Related literature {#sec1}
==================

For the previous structure determination, see: Anulewicz *et al.* (1991[@bb1]). For Br⋯Br inter­actions, see: Fujiwara *et al.* (2006[@bb6]); Reddy *et al.* (1996[@bb8]). For N---H⋯N hydrogen bonds, see: Del Bene & Elguero (2006[@bb5]); Grotjahn *et al.* (2000[@bb7]); Thar & Kirchner (2006[@bb11]).

Experimental {#sec2}
============

 {#sec2.1}

### Crystal data {#sec2.1.1}

C~13~H~10~Br~2~N~2~*M* *~r~* = 354.05Monoclinic,*a* = 11.563 (2) Å*b* = 23.447 (5) Å*c* = 9.881 (2) Åβ = 95.43 (3)°*V* = 2666.9 (9) Å^3^*Z* = 8Mo *K*α radiationμ = 6.06 mm^−1^*T* = 293 K0.15 × 0.07 × 0.06 mm

### Data collection {#sec2.1.2}

Bruker SMART CCD diffractometerAbsorption correction: multi-scan (*SADABS*; Sheldrick, 2004[@bb9]) *T* ~min~ = 0.403, *T* ~max~ = 0.6955954 measured reflections2611 independent reflections1715 reflections with *I* \> 2σ(*I*)*R* ~int~ = 0.061

### Refinement {#sec2.1.3}

*R*\[*F* ^2^ \> 2σ(*F* ^2^)\] = 0.048*wR*(*F* ^2^) = 0.114*S* = 1.002611 reflections155 parametersH-atom parameters constrainedΔρ~max~ = 0.48 e Å^−3^Δρ~min~ = −0.91 e Å^−3^

 {#d5e434}

Data collection: *APEX2* (Bruker, 2004[@bb4]); cell refinement: *SAINT-Plus* (Bruker, 2001[@bb3]); data reduction: *SAINT-Plus*; program(s) used to solve structure: *SHELXS97* (Sheldrick, 2008[@bb10]); program(s) used to refine structure: *SHELXL97* (Sheldrick, 2008[@bb10]); molecular graphics: *XP* (Sheldrick, 2008[@bb10]) and *DIAMOND* (Brandenburg, 1999[@bb2]); software used to prepare material for publication: *SHELXL97*.

Supplementary Material
======================

Crystal structure: contains datablocks global, I. DOI: [10.1107/S1600536811013419/wm2476sup1.cif](http://dx.doi.org/10.1107/S1600536811013419/wm2476sup1.cif)

Structure factors: contains datablocks I. DOI: [10.1107/S1600536811013419/wm2476Isup2.hkl](http://dx.doi.org/10.1107/S1600536811013419/wm2476Isup2.hkl)

Additional supplementary materials: [crystallographic information](http://scripts.iucr.org/cgi-bin/sendsupfiles?wm2476&file=wm2476sup0.html&mime=text/html); [3D view](http://scripts.iucr.org/cgi-bin/sendcif?wm2476sup1&Qmime=cif); [checkCIF report](http://scripts.iucr.org/cgi-bin/paper?wm2476&checkcif=yes)

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: [WM2476](http://scripts.iucr.org/cgi-bin/sendsup?wm2476)).

This work was supported by the National Natural Scientific Foundation of China (No.20741004/B010303).

Comment
=======

With the determination of reliable intermolecular distances, Br···Br interactions (Fujiwara *et al.*, 2006; Reddy *et al.*, 1996) and N--H···N hydrogen bonding (Del Bene & Elguero, 2006; Grotjahn *et al.* 2000; Thar & Kirchner, 2006) became important criteria in the description of supramolecular chemistry and in applied crystal engineering. The title compound C~13~H~10~Br~2~N~2~, (I), has been determined previously by Anulewicz *et al.* (1991). However, in that study only coordinates of all non-H atoms and of some H atoms were given. The present re-determination additionally reports anisotropic displacement parameters for all non-H atoms and the coordinates of all H atoms, accompanied by higher accuracy of all geometric parameters.

