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The title compound, C14H13BrN4, has a planar central unit, (C)2C6H3Br, the pendant pyrazole rings forming dihedral angles of 83.8 (3) and 89.3 (3)° with this plane. The pyrazole rings are oriented such that there is an approximate twofold axis coincident with the C-Br bond.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103027525/ta1429sup1.cif
Contains datablocks global, II

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103027525/ta1429IIsup2.hkl
Contains datablock II

CCDC reference: 231092

Comment top

Aryl halides containing nitrogen donor groups are useful reagents for the synthesis of organometallic compounds with interesting stability, structural and reactivity properties (Canty & van Koten, 1995; Albrecht & van Koten, 2001). The most extensively explored reagent is 2,6-bis[(dimethylamino)methyl]bromobenzene, 2,6-(Me2CH2)2C6H3Br, (I), which gives a wide range of organometallic compounds, including square-planar palladium(II) and platinum(II) complexes, and octahedral platinum(IV) complexes. In these complexes, the [N—C—N] ligand normally acts in a planar tridentate fashion, e.g. square-planar PtI{2,6-(Me2NCH2)2C6H3—N,C,N} (Smeets et al., 1987) and mer-PtCl3{2,6-(Me2CH2)2C6H3—N,C,N} (van Koten et al., 1990). We have reported that the closely related reagent 2,6-bis[(pyrazol-1-yl)methyl]bromobenzene, (II), undergoes an oxidative addition reaction with [PtMe2(SEt2)]2 to form fac-PtBrMe2[2,6-(pzCH2)2C6H3—N,C,N], a platinum(IV) complex with the [N—C—N] group as a tripodal tridentate ligand (Canty et al., 1990; Canty et al., 2000). Additional interest in these ligand systems has arisen from the discovery that 2,6-(3,5-Me2pz)2C6H3Br reacts with [Pt(p-Tol)2(SEt2)]2 to form PtBr{2,6-(3,5-Me2pz)2C6H3—N,C,N}, rather than a PtIV complex, providing a new and facile route to PtII complexes containing [N—C—N] ligands that coordinate in a planar rather than a tripodal mode. Nevertheless, the puckering of the five-membered chelate rings is such that the ligand as a whole is not planar, having symmetry degraded to quasi-2 rather than m (Canty et al., 2000). This methodology has been extended to 2,6-(Me2CH2)2C6H3Br, resulting in a wide range of applications, e.g. the synthesis of nanosize multimetallic catalysts (Dijkstra et al., 2001). The precursor (II) itself is of interest, the Br atom occupying the position of the coordinated metal atom in the above, with the possibility of interaction of? the position of the coordinated metal with the pyrazole N atom or CH components should the peripheral rings lie quasi-coplanar with the central ring. A structure determination was therefore undertaken in order to explore this point.

In the event, the structure was found to be otherwise. The asymmetric unit of the structure comprises a single molecule, devoid of crystallographic symmetry, the planes of the peripheral pyrazolyl rings lying quasi-normal to the central ring [the interplanar dihedral angles are 83.3 (3) and 89.3 (3)°]. In the central ring, the C2—C1—C6 angle is enlarged to greater than 120°, at the expense of the pair of exocyclic angles. The capability of derivative ligands to coordinate in planar or tripodal tridentate modes is a consequence of the latitude available in terms of free rotation about the bonds to either side of Cn0 in the pendants, with the capacity to adjust chelate bite in the resultant six-membered rings by puckering of the latter, degrading the overall symmetry as above. In this mode in the present ?, pyrazole atoms Nn2 may lie in proximity to the Br atom or, by virtue of the exocyclic asymmetry at atom Nn1, ?to the CHn3 group?, directed away, as extremes. In the event, the C1—C2—C10—N11 and C1—C6—C20—N21 angles are 157.7 (6) and −157.7 (6)°, with C2—C10—N11—N12 and C6—C20—N21—N22 angles of 91.5 (9) and 78.4 (8)°, the ambience of the Br atom being the pair of methylene H atoms, H10b and H20a, at ca 2.7 and 2.8 Å. The angles at atoms C10 and C20 [113.9 (6) and 113.5 (5)°] are appreciably higher than the tetrahedral values, perhaps in consequence of repulsion between the faces of the pyrazole rings and atoms H3 and H5 (N11···H3 and N21—H5 = 2.5 Å). The exocyclic angles at atoms C2 and C6 are essentially equivalent.

