Bis[(amidomethyl)pyridine] Zirconium(IV) Complexes: Synthesis, Characterization, and Activity as Olefin Polymerization Catalysts

This is the authors' abstract. We don't add key points for this paper.

This contribution describes the synthesis, characterization, and olefin polymerization reactivity of bis(chelate)zirconium complexes bearing (amidomethyl)pyridine ligands [(6-X-C 5 H 3 N)CH 2 NC 6 F 5, X = CH 3 (Lig 1 H), Br (Lig 2 H), H (Lig 3 H)]. Metathesis reaction, alkane elimination, and amine elimination provided routes to compounds (Lig 1 ) 2 ZrCl 2 ( 1 ), (Lig 1 ) 2 ZrBz 2 ( 4; Bz = CH 2 C 6 H 5 ), and (Lig 2 ) 2 Zr(NMe 2 ) 2 ( 5 ). Attempts to prepare (Lig 1 ) 2 Zr(NMe 2 ) 2 in a reaction between Zr(NMe 2 ) 4 and Lig 1 H led instead to compound (Lig 1 )(Lig 1 *)ZrF(NMe 2 ) ( 2 ), in which one dimethylamino group had been exchanged with one ortho fluoride on the perfluorophenyl ring of the ligand via an aromatic nucleophilic substitution reaction. Halide displacement reaction performed on compound 2 afforded the dichloride compound (Lig 1 )(Lig 1 *)ZrCl 2 ( 3 ). Reaction between Zr(NMe 2 ) 4 and Lig 3 H provided a mixture of (Lig 3 ) 2 Zr(NMe 2 ) 2 and (Lig 3 )(Lig 3 *)ZrF(NMe 2 ), the latter being analogous to 2 . X-ray crystallographic analysis showed for compound 1 a distorted octahedral geometry with C 1 symmetry and for compound 2 a 7-coordinate species. Variable-temperature NMR studies established for compound 1 an inversion of metal configuration through dynamic interchange of the all-cis enantiomers. Fluxional behaviors in solution were also observed for compounds 2, 3, and 4 . Treatment of complexes with Al i Bu 2 H and methylalumoxane (MAO) yields active, multisite ethylene and propylene polymerization catalysts.