Diphenyl [(S)-1-phenylpropanamido]phosphate

The title compound, C21H22NO3P, was synthesized from the reaction of (C6H5O)2P(O)(Cl) and S-1-phenylpropylamine (1:2 mole ratio) at 273 K, followed by removal of the S-1-phenylpropylamine hydrochloride by-product by dissolving in H2O. The P atom is located in a distorted tetrahedral environment. The bond angles at the P atom vary from 99.51 (12) to 116.68 (12)°. The sp 2 character of the N atom is reflected by the C—N—P angle [120.9 (2)°]. The P=O group and the N—H unit adopt an anti orientation with respect to one another. In the crystal, adjacent molecules are linked via N—H⋯O(P) hydrogen bonds into a one-dimensional arrangement running parallel to the a axis.

The title compound, C 21 H 22 NO 3 P, was synthesized from the reaction of (C 6 H 5 O) 2 P(O)(Cl) and S-1-phenylpropylamine (1:2 mole ratio) at 273 K, followed by removal of the S-1phenylpropylamine hydrochloride by-product by dissolving in H 2 O. The P atom is located in a distorted tetrahedral environment. The bond angles at the P atom vary from 99.51 (12) to 116.68 (12) . The sp 2 character of the N atom is reflected by the C-N-P angle [120.9 (2) ]. The P O group and the N-H unit adopt an anti orientation with respect to one another. In the crystal, adjacent molecules are linked via N-HÁ Á ÁO(P) hydrogen bonds into a one-dimensional arrangement running parallel to the a axis.   Table 1 Hydrogen-bond geometry (Å , ).

family.
The molecular structure of the title compound is given in Fig. 1. The P═O, P-O and P-N bond lengths and the C-N-P and C-O-P angles are standard for this category of phosphoramidate compounds (Pourayoubi et al., 2010).
In the crystal structure, molecules are linked via N-H···O(P) hydrogen bonds into extended chains running parallel to the a axis (Table 1, Fig. 2).

Experimental
To a solution of (C 6 H 5 O) 2 P(O)Cl in chloroform, a solution of S-1-phenylpropylamine (1:2 mole ratio) in chloroform was added at 273 K. After 4 h of stirring, the solvent was removed and the obtained solid was washed with distilled water. Single crystals were obtained from a solution of the title compound in CHCl 3 /n-C 7 H 16 after slow evaporation at room temperature.

Refinement
All carbon bound H atoms were placed at calculated positions and treated as riding with their U iso set to either 1.2U eq or 1.5U eq (methyl) of the respective carrier atoms; in addition, the methyl H atoms were allowed to rotate about the C-C bond. Nitrogen bound H atom was located in a difference Fourier map and its coordinates were refined using restraint on the N-H distance (0.85 (1) Å) with U iso = 1.5U eq (N). Fig. 1. An ORTEP style plot and atom labeling scheme for the title compound. Displacement ellipsoids are given at 50% probability level and H atoms are drawn as small spheres of arbitrary radii.

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 > σ(F 2 ) is used only for calculating Rfactors(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.