| abstract |
patent summary: "catalysts". the present invention relates to a racemic complex of formula (i), where m is zirconium or hafnium; each x is a sigma ligand; l is a divalent bridge selected from -r'2c-, -r'2c-cr'2-, -r'2si-, -r'2si-sir'2-, -r'2ge-, where each r ' it is independently a hydrogen atom, c1-20-hydrocarbyl, tri (c1-20-alkyl) silyl, c6-20-aryl, c7-20-arylalkyl or c7-20-alkylaryl; r2 and r2 'are each independently a c1-20 hydrocarbyl radical optionally containing one or more heteroatoms of groups 14-16; r5 'is a c1-20 hydrocarbyl group optionally containing one or more heteroatoms of groups 14-16 and optionally substituted by one or more halo atoms. |