In (I) two independent half-molecules are present in the asymmetric unit which are completed by a twofold rotation axis as symmetry element that runs to the central C---H groups (C1---H1 and C2---H2, respectively). One molecule is displayed in Fig. 1. The dihedral angles between the two benzene rings in the individual molecules are 50.05 (15) ° for the first and and 75.61 (11) ° for the second molecule.

In the crystal, intermolecular N---H···N hydrogen bonds link the individual molecules into dimers (Fig. 2). Linear chains parallel to \[102\] are formed by intermolecular Br···Br interactions of 3.4328 (7) Å between two bromine atoms of adjacent molecules (Fig. 3). This interaction is significantly less than the van der Waals contact of 3.90 Å (Reddy *et al.*, 1996; Fujiwara *et al.*, 2006), hence making this interaction important for consolidation of the crystal packing.

Experimental {#experimental}
============

The title compound was synthesized by the following reaction. 17.202 g (0.1 mol) of 4-bromobenzenamine and 8.33 ml (0.05 mol) of triethyl orthoformate were combined in a round-bottom flask equipped with a distillation tube and heated at 160 until the distillation of ethanol creased. The retained solid was washed with ether, and dried under a dynamic vacuum to yield 16.10 g of white solid, (91%). 0.04 g of the white solid was dissolved in THF (3 ml) and the solution was layered with hexane. Colourless needle-shaped crystals formed after several days. ^1^HNMR(CDCl~3~, p.p.m.): 8.08(s, 1H, --NCHN--), 7.43(d, 2H, aromatic), 7.40(d, 2H, aromatic), 6.93(d, 2H, aromatic), 6.91(d, 2H, aromatic). Anal. Calcd. C~13~H~10~Br~2~N~2~: C, 44.10; H, 2.85; N, 7.91; Found: C, 43.83; H, 2.69; N, 8.02.

Refinement {#refinement}
==========

H atoms attached to C atoms were positioned geometrically with C---H = 0.93 (CH), and constrained to ride on their parent atoms, with *U*~iso~(H) = 1.2*U*~eq~(C). H atoms attached to N atoms were found from difference Fourier maps and were fixed. They were refined with *U*~iso~(H) = 1.2*U*~eq~(N). Owing to the 2 symmetry of the molecules, the H atoms attached to the N atoms are only half-occupied, leading to being disordered over two positions of equal occupancy.

Figures
=======

![Molecular structure of one of the two molecules of (I) drawn with displacement ellipsoids at the 30% probability level. \[Symmetry code A) -x+1, y. -z+1/2.\]](e-67-o1159-fig1){#Fap1}

![A dimer formed by intermolecular N--H···N hydrogen bonds.](e-67-o1159-fig2){#Fap2}

![Part of an one-dimensional linear chain of the title compound, viewed along \[010\]. Br···Br interactions are drawn with blue dashed lines.](e-67-o1159-fig3){#Fap3}

Crystal data {#tablewrapcrystaldatalong}
============

  ----------------------- ---------------------------------------
  C~13~H~10~Br~2~N~2~     *F*(000) = 1376
  *M~r~* = 354.05         *D*~x~ = 1.764 Mg m^−3^
  Monoclinic, *C*2/*c*    Mo *K*α radiation, λ = 0.71073 Å
  Hall symbol: -C 2yc     Cell parameters from 4303 reflections
  *a* = 11.563 (2) Å      θ = 2.5--26.7°
  *b* = 23.447 (5) Å      µ = 6.06 mm^−1^
  *c* = 9.881 (2) Å       *T* = 293 K
  β = 95.43 (3)°          Needle, colourless
  *V* = 2666.9 (9) Å^3^   0.15 × 0.07 × 0.06 mm
  *Z* = 8                 
  ----------------------- ---------------------------------------

