Rearrangements versus ligand exchange reactions of organocobalt polymer having cobaltacyclopentadiene moieties in the main chain

• Published in: Applied organometallic chemistry Vol. 12; no. 10-11; pp. 735 - 742
• Main Authors: Tomita, Ikuyoshi, Nishio, Akinori, Endo, Takeshi
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.10.1998
• Subjects: organocobalt; polymer
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/(SICI)1099-0739(199810/11)12:10/11<735::AID-AOC780>3.0.CO;2-L

The rearrangement reaction of an organocobalt polymer with cobaltacyclopentadiene moieties in the main chain (1) was carried out to yield a­new polymer bearing (η5‐cyclopentadienyl) (η4‐­cyclobutadiene)cobalt moieties in the main chain (2). For instance, a polymer (2) containing pure η4‐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.