CRYSTAL AND MOLECULAR-STRUCTURE OF 2-PHENYL-2-THIONO-5,6-(4',5'-DIMETHYLBENZO)-1,3,2-DITHIAPHOSPHEPINE AND 2-METHOXY-2-OXO-5,6-BENZO-1,3,2-DIOXAPHOSPHEPINE

An x-ray diffraction structural analysis was carried out on two seven-membered cyclic organophosphorus compounds (A and B). The unit cell parameters for the orthorhombic crystals of A at 20-degrees-C are as follows: a = 18.127(4), b = 8.471(3), c = 21.468(5) angstrom, space group Pbca, Z = 8, lambda-MoK(alpha). A total of 728 reflection were measured; R = 0.041. The unit cell parameters for the monoclinic crystals of B at -145-degrees-C are as follows: a = 8.627(9), b = 12.320(6), c = 9.448(7) angstrom, beta = 99.26(7)-degrees-C, space group P2(1)/n, Z = 4, lambda-MoK(alpha). A total of 1596 reflections were measured; R = 0.040. The seven-membered rings in both phosphepines have chair conformation. The P = S bond in A and the methoxy group in B are axial, while the phenyl substituent in A and P = O bond in B are equatorial. The plane of the phenyl substituent in the 1,3,2-dithiaphosphepine (A) coincides with the plane of symmetry of the seven-membered ring.