N,N′-Dimethyl-N′′-(trichloroacetyl)phosphoramide

In the title compound, C4H9Cl3N3O2P or CCl3C(O)NHP(O)(NHCH3)2, the P atom has a strongly distorted tetrahedral geometry due to the formation of intermolecular strong hydrogen bonds involving the N atoms. In the crystal, N—H⋯O=P and N—H⋯O=C hydrogen bonds connect the molecules into a two-dimensional array parallel to (100). An intramolecular P⋯O contact [P⋯O = 2.975 (3) Å] is observed. The CCl3 group is rotationally disordered, with occupancies of 0.60 (3) and 0.40 (3)

In the title compound, C 4 H 9 Cl 3 N 3 O 2 P or CCl 3 C(O)NHP(O)-(NHCH 3 ) 2 , the P atom has a strongly distorted tetrahedral geometry due to the formation of intermolecular strong hydrogen bonds involving the N atoms. In the crystal, N-HÁ Á ÁO P and N-HÁ Á ÁO C hydrogen bonds connect the molecules into a two-dimensional array parallel to (100). An intramolecular PÁ Á ÁO contact [PÁ Á ÁO = 2.975 (3) Å ] is observed. The CCl 3 group is rotationally disordered, with occupancies of 0.60 (3) and 0.40 (3)
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BG2520).

Synthesis and crystallization
The dichloranhydride of trichloroacetylamidophosphoric acid was prepared according to the method reported by Kirsanov (Kirsanov & Derkach, 1956). The dioxane solution (200 ml) of dichloranhydride of trichloroacetylamidophosphoric acid (27.9 g, 0.1 mol) was placed in a three-neck round-bottomed flask and cooled by ice to 268 K. Then the dry methylamine was bubbled through the dioxane solution of CCl 3 C(O)NHP(O)Cl 2 under stirring until the solution became alkaline. The temperature was not allowed to rise above 278 K. The stirring was continued for 1 h and the solution was left under ambient conditions. H 2 NCH 3 ·HCl was filtered off after 12 h and the filtrate was evaporated. The oily precipitate of I was added to acetone which led to the formation of a white crystalline powder (yield 80%). White crystals suitable for X-ray analysis were obtained from slow evaporation of a 2-propanol solution.

Refinement
H atoms of methyl groups were placed at calculated positions and treated as riding on the parent atoms, with U iso (H) = 1.5 U eq (C). H atoms of the amide group were located in a difference Fourier map and and further refined with similarity restraints for d(N-H) and U iso (H) = 1.2U eq (N). The CCl 3 group apperas rotationally disordered around the C1-C2 bond, with occupations of 0.60/0.40 (3)

Results and discussion
In the title compound (I), the phosphorus environment has a strong distorted tetrahedral conformation due to the formation of strong N1-H1···O1 and N3-H3···O1 hydrogen bonds (Table 2, Fig.1). The N1-P-N3 angle has a value 98.72° and as a consequence there is an increase in the O1-P1-N3 and O1-P1-N1 angles (119.2° and 111.29°, respectively). The orientation of the C(O) and P(O) groups differs from the conformation of most CAF-ligands (Gubina & Amirkhanov, 2000), the angle between the O2C1N1 and N1PO1 planes having a value 57.3° (the pseudo-torsion angle O=C···P=O is -53.39°).
In the crystal, two intermolecular N-H···O=P hydrogen bonds connect molecules into a chain and a third N-H···O=C hydrogen bond connects the chains into a 2D array parallel to (100) (Fig.2). An intramolecular P···O contact is also

Figure 1
A view of the title compound (I) showing the atom-numbering scheme and the formation of three type of hydrogen bonds (dashed lines). Displacement ellipsoids drawn at a 30% probability level.

Figure 2
Packing view of (I) along the b axis. Only the major fraction of the CCl 3 group has been represented. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.82 e Å −3 Δρ min = −0.77 e Å −3 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.

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