Experimental top

Colourless crystals of the title compound, prepared as reported by Canty et al. (2000), were crystallized from dichloromethane/petroleum and were found to be suitable for structural studies.

Refinement top

H atoms were located from difference Fourier maps and placed at idealized positions (C—H = 0.95 Å), with Uiso(H) = 1.25Ueq(C), ?N versus C being unambiguously assigned in the process.

Computing details top

Data collection: Syntex software; cell refinement: Syntex software; data reduction: Xtal3.5 (Hall et al., 1995); program(s) used to solve structure: Xtal3.5; program(s) used to refine structure: CRYLSQ in Xtal3.5; molecular graphics: Xtal3.5; software used to prepare material for publication: BONDLA and CIFIO in Xtal3.5.

Figures top
[Figure 1] Fig. 1. A molecule of 2,6-(pzCH2)2C6H3Br projected (a) normal and (b) through the central aromatic plane. Anisotropic displacement ellipsoids are shown at the 50% probability level. H atoms, where shown, have arbitrary radii of 0.1 Å.
(II) top
Crystal data top
C14H13BrN4Z = 2
Mr = 317.19F(000) = 320
Triclinic, P1Dx = 1.528 Mg m3
Hall symbol: -p 1Mo Kα radiation, λ = 0.71069 Å
a = 10.758 (6) ÅCell parameters from 12 reflections
b = 8.951 (5) Åθ = 12.2–14.3°
c = 8.425 (5) ŵ = 2.97 mm1
α = 111.24 (4)°T = 296 K
β = 100.94 (4)°Plate, colourless
γ = 105.74 (4)°0.67 × 0.32 × 0.12 mm
V = 689.3 (8) Å3
Data collection top
Syntex P21
diffractometer
1304 reflections with I > 2.00 σ(I)
Radiation source: sealed tubeRint = 0
Graphite monochromatorθmax = 25.1°, θmin = 2.1°
2θω scansh = 010
Absorption correction: gaussian
Xtal absorb
k = 1010
Tmin = 0.41, Tmax = 0.72l = 99
2231 measured reflections8 standard reflections every 60 min
2231 independent reflections intensity decay: none
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)] = 0.040Hydrogen site location: difference Fourier map
wR(F2) = 0.155H-atom parameters not refined
S = 1.10 w = 1/(σ2(F2) + 2.5F2 + .002F4)
2231 reflections(Δ/σ)max = 0.001
172 parametersΔρmax = 0.77 e Å3
0 restraintsΔρmin = 0.50 e Å3
0 constraints
Crystal data top
C14H13BrN4γ = 105.74 (4)°
Mr = 317.19V = 689.3 (8) Å3
Triclinic, P1Z = 2
a = 10.758 (6) ÅMo Kα radiation
b = 8.951 (5) ŵ = 2.97 mm1
c = 8.425 (5) ÅT = 296 K
α = 111.24 (4)°0.67 × 0.32 × 0.12 mm
β = 100.94 (4)°
Data collection top
Syntex P21
diffractometer
1304 reflections with I > 2.00 σ(I)
Absorption correction: gaussian
Xtal absorb
Rint = 0
Tmin = 0.41, Tmax = 0.728 standard reflections every 60 min
2231 measured reflections intensity decay: none
2231 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0400 restraints
wR(F2) = 0.155H-atom parameters not refined
S = 1.10Δρmax = 0.77 e Å3
2231 reflectionsΔρmin = 0.50 e Å3
172 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Br10.16921 (7)0.03801 (11)0.40814 (11)0.0862 (4)
C10.3197 (6)0.0461 (8)0.5790 (7)0.058 (2)
C20.4423 (6)0.1855 (7)0.6431 (7)0.055 (2)
C30.5526 (6)0.1823 (8)0.7590 (8)0.060 (2)
C40.5382 (6)0.0492 (8)0.8064 (8)0.058 (2)
C50.4135 (6)0.0827 (8)0.7434 (8)0.059 (3)
C60.3016 (6)0.0881 (7)0.6290 (8)0.054 (2)
C100.4582 (7)0.3336 (9)0.5910 (9)0.069 (3)
N110.5703 (6)0.4906 (6)0.7166 (7)0.064 (2)
N120.6938 (6)0.5228 (8)0.6940 (8)0.072 (3)
C130.5701 (8)0.6167 (9)0.8621 (10)0.074 (3)
C140.6972 (10)0.7358 (10)0.9406 (10)0.087 (4)
C150.7699 (8)0.6760 (10)0.8314 (12)0.081 (3)
