Titanium amidate complexes as active catalysts for the synthesis of high molecular weight polyethylene

A series of titanium and zirconium bis(amidate) complexes of the type L₂MX₂, where L is an amidate ligand, and X is either -NMe₂ or -Cl, were prepared in 60%-83% yield and fully characterized. Multiple binding motifs are observed as the amidate ligand can bind in κ¹- and κ²-modes. These complexes were then subjected to screening the catalytic polymerization of ethylene. All catalysts, after reaction with suitable co-catalyst, were functional for ethylene polymerization, though not for the copolymerization of ethylene and longer linear 1-alkenes. Polyethylene was formed in the range of 1000-4000 kDa, and with PDI values as low as 1.3. These long polymeric chains are considered as ultra-high molecular weight polyethylene (UHMWPE). (author)