Dehalogenation Polymerization of 1, 1’-Dihaloferrocene with Magnesium as a New Convenient Synthetic Route to Poly(1, 1’-ferrocenylene)

Abstract

1, 1’-Dibromoferrocene and 1, 1’-diiodoferrocene are readily converted into poly(1, 1’-ferrocenylene) in a 45—77% yield by dehalogenation polymerization with magnesium, n(XC5H4FeC5H4X) + nMg → (C5H4FeC5H4)n + nMgX2. The polymer obtained was fractionated into four parts by solubilities in organic solvents: Fraction I (soluble in hexane, 23—29 wt%), Fraction II (soluble in C6H6 at room temperature but nonsoluble in hexane, 6—11 wt%), Fraction III (soluble in C6H6 at 80°C but nonsoluble at room temperature, 6—12 wt%), and Fraction IV (insoluble in C6H6 at 80°C, 47—62 wt%). Infrared (IR) and nuclear magnetic resonance (NMR) spectra of Fractions I—IV indicate that they are constituted of regularly recurring 1, 1’-ferrocenylene units. The number-average molecular weights of Fractions I and II are about 900 and 1500 respectively as determined by vapor pressure osmometry (VPO), whereas that of Fraction IV was calculated as about 4600 from analytical data, assuming that both polymer ends have halogen. The polymers have high thermal stabilities and the thermal stabilities are enhanced by preparing the polymer in the presence of a nickel compound, NiCl2(2, 2’-bipyridine). The X-ray diffraction pattern of the powdery polymer shows fairly sharp peaks, indicating the presence of micro crystals. Doping of Fraction IV with acceptors such as iodine and 7, 7, 8, 8-tetracyano-p-quinodimethane (TCNQ) afforded semi-conducting materials having electric condutivities of 10-2—10-4S cm-1 at room temperature. © 1981 The Society of Polymer Science, Japan.