Task: Text Categorization
Input (English): Britzinger showed that chiral ansa-indenyl ligands can help direct the action of these compounds, and these compounds use MgCl2 or SiO2 as a support. Using vanadium instead of the usual central atom reverses the stereochemistry of the product, and metallocenes are sometimes used to improve control of the product distribution. The less-accepted Green-Mooney mechanism for their operation has a hydride shift, while a competing theory has a substrate occupy a vacant site in the coordination sphere of the central metal atom, followed by a migration. This results in repeated 1,2-insertions and is known as the Cosee-Arleman mechanism, which produces either iso or syndiotactic products. Usually terminating via beta-hydride elimination, for 10 points, name these aluminum and titanium chloride compounds used to create polyethylenes, a type of catalyst named for two chemists.
Output (English): Science