Crystalline structure of some poly(ferrocenylenedialkylsilylenes)

X-ray diffraction studies on poly(ferrocenylenedimethylsilylene), PFDMS, in dicate a 3D crystalline phase with monoclinic packing of the macromolecules with possible unit cell parameters a = 13.29 Angstrom, b = 6.01 Angstrom, c = 13.9 Angstrom, and gamma = 93.6 degrees. There are two main chains with four monomer units per unit cell, X-ray crystal density rho(c) = 1.455 g c m(-3), possessing a planar all-trans zigzag conformation of the main chain, helix 2/1. Poly(ferrocenylenedibutylsilylene), PFDBS, also appears to crys tallize in a monoclinic lattice with unit cell parameters a = 11.57 Angstro m, b = 6.71 Angstrom, c = 13.6 Angstrom and gamma = 107.1 degrees (two mono mer units of one macromolecule per unit cell; X- ray crystal density rho(c) = 1.239 K cm(-3)). A particular feature of crystalline PFDMS, and PFDBS, i s the coexistence of the 3D monoclinic crystalline phases with mesophases ( 2D crystals with a hexagonal or tetragonal packing of macromolecules). Upon doping with iodine vapor, the crystalline poly(ferrocenylenedimethylsilyle ne) converts into a crystalline mixed-valence complex. Doped oriented sampl es retain the initial orientation of the macromolecules and also give relat ively good fiber diffraction patterns. Equatorial reflections on such fiber patterns can be indexed by a 2D monoclinic packing of the complex macromol ecules in the (ab) plane with unit cell parameters a = 10.36 Angstrom, b = 6.03 Angstrom, and gamma = 90.7 degrees. The values of the a and b dimensio ns suggest that [I-3](-) species are placed between macromolecules and alon g their backbone. Three meridional reflections at 3.0, 4.0, and 6.0 Angstro m yield a fiber repeat equal to 12.0 Angstrom, which probably arises from a one-dimensional order of [I-3]arrays.