Angewandte Chemie International Edition
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Inside Cover: Synthesis, Electronic Structure, and Ethylene Polymerization Activity of Bis(imino)pyridine Cobalt Alkyl Cations (Angew. Chem. Int. Ed. 35/2011)
The controversy surrounding the nature of the active species in ethylene polymerization catalyzed by bis(imino)pyridine cobalt compounds has been resolved by P. J. Chirik et al. In their Communication on page 8143 ff., they report the synthesis and characterization of a family of alkyl cations, which serve as single-component catalysts for the polymerization of ethylene. These compounds were characterized definitively as CoII species that deactivate by ligand-induced metal–alkyl bond homolysis.