C~sH13P, Mr = 260.3, orthorhombic, Pbc2~ [alternative setting of Pca2~ (No.29)], a = 8.486 (2), b = 12.387 (3), c = 26.244 (5) A, V= 2759 (1) A 3, Z = 8, Dx=l.25gcm -3, a(MoKa)=0.71073A, i z= 1.8 cm-~, F(000) = 1088, T= 288 K, R = 0.050 for 1512 observed reflections. The structure contains two 5-phenyldibenzophosphole molecules per asymmetric unit and these have almost identical conformations in the crystal lattice [as defined by the torsion angles C(ll)--P(1A)--C(31)--C(32) 32.0(5) and C(41)-- P(2A)--C(61)~C(62) 34.1 (6)°]. The central fivemembered rings in both molecules have envelope conformations, with the P atom 0.136(15) and 0.104(15) A from the relevant four-C-atom plane; the dibenzophosphole moieties are both bowed slightly, with the aromatic rings bent in a direction away from the pendant phenyl ring bonded to the P atom [dihedral angles between the plane of the C atoms of the central ring and the aromatic rings are in the range 1.1 (4)-3.0 (4)°]. There is also a small rotation about the central C--C bond as shown by the relevant torsion angles which are in the range 0.2 (5)-3.3 (6) ° . Difference maps show that there is disorder in the crystal lattice in that each molecule is disordered over two sites [a major and a minor one in each case; occupancies 0.89 and 0.11 for molecule (1) and 0.95 and 0.05 for molecule (2)]. For the minor sites, only the P atoms could be detected. Main dimensions are: P--C(phenyl) 1.841(9), 1.846 (10) A, P--C(dibenzophosphole) 1.808 (9)- 1.838(10), mean 1.819 (9) A, phosphole ring C--P--C 88.9 (4) and 89.5 (4) °, exocyclic C--P--C 101.7 (4)-104.2 (4), mean 103.0 (4) ° .