C200.1659 (6)0.2331 (8)0.5585 (9)0.069 (3)
N210.1497 (5)0.3219 (7)0.6699 (7)0.062 (2)
N220.1199 (6)0.2519 (8)0.8223 (8)0.083 (3)
C230.1705 (7)0.4696 (9)0.6506 (9)0.072 (3)
C240.1512 (7)0.4978 (10)0.7925 (11)0.084 (4)
C250.1201 (7)0.3646 (12)0.8924 (10)0.088 (4)
H30.641110.275640.805190.07200*
H40.617350.047130.884270.06900*
H50.405580.172530.786080.07400*
H10a0.470100.295220.473460.08100*
H10b0.372840.351230.575900.08100*
H130.479340.586200.875770.09900*
H140.728930.845691.049650.10500*
H150.860490.704680.818300.09500*
H20a0.081880.213000.534410.08400*
H20b0.165010.317430.448580.08400*
H230.192580.516430.539730.08800*
H240.159280.594590.816560.10400*
H250.098240.317641.005790.10700*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.0701 (5)0.1022 (6)0.0934 (6)0.0360 (4)0.0115 (4)0.0548 (5)
C10.055 (4)0.070 (4)0.050 (3)0.030 (3)0.017 (3)0.022 (3)
C20.063 (4)0.058 (3)0.052 (3)0.025 (3)0.027 (3)0.027 (3)
C30.056 (4)0.065 (4)0.060 (3)0.023 (3)0.017 (3)0.029 (3)
C40.057 (4)0.068 (4)0.061 (3)0.029 (3)0.018 (3)0.038 (3)
C50.059 (4)0.068 (4)0.062 (4)0.027 (3)0.022 (3)0.036 (3)
C60.051 (3)0.058 (3)0.058 (3)0.023 (3)0.022 (3)0.026 (3)
C100.074 (4)0.079 (4)0.078 (4)0.037 (4)0.030 (3)0.048 (4)
N110.075 (4)0.057 (3)0.072 (3)0.032 (3)0.031 (3)0.031 (3)
N120.075 (4)0.079 (4)0.081 (4)0.038 (3)0.044 (3)0.041 (3)
C130.094 (5)0.076 (4)0.075 (4)0.053 (4)0.041 (4)0.036 (4)
C140.110 (6)0.078 (5)0.072 (5)0.045 (5)0.021 (4)0.027 (4)
C150.073 (5)0.085 (5)0.106 (6)0.033 (4)0.035 (4)0.057 (5)
C200.056 (4)0.072 (4)0.078 (4)0.017 (3)0.016 (3)0.038 (3)
N210.047 (3)0.069 (3)0.063 (3)0.016 (2)0.016 (2)0.026 (3)
N220.069 (4)0.092 (4)0.077 (4)0.023 (3)0.031 (3)0.028 (3)
C230.061 (4)0.077 (4)0.077 (4)0.026 (3)0.020 (3)0.034 (4)
C240.069 (5)0.083 (5)0.094 (5)0.016 (4)0.014 (4)0.049 (5)
C250.060 (4)0.121 (7)0.070 (5)0.013 (4)0.019 (3)0.044 (5)
Geometric parameters (Å, º) top
Br1—C11.917 (7)N12—C151.331 (8)
C1—C21.392 (8)C13—C141.341 (10)
C1—C61.389 (11)C13—H130.981
C2—C31.401 (10)C14—C151.374 (14)
C2—C101.519 (11)C14—H140.986
C3—C41.368 (11)C15—H150.976
C3—H30.974C20—N211.439 (11)
C4—C51.375 (8)C20—H20a0.967
C4—H40.980C20—H20b0.956
C5—C61.370 (9)N21—N221.352 (9)
C5—H50.983N21—C231.357 (11)
C6—C201.501 (8)N22—C251.341 (15)
C10—N111.438 (7)C23—C241.349 (14)
C10—H10a0.970C23—H230.980
C10—H10b0.966C24—C251.356 (13)
N11—N121.346 (9)C24—H240.980
N11—C131.333 (9)C25—H250.996
Br1—C1—C2117.6 (6)N11—C13—C14107.3 (8)
Br1—C1—C6118.6 (4)N11—C13—H13109.5
C2—C1—C6123.7 (6)C14—C13—H13143.2
C1—C2—C3116.3 (7)C13—C14—C15105.3 (6)
C1—C2—C10122.7 (6)C13—C14—H14126.6
C3—C2—C10121.0 (5)C15—C14—H14128.0
C2—C3—C4121.0 (5)N12—C15—C14111.7 (7)
C2—C3—H3119.4N12—C15—H15105.8
C4—C3—H3119.6C14—C15—H15142.5
C3—C4—C5120.3 (6)C6—C20—N21113.5 (5)
C3—C4—H4119.8C6—C20—H20a120.9
C5—C4—H4119.9C6—C20—H20b105.6
C4—C5—C6121.8 (7)N21—C20—H20a103.6
C4—C5—H5118.0N21—C20—H20b104.5
C6—C5—H5120.1H20a—C20—H20b107.5
C1—C6—C5116.9 (5)C20—N21—N22120.2 (6)
C1—C6—C20121.3 (6)C20—N21—C23128.0 (6)
C5—C6—C20121.8 (7)N22—N21—C23111.6 (7)
C2—C10—N11113.9 (6)N21—N22—C25103.0 (7)
C2—C10—H10a107.1N21—C23—C24107.0 (7)
C2—C10—H10b107.6N21—C23—H23109.5
N11—C10—H10a110.0C24—C23—H23143.5
N11—C10—H10b111.3C23—C24—C25105.5 (9)
H10a—C10—H10b106.5C23—C24—H24126.3
C10—N11—N12120.0 (6)C25—C24—H24128.2
C10—N11—C13127.8 (7)N22—C25—C24112.9 (8)
N12—N11—C13112.2 (5)N22—C25—H25105.7
N11—N12—C15103.4 (6)C24—C25—H25141.4

