Crystal structure of the solid solution of 1,1,1-tris(diphenylphosphinomethyl)propane and its phosphine oxide analogs

The crystal and molecular structure of the solid solution of 1,1,1-tris(diphenylphosphinomethyl)propane and its phosphine oxide analogs C42H41O0.64P3 (I) was determined by X-ray diffraction analysis; space group P (1) over bar, a = 10.945(3), b = 11.277(2), c = 15.985(6) Angstrom, alpha = 76.10(2), beta = 72.03(2), gamma = 71.71(2)degrees, Z = 2. Structure I was solved by direct methods and refined by the full-matrix least-squares procedure in art anisotropic approximation to R = 0.045 for all 5227 unique measured reflections (CAD-4 automatic diffractometer; lambda CuKalpha). Low-occupied phosphoryl O sites are found near each of the three P atoms in structure I. The total occupancy of the three O sites is 0.64(1), front which it follows that the contents of the -CH2PPh2 and -CH2P(O)Ph-2 fragments in I are 78.6 and 21.4%, respectively. In averaged (mixed) molecule I, all P = O bonds were obtained effectively shortened, and the average PC bonds P-C(sp(3)) and P-C(ar) equal 1.846 and 1.834 Angstrom, respectively.