2,6-Diisopropylanilinium chloride

The title compound, C12H20N+·Cl−, crystallizes with the chloride anions situated on twofold axes, while the cation is on a general position. All conventional hydrogen-bond donors and acceptors are utilized, forming a hydrogen-bonded ladder motif along the c axis. Investigation of the torsion angles between aromatic systems and isopropyl groups reveals unusual geometrical features. One isopropyl groups exhibits an expected eclipsed conformation with respect to the aromatic ring. The other isopropyl group shows a slight twist with respect to the aromatic ring. The short Cl⋯HC(methine) contact (2.88 Å) observed in the asymmetric unit is the probable reason for the twist feature around the isopropyl area.

The title compound, C 12 H 20 N + ÁCl À , crystallizes with the chloride anions situated on twofold axes, while the cation is on a general position.All conventional hydrogen-bond donors and acceptors are utilized, forming a hydrogen-bonded ladder motif along the c axis.Investigation of the torsion angles between aromatic systems and isopropyl groups reveals unusual geometrical features.One isopropyl groups exhibits an expected eclipsed conformation with respect to the aromatic ring.The other isopropyl group shows a slight twist with respect to the aromatic ring.The short ClÁ Á ÁHC(methine) contact (2.88A ˚) observed in the asymmetric unit is the probable reason for the twist feature around the isopropyl area.

Related literature
For the structure of the tetrahydrofuran solvate of the title salt, see: Bond & Doyle (2003).
The structure has all conventional hydrogen-bond donors used.In the crystal structure, four of the protonated NH 3 groups face the counter-ions sitting on above mentioned special positions, forming two-dimensional sheets parallel to the (010) planes (Fig. 2).Hydrogen-bond network confirms the following interactions between 50% populated Cl -anions and polar ends of DIPAH + (NH 3 + groups): Cl1X participates a hydrogen-bonding interaction with H13X (2.54 Å separation), H13Z (2.35 Å), and H13Y (2.16 Å) are hydrogen-bonded to Cl1X and Cl1Y, respectively.There is an additional short contact within van der Waals radii between Cl1X and H7 (2.88 Å) yet this interaction does not occur with the Cl1Y occupancy.
The torsion angles from the aromatic group to the isopropyl groups are interesting.The expectation is that the isopropyl groups would eclipse the aromatic ring plane so that the C7-H7 and C10-H10 bonds lie in the same plane as atoms N13, C1, C6 and C7.One of these groups exhibits such a conformation (C1-C2-C10-H10 = -0.21°),while the other shows a slight twist (C1-C6-C7-H7 = -34.62°).The above mentioned Cl1X•••H7 short contact is the probable reason for the obvious twist event around C1-C6-C7-H7 area.Similar events are observed in a related DIPA chloride salt structure, where only one of isopropyl hydrogen experiences van der Waals contacts with a Cl -anion (Bond & Doyle, 2003).

S2. Experimental
A stock solution of DIPA was made in 2-propanol (85 mg, 2 ml).To a crystallizer vessel, 0.43 ml of stock solution was added with 1 equivalent of concentrated hydrochloric acid.For salt formation participation we gradually added 6 ml of methyl t-butyl ether, then the sample was purged with dry nitrogen for evaporation until dryness, allowed to evaporate over 24 h mark.A crystal of the title salt was removed from the crystallizer vessel and mounted on a MiTeGen loop with Paratone-N oil.

S3. Refinement
H atoms bonded to C atoms were placed in idealized positions and refined using a riding model with C-H = 0.93 Å for Csp 2 -H, 0.96 Å for CH 3 , and 0.98 Å for CH.U iso (H) values were fixed to 0.08 Å 2 .H atoms bound to N3 were located in a difference maps and their positions and isotropic displacement parameters were refined freely.

Figure 2
The crystal structure viewed along the [001] direction, showing four Cl -anions spaced between four DIPA + cations.

Figure 1
Figure 1View of the constituents of (I), showing the atom-labeling scheme and displacement ellipsoids drawn at the 30% probability level.H atoms are represented by circles of arbitrary size.