Data collection {#tablewrapdatacollectionlong}
===============

  --------------------------------------------------------------- --------------------------------------
  Bruker SMART CCD diffractometer                                 2611 independent reflections
  Radiation source: fine-focus sealed tube                        1715 reflections with *I* \> 2σ(*I*)
  graphite                                                        *R*~int~ = 0.061
  ω scans                                                         θ~max~ = 26.0°, θ~min~ = 1.7°
  Absorption correction: multi-scan (*SADABS*; Sheldrick, 2004)   *h* = −12→14
  *T*~min~ = 0.403, *T*~max~ = 0.695                              *k* = −26→28
  5954 measured reflections                                       *l* = −12→11
  --------------------------------------------------------------- --------------------------------------

Refinement {#tablewraprefinementdatalong}
==========

  ------------------------------------- -------------------------------------------------------------------------------------
  Refinement on *F*^2^                  Primary atom site location: structure-invariant direct methods
  Least-squares matrix: full            Secondary atom site location: difference Fourier map
  *R*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.048   Hydrogen site location: inferred from neighbouring sites
  *wR*(*F*^2^) = 0.114                  H-atom parameters constrained
  *S* = 1.00                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.0533*P*)^2^\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  2611 reflections                      (Δ/σ)~max~ = 0.001
  155 parameters                        Δρ~max~ = 0.48 e Å^−3^
  0 restraints                          Δρ~min~ = −0.91 e Å^−3^
  ------------------------------------- -------------------------------------------------------------------------------------

Special details {#specialdetails}
===============

  -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  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 *F*^2^ against ALL reflections. The weighted *R*-factor *wR* and goodness of fit *S* are based on *F*^2^, conventional *R*-factors *R* are based on *F*, with *F* set to zero for negative *F*^2^. The threshold expression of *F*^2^ \> σ(*F*^2^) is used only for calculating *R*-factors(gt) *etc*. and is not relevant to the choice of reflections for refinement. *R*-factors based on *F*^2^ 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 (Å^2^) {#tablewrapcoords}
==================================================================================================

  ------ ------------- -------------- ------------- -------------------- ------------
         *x*           *y*            *z*           *U*~iso~\*/*U*~eq~   Occ. (\<1)
  Br1    0.24399 (5)   0.73912 (2)    0.82770 (5)   0.0708 (2)           
  N1     0.4449 (3)    0.63281 (13)   0.3396 (3)    0.0429 (8)           
  H2A    0.4352        0.5975         0.3271        0.052\*              0.50
  C1     0.5000        0.6600 (2)     0.2500        0.0428 (13)          
  H1     0.5000        0.6997         0.2500        0.051\*              
  C11    0.3994 (4)    0.65996 (16)   0.4505 (4)    0.0404 (9)           
  C12    0.4347 (4)    0.71277 (17)   0.4995 (4)    0.0525 (11)          
  H12A   0.4903        0.7329         0.4570        0.063\*              
  C13    0.3885 (4)    0.73617 (18)   0.6108 (5)    0.0569 (11)          
  H13A   0.4131        0.7719         0.6428        0.068\*              
  C14    0.3065 (4)    0.70681 (17)   0.6738 (4)    0.0459 (10)          
  C15    0.2716 (4)    0.65412 (19)   0.6293 (4)    0.0560 (11)          
  H15A   0.2171        0.6340         0.6737        0.067\*              
  C16    0.3177 (4)    0.63066 (17)   0.5178 (4)    0.0546 (11)          
  H16A   0.2935        0.5947         0.4873        0.066\*              
  Br2    0.02928 (6)   0.61567 (3)    1.05388 (8)   0.1036 (3)           
  N2     0.4121 (3)    0.49146 (13)   0.7963 (3)    0.0507 (8)           
  H3A    0.4085        0.4541         0.7936        0.061\*              0.50
  C2     0.5000        0.5180 (2)     0.7500        0.0520 (15)          
  H2B    0.5000        0.5577         0.7500        0.062\*              
  C21    0.3242 (4)    0.52137 (16)   0.8556 (4)    0.0455 (10)          
  C22    0.2110 (4)    0.50352 (19)   0.8320 (5)    0.0588 (12)          
  H32A   0.1933        0.4723         0.7758        0.071\*              
  C23    0.1229 (4)    0.53143 (19)   0.8908 (5)    0.0635 (12)          
  H33A   0.0466        0.5189         0.8746        0.076\*              
  C24    0.1488 (4)    0.57764 (18)   0.9729 (5)    0.0561 (11)          
  C25    0.2603 (4)    0.59524 (19)   0.9991 (4)    0.0584 (12)          
  H35A   0.2774        0.6264         1.0557        0.070\*              
  C26    0.3483 (4)    0.56719 (17)   0.9422 (4)    0.0561 (11)          
  H36A   0.4247        0.5791         0.9621        0.067\*              
  ------ ------------- -------------- ------------- -------------------- ------------

