2-Amino-5-methyl-3-(2-oxo-2-phenylethyl)-7-phenyl-4,5,6,7-tetrahydro-3H-[1,2,4]triazolo[1,5-a]pyrimidin-8-ium bromide ethanol monosolvate

In the title compound, C20H22N5O+·Br−·C2H6O, the tetrahydropyrimidine ring of the bicyclic cation adopts a half-chair conformation with an equatorial orientation of the phenyl and methyl substituents. The amino group is nearly coplanar with the 1,2,4-triazole ring [interplanar angle = 4.08 (8)°] and has a slightly pyramidal configuration. The mean planes of the triazole ring and the benzene ring of the phenacyl group form a dihedral angle of 88.58 (7)°. In the crystal, N—H⋯Br, N—H⋯O and O—H⋯Br hydrogen bonds link the cations, anions and ethanol molecules into layers parallel to the bc plane.

In the title compound, C 20 H 22 N 5 O + ÁBr À ÁC 2 H 6 O, the tetrahydropyrimidine ring of the bicyclic cation adopts a half-chair conformation with an equatorial orientation of the phenyl and methyl substituents. The amino group is nearly coplanar with the 1,2,4-triazole ring [interplanar angle = 4.08 (8) ] and has a slightly pyramidal configuration. The mean planes of the triazole ring and the benzene ring of the phenacyl group form a dihedral angle of 88.58 (7) . In the crystal, N-HÁ Á ÁBr, N-HÁ Á ÁO and O-HÁ Á ÁBr hydrogen bonds link the cations, anions and ethanol molecules into layers parallel to the bc plane.
The title compound contains four acidic hydrogen atoms at the NH 2 , NH and OH groups which all participate in Hbonding. Three H-bonds are formed with the bromine anion and one with the oxygen atom of the hydroxyl group.
However the carbonyl oxygen atom which is known to be a strong proton-acceptor is not involved in H-bonding. Four Hbonds listed in Table 1 leads to formation of H-bonded layers parallel to bc crystallographic plane. All the other intermolecular contacts correspond to the ordinary van-der-Waals interactions.

Experimental
The crystals of the title compound suitable for X-ray analysis were grown by slow evaporation of ethanol solution of 2- (1) at room temperature within a week. The compound 1 was prepared by the following procedure.

Refinement
The hydrogen atoms of NH, NH 2 and OH groups were found in difference Fourier synthesis and normalized to the standard X-ray value of 0.90 Å for NH and NH 2 groups, and 0.85 Å for OH group. The H(C) atom positions were calculated. All the hydrogen atoms were refined in isotropic approximation in riding model with the U iso (H) parameters equal to 1.5 U eq (Ci), 1.2 U eq (Cj), 1.2 U eq (N), 1.5 U eq (O) where U eq (Ci) and U eq (Cj) are the equivalent thermal parameters of the methyl carbon atoms and all the other carbon atoms, respectively, to which corresponding H atoms are bonded; U eq (N) and U eq (O) are the equivalent thermal parameters of the nitrogen and oxygen atoms, respectively, to which corresponding H atoms are bonded.

Computing details
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008), publCIF (Westrip, 2010) and PLATON (Spek, 2009     Crystal packing fragment showing layered structure of the title compound. Projection onto ab crystallographic plane. Special details Geometry. All s.u.'s (except the s.u.'s 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 > 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.