N-Ethyl-6-ethylamino-4-oxo-1,3,5-triazin-2-aminium chloride (Oxysimazine·HCl)

In the title molecular salt, C7H14N5O+·Cl− (the HCl salt of the oxo derivative of the triazine herbicide simazine), the cation and anion are linked by N—H⋯Cl hydrogen bonds. The chloride ion is also involved in a close electrostatic interaction with an inversion-related triazine ring [Cl⋯centroid distance = 3.201 (1) Å]. A π–π interaction having a centroid⋯centroid distance of 3.456 (2) Å exists between pairs of rings via another inversion relation. The triazine ring and adjacent non-H atoms are essentially planar (r.m.s. deviation = 0.042 Å), while both methyl groups are approximately perpendicular and on the same side of the plane [torsion angles = 79.3 (3) and −84.6 (3)°]. Upon exposure to X-rays for about two days, the color of the title compound changed from colorless to a pale yellow-orange with no apparent affect on the structure as evidenced by no significant change in the intensities of the standard reflections.

In the title molecular salt, C 7 H 14 N 5 O + ÁCl À (the HCl salt of the oxo derivative of the triazine herbicide simazine), the cation and anion are linked by N-HÁ Á ÁCl hydrogen bonds. The chloride ion is also involved in a close electrostatic interaction with an inversion-related triazine ring [ClÁ Á Ácentroid distance = 3.201 (1) Å ]. Ainteraction having a centroidÁ Á Ácentroid distance of 3.456 (2) Å exists between pairs of rings via another inversion relation. The triazine ring and adjacent non-H atoms are essentially planar (r.m.s. deviation = 0.042 Å ), while both methyl groups are approximately perpendicular and on the same side of the plane [torsion angles = 79.3 (3) and À84.6 (3) ]. Upon exposure to X-rays for about two days, the color of the title compound changed from colorless to a pale yellow-orange with no apparent affect on the structure as evidenced by no significant change in the intensities of the standard reflections.
Two intramolecular hydrogen bonds involve the chloride ion (Cl1) with H1a and H4c (Table 1 and Figs. 1 & 2). The same chloride ion is also intermolecularly bonded to the H2a and H5d H atoms present in a symmetry-related molecule.
A weak intermolecular interaction was observed between H5a and O1 in another symmetry-related molecule. See Table 1 for the various symmetry operations.
The cation displays a pseudo-vertical mirror perpendicular to Fig. 1  supplementary materials sup-2 Experimental Simazine (99.9%), the parent compound, was purchased from Sigma-Aldrich (Riedel-de Haën) and used without further purification. Crystals of the title compound were grown by slow evaporation of a solution in dilute HCl (aq) .

Refinement
Approximate positions of the all of the H's were first obtained from a difference map, then placed into "ideal" positions and refined as a rotational group. Bond lengths were constrained at 0.93 Å (AFIX 43) for aromatic C-H's; at 0.96 Å (AFIX 137) for methyl C-H's; at 0.97 Å (AFIX 137) for ethyl C-H's; and at 0.86 Å (AFIX 43) for N-H's. U iso (H) were fixed at 1.5U eq (parent) for OH and methyl H's, and 1.2 U eq (parent) for all other H's.
In the final stages of refinement 11 very small or negative F o 's were deemed to be in high disagreement with their F c 's and were eliminated from final refinement.
For the set of standard reflection I's monitored during data collection, an average and standard deviation were calculated, as was the ratio of this standard deviation to the average I for each standard. The average of these 3 ratios, expressed as a percentage, is reported. Fig. 1. The asymmetric unit of the title compound, showing the labeling of the non-H atoms and H atoms involved in intramolecular hydrogen bonding (dashed lines). Displacement ellipsoids are drawn at the 50% probability levels and H atoms are drawn as small spheres of arbitrary radius. Fig. 2. View of inversion-related molecules at (1-x, 1-y, 1-z) and (2-x, 1-x, 1-z) showing Cl···ring and ring···ring (π-π) interactions. Only 4 Cl's are shown for charge balance; four others (not shown) are H-bonded to H2 and H5-type H's on the periphery of this view. To minimize congestion, displacement ellipsoids are drawn at the 30% probability levels.

Special details
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.