2-Aminoethanaminium iodide

The title salt, [NH3CH2CH2NH2]+·I−, has an array structure based on strong intermolecular N—H⋯N hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This interaction gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation–cation chains.

The title salt, [NH 3 CH 2 CH 2 NH 2 ] + ÁI À , has an array structure based on strong intermolecular N-HÁ Á ÁN hydrogen bonding formed between the ammonium and amine groups of adjacent cations. This interaction gives a helical chain of cations that runs parallel to the b axis. The four remaining NH group H atoms all form hydrogen bonds to the iodide anion, and these iodide anions lie in channels parallel to the cation-cation chains.

Related literature
For syntheses and structures of salt forms of the related ethylene-1,2-diammonium, see: Chen (2009) ;Saidi et al. (2011). For a structural example of a complex of ethylene-1,2diammonium, see: Zhang et al. (2006). For the synthesis that gave the title compound as a by-product, see: Kennedy et al. (2011). For C-N bond length changes in another monoprotonated symmetrical diamine, see: Craig et al. (2012).  Table 1 Hydrogen-bond geometry (Å , ). Symmetry codes:
MOO thanks the Commonwealth Scholarship Commission and the British Council for funding and Moi University for sabbatical leave.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BR2201).

Figure 1
The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level with H-atoms drawn as spheres of arbitary size.

Figure 2
Hydrogen bonding forms helical, one-dimensional chains of cations that propagate in the crystallographic b direction.  Packing in (I) viewed along the b direction. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.003 Δρ max = 0.58 e Å −3 Δρ min = −0.39 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.00618 (17) Special details Experimental. Absorption correction: CrysAlis PRO (Oxford Diffraction, 2010). Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.