Kaminsky catalyst

[1] Kaminsky catalysts are based on metallocenes of group 4 transition metals (Ti, Zr, Hf) activated with methylaluminoxane (MAO).

These and other innovations have inspired development of new classes of catalysts that in turn led to commercialization of novel engineering polyolefins.

[3][4] Prior to Kaminsky's work, titanium chlorides supported on various materials were widely used (and still are) as heterogeneous catalysts for alkene polymerization.

The MAO serves two roles: (i) alkylation of the metallocene halide and (ii) abstraction of an anionic ligand (chloride or methyl) to give an electrophilic catalyst with a labile coordination site.

[1][5] Kaminsky's discovery of well-defined, high activity homogeneous catalysts led to many innovations in the design of novel cyclopentadienyl ligands.

A constrained geometry organotitanium complex in the (inactive) chloride form
Using metallocene 1 for polymerization of propene gives atactic polypropylene , while C 2 symmetric metallocene 2 and C s symmetric metallocene 3 catalytic systems produce isotactic polymer and syndiotactic polymer, respectively.