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Acta Crystallogr Sect E Struct Rep Online. 2010 September 1; 66(Pt 9): o2470.
Published online 2010 August 28. doi:  10.1107/S1600536810033313
PMCID: PMC3007993

Ethane-1,2-diammonium dibromide: a redetermination at 100 K


In the redetermined [for the previous study, see Søtofte (1976 [triangle]). Acta Chem. Scand. Ser. A, 30, 309–311] crystal structure of the title compound, C2H10N2 2+·2Br, the H atoms have been located and the hydrogen-bonding scheme is described. The ethane-1,2-diammonium cation lies over a crystallographic inversion centre and straddles a crystallographic mirror plane with the C and N atoms in special positions. In the crystal, the cations and anions are linked by N—H(...)Br and N—H(...)(Br,Br) hydrogen bonds, which generate various ring and chain motifs including an R 10 5(32) loop.

Related literature

For the previous structure, see: Søtofte (1976 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]). For information on the Cambridge Database, see: Allen (2002 [triangle]).

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Object name is e-66-o2470-scheme1.jpg


Crystal data

  • C2H10N2 2+·2Br
  • M r = 221.94
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-o2470-efi1.jpg
  • a = 15.144 (2) Å
  • b = 4.7598 (7) Å
  • c = 4.8146 (7) Å
  • β = 101.323 (2)°
  • V = 340.30 (8) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 11.80 mm−1
  • T = 100 K
  • 0.36 × 0.24 × 0.20 mm

Data collection

  • Bruker APEXII CCD diffractometer
  • Absorption correction: multi-scan (AXScale; Bruker, 2010 [triangle]) T min = 0.101, T max = 0.201
  • 3261 measured reflections
  • 481 independent reflections
  • 475 reflections with I > 2σ(I)
  • R int = 0.024


  • R[F 2 > 2σ(F 2)] = 0.013
  • wR(F 2) = 0.035
  • S = 1.17
  • 481 reflections
  • 28 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.62 e Å−3
  • Δρmin = −0.39 e Å−3

Data collection: APEX2 (Bruker, 2010 [triangle]); cell refinement: SAINT (Bruker, 2010 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: X-SEED (Barbour, 2001 [triangle]) and Mercury (Macrae et al., 2006 [triangle]).; software used to prepare material for publication: publCIF (Westrip, 2010 [triangle]) and PLATON (Spek, 2009 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810033313/hb5586sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810033313/hb5586Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report


The authors acknowledge the National Research Foundation Thuthuka programme (GUN 66314) and the University of Johannesburg for funding and facilities for this study.

supplementary crystallographic information


As part of our ongoing study of the structural characteristics of organic-inorganic layered diammonium salts, the crystal structure of ethane-1,2-diammonium dibromide, (I), was determined. A search of the Cambridge Structural Database (Version 5.31, May 2010 release; Allen, 2002) revealed that the crystal structure of (I) had been previously determined 34 years ago (Søtofte, 1976) at room temperature. The information in the CSD CIF file however appears incomplete and the author also states that the contributions from the hydrogen atoms in the structure was ignored. Here we report the redetermined structure of the title compound at 100 K. All the H atom positions were clearly visible in the difference Fourier map and they were independently refined with ADP's constrained to values of 1.2 and 1.5 times the isotropic U values of the C and N atoms on which they ride. We also show packing arrangements, hydrogen bonding interactions, hydrogen bonding motifs as well as calculated torsion angles (Table 3) that were previously not reported.

The ethane-1,2-diammonium cation lies over a centre of inversion and also straddles a mirror plane. The asymmetric unit contains one bromide anion and half of the ethane-1,2-diammonium cation (Figure 1).

Figure 2 illustrates the packing of the title compound viewed down the b axis. The ethane-1,2-diammonium cations are stacked above one another in the ac plane linked together by hydrogen bonds.

A close-up view of the hydrogen bonding interactions can be viewed in Figure 3. The hydrogen bond distances and angles for (I) can be found in Table 2. The hydrogen bonding network is three-dimensional and particularly complex, consisting of a variety of ring and chain motifs (identified using graphs sets in Mercury (Macrae et al., 2006). Because of the complexity and number of different motifs identified, we focus on one particularly interesting hydrogen-bonding ring motif in the structure that appears to be in the shape of a T (Figure 4.) and it was chosen to best describe the highest level hydrogen bonding motif evident in the crystal structure.

