Bis(imino)pyridyl iron and cobalt complexes: the effect of nitrogen substituents on ethylene oligomerisation and polymerisation

Abstract

The synthesis and characterisation of 2,6-bis(imino)pyridyl iron and cobalt complexes [(2,6-(RNCMe)2C5H3N)MCl2] containing nitrogen substituents of the type R = NPh2, NPhMe, NMe2 or 2,5-dimethylpyrrolyl are described. These complexes, in combination with the co-catalyst MAO, give active catalysts for the oligomerisation or polymerisation of ethylene. The catalytic activity is strongly affected by the substituents R and the polymerisation conditions used. The polymer properties are also a function of the R substituents. With R = NPhMe or NMe2, toluene soluble α-olefins are obtained, whereas the bulkier substituents (R = NPh2 or 2,5-dimethylpyrrolyl) give low molecular weight solid polyethylene.