An amine bis( phenolate) dibenzyl titanium complex having a methoxy donor on a side arm leads, upon activation with tris( pentafluorophenyl) borane, to unique living properties in alpha -olefin polymerization: exceptionally high molecular weight poly(1-hexene) is obtained in a living fashion at room temperature, living polymerization of 1-hexene is obtained above room temperature, and block copolymerization of 1-hexene and 1-octene at room temperature is described as well.