Stereospecific olefin polymerization catalysts

A metallocene of the formula ##STR21## wherein:

• the metallocene has C.sub.S - or C.sub.1 -symmetry;
• M is an element selected from the group consisting of group III, group IV, group V, and lanthanide group elements;
• n is the valence of M minus 2;
• X is selected from the group consisting of trimethylsilymethyl and bis(trimethylsilyl)methyl;
• R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl wherein each pair of adjacent radicals, R.sup.1 and R.sup.2 or R.sup.2 and R.sup.3, together may also form a substituted or unsubstituted cyclic group having 4 to 15 carbon atoms, and Si(R.sub.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl and C.sub.3 to C.sub.10 cycloalkyl;
• R.sup.4 and R.sup.6 are substituents both having van der Waals radii that are larger than the van der Waals radii of groups R.sup.1 and R.sub.3 ;
• R.sup.5 is a substituent having a van der Waals radius that is less than the van der Waals radius of a methyl group;
• and
• E.sup.1 and E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, and C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl, and C.sub.3 to C.sub.10 cycloalkyl.

A catalyst comprising a metal and a ligand of the formula ##STR22## wherein:

• R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl wherein each pair of adjacent radicals, R.sup.1 and R.sup.2 or R.sup.2 and R.sup.3, together may also form a substituted or unsubstituted cyclic group having 4 to 15 carbon atoms, and Si(R.sup.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl;
• R.sup.4 and R.sup.6 are substituents both having van der Waals radii larger than the van der Waals radii of groups R.sup.1 and R.sup.3 ;
• R.sup.5 is a substituent having a van der Waals radius that is less than the van der Waals radius of a methyl group;
• E.sup.1 and E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, and C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl, and C.sub.3 to C.sub.10 cycloalkyl.

A method for polymerizing olefins comprising the step of contacting an olefin with a catalyst comprising a metal and a ligand of the formula ##STR23## wherein:

• R.sup.1, R.sup.2, and R.sup.3 are independently selected from the group consisting of hydrogen, C.sub.1 to C.sub.10 alkyl, 5 to 7 membered cycloalkyl, which in turn may have from 1 to 3 C.sub.1 to C.sub.10 alkyls as a substituent, C.sub.6 to C.sub.15 aryl or arylalkyl wherein each pair of adjacent radicals, R.sup.1 and R.sup.2 or R.sup.2 and R.sup.3, together may also form a substituted or unsubstituted cyclic group having 4 to 15 carbon atoms, and Si(R.sup.8).sub.3 where R.sup.8 is selected from the group consisting of C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl;
• R.sup.4 and R.sup.6 are substituents both having van der Waals radii larger than the van der Waals radii of groups R.sup.1 and R.sup.3 ;
• R.sup.5 is a substituent having a van der Waals radius less than the van der Waals radius of a methyl group;
• E.sup.1 and E.sup.2 are independently selected from the group consisting of Si(R.sup.9).sub.2, Si(R.sup.9).sub.2 --Si(R.sup.9).sub.2, Ge(R.sup.9).sub.2, Sn(R.sup.9).sub.2, C(R.sup.9).sub.2, and C(R.sup.9).sub.2 --C(R.sup.9).sub.2, where R.sup.9 is C.sub.1 to C.sub.10 alkyl, C.sub.6 to C.sub.15 aryl or C.sub.3 to C.sub.10 cycloalkyl.