Cationic Group-IV pincer-type complexes for polymerization and hydroamination catalysis

摘要

Neutral Zr~(IV) and Hf~(IV) dimethyl complexes stabilized by unsymmetrical dianionic {N,C,N′} pincer ligands have been prepared from their corresponding bis-amido complexes upon treatment with AlMe3. Their structure consists of a central σ-bonded aryl donor group (C) capable of forming robust M-C bonds with the metal center, enforced by the synergic effect of both the coordination of peripheral donor groups (N) and the chelating rigid structure of the {N,C,N} ligand framework. Such a combination translates into systems having a unique balance between stability and reactivity. These Zr~(IV) and Hf~(IV) dimethyl complexes were converted in situ into cationic species [M~(IV){N~-,C ~-,N}Me][B(C_6F_5)_4] which are active catalysts for the room temperature (r.t.) intramolecular hydroamination/ cyclization of primary and secondary aminoalkenes as well as for the high temperature ethylene-1-octene copolymerizations.