PENTACOORDINATED MOLECULES .35. STRUCTURES OF MIXED-LIGAND SULFUR-CONTAINING SPIROCYCLIC PHOSPHORANES

Single-crystal X-ray analysis of the sulfur-containing spirocyclic phosphorane (CH3C6H3S2)(C|4H8O2)PPh (111) revealed a geometry only slightly displaced from a rectangular pyramid. The X-ray analyses of the related thio spirocyclics, (C6H4OS)2PPh (IV) and (C6H4S2)2PPh (V), showed geometries closer to the idealized trigonal pyramid. Ill crystallizes in the monoclinic space group P21n, with a = 9.816 (2) Å, b = 14.047 (2) Å, c = 16.857 (3) Å, ² = 100.19 (1)°, and Z = 4. IV crystallizes in the monoclinic space group P21/c, with a = 9.042 (4) k, b = 10.119 (4) Å, c = 18.787 (4) Å, (3 = 96.63 (3)°, and Z = 4. V crystallizes in the monoclinic space group P21/n, with a = 16.701 (4) Å, b = 6.638 (1) Å, c = 16.994 (2) Å, ² = 114.29(2)°, and Z = 4. Data for all three compounds were collected, using an automated Enraf-Nonius CAD4 diffractometer, out to a maximum 2ΘMoKα of 55°. Full-matrix least-squares refinement techniques led to the final agreement factors of R = 0.043, Rw= 0.048 for III based on the 3171 reflections having 1≥2σ, R = 0.034, Rw= 0.043 for IV for the 3025 reflections having I > 2σ1, and R = 0.030 and Rw= 0.037 for V for the 2980 reflections having I > 2σ. The specific geometries obtained for III and IV are related to the different placement of the ring sulfur and oxygen atoms that constitute an identical set in each of the two structures. It is concluded that the general structural principles formulated for spirocyclic oxyphosphoranes thus far appear to apply to the related sulfur derivatives. © 1979, American Chemical Society. All rights reserved.