Figure 4 shows a view of five diammonium cations and five bromide anions (viewed down the c axis) that are hydrogen bonded together to form a large, 32-membered T-shaped ring motif with graph set notation R510(32). Other ring motifs are evident - eight ring motifs and four chain motifs were identified from Mercury (Macrae et al., 2006) but are not depicted here.


Compound (I) was prepared by adding 1,2-diamino-ethane (0.50 g, 2.25 mmol) to 47% hydrobromic acid (HBr, 2 ml, 37.07 mmol, Merck) in a sample vial. The mixture was then refluxed at 363 K for 2 h. The solution was cooled at 2 K h-1 to room temperature. Colourless blocks of (I) were collected.


H atoms were clearly visible from the difference Fourier map. They were independently refined with the constraints Uiso(H) = 1.2Ueq(C) and 1.5Ueq(N). For (I), the highest peak in the final difference map is 0.80Å from Br1 and the deepest hole is 0.98Å from C1.


Fig. 1.
: Molecular structure of (I), with displacement ellipsoids drawn at the 50% probability level. Atoms labelled with (i) are at the symmetry position (1 - x, y, 1 - z)
Fig. 2.
: Packing arrangement if (I) viewed down the b axis and rotated slightly. Hydrogen bonds are indicated by dashed lines.
Fig. 3.
: Close-up view of (I) viewed down the b axis with a slight offset clearly showing the hydrogen-bonding interactions. Hydrogen bonds are indicated by dashed lines.
Fig. 4.
: Close up view of (I) viewed down the c axis showing the T-shaped ring motif involving five diammonium cations and five bromide anions.

Crystal data

C2H10N22+·2BrF(000) = 212
Mr = 221.94Dx = 2.166 Mg m3
Monoclinic, C2/mMo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yCell parameters from 2937 reflections
a = 15.144 (2) Åθ = 2.7–28.4°
b = 4.7598 (7) ŵ = 11.80 mm1
c = 4.8146 (7) ÅT = 100 K
β = 101.323 (2)°Block, colourless
V = 340.30 (8) Å30.36 × 0.24 × 0.20 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer481 independent reflections
Radiation source: fine-focus sealed tube475 reflections with I > 2σ(I)
graphiteRint = 0.024
[var phi] and ω scansθmax = 28.4°, θmin = 2.7°
Absorption correction: multi-scan (AXScale; Bruker, 2010)h = −20→20
Tmin = 0.101, Tmax = 0.201k = −6→6
3261 measured reflectionsl = −6→6


Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.013H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.035w = 1/[σ2(Fo2) + (0.0165P)2 + 0.5674P] where P = (Fo2 + 2Fc2)/3
S = 1.17(Δ/σ)max < 0.001
481 reflectionsΔρmax = 0.62 e Å3
28 parametersΔρmin = −0.39 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.051 (3)

Special details

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)

C10.47174 (14)0.00000.3516 (4)0.0119 (4)
N10.37420 (13)0.00000.3658 (4)0.0113 (4)
Br10.151104 (12)0.00000.17162 (4)0.01051 (13)
H1A0.4815 (14)0.166 (5)0.246 (4)0.013*
H2A0.344 (2)0.00000.203 (8)0.016*
H2B0.3589 (15)0.147 (5)0.457 (5)0.016*

Atomic displacement parameters (Å2)

C10.0081 (9)0.0184 (11)0.0088 (9)0.0000.0007 (7)0.000
N10.0097 (8)0.0157 (9)0.0079 (8)0.0000.0001 (7)0.000
Br10.00972 (15)0.01224 (16)0.00940 (15)0.0000.00147 (8)0.000

Geometric parameters (Å, °)

C1—N11.492 (3)N1—H2A0.83 (4)
C1—C1i1.515 (4)N1—H2B0.88 (2)
C1—H1A0.97 (2)
N1—C1—C1i109.8 (2)C1—N1—H2A109 (2)
N1—C1—H1A106.2 (12)C1—N1—H2B112.5 (14)
C1i—C1—H1A112.3 (12)H2A—N1—H2B108.7 (19)

Symmetry codes: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, °)

N1—H2A···Br10.83 (4)2.89 (3)3.324 (2)115 (3)
N1—H2A···Br1ii0.83 (4)3.00 (2)3.4808 (14)120.(1)
N1—H2B···Br1iii0.88 (2)2.48 (2)3.3326 (14)163 (2)

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


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5586).


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