Tris(naphthalen-1-yl)phosphane chloroform hemisolvate

The title compound, P(C10H7)3·0.5CHCl3, was isolated after the unsuccessful reaction of KSeCN and tris(naphthalen-1-yl)phosphane. The solvent molecule is disordered about an inversion center. The effective cone angle of the phosphine is 203°. In the crystal, weak C—H⋯Cl and C—H⋯π interactions are observed.

The molecular structure of the title compound is shown in Fig. 1. The chloroform solvent molecule is disordered across an inversion center. The average P-C distance and C-P-C angle are 1.837 (3) Å and 102.43 (12)°, respectively. To describe the steric demand of the phosphane ligands the Tolman cone angle (Tolman, 1977) is still the most commonly used model. Applying this model to the geometry obtained from the title compound with a dummy atom positioned at a distance of 2.28 Å from the P-atom, we calculated an effective cone angle (Otto, 2001) of 203°. This large value may account for the unreactiveness of the phosphorus centre with selenium.
Packing in the crystals is assisted by weak C-H···Cl and C-H···π interactions (see table 1 and Fig. 2 for a graphical representation of these interactions).

Refinement
The aromatic and methine H atoms were placed in geometrically idealized positions (C-H = 0.93 and 0.98) Å and allowed to ride on their parent atoms, with U iso (H) = 1.2U eq (C). The chloroform solvate molecule is disordered across an inversion centre, H atom connectivity was correctly assigned by using a PART -1 instruction in SHELXL-97 (Sheldrick, 2008). Occupancies of each disordered component were constrained to 50% conforming to the imposed crystallographic symmetry. No additional geometrical or thermal ellipsoid restrains were employed in the final refinement cycles.   Packing diagram showing the C-H···Cl/π interactions (indicated by red dashed lines).

Special details
Experimental. The intensity data was collected on a Bruker Apex DUO 4 K CCD diffractometer using an exposure time of 120 s/frame. A total of 1041 frames were collected with a frame width of 0.5° covering up to θ = 28.38° with 99.2% 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.

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