Crystalline Structure of Some Poly(ferrocenylenedialkylsilylenes)

Abstract

X-ray diffraction studies on poly(ferrocenylenedimethylsilylene), PFDMS, indicate a 3D crystalline phase with monoclinic packing of the macromolecules with possible unit cell parameters a = 13.29 A, b = 6.01 A, c = 13.9 A, and γ = 93.6°. There are two main chains with four monomer units per unit cell, X-ray crystal density ρc = 1.455 g cm-3, possessing a planar all-trans zigzag conformation of the main chain, helix 2/1. Poly(ferrocenylenedibutylsilylene), PFDBS, also appears to crystallize in a monoclinic lattice with unit cell parameters a = 11.57 A, b = 6.71 A, c = 13.6 A and γ = 107.1° (two monomer units of one macromolecule per unit cell; X- ray crystal density ρc = 1.239 g cm-3). A particular feature of crystalline PFDMS, and PFDBS, is 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(ferrocenylenedimethylsilylene) converts into a crystalline mixed-valence ...