THE CRYSTAL-STRUCTURE AND SOLID-STATE POL YMERIZATION OF HEXAPHENYLCYCLOTRISILOXANE

The structure of triclinic and orthorhombic crystals of hexaphenylcycl otrisiloxane was studied by X-ray diffraction. The unit cell parameter s are as follows: triclinic, a = 12.890 Angstrom, b = 15.060 Angstrom, c = 16.549 Angstrom, alpha = 83.98 degrees, beta = 83.98 degrees, gam ma = 77.91 degrees; orthorhombic, a = 10.123 Angstrom, b = 15.802 Angs trom, c = 20.245 Angstrom. A comparison of the two crystal structures with that of poly(diphenylsiloxane) showed that a topotaxic polymeriza tion may, in principle, occur in the most closely packed rows of molec ules in the [1 (2) over bar 1] direction of a triclinic hexaphenylcycl otrisiloxane crystal.