P,P-Bis[4-(dimethylamino)phenyl]-N,N-bis(propan-2-yl)phosphinic amide

The molecular structure of the title compound, C22H34N3OP, adopts a distorted tetrahedral geometry at the P atom, with the most noticeable distortion being for the O—P—N angle [117.53 (10)°]. An effective cone angle of 187° was calculated for the compound. In the crystal, weak C—H⋯O interactions create infinite chains along [100], whereas C—H⋯π interactions propagating in [001] generate a herringbone motif.

The molecular structure of the title compound, C 22 H 34 N 3 OP, adopts a distorted tetrahedral geometry at the P atom, with the most noticeable distortion being for the O-P-N angle [117.53 (10) ]. An effective cone angle of 187 was calculated for the compound. In the crystal, weak C-HÁ Á ÁO interactions create infinite chains along [100], whereas C-HÁ Á Á interactions propagating in [001] generate a herringbone motif.
Cg1 and Cg2 are the centroids of the C11-C16 and C21-C26 rings, respectively. affords arylphosphine ligands resistant to oxidation and hydrolysis while maintaining high catalyst activity. The synthesis rests strongly on DoM technology (Snieckus, 1990) making use of a directing group that is highly underrepresented in this type of chemistry. We envisioned that the use of phosphinic amides as directing groups, together with phosphinous chloride (Cy 2 PCl) electrophiles would allow the synthesis of sterically hindered phosphines that are stable to hydrolysis and oxidation. Manipulating the phosphinic amide functionality has been shown to influence the catalytic performance of the resulting alkyl phosphine ligands and the structure reported here is one of the substrates for further ligand studies.

D-HÁ
The title compound (see Fig. 1) crystallizes in the orthorhombic space group P2 1 2 1 2 1 (Z=4) with its molecules adopting a distorted tetrahedral arrangement about the phosphorus atom. The O3-P1-N3 angle of 117.53 (10)° shows this distorted arrangement the most prominent, and it is further exemplified by the twisted orientation of the bulky amide substituent to fit into the coordination sphere of the phosphorus atom (seen from the torsion angles C34-N3-P1-O1 = -63.71 (19)° and C31-N3-P1-O1 = 87.2 (2)° respectively). The most common method used for determining the steric behaviour of a phosphane ligand is the Tolman cone angle (Tolman, 1977). We used the geometry from the title compound and adjusted the P═O distance to 2.28 Å (the average Ni-P distance used in the original Tolman model) to cancel the bias this may have on the calculated cone angle value. In this way we obtain the effective cone angle (Otto, 2001) value of 187°. Several weak C-H···O interactions are observed in the crystal lattice creating infinitely long chains along the [100] direction (Fig. 2). Additional C-H···π interactions are also observed which propagates along the [001] direction in the crystal lattice (Fig. 3). These interactions (summarized in Table 1) generate a herring-bone packing motif ( Fig. 4).
The reaction was initiated with a crystal of iodine and the suspension allowed to stir for 3 h at that temperature. Once the magnesium had fully reacted the two solutions were combined and the salts were removed by filtration through a pad of celite under argon.
The solution was cooled to 0 °C and hydrogen peroxide (30%, 15 ml) was added over 20 minutes. The mixture was allowed to stir for a further 1 h. The product was extracted with EtOAc and H 2 O and the solvent removed in vacuo. The product was isolated by flash column chromatography (EtOAc). Crystals were grown by dissolving in a minimal amount of DCM and layering an excess of hexane on top and allowing to stand in a refrigerator until the crystals were formed.
Yield: 60% (yellow solid). 1 H NMR: (300 MHz, CDCl 3 ) δH 7.58 (t, 4H, H2, H2`, H6 and H6`, J = 9.9 Hz), 6.61 (d, 4H, H3, H3`, H5 and H5`, J = 7.2 Hz), 3.41 (sept, 2H, NCH(CH 3 ) 2 , J = 6.9 Hz), 2.90 (s, 12H, NCH(CH 3 ) 2 ), 1.12 (d, 12H, NCH(CH 3 ) 2 , J = 6.9 Hz). 13  constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C) for the aromatic and methine H and U iso (H) = 1.5U eq (C) for the methyl H respectively. The Flack parameter refined to 0.11 (10).     Packing diagram showing the generated herring-bone motif from the interactions. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.002 Δρ max = 0.30 e Å −3 Δρ min = −0.35 e Å −3 Absolute structure: Flack (1983), 2224 Friedel pairs Flack parameter: 0.11 (10) Special details Experimental. The intensity data was collected on a Bruker X8 APEXII 4 K KappaCCD diffractometer using an exposure time of 20 s/frame. A total of 1010 frames were collected with a frame width of 0.5° covering up to θ = 28.33° with 99.9% completeness accomplished. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.