Search tips
Search criteria 


Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
Acta Crystallogr Sect E Struct Rep Online. 2009 May 1; 65(Pt 5): o1008.
Published online 2009 April 8. doi:  10.1107/S1600536809012963
PMCID: PMC2977696

Hexane-1,6-diammonium dinitrate


The hexane-1,6-diammonium cation of the title compound, C6H18N2 2+·2NO3 , lies across a crystallographic inversion centre and shows significant deviation from planarity in the hydro­carbon chain. This is evident from the torsion angle of −64.0°(2) along the N—C—C—C bond and thse torsion angle of −67.1°(2) along the C—C—C—C bonds. An intricate three-dimensional hydrogen-bonding network exists in the crystal structure, with each H atom on the ammonium group exhibiting bifurcated inter­actions to the nitrate anion. Complex hydrogen-bonded ring and chain motifs are also evident, in particular a 26-membered ring with graph-set notation R 4 4(26) is observed.

Related literature

For related structural studies of hexane-1,6-diammonium salts, see: van Blerk & Kruger (2008 [triangle]). For hydrogen-bond motifs, see: Bernstein et al. (1995 [triangle]). For a description of the Cambridge Structural Database, see: Allen (2002 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-65-o1008-scheme1.jpg


Crystal data

  • C6H18N2 2+·2NO3
  • M r = 242.24
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o1008-efi1.jpg
  • a = 6.2947 (1) Å
  • b = 11.6783 (3) Å
  • c = 8.1211 (2) Å
  • β = 92.840 (1)°
  • V = 596.26 (2) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.12 mm−1
  • T = 295 K
  • 0.46 × 0.20 × 0.16 mm

Data collection

  • Bruker SMART CCD diffractometer
  • Absorption correction: multi-scan (AX-Scale; Bruker, 2008 [triangle]) T min = 0.948, T max = 0.981
  • 14665 measured reflections
  • 1718 independent reflections
  • 1107 reflections with I > 2σ(I)
  • R int = 0.026


  • R[F 2 > 2σ(F 2)] = 0.045
  • wR(F 2) = 0.147
  • S = 1.02
  • 1718 reflections
  • 74 parameters
  • H-atom parameters constrained
  • Δρmax = 0.37 e Å−3
  • Δρmin = −0.19 e Å−3

Data collection: SMART-NT (Bruker, 1998 [triangle]); cell refinement: SAINT (Bruker, 2008 [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, 2009 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809012963/fj2206sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809012963/fj2206Isup2.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 for this study. The University of the Witwatersrand is thanked for the use of their facilities and the use of the diffractometer in the Jan Boeyens Structural Chemistry Laboratory.

supplementary crystallographic information


The crystal structure of the title compound (I) adds to our current ongoing studies of long-chained diammonium salts. Colourless needle-like rectangular crystals of hexane-1,6-diammonium dinitrate were synthesized and formed as part of our structural chemistry study of the inorganic mineral acid salts of hexane-1,6-diamine. A search of the Cambridge Structural Database (Version 5.30, February 2009 release; Allen, 2002) revealed that this compound had not previously been determined.

The diammonium hexane chain lies across a crystallographic inversion centre and hence the asymmetric unit contains one nitrate anion and one-half of the hexane diammonium cation. The hydrocarbon chain is also not extended as is common in long chained hydrocarbons but shows significant folding and deviation from planarity. This is clearly evident from the torsion angle along the N1—C1—C2—C3 bond (–64.0°(2)) and along the C1—C2—C3—C3i bond (–67.1°(2)). Selected torsion angles can be found in Table 1. The molecular structure of (I) is shown in Figure 1.

Figure 2 illustrates the layered packing arrangement of the title compound (I). Single stacked layers of folded cations pack in between layers of nitrate anions showing a distinct inorganic - organic layering effect that is a common feature of these long-chained diammonium salts. The diammonium cations form bridges between the nitrate anion layers and an extensive three-dimensional hydrogen-bonding network is formed.

A close-up view of the hydrogen bonding interactions can be viewed in Figure 3 where very clear evidence of bifurcated interactions can be seen on each hydrogen atom of both ammonium groups. The hydrogen bond distances and angles for (I) can be found in Table 2. Since the hydrogen bonding network is complex, we focus on one particularly interesting hydrogen-bonding ring motif in the structure. Figure 4 shows a view of two diammonium cations and two nitrate anions (viewed down the c axis) that are hydrogen bonded together to form a large, 26-membered ring motif with graph set notation R44(26). Another smaller ring motif is evident as a result of the bifurcated hydrogen-bond interaction with the nitrate anion and this ring has the graph-set notation R21(4) but is not depicted graphically. Chain motifs also exist and were identified with Mercury (Macrae et al.), but again, these are not shown graphically.


Compound (I) was prepared by adding 1,6-diamino-hexane (0.50 g, 4.30 mmol) to 55% nitric acid (2 ml, 42.5 mmol) 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 rectangular needles of hexane-1,6-diammonium dinitrate were collected and a suitable single-crystal was selected for the X-ray diffraction study.


H atoms were geometrically positioned and refined in the riding-model approximation, with C—H = 0.97 Å, N—H = 0.89 Å, and Uiso(H) = 1.2Ueq(C) or 1.5Ueq(N). For (I), the highest peak in the final difference map is 0.99Å from C3 and the deepest hole is 0.63Å from N2.


