Organozirconium compounds with inorganic donor ligands N,N'-bis(trimethylsilyl)benzamidinate (Siam) in compounds of the type (Siam)(2)ZrX(2) (X=methyl, benzyl, allyl, chloride or iodide) and (Siam)(3)ZrX (X=chloride)

Organometallic compounds of the type (Siam)(2)ZrX(2) (Siam = N,N'-bis(trimethylsilyl)benzamidinat; X = methyl, benzyl or allyl) have been synthesized by reaction of (Siam)(2)ZrCl2 and Grignard reagents. The structures of (Siam)(2)ZrX(2) (X = Cl, I, CH3 or CH2-C6H5) and (Siam)(3)ZrCl have been investigated by X-ray crystal structure analysis. (Siam)(3)ZrCl shows a capped octahedral structure with the coordination number 7 at the zirconium. (Siam)(2)ZrX(2) compounds have distorted octahedral structures and the ligands occupy cis-positions. The distortion depends on the bulkiness of the ligand X. The systems (Siam)(2)ZrCl2-methylalumoxan (MAO) and (Siam)(3)ZrCl-MAO polymerize at 30 degrees C reactive olefins such as ethylene or norbornene. Less reactive olefins (e.g. propene) can be reacted with (Siam)ZrCl3-MAO to yield oligomers and polymers. The same catalytic system is able to convert 1,5-hexadiene selectively under formation of methylene-cyclopentane.