| abstract |
High-melting polyolefins can be prepared in bulk, in solution, in suspension or in the gas phase, the catalysts employed being metallocene compounds or pi complex compounds of the formulain whichCpI and CpII represent carbanions having a cyclopentadienyl-containing structure,piI and piII represent charged or electrically neutral pi systems,D represents a donor atom andA represents an acceptor atom,where D and A are linked by a reversible coordinate bond such that the donor groups assumes a positive (part) charge and the acceptor group assumes a negative (part) charge,M represents a transition metal of sub-group III, IV, V or VI of the Periodic Table of the Elements (Mendeleev), including the lanthanides and the actinides,X denotes one anion equivalent andn denotes the number zero, one, two, three or four, depending on the charge of M. |