analogue and similar mono-coordinated complexes such as [Cu(quinox)2(H2O)3](ClO4)2 (Lumme et al., 1988) and [Cu(quinox)2(C2N3)2] (Luo et al., 2004).

Complex (I) packs in the lattice such that π-stacking is observed between inversion related quinoxaline rings, generating layers parallel to the bc-plane. The ring overlap occurs between both the nitrogen-containing rings and the non-nitrogen containing rings. The interplanar distance between the stacked N1-rings is 3.30 (1)Å and the displacement angle (defined as the angle between the mean plane of the ring and the line connecting the ring centroids) is 19.1 (1)° while the values for the carbocyclic rings containing C6 are 3.41 (1)Å and 13.9 (1)°, respectively. For the stacked N11 rings the distance is 3.25 (2)Å with a displacement angle of 19.3 (1)° while the carbocyclic C16 rings are separated by 3.51 (1) Å and 6.0 (1)°. Both show that the carbocyclic rings are slightly further apart, but show greater overlap compared to the heterocyclic rings.

Related literature top

For related literature, see: Landee et al. (2003); Lindroos & Lumme (1990); Lumme et al. (1988); Luo et al. (2004); Markowitz et al. (2006); Turnbull et al. (2005).

Experimental top

A solution of quinoxaline (1.4 g, 10 mmol) in absolute ethanol (10 ml) was added to a solution of ZnBr2 (2.3 g, 10 mmol) in absolute ethanol (10 ml) yielding a pale-orange solution. The flask was wrapped in aluminium foil and allowed to evaporate under a slow flow of argon. After 12 h, light-brown crystals of (I) were collected, washed with cold ethanol and allowed to air dry yielding 1.62 g (67%). IR (KBr, cm-1): 1504 s, 1466m, 1383w, 1360 s, 1215m, 1147m, 1131m, 1046 s, 965 s,876m, 772 s, 766 s.