Experimental details

Crystal data
Chemical formulaC14H13BrN4
Mr317.19
Crystal system, space groupTriclinic, P1
Temperature (K)296
a, b, c (Å)10.758 (6), 8.951 (5), 8.425 (5)
α, β, γ (°)111.24 (4), 100.94 (4), 105.74 (4)
V3)689.3 (8)
Z2
Radiation typeMo Kα
µ (mm1)2.97
Crystal size (mm)0.67 × 0.32 × 0.12
Data collection
DiffractometerSyntex P21
diffractometer
Absorption correctionGaussian
Xtal absorb
Tmin, Tmax0.41, 0.72
No. of measured, independent and
observed [I > 2.00 σ(I)] reflections
2231, 2231, 1304
Rint0
(sin θ/λ)max1)0.597
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.155, 1.10
No. of reflections2231
No. of parameters172
H-atom treatmentH-atom parameters not refined
Δρmax, Δρmin (e Å3)0.77, 0.50

Computer programs: Syntex software, Xtal3.5 (Hall et al., 1995), CRYLSQ in Xtal3.5, BONDLA and CIFIO in Xtal3.5.

Selected geometric parameters (Å, º) top
Br1—C11.917 (7)
Br1—C1—C2117.6 (6)C1—C6—C5116.9 (5)
Br1—C1—C6118.6 (4)C1—C6—C20121.3 (6)
C2—C1—C6123.7 (6)C5—C6—C20121.8 (7)
C1—C2—C3116.3 (7)C2—C10—N11113.9 (6)
C1—C2—C10122.7 (6)C6—C20—N21113.5 (5)
C3—C2—C10121.0 (5)
 

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