Bis[2-(morpholinomethyl)phenyl]phenylphosphane

The title compound, C28H33N2O2P, contains a pentacoordinated P atom as a result of the weak N→P intramolecular interactions, with three C atoms, two N atoms and the lone pair arranged in a dicapped pseudo-tetrahedral geometry. The morpholine rings exhibit an almost ideal chair conformation. In the crystal, two weak C—H⋯O hydrogen-bond interactions link the molecules in layers stacked along the a axis; there are no further interactions between the layers.

The title compound, C 28 H 33 N 2 O 2 P, contains a pentacoordinated P atom as a result of the weak N!P intramolecular interactions, with three C atoms, two N atoms and the lone pair arranged in a dicapped pseudo-tetrahedral geometry. The morpholine rings exhibit an almost ideal chair conformation. In the crystal, two weak C-HÁ Á ÁO hydrogenbond interactions link the molecules in layers stacked along the a axis; there are no further interactions between the layers.
The structure of (I) with its atomic numbering scheme is depicted in Figure 1. The N atoms from the two morphilinyl pendant arms form weak intramolecular interactions with the central phosphorus atom [N1···P1 = 3.038 (4) and N2···P1 = 3.105 (4) Å; c.f. sums of the covalent radii, Σr cov (P,N) 1.80 Å, and van der Waals radii, Σr vdW (P,N) 3.44 Å (Emsley, 1994)]. The magnitude of the N→P interactions is similar to the ones present in tris[2-(dimethylaminomethyl)phenyl]phosphane (Chuit et al., 1993). Taking into account these intramolecular interactions a dicapped pseudo-tetrahedron can be considered around the phosphorus, with the three carbon atoms and the phosphorus lone pair describing the tetrahedral skeleton.

S2. Experimental
To a solution of the [2-{O(CH 2 CH 2 ) 2 NCH 2 }C 6 H 4 ]Li (2.72 g, 14 mmol) in cold thf (-70 °C) was added dropwise a solution of PPhCl 2 (1.01 ml, ρ = 1.319 g/ml, 7 mmol) in thf. The reaction mixture was stirred at -70 °C for additional 2 h, then it was allowed to reach the room temperature and the solvent was removed under vacuum. The obtained oily product was extracted with CH 2 Cl 2 . The solid residue was filtered off and the solvent was removed in vacuum. The remaining viscous oil solidified on addition of hexane. The title compound was isolated as a white solid. Colorless crystals suitable for Xray diffraction studies were obtained by slow diffusion of hexane into a CH 2 Cl 2 solution of the title compound (1:1 v/v ratio) (yield: 2.76 g, 81%; m.p. 89 °C).

S3. Refinement
All H atoms were placed in calculated positions (C-H = 0.93-0.97 Å) and treated using a riding model with U iso = 1.2U eq (C). The R factor is 0.112 due to the crystal quality and because the measurement was made at room temperature.
We tried several times to grow quality crystals and measured 4 different ones but only the one submitted was acceptable.

Figure 1
The molecular structure of the title compound showing 30% probability displacement ellipsoids and the atom-numbering scheme.  Hydrogen bonds in the title compound (dashed lines; only H atoms involved in interactions are shown). Symmetry codes: 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.