Fig. 1.
: Molecular structure of (I), with atomic numbering scheme and displacement ellipsoids drawn at the 50% probability level. Atoms labelled with (i) are at the symmetry position (1 - x, - y, - z)
Fig. 2.
: Packing arrangement if (I) viewed down the a axis. Hydrogen bonds are indicated by dashed lines.
Fig. 3.
: Close-up view of (I) viewed down the a axis clearly showing the bifurcated hydrogen-bonding interactions. Hydrogen bonds are indicated by dashed lines.
Fig. 4.
: Close up view of (I) viewed down the c axis showing the ring motif involving two diammonium cations and two nitrate anions. Hydrogen atoms on the hydrocarbon chain are omitted for clarity.

Crystal data

C6H18N22+·2NO3F(000) = 260
Mr = 242.24Dx = 1.349 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 5933 reflections
a = 6.2947 (1) Åθ = 2.5–25.2°
b = 11.6783 (3) ŵ = 0.12 mm1
c = 8.1211 (2) ÅT = 295 K
β = 92.840 (1)°Rectangular, colourless
V = 596.26 (2) Å30.46 × 0.20 × 0.16 mm
Z = 2

Data collection

Bruker SMART CCD diffractometer1718 independent reflections
Radiation source: fine-focus sealed tube1107 reflections with I > 2σ(I)
graphiteRint = 0.026
[var phi] and ω scansθmax = 30.0°, θmin = 3.1°
Absorption correction: multi-scan (AX-Scale; Bruker, 2008)h = −8→8
Tmin = 0.948, Tmax = 0.981k = −16→16
14665 measured reflectionsl = −11→11


Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.045Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.147H-atom parameters constrained
S = 1.02w = 1/[σ2(Fo2) + (0.0674P)2 + 0.1254P] where P = (Fo2 + 2Fc2)/3
1718 reflections(Δ/σ)max < 0.001
74 parametersΔρmax = 0.37 e Å3
0 restraintsΔρmin = −0.19 e Å3

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)

C10.7036 (3)0.01369 (13)0.31554 (19)0.0599 (4)
C20.7584 (3)−0.01708 (14)0.1427 (2)0.0593 (4)
C30.6095 (2)0.02648 (14)0.00229 (18)0.0540 (4)
N10.7138 (2)0.13945 (11)0.34353 (15)0.0544 (4)
N20.2075 (2)0.23209 (11)0.22415 (16)0.0510 (3)
O10.03639 (19)0.26482 (12)0.15889 (16)0.0710 (4)
O20.2102 (2)0.15918 (11)0.33405 (15)0.0732 (4)
O30.3767 (2)0.27276 (12)0.17480 (16)0.0714 (4)

Atomic displacement parameters (Å2)

C10.0791 (11)0.0552 (9)0.0448 (8)0.0006 (8)−0.0042 (7)0.0031 (6)
C20.0622 (9)0.0591 (9)0.0559 (9)0.0067 (7)−0.0052 (7)−0.0109 (7)
C30.0632 (9)0.0583 (9)0.0407 (7)−0.0024 (7)0.0046 (6)−0.0062 (6)
N10.0544 (8)0.0610 (8)0.0479 (7)−0.0035 (6)0.0033 (6)−0.0087 (5)
N20.0584 (8)0.0501 (7)0.0451 (7)0.0059 (6)0.0070 (6)−0.0002 (5)
O10.0567 (7)0.0808 (9)0.0755 (9)0.0130 (6)0.0018 (6)0.0188 (6)
O20.0782 (9)0.0798 (8)0.0615 (7)0.0012 (7)0.0045 (6)0.0279 (6)
O30.0576 (8)0.0846 (9)0.0731 (8)−0.0041 (6)0.0131 (6)0.0188 (6)

Geometric parameters (Å, °)

C1—N11.487 (2)C3—H3A0.9700
C1—C21.505 (2)C3—H3B0.9700
C2—C31.527 (2)N1—H1E0.8900
C2—H2A0.9700N2—O21.2330 (16)
C2—H2B0.9700N2—O11.2369 (17)
C3—C3i1.510 (3)N2—O31.2504 (17)
N1—C1—C2111.60 (13)C2—C3—H3A108.7
C1—C2—C3117.17 (14)H1C—N1—H1D109.5
C3—C2—H2B108.0O2—N2—O1120.27 (14)
H2A—C2—H2B107.2O2—N2—O3120.85 (14)
C3i—C3—C2114.07 (17)O1—N2—O3118.86 (13)
N1—C1—C2—C3−64.0 (2)C1—C2—C3—C3i−67.1 (2)

Symmetry codes: (i) −x+1, −y, −z.

Hydrogen-bond geometry (Å, °)

N1—H1C···O20.892.533.1760 (19)130
N1—H1C···O30.892.042.9184 (19)171
N1—H1D···O1ii0.892.132.9692 (18)158
N1—H1D···O2ii0.892.363.1374 (19)146
N1—H1E···O1iii0.892.263.0561 (18)149
N1—H1E···O3iii0.892.233.0110 (18)146

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


Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FJ2206).


  • Allen, F. H. (2002). Acta Cryst. B58, 380–388. [PubMed]
  • Barbour, L. J. (2001). J. Supramol. Chem.1, 189–191.
  • Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl 34, 1555–1573.
  • Blerk, C. van & Kruger, G. J. (2008). Acta Cryst. C64, o537–o542. [PubMed]
  • Bruker (1998). SMART-NT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Bruker (2008). APEX2, AX-Scale, SAINT and XPREP Bruker AXS Inc., Madison, Wisconsin, USA.
  • Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst.39, 453–457.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Westrip, S. P. (2009). publCIF. In preparation.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography