Cover Picture: ZAAC ‐ Journal of Inorganic and General Chemistry 12/2010

The cover picture shows the polymerization of ethylene and chain growing of polyethylene at aluminum catalyzed by rare earth complexes with the ligand N ‐(2,6‐diisopropylphenyl)‐6‐(2,4,6‐triisopropylphenyl)pyridin‐2‐amine (Ap*‐H). On November 18, 1953 Karl Ziegler et al. applied for a patent that would cause a revolution in the chemical industry and, within a short time, provide a strong impetus to basic research around the world. The title of the German patent was a „Process for Preparing High‐Molecular Polyethylenes“. They discovered that polyethylene could be obtained by simply passing ethylene, at atmospheric pressure, into a catalytic amount of TiCl 3 and Et 2 AlCl. The background shows the first page of the German patent DBP 973 626 ( Angew. Chem. Int. Ed. 2003 , 41 , 5000). In the Research Report by Rhett Kempe it is shown that the polymerization of ethylene especially in the low molecular weight range could be established in a highly controlled fashion by a chain growing process on aluminum, which is catalyzed by a lanthanide complex through Coordinative Chain Transfer Polymerization (CCTP). Chain growing takes place via ethylene insertion into the lanthanide carbon bond. The polymerization of ethylene was studied using organoyttrium cations as catalysts. High control in ethylene polymerization was observed for the Ap*Y catalyst system in combination with triisobutylalumoxane (TIBAO). More details are discussed in the Research Report by Rhett Kempe on pp. 2135 ff.