| 摘要 |
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 formulae (see formulae Ia, Ib, XIII and XIIIb) in which CpI and CpII represent carbanions having a cyclopentadienyl-containing structure, .pi.I and .pi.II represent charged or electrically neutral .pi. systems, D represents a donor atom and A represents an acceptor atom, where D and A are linked by a reversible coordinate bond such that the donor group 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 Period ic Table of the Elements (Mendeleev), including the lanthanides and the actinides, X denotes one anion equivalent and n denotes the number zero, one, two, three or four, depending on the charge of M.
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