Rearrangements versus ligand exchange reactions of organocobalt polymer having cobaltacyclopentadiene moieties in the main chain Part of the work presented here was communicated in Ref. 1: Macromolecules , 27 , 7009 (1994).

Abstract

The rearrangement reaction of an organocobalt polymer with cobaltacyclopentadiene moieties in the main chain ( 1 ) was carried out to yield a­new polymer bearing (η 5 -cyclopentadienyl) (η 4 -­cyclobutadiene)cobalt moieties in the main chain ( 2 ). For instance, a polymer (2) containing pure η 4 -cyclobutadienecobalt units was obtained as a yellow powder in 79% yield by the reaction of 1 in tetrahydrofuran (THF) at 110 °C for 1 h in a sealed tube. The polymer ( 2 ) obtained was soluble in organic solvents such as chloroform, THF and N , N -dimethylformamide and was quite stable under air. It showed good thermal stability and a weight loss of 5% was observed at 482 °C by thermogravimetric analysis (TGA). On the other hand, displacement of the triphenylphosphine ligands on the main chain of the organocobalt polymer ( 1 ), without rearrangement of the cobaltacyclopentadiene rings, was observed when the reaction was carried out in the presence of appropriate ligands such as P(n-Bu) 3 . The resulting ligand-exchanged polymer showed different properties in comparison with 1 . For instance a polymer bearing tri-n-octylphosphine is soluble in n-hexane, which is a poor solvent for 1 . © 1998 John Wiley & Sons, Ltd.