N 1,N 2-Dimethylethane-1,2-diaminium dichloride

The cation of the title salt, C4H14N2 2+·2Cl−, is located on a crystallographic inversion center and is bisected by a mirror plane, with one quarter of the C4H14N2 2+·2Cl− formula unit being crystallographically unique. he chloride ions also sit on a mirror plane. The conformation of the cation is a regular straight-chain conformation with all non-H atoms in anti positions. In the crystal, hydrogen bonding between N—H groups and chloride anions yields a zigzag ladder-type structure along [010].

The cation of the title salt, C 4 H 14 N 2 2+ Á2Cl À , is located on a crystallographic inversion center and is bisected by a mirror plane, with one quarter of the C 4 H 14 N 2 2+ Á2Cl À formula unit being crystallographically unique. he chloride ions also sit on a mirror plane. The conformation of the cation is a regular straight-chain conformation with all non-H atoms in anti positions. In the crystal, hydrogen bonding between N-H groups and chloride anions yields a zigzag ladder-type structure along [010].
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Supporting information for this paper is available from the IUCr electronic archives (Reference: ZL2574).  (Wolstenholme et al., 2008) as well as with a number of metal complex anions, the structure of the chloride salt has not been determined previously.
The title compound crystallizes in the C2/m space group and the molecule is located on a crystallographic inversion center and is bisected by a mirror plane, with one quarter of a molecule of [C 4 H 14 N 2 ] 2+ 2Clbeing crystallographically unique. Figure 1 shows the thermal ellipsoid plot of the asymmetric unit and Figure 2 shows the thermal ellipsoid plot of the entire molecule with atoms labeled with name and symmetry operation that generates them. The diaminium cation adopts a classical linear geometry with all heavy atoms lying in a plane and all bond angles being ± one degree from the ideal tetrahedrality.
The presence of two hydrogen atoms on each nitrogen atom leads to a ladder hydrogen-bonding motif with each N-H bonding to a chloride anion. Figure 3 shows a view down the c-axis showing the ladder arrangement while figure 4 shows the same arrangement down the a-axis.
Other ethanediaminium chlorides have been structurally characterized, but all have very different hydrogen bonding motifs. Obviously, hexamethylethylenediaminium chloride has no N-H groups and therefore, no H-bonding, so the lack of a chloride ion comparison for that dication is not important. The unsubstituted ethylenediaminium chloride, having 3 N -H hydrogen bonds to the chloride ion has a more complex, three-dimensional H-bonding network (Liu et al., 2010).
The [N 1 ,N 1 ,N 2 ,N 2 -tetramethylethane-1,2-diaminium]chloride structure, with only one N-H per nitrogen atom, shows clear hydrogen-bonding, but there is no extended lattice structure, just isolated N-H···Cl bonds (Schneider & Schier, 2004) and (Kabak et al., 2000). The trimethyl compound, [N 1 ,N 1 ,N 2 -trimethyldiaminium chloride has a complicated structure with two different conformations of the dication in the asymmetric unit, each hydrogen-bonding to the chloride ions in different ways and yielding an iregular motif (Errington et al., 2001).

Experimental
The crystal used in this experiment was obtained from a reaction between [Ir(COD)Cl] 2 (COD = 1,5-cyclooctadiene) (0.100 g) and N 1 ,N 2 -ethane-1,2-diamine (0.200 g) in dichloromethane solution. After stirring at room temperature overnight, the solvent was removed under reduced pressure to yield 0.147 g of a white powder. Some of the powder was dissolved in dichloromethane and allowed to evaporate slowly in a vial with the serum cap punctured with a needle. Upon evaporation of all of the solvent, most of the solid was a powder with only a few nicely shaped crystals in the mixture. A crystal was chosen and epoxied onto a thin quartz fiber and placed in a goniometer. Apparently, on sitting, some amount of decomposition occurred to yield the free diamine as well as the generation of hydrogen chloride resulting in the formation of the title compound.

Refinement
All hydrogen atoms in the structure were located by difference map and all parameters not fixed by location on a symmetry element (mirror plane) were refined. N-H bonds are 0.94 (2) Å (Table 1) and are identical by symmetry (mirror plane and inversion center).

Computing details
Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008;program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).    where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.24 e Å −3 Δρ min = −0.15 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.041 (6) 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 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.