Crystal structure of diethyl [(4-chloroanilino)(4-hydroxyphenyl)methyl]phosphonate N,N-dimethylformamide monosolvate

In the title compound, C17H21ClNO4P·C3H7NO, the dihedral angle formed by the aromatic rings is 83.98 (7)°. In the crystal, O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds link the molecules into double layers parallel to (011).

In the title compound ( Fig. 1), the P1 atom has a distorted tetrahedral geometry involving two O atoms from ethoxy groups (O1, O3), one C α atom (C7), and a doubly-bonded O atom(O2). The C α atom is chiral. The C-P and P═O bond lengths are comparable with those reported for similar structures (Li et al., 2008, Wang et al., 2012. The dihedral angle formed by the aromatic rings is 83.98 (7)°. The molecular conformation is stabilized by an intramolecular C-H···O hydrogen bond (Table 1). In the crystal structure, the molecules interact through O-H···O, N-H···O and C-H···O hydrogen bonds to form double layers parallel to the (0 1 1) plane (Fig. 2, Table 1).

S2. Experimental
The title compound was synthesized according to a recently reported procedure (Wang et al., 2012). 4-Chlorobenzenamine (0.64 g) and 4-hydroxybenzaldehyde (0.61 g) were mixed in 20.0 mL ethanol and refluxed for 1 h, then cooled to room temperature. The light yellow solid obtained was separated and washed with ethanol and ether. Part of the solid (0.462 g) was mixed with 300 mL diethyl phosphonate in 15 mL ethanol, and the mixture refluxed for 24 h. After cooling to room temperature, the light yellow oil obtained was dissolved in 10 mL DMF. Block yellow crystals of the title compound formed from the filtrate on slow evaporation of the solvent in air after two weeks.

S3. Refinement
The amine H atom was located in a difference Fourier map and refined freely. All other H atoms were placed in geometrically idealized positions and refined as riding, with C-H = 0.93-0.97 Å, O-H = 0.82 Å, and with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C, O) for hydroxyl and methyl H atoms. A rotating model was used for the hydroxyl and methyl groups.
During the refinement, the C16-C17 bond length was constrained to be 1.54 (1) Å. 13 Outliers were omitted in the last cycles of refinement.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level. An intramolecular hydrogen bond is shown as a dashed line. Partial crystal packing of the title compound showing the intra-and intermolecular hydrogen bonding network (dashed lines).  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 0.3710 (