Weak attractive ligand-polymer and related interactions in catalysis and reactivity : Impact, applications, and modeling

The notion of weak attractive ligand-polymer interactions is introduced, and its potential application, importance, and conceptual links with "cooperative" ligand-substrate interactions are discussed. Synthetic models of weak attractive ligand-polymer interactions are described, in which intramolecular weak C-H⋯F-C interactions (the existence of which remains contentious) have been detected by NMR spectroscopy and neutron and X-ray diffraction experiments. These C-H⋯F-C interactions carry important implications for the design of catalysts for olefin polymerization, because they provide support for the practical feasibility of ortho-F⋯H _β ligand-polymer contacts proposed for living Group 4 fluorinated phenoxyimine catalysts. The notion of weak attractive noncovalent interactions between an "active" ligand and the growing polymer chain is a novel concept in polyolefin catalysis. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.