Atomic displacement parameters (Å^2^) {#tablewrapadps}
=====================================

  ----- ------------ ------------- ------------- ------------- ------------- --------------
        *U*^11^      *U*^22^       *U*^33^       *U*^12^       *U*^13^       *U*^23^
  Br1   0.0872 (4)   0.0873 (4)    0.0409 (3)    0.0246 (3)    0.0215 (2)    −0.0074 (2)
  N1    0.046 (2)    0.0446 (17)   0.0413 (18)   0.0019 (15)   0.0199 (15)   −0.0018 (14)
  C1    0.040 (3)    0.042 (3)     0.047 (3)     0.000         0.006 (3)     0.000
  C11   0.044 (2)    0.046 (2)     0.033 (2)     0.0046 (18)   0.0111 (17)   0.0051 (17)
  C12   0.059 (3)    0.056 (2)     0.045 (2)     −0.014 (2)    0.017 (2)     −0.001 (2)
  C13   0.070 (3)    0.056 (2)     0.046 (3)     −0.009 (2)    0.012 (2)     −0.007 (2)
  C14   0.056 (3)    0.055 (2)     0.028 (2)     0.010 (2)     0.0129 (18)   −0.0038 (18)
  C15   0.053 (3)    0.073 (3)     0.047 (2)     −0.005 (2)    0.029 (2)     0.000 (2)
  C16   0.064 (3)    0.051 (2)     0.053 (3)     −0.009 (2)    0.025 (2)     −0.003 (2)
  Br2   0.0764 (5)   0.0940 (5)    0.1485 (7)    0.0149 (3)    0.0538 (4)    −0.0264 (4)
  N2    0.046 (2)    0.0459 (18)   0.063 (2)     0.0002 (16)   0.0217 (17)   −0.0012 (17)
  C2    0.055 (4)    0.043 (3)     0.059 (4)     0.000         0.011 (3)     0.000
  C21   0.047 (3)    0.044 (2)     0.047 (2)     0.0014 (18)   0.0127 (19)   0.0011 (18)
  C22   0.049 (3)    0.061 (3)     0.067 (3)     −0.010 (2)    0.014 (2)     −0.019 (2)
  C23   0.035 (3)    0.078 (3)     0.079 (3)     −0.006 (2)    0.014 (2)     −0.016 (3)
  C24   0.052 (3)    0.057 (3)     0.062 (3)     0.011 (2)     0.019 (2)     0.000 (2)
  C25   0.057 (3)    0.053 (3)     0.067 (3)     0.000 (2)     0.017 (2)     −0.014 (2)
  C26   0.047 (3)    0.059 (3)     0.061 (3)     −0.007 (2)    0.005 (2)     −0.010 (2)
  ----- ------------ ------------- ------------- ------------- ------------- --------------

