4-(o-Tolyl)piperazin-1-ium chloride

In the title molecular salt, C11H17N2 +·Cl−, the piperazin-1-ium ring adopts a chair conformation with the aromatic ring in a pseudo-equatorial orientation. The dihedral angle between the benzene ring and the mean plane of the piperazin-1-ium ring is 51.22 (6)°. In the crystal, N—H⋯Cl hydrogen bonds link the molecules into chains propagating in [100]. Weak C—H⋯π interactions also ocur.

In the title molecular salt, C 11 H 17 N 2 + ÁCl À , the piperazin-1-ium ring adopts a chair conformation with the aromatic ring in a pseudo-equatorial orientation. The dihedral angle between the benzene ring and the mean plane of the piperazin-1-ium ring is 51.22 (6) . In the crystal, N-HÁ Á ÁCl hydrogen bonds link the molecules into chains propagating in [100]. Weak C-HÁ Á Á interactions also ocur.

Experimental
To a stirred solution of 2-flurotoluene (2g, 0.0181 mol) and anhydrous potassium carbonate (3.7g, 0.027 mol) in dry acetonitrile (20 ml), piperizine-1-carboxylic acid tert butyl ester (3.38g, 0.0181 mol) was added dropwise at RT and reaction mixture was stirred at RT for 5h. After the completion of reaction, the reaction mixture was filtered and the filtrate was concentrated. The product (5g) was then dissolved with HCl in dioxane (25 ml) and stirred at RT for 2 h. The reaction mixture was concentrated through high vacuum. The crude product was recrystallised from hot ethanol to afford title compound as colourless blocks (3.0g, 66%). M.p > 620K.

Refinement
Atom H1N1 and H2N1 were located in a difference Fourier map and fixed to the positions with N-H = 0.8702 and 0.8662 Å. The remaining H atoms were positioned geometrically and refined using a riding modelwith C-H = 0.93-0.97 Å. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. 1943 Freidel pairs were used to determine the absolute configuration.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq