4-(4-Chlorophenyl)-3-cyano-7-(4-methoxyphenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromen-2-aminium methanolate

In the cation of the title organic ion pair compound, C23H20ClN2O3 +·CH3O−, the cyclohexyl ring shows a half-boat conformation and the dihedral angles between two benzene rings and the pyran ring are 83.14 (7) and 73.18 (9)°. In the crystal, centrosymmetrically related cations are linked into a dimer by pairs of N—H⋯N hydrogen bonds, generating an R 2 2(12) ring motif. The anion interacts with the dimer through an N—H⋯O hydrogen bond. π–π interactions between pyran rings of adjacent dimers, with a centroid–centroid distance of 3.861 (2) Å, are also observed.

In the cation of the title organic ion pair compound, C 23 H 20 ClN 2 O 3 + ÁCH 3 O À , the cyclohexyl ring shows a half-boat conformation and the dihedral angles between two benzene rings and the pyran ring are 83.14 (7) and 73.18 (9) . In the crystal, centrosymmetrically related cations are linked into a dimer by pairs of N-HÁ Á ÁN hydrogen bonds, generating an R 2 2 (12) ring motif. The anion interacts with the dimer through an N-HÁ Á ÁO hydrogen bond.interactions between pyran rings of adjacent dimers, with a centroid-centroid distance of 3.861 (2) Å , are also observed.

Comment
Chromenes and their benzo-derivatives are very important heterocyclic compounds, in particular due to their application in a variety of industrial, biological and chemical syntheses (Geen et al., 1996;Ercole et al., 2009;Takakazu et al., 2001).
Herein, we report the synthesis and crystal structure of a new chromene derivative.
The molecular structure of the title compound is shown in Figure 1. In the cation of this novel organic ion pair compound, the cyclohexyl ring shows in a half-boat conformation. The dihedral angles between the C1-C6 and C16-C21 benzene rings and the pyran ring are 83.14 (7) and 73.18 (9)°, respectively. In the crystal structure ( Fig. 2), centrosymmetrically related cations form a dimer by two intermolecular N-H···N hydrogen bonds (Table 1). Between neighbouring dimers, π-π interactions between pyran rings (centroid-centroid distance = 3.861 (2) Å) are observed.
Furthermore, the organic cations and the methanolate anion are linked by intermolecular N-H···O hydrogen bonds.

Experimental
The title compound were synthesized by the reaction of 4-chlorobenzaldehyde (10 mmol), malononitrile (10 mmol) and 5-(4-methoxyphenyl)-1,3-cyclo-hexane-dione (10 mmol) according to the similar synthesis route reported in the literature (Wen et al., 2006;Kidwai et al., 2005). Single crystals of the title compound suitable for X-ray analysis were obtained by slow evaporation of a methanol solution at room temperature for one week.

Refinement
The aminium H atoms were located in a difference Fourier map ans refined with N-H fixed to 0.89 Å and U iso (H) = 1.5U eq (N). All other H atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93-0.98 Å, and with U iso (H) = 1.2U eq (C) or 1.5U eq (N) for methyl H atoms. Rigid bond restraints were applied to the U ij values of atoms O1, C4, C5, C10, C14, C15, C17, C18, C20 and C21 with the DELU command in SHELXL97.   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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1