Geometric parameters (Å, °) {#tablewrapgeomlong}
===========================

  ------------------ ----------- ------------------- -----------
  Br1---C14          1.901 (4)   Br2---C24           1.886 (4)
  N1---C1            1.305 (4)   N2---C2             1.311 (4)
  N1---C11           1.412 (5)   N2---C21            1.407 (5)
  N1---H2A           0.8422      N2---H3A            0.8763
  C1---N1^i^         1.305 (4)   C2---N2^ii^         1.311 (4)
  C1---H1            0.9300      C2---H2B            0.9300
  C11---C12          1.377 (5)   C21---C22           1.373 (6)
  C11---C16          1.388 (6)   C21---C26           1.385 (5)
  C12---C13          1.381 (6)   C22---C23           1.383 (6)
  C12---H12A         0.9300      C22---H32A          0.9300
  C13---C14          1.369 (6)   C23---C24           1.369 (6)
  C13---H13A         0.9300      C23---H33A          0.9300
  C14---C15          1.360 (6)   C24---C25           1.355 (6)
  C15---C16          1.383 (6)   C25---C26           1.375 (6)
  C15---H15A         0.9300      C25---H35A          0.9300
  C16---H16A         0.9300      C26---H36A          0.9300
                                                     
  C1---N1---C11      123.2 (3)   C2---N2---C21       121.5 (3)
  C1---N1---H2A      116.6       C2---N2---H3A       120.0
  C11---N1---H2A     120.1       C21---N2---H3A      118.5
  N1^i^---C1---N1    121.4 (5)   N2^ii^---C2---N2    123.3 (5)
  N1^i^---C1---H1    119.3       N2^ii^---C2---H2B   118.4
  N1---C1---H1       119.3       N2---C2---H2B       118.4
  C12---C11---C16    118.0 (4)   C22---C21---C26     118.3 (4)
  C12---C11---N1     123.9 (4)   C22---C21---N2      119.4 (3)
  C16---C11---N1     118.0 (3)   C26---C21---N2      122.2 (4)
  C11---C12---C13    120.9 (4)   C21---C22---C23     120.8 (4)
  C11---C12---H12A   119.6       C21---C22---H32A    119.6
  C13---C12---H12A   119.6       C23---C22---H32A    119.6
  C14---C13---C12    120.0 (4)   C24---C23---C22     119.6 (4)
  C14---C13---H13A   120.0       C24---C23---H33A    120.2
  C12---C13---H13A   120.0       C22---C23---H33A    120.2
  C15---C14---C13    120.5 (4)   C25---C24---C23     120.3 (4)
  C15---C14---Br1    119.8 (3)   C25---C24---Br2     119.8 (3)
  C13---C14---Br1    119.7 (3)   C23---C24---Br2     119.8 (3)
  C14---C15---C16    119.6 (4)   C24---C25---C26     120.2 (4)
  C14---C15---H15A   120.2       C24---C25---H35A    119.9
  C16---C15---H15A   120.2       C26---C25---H35A    119.9
  C15---C16---C11    121.1 (4)   C25---C26---C21     120.7 (4)
  C15---C16---H16A   119.5       C25---C26---H36A    119.7
  C11---C16---H16A   119.5       C21---C26---H36A    119.7
  ------------------ ----------- ------------------- -----------

Symmetry codes: (i) −*x*+1, *y*, −*z*+1/2; (ii) −*x*+1, *y*, −*z*+3/2.

Hydrogen-bond geometry (Å, °) {#tablewraphbondslong}
=============================

  -------------------- --------- --------- ----------- ---------------
  *D*---H···*A*        *D*---H   H···*A*   *D*···*A*   *D*---H···*A*
  N1---H2A···N2^iii^   0.85      2.12      2.964 (4)   180
  N2---H3A···N1^iv^    0.88      2.12      2.964 (4)   161
  -------------------- --------- --------- ----------- ---------------

Symmetry codes: (iii) *x*, −*y*+1, *z*−1/2; (iv) *x*, −*y*+1, *z*+1/2.

###### Hydrogen-bond geometry (Å, °)

  *D*---H⋯*A*         *D*---H   H⋯*A*   *D*⋯*A*     *D*---H⋯*A*
  ------------------- --------- ------- ----------- -------------
  N1---H2*A*⋯N2^i^    0.85      2.12    2.964 (4)   180
  N2---H3*A*⋯N1^ii^   0.88      2.12    2.964 (4)   161

Symmetry codes: (i) ; (ii) .
