Pyridyl amines have been used to prepare Group 4 complexes which are useful transition metal components for use in the polymerization of alkenes, see for example US 2002/0142912, U.S. Pat. No. 6,900,321, and U.S. Pat. No. 6,103,657, where the ligands have been used in complexes in which the ligands are coordinated in a bidentate fashion to the transition metal atom.
WO 2005/095469 shows catalyst compounds that use tridentate ligands through two nitrogen atoms (one amido and one pyridyl) and one oxygen atom.
US 2004/0220050A1 and WO 2007/067965 disclose complexes in which the ligand is coordinated in a tridentate fashion through two nitrogen (one amido and one pyridyl) and one carbon (aryl anion) donors.
A key step in the activation of these complexes is the insertion of an alkene into the metal-aryl bond of the catalyst precursor (Froese, R. D. J. et al., J. Am. Chem. Soc. 2007, 129, 7831-7840) to form an active catalyst that has both five-membered and a seven-membered chelate rings.
There still is need for adding synthetic routes to widen the range of catalysts complexes that may be prepared and broaden their performance in alkene polymerization. The performance may be varied in respect of the amount of polymer produced per amount of catalyst (generally referred to as the “activity”) under the prevailing polymerization conditions; the molecular weight and molecular weight distribution achieved at a given temperature; and the placement of higher alpha-olefins in terms of the degree of stereoregular placement.