N-{Bis[methyl(phenyl)amino]phosphoryl}-2,2,2-trichloroacetamide

In the asymmetric unit of the crystal structure of the title compound, C16H17Cl3N3O2P, there are two crystallographically independent molecules, which form dimers via N—H⋯O hydrogen bonding between the N—H group and the P=O group. In the molecular structure, the phosphoryl group is anti to the carbonyl group. The two benzene rings are oriented at dihedral angles of 54.3 (2) and 49.7 (2)° in the two independent molecules.

In the asymmetric unit of the crystal structure of the title compound, C 16 H 17 Cl 3 N 3 O 2 P, there are two crystallographically independent molecules, which form dimers via N-HÁ Á ÁO hydrogen bonding between the N-H group and the P O group. In the molecular structure, the phosphoryl group is anti to the carbonyl group. The two benzene rings are oriented at dihedral angles of 54.3 (2) and 49.7 (2) in the two independent molecules.

S1. Comment
The intensive development of the chemistry of the phosphorus containing systems during the last decades has given rise to synthesis of many compounds bonded by phosphorus and nitrogen atoms (Helm et al., 1999;Katti et al., 1991).
The title compound contains two crystallographically independent molecules in the asymmetric unit of the unit cell, which aggregate into the non-centrosymmetric dimers (HL) 2 formed by the hydrogen bonds of N-H···OP (Figs. 1 and 2, Table 1). In the crystal structure of the HL the phosphoryl and carbonyl groups are in an anti-position to each other as in the most of the carbacylamidophosphates (Gubina et al., 1999). The bond distances P(1)O(11) and P(2)O(21) are typical for compounds with amide substituents close to phosphorus atoms (1.465-1.482 Å) (Rebrova et al., 1982). The values of

S2. Experimental
The dichloranhydride of trichloroacetylamidophosphoric acid was prepared according to the method reported by Kirsanov (Kirsanov et al., 1956).
The dioxane solution (100 ml) of methylaniline (21.4 g, 0.2 mol) and triethylamine (20.2 g, 0.2 mol) was placed in a three-neck round-bottomed flask and cooled by ice to 268 K. Then the dioxane solution (400 ml) of dichloranhydride of trichloroacetylamidophosphoric acid (27.9 g, 0.1 mol) was added dropwise under vigorous stirring. The temperature was not allowed to rise above 278 K. The stirring was continued for 1 h. The formed precipitate of N(C 2 H 5 ) 3  was isolated and recrystallized from the 2-propanol as white crystalline powder. The colourless crystals of the HL were obtained by slow evaporation of the mother liquor, washed with cool 2-propanol (10 ml) and finally dried in air (yield 85%).

S3. Refinement
All H atoms were placed at calculated positions and treated as riding on their parent atoms [C-H = 0.93 and 0.96 Å, and U iso (H) = 1.2 and 1.5U eq (C), N-H = 0.86 Å and U iso (H) = 1.2U eq (N)].

Figure 1
A view of hydrogen bonding between the two independent molecules in the unit cell of the title compound with atom numbering scheme. Displacement ellipsoids are shown at 50% probability level. Hydrogen atoms not involved in hydrogen bonding are omitted for clarity.

Figure 2
A projection of packing diagram of the title compound along the y-direction.   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.