Crystal structure of N-(diphenylphosphoryl)-2-methoxybenzamide

In the title compound, C20H18NO3P, the C=O and P=O groups of the carbacylamidophosphate (CAPh) fragments are located in a synclinal position relative to each othe. The N—H group is involved in the formation of an intramolecular hydrogen bond.

In the title compound, C 20 H 18 NO 3 P, the C O and P O groups of the carbacylamidophosphate (CAPh) fragments are located in a synclinal position relative to each other and are pre-organized for bidentate chelate coordination of metal ions. The N-H group is involved in the formation of an intramolecular hydrogen bond. In the crystal, molecules do not form strong intermolecular interactions but the molecules are linked via weak C-HÁ Á Á interactions, forming chains along [001].

Structural commentary
The molecular structure of the title compound is shown in Fig. 1. The bonds lengths in the C(O)NHP(O) fragment are typical for CAPh type ligands. The C O and P O groups are located in a synclinal position relatively to each other as evidenced by the O1-P1-N1-C13 torsion angle of À45.5 (2) , O2-C13-N1-P1 torsion angle of À2.7 (3) , and the O1-P1Á Á ÁC13-O2 pseudo-torsion angle of À42.9 (2) .

ISSN 2056-9890
As a result the CAPh fragment conformation is pre-organized for bidentate chelate coordination of metal ions.
The conjugation between the carbamide group and the anisole substituent is broken, as evidenced by the value of the C13-C14 bond length of 1.496 (3) Å , which is comparable to the mean value for non-conjugated C ar -Csp 2 bonds (1.488 Å ; Burgi & Dunitz, 1994). At the same time, the anisole and carbamide fragments are slightly non-coplanar. The C19-C14-C13-N1 torsion angle is 13.6 (3) despite the formation of the N1-H1Á Á ÁO3 strong enough hydrogen bond (the H1Á Á ÁO3 distance is 1.93 Å and the N1-H1Á Á ÁO3 angle is 137 ; Table 1). The methyl group of the methoxy substituent lies in the plane of the attached benzene ring despite the significant steric repulsion [the shortened intramolecular contacts are: H20AÁ Á ÁH18 = 2.26 Å (the sum of the vdW radii is 2.32 Å ; Zefirov, 1997), H20CÁ Á ÁH18 = 2.28 Å and C20Á Á ÁH18 = 2.48 Å (the sum of the vdW radii is 2.87 Å )]. The phosphorus atom environment has a distorted tetrahedral configuration. The C1-C6 phenyl ring is almost coplanar with the P O bond [the C6-C1-P1-O1 torsion angle is À5.7 (2) ] while the C7-C12 phenyl ring is rotated significantly relatively to the P O bond as defined by the C8-C7-P1-O1 torsion angle of À72.7 (2) .

Supramolecular features
It has been shown that CAPhs display different solid-state motifs (Breuer et al., 1990;Amirkhanov et al.,1997;Milton et al., 2004a,b;Kariaka et al., 2014), i.e. chains, dimers and more seldom monomers. These motifs are realized through existence of hydrogen bonds with participation of the -N-H group. In crystal of (I), the -N--H group participates in an intramolecular hydrogen bond. There are no strong proton donors capable of forming intermolecular hydrogen bonds in this molecule. Thus the title molecules form only weak C-HÁ Á Á interactions leading to chains of molecules along the caxis direction (Figs. 2 and 3).

Database survey
A search of the Cambridge Structural Database (CSD, Version 5.40, update of November 2018; Groom et al., 2016) for complexes containing CAPh ligands yielded 189 hits. In the CAPh fragments, the mean C O bond length is 1.222 Å , the mean C-N bond length is 1.364 Å , the mean N-P bond length is 1.686 Å and the mean P O bond length is 1.504 Å .

Figure 2
A section of a chain along the c axis formed by weak C-HÁ Á Á interactions (shown as blue dotted lines).

Figure 3
The crystal packing of the title compound viewed along the b axis.

Figure 1
The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms were placed in calculated positions (N-H = 0.86, C-H = 0.93-0.96 Å ) and refined as riding with U iso (H) = 1.2U eq (C,N) or 1.5U eq (C-methyl).

Figure 4
The two-step reaction for the preparation of the title compound (I).

N-(Diphenylphosphoryl)-2-methoxybenzamide
Crystal data C 20 H 18 NO 3 P M r = 351.32 Orthorhombic, P2 1 2 1 2 1 a = 8.317 (2)  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.