Decane-1,10-diaminium dinitrate

The crystal structure of the title compound, C10H26N2 2+·2NO3 −, exhibits a back-to-back paired double-stacked packing arrangement culminating in an overall double zigzag pattern of the dications. Each pair of double-stacked dications is surrounded by a ring of ten nitrate anions. An intricate three-dimensional N---H...O and N---H...(O,O) hydrogen-bonding network exists in the crystal structure.

The author acknowledges 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 data and figures for this paper are available from the IUCr electronic archives (Reference: LR2031).
The asymmetric unit of compound (I) contains one diammonium dication and two nitrate anions with all atoms occupying general positions. The hydrocarbon chain is also fully extended with slight deviations from planarity chain as is evident from the torsion angles along the hydrocarbon chain (tabulated in Table 1). The molecular structure of (I) is shown in Figure 1. anions. An extensive three-dimensional hydrogen-bonding network is also formed of N-H···O hydrogen bonds.
A close-up view of selected hydrogen bonding interactions can be viewed in Figure 3. The three-dimensional hydrogen bonding network is built and linked through hydrogen bonding interactions between the ammonium groups of the dication and the nitrate anions. Clear evidence of bifurcated hydrogen bonding interactions can also be seen in this illustration. The hydrogen bond distances and angles for the title compound (I) can be found in Table 2.

Experimental
Compound (I) was prepared by adding decane-1,10-diamine (0.50 g, 2.90 mmol) to 55% nitric acid (2 ml, 42.5 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 crystals of decane-1,10-diammonium dinitrate were collected and a suitable single-crystal was selected for the X-ray diffraction study.

Refinement
H atoms were geometrically positioned and refined in the riding-model approximation, with C-H = 0.97 Å, N-H = 0.89 Å, and U iso (H) = 1.2Ueq(C) or 1.5Ueq(N). For (I), the highest peak in the final difference map is 0.85Å from C6 and the deepest hole is 0.39Å from N2.