Computing details top

Data collection: XSCANS (Siemens, 1992); cell refinement: XSCANS; data reduction: SHELXTL (Siemens, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. Molecular structure of (I), showing atom labelling scheme and 50% atom displacement ellipsoids.
Dibromidobis(quinoxaline-κN)zinc(II) top
Crystal data top
[ZnBr2(C8H6N2)2]Z = 2
Mr = 485.49F(000) = 472
Triclinic, P1Dx = 1.911 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.2527 (11) ÅCell parameters from 31 reflections
b = 8.6670 (9) Åθ = 3.3–15.6°
c = 12.4651 (17) ŵ = 6.19 mm−1
α = 80.067 (13)°T = 295 K
β = 86.260 (12)°Parallelpiped, colourless
γ = 73.94 (1)°0.2 × 0.15 × 0.12 mm
V = 843.80 (18) Å3
Data collection top
Bruker P4
diffractometer		1703 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.082
graphiteθmax = 24.6°, θmin = 2.5°
ω scansh = −9→1
Absorption correction: ψ scan
(SHELXTL; Siemens, 1990)		k = −10→9
Tmin = 0.363, Tmax = 0.476l = −14→14
3382 measured reflections3 standard reflections every 97 reflections
2781 independent reflections intensity decay: 2.1%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.055Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.129H-atom parameters constrained
S = 1.01 w = 1/[σ2(Fo2) + (0.0507P)2 + 0.6175P]
where P = (Fo2 + 2Fc2)/3
2781 reflections(Δ/σ)max < 0.001
208 parametersΔρmax = 0.68 e Å−3
0 restraintsΔρmin = −0.53 e Å−3
Crystal data top
[ZnBr2(C8H6N2)2]γ = 73.94 (1)°
Mr = 485.49V = 843.80 (18) Å3
Triclinic, P1Z = 2
a = 8.2527 (11) ÅMo Kα radiation
b = 8.6670 (9) ŵ = 6.19 mm−1
c = 12.4651 (17) ÅT = 295 K
α = 80.067 (13)°0.2 × 0.15 × 0.12 mm
β = 86.260 (12)°
Data collection top
Bruker P4
diffractometer		1703 reflections with I > 2σ(I)
Absorption correction: ψ scan
(SHELXTL; Siemens, 1990)		Rint = 0.082
Tmin = 0.363, Tmax = 0.476θmax = 24.6°
3382 measured reflections3 standard reflections every 97 reflections
2781 independent reflections intensity decay: 2.1%
Refinement top
R[F2 > 2σ(F2)] = 0.055H-atom parameters constrained
wR(F2) = 0.129Δρmax = 0.68 e Å−3
S = 1.01Δρmin = −0.53 e Å−3
2781 reflectionsAbsolute structure: ?
208 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
Zn0.34064 (11)0.66777 (11)0.75037 (8)0.0414 (3)
Br10.48802 (12)0.39624 (11)0.73519 (9)0.0618 (3)
Br20.48360 (11)0.86374 (11)0.76689 (8)0.0560 (3)
N10.2157 (8)0.7537 (7)0.6045 (5)0.0396 (16)
C20.2853 (11)0.8412 (10)0.5272 (7)0.048 (2)
H2A0.38350.86500.54270.058*
C30.2186 (13)0.8992 (11)0.4236 (8)0.057 (2)
H3A0.27360.96060.37330.068*
N40.0816 (11)0.8707 (9)0.3944 (6)0.058 (2)
C50.0051 (11)0.7813 (10)0.4701 (8)0.049 (2)
C6−0.1435 (11)0.7466 (12)0.4439 (8)0.057 (3)
H6A−0.18950.78560.37510.069*
C7−0.2190 (12)0.6551 (12)0.5204 (9)0.060 (3)
H7A−0.31780.63360.50350.072*
C8−0.1515 (11)0.5936 (11)0.6230 (8)0.056 (2)
H8A−0.20550.53050.67280.067*
C9−0.0086 (10)0.6229 (10)0.6527 (7)0.047 (2)
H9A0.03590.58010.72150.057*
C100.0702 (9)0.7198 (9)0.5763 (7)0.038 (2)
N110.2023 (8)0.6495 (8)0.8954 (5)0.0393 (16)
C120.2657 (11)0.5273 (11)0.9726 (8)0.051 (2)
H12A0.36410.45010.95770.061*
C130.1906 (13)0.5087 (12)1.0769 (8)0.060 (3)
H13A0.24380.42261.12940.071*
N140.0498 (11)0.6075 (10)1.1023 (6)0.059 (2)
C15−0.0207 (11)0.7367 (10)1.0254 (7)0.046 (2)
C16−0.1749 (11)0.8485 (12)1.0501 (8)0.054 (2)
H16A−0.22800.83391.11780.065*
C17−0.2415 (12)0.9746 (12)0.9740 (8)0.057 (2)
H17A−0.34271.04740.98990.068*
C18−0.1666 (11)1.0026 (11)0.8715 (7)0.051 (2)
H18A−0.21651.09380.82160.062*
C19−0.0202 (10)0.8964 (10)0.8445 (7)0.044 (2)
H19A0.02910.91380.77590.052*
C200.0556 (9)0.7603 (9)0.9212 (6)0.0368 (19)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn0.0367 (6)0.0398 (6)0.0459 (7)−0.0105 (4)−0.0020 (5)−0.0017 (5)
Br10.0525 (6)0.0409 (5)0.0840 (8)−0.0006 (4)−0.0017 (5)−0.0081 (5)
Br20.0524 (6)0.0567 (6)0.0657 (7)−0.0249 (5)0.0031 (5)−0.0132 (5)
N10.031 (4)0.035 (4)0.046 (4)−0.003 (3)0.003 (3)0.001 (3)
C20.044 (5)0.045 (5)0.051 (6)−0.011 (4)0.013 (4)−0.001 (5)
C30.072 (7)0.054 (6)0.042 (6)−0.021 (5)0.014 (5)0.001 (5)
N40.084 (6)0.043 (4)0.040 (5)−0.010 (4)−0.001 (4)−0.001 (4)
C50.052 (5)0.040 (5)0.050 (6)0.000 (4)−0.006 (5)−0.014 (5)
C60.047 (6)0.066 (6)0.055 (7)0.000 (5)−0.013 (5)−0.020 (5)
C70.043 (5)0.061 (6)0.080 (8)−0.008 (5)−0.010 (5)−0.030 (6)
C80.052 (6)0.067 (6)0.053 (7)−0.021 (5)0.006 (5)−0.017 (5)
C90.047 (5)0.051 (5)0.046 (6)−0.014 (4)0.002 (4)−0.011 (4)
C100.032 (5)0.034 (4)0.044 (6)0.000 (4)0.001 (4)−0.010 (4)
N110.036 (4)0.041 (4)0.040 (4)−0.014 (3)−0.007 (3)0.006 (3)
C120.044 (5)0.050 (5)0.057 (7)−0.013 (4)−0.011 (5)−0.002 (5)
C130.068 (7)0.060 (6)0.050 (7)−0.027 (6)−0.018 (5)0.017 (5)
N140.068 (6)0.066 (5)0.047 (5)−0.031 (5)−0.004 (4)0.002 (4)
C150.051 (5)0.051 (5)0.040 (5)−0.023 (5)−0.011 (4)−0.001 (4)
C160.054 (6)0.069 (6)0.044 (6)−0.023 (5)0.009 (5)−0.012 (5)
C170.049 (5)0.065 (6)0.060 (7)−0.009 (5)−0.002 (5)−0.031 (6)
C180.054 (6)0.055 (6)0.043 (6)−0.004 (5)−0.010 (5)−0.016 (5)
C190.041 (5)0.045 (5)0.044 (5)−0.015 (4)0.001 (4)0.002 (4)
C200.030 (4)0.046 (5)0.035 (5)−0.018 (4)−0.003 (4)0.002 (4)
Geometric parameters (Å, °) top
Zn—N12.068 (7)C9—C101.406 (11)
Zn—N112.080 (6)C9—H9A0.9300
Zn—Br22.3623 (12)N11—C121.315 (10)
Zn—Br12.3650 (13)N11—C201.380 (10)
N1—C21.323 (10)C12—C131.406 (13)
N1—C101.392 (9)C12—H12A0.9300
C2—C31.391 (13)C13—N141.296 (12)
C2—H2A0.9300C13—H13A0.9300
C3—N41.308 (11)N14—C151.361 (11)
C3—H3A0.9300C15—C201.414 (11)
N4—C51.353 (11)C15—C161.422 (12)
C5—C61.412 (12)C16—C171.333 (13)
C5—C101.421 (12)C16—H16A0.9300
C6—C71.364 (13)C17—C181.395 (12)
C6—H6A0.9300C17—H17A0.9300
C7—C81.386 (13)C18—C191.363 (11)
C7—H7A0.9300C18—H18A0.9300
C8—C91.360 (11)C19—C201.406 (11)
C8—H8A0.9300C19—H19A0.9300
N1—Zn—N11119.5 (2)N1—C10—C9119.6 (7)
N1—Zn—Br2104.56 (18)N1—C10—C5119.4 (7)
N11—Zn—Br2103.95 (18)C9—C10—C5121.0 (8)
N1—Zn—Br1103.70 (18)C12—N11—C20116.5 (7)
N11—Zn—Br1104.58 (18)C12—N11—Zn117.3 (6)
Br2—Zn—Br1121.69 (5)C20—N11—Zn125.9 (5)
C2—N1—C10116.0 (7)N11—C12—C13122.7 (9)
C2—N1—Zn117.5 (6)N11—C12—H12A118.7
C10—N1—Zn126.4 (5)C13—C12—H12A118.7
N1—C2—C3123.2 (9)N14—C13—C12122.2 (9)
N1—C2—H2A118.4N14—C13—H13A118.9
C3—C2—H2A118.4C12—C13—H13A118.9
N4—C3—C2122.6 (8)C13—N14—C15117.5 (8)
N4—C3—H3A118.7N14—C15—C20121.1 (8)
C2—C3—H3A118.7N14—C15—C16119.3 (9)
C3—N4—C5116.9 (8)C20—C15—C16119.6 (8)
N4—C5—C6119.8 (9)C17—C16—C15118.4 (8)
N4—C5—C10122.0 (8)C17—C16—H16A120.8
C6—C5—C10118.3 (8)C15—C16—H16A120.8
C7—C6—C5119.4 (9)C16—C17—C18123.1 (9)
C7—C6—H6A120.3C16—C17—H17A118.4
C5—C6—H6A120.3C18—C17—H17A118.4
C6—C7—C8121.4 (9)C19—C18—C17120.0 (9)
C6—C7—H7A119.3C19—C18—H18A120.0
C8—C7—H7A119.3C17—C18—H18A120.0
C9—C8—C7121.8 (9)C18—C19—C20119.6 (8)
C9—C8—H8A119.1C18—C19—H19A120.2
C7—C8—H8A119.1C20—C19—H19A120.2
C8—C9—C10118.2 (9)N11—C20—C19120.7 (7)
C8—C9—H9A120.9N11—C20—C15119.9 (7)
C10—C9—H9A120.9C19—C20—C15119.4 (8)
N11—Zn—N1—C2145.7 (6)N1—Zn—N11—C12145.1 (6)
Br2—Zn—N1—C230.0 (6)Br2—Zn—N11—C12−98.9 (6)
Br1—Zn—N1—C2−98.5 (6)Br1—Zn—N11—C1229.7 (6)
N11—Zn—N1—C10−38.9 (7)N1—Zn—N11—C20−39.9 (7)
Br2—Zn—N1—C10−154.6 (5)Br2—Zn—N11—C2076.2 (6)
Br1—Zn—N1—C1076.9 (6)Br1—Zn—N11—C20−155.2 (6)
C10—N1—C2—C30.8 (11)C20—N11—C12—C13−0.4 (11)
Zn—N1—C2—C3176.7 (7)Zn—N11—C12—C13175.1 (6)
N1—C2—C3—N4−0.4 (14)N11—C12—C13—N142.9 (14)
C2—C3—N4—C50.2 (13)C12—C13—N14—C15−3.1 (13)
C3—N4—C5—C6179.8 (8)C13—N14—C15—C201.1 (12)
C3—N4—C5—C10−0.4 (12)C13—N14—C15—C16−179.7 (8)
N4—C5—C6—C7179.5 (9)N14—C15—C16—C17179.7 (8)
C10—C5—C6—C7−0.3 (12)C20—C15—C16—C17−1.1 (13)
C5—C6—C7—C8−0.9 (14)C15—C16—C17—C18−0.4 (14)
C6—C7—C8—C90.8 (14)C16—C17—C18—C191.5 (14)
C7—C8—C9—C100.6 (13)C17—C18—C19—C20−1.0 (12)
C2—N1—C10—C9177.9 (8)C12—N11—C20—C19179.0 (7)
Zn—N1—C10—C92.4 (10)Zn—N11—C20—C193.9 (10)
C2—N1—C10—C5−1.0 (10)C12—N11—C20—C15−1.6 (10)
Zn—N1—C10—C5−176.5 (5)Zn—N11—C20—C15−176.7 (5)
C8—C9—C10—N1179.3 (7)C18—C19—C20—N11178.9 (7)
C8—C9—C10—C5−1.9 (12)C18—C19—C20—C15−0.5 (11)
N4—C5—C10—N10.8 (12)N14—C15—C20—N111.3 (12)
C6—C5—C10—N1−179.4 (7)C16—C15—C20—N11−177.9 (7)
N4—C5—C10—C9−178.1 (7)N14—C15—C20—C19−179.3 (7)
C6—C5—C10—C91.8 (11)C16—C15—C20—C191.5 (12)
Acknowledgements top

BMEM is grateful for a Maurine H. Milburn Summer Science Fellowship.

references
References top

Landee, C. P., Delcheva, A., Galeriu, C., Pena, G., Turnbull, M. M. & Willett, R. D. (2003). Polyhedron, 22, 2325–2329.

Lindroos, S. & Lumme, P. (1990). Acta Cryst. C46, 2039–2041.

Lumme, P., Lindroos, S. & Lindell, E. (1988). Inorg. Chim. Acta, 144, 75–79.

Luo, J., Liu, B.-S., Zhou, X.-G., Weng, L.-H., Li, Y.-R. & Wu, H.-X. (2004). Acta Cryst. C60, m520–m522.

Markowitz, B. M. E., Turnbull, M. M. & Awwadi, F. F. (2006). Acta Cryst. E62, m1278–m1280.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.

Siemens (1990). SHELXTL-Plus. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. [SHELXTL or SHELXTL-Plus?]

Siemens (1992). XSCANS. Version?. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.

Turnbull, M. M., Landee, C. P. & Wells, B. M. (2005). Coord. Chem. Rev. 249, 2567–2576.