Catalysts

1. A process for the preparation of a propylene polymer, the process comprising:

polymerizing propylene optionally with ethylene and/or a C4-10 alpha olefin in the presence of a catalyst;

wherein the catalyst comprises:

(i) a complex;

(ii) a cocatalyst of an aluminum compound; and

(iii) a cocatalyst of a boron compound;

wherein the complex is of formula (I):

wherein:

M is Hf

each X is a sigma ligand;

L is an alkylene group or a bridge of formula -(ER 8 2 ) y —;

y is 1 or 2;

E is C or Si; and

each R 8 is independently a C 1 -C 20 -hydrocarbyl, tri(C 1 -C 20 -alkyl)silyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl, or C 7 -C 20 -alkylaryl;

Ar and Ar′ are each independently an aryl or heteroaryl group optionally substituted by 1 to 3 R 1 or R 1′ groups respectively;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl group, C 7-20 alkylaryl group, or C 6-20 aryl group,

with the proviso that when there are four or more R 1 and R 1′ groups present in total, then one or more of R 1 and/or R 1′ is other than tert butyl;

R 2 and R 2′ are each independently a CH 2 —R 9 group, with R 9 being H, linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, or C 6-10 aryl group;

each R 3 is a —CH 2 —, —CHRx-, or C(Rx) 2 - group wherein Rx is C1-4 alkyl;

m is 2-6;

R 5 is a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group, or C 6 -C 20 -aryl group;

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 6 alkyl group; and

R 7 and R 7′ are each independently H or a linear or branched C 1 -C 6 -alkyl group.

2. The process of claim 1 , wherein the complex is of formula (Ia):

wherein:

M is Hf;

each X is a sigma ligand;

L is an alkylene group or a bridge of formula -(ER 8 2 ) y —;

y is 1 or 2;

E is C or Si; and

each R 8 is independently a C 1 -C 20 -hydrocarbyl, tri(C 1 -C 20 -alkyl)silyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl, or C 7 -C 20 -alkylaryl;

each n is independently 0, 1, 2 or 3;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl group, C 7-20 alkylaryl group, or C 6-20 aryl group,

with the proviso that when there are four or more R 1 and R 1′ groups present in total, then one or more of R 1 and/or R 1′ is other than tert butyl;

R 2 and R 2′ are each independently a CH 2 —R 9 group, with R 9 being H, linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, or C 6-10 aryl group;

each R 3 is a —CH 2 —, —CHRx-, or C(Rx) 2 - wherein Rx is C 1-4 alkyl;

m is 2-6;

R 5 is a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group, or C 6 -C 20 -aryl group;

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 6 alkyl group; and

R 7 and R 7′ are each independently H or a linear or branched C 1 -C 6 -alkyl group.

3. The process of claim 2 , wherein L is of formula —SiR 8 2 —, wherein each R 8 is independently a C 1 -C 20 -hydrocarbyl, tri(C 1 -C 20 -alkyl)silyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl, or C 7 -C 20 -alkylaryl.

4. The process of claim 1 , wherein the complex is of formula (Ib):

wherein

M is Hf;

each X is a sigma ligand;

L is an alkylene bridge or a bridge of the formula —SiR 8 2 —, wherein each R 8 is independently a C 1 -C 20 -hydrocarbyl, tri(C 1 -C 20 -alkyl)silyl, C 6 -C 20 -aryl, C 7 -C 20 -arylalkyl, or C 7 -C 20 -alkylaryl;

each n is independently 0, 1, 2 or 3;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl, C 7-20 alkylaryl group, or C 6-20 aryl group,

with the proviso that when there are four or more R 1 and R 1′ groups present in total, then one or more of R 1 and R 1′ is other than tert butyl;

R 2 and R 2′ are each independently a CH 2 —R 9 group, with R 9 being H, linear or branched C 1-6 -alkyl group, C 3-8 cycloalkyl group, or C 6-10 aryl group;

R 5 is a linear or branched C 1 -C 6 -alkyl group, C 7-20 arylalkyl group, C 7-20 alkylaryl group, or C 6 -C 20 -aryl group;

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 6 alkyl group; and

R 7 and R 7′ are each independently H or a linear or branched C 1 -C 6 -alkyl group.

5. The process of claim 4 , wherein each n is 1 or 2.

6. The process of claim 1 , wherein the complex is of formula (II):

wherein

M is Hf;

X is a sigma ligand;

L is an alkylene bridge or a bridge of the formula wherein each R 8 is independently C 1 -C 6 -alkyl, C 3-8 cycloalkyl, or C 6 -aryl group;

each n is independently 1 or 2;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl;

R 2 and R 2′ are each independently a CH 2 —R 9 group, with R 9 being H or linear or branched C 1-6 -alkyl group;

R 5 is a linear or branched C 1 -C 6 -alkyl group; and

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 6 alkyl group.

7. The process of claim 1 , wherein the complex is of formula (III):

wherein

M is Hf;

each X is a sigma ligand;

L is —SiR 8 2 —, wherein each R 8 is C 1-6 alkyl or C 3-8 cycloalkyl;

each n is independently 1 or 2;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl;

R 5 is a linear or branched C 1 -C 6 -alkyl group; and

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 6 alkyl group.

8. The process of claim 1 , wherein the complex is of formula (IV):

wherein

M is Hf;

each X is a hydrogen atom, a halogen atom, C 1-6 alkoxy group, C 1-6 alkyl, phenyl, or benzyl group;

L is —SiR 8 2 —, wherein each R 8 is C 1-4 alkyl or C 5-6 cycloalkyl;

each n is independently 1 or 2;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl;

R 5 is a linear or branched C 1 -C 6 -alkyl group; and

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 6 alkyl group.

9. The process of claim 1 , wherein the complex is of formula (V):

wherein

M is Hf;

X is a hydrogen atom, a halogen atom, C 1-6 alkoxy group, C 1-6 alkyl, phenyl, or benzyl group;

L is —SiMe 2 ;

each n is independently 1 or 2;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl,

R 5 is a linear or branched C 1 -C 4 -alkyl group; and

R 6 is a C(R 10 ) 3 group, with R 10 being a linear or branched C 1 -C 4 alkyl group.

10. The process of claim 1 , wherein the complex is of formula (VI):

wherein

M is Hf;

X is a hydrogen atom, a halogen atom, C 1-6 alkoxy group, C 1-6 alkyl, phenyl, or benzyl group;

L is —SiMe 2 ;

each n is independently 1 or 2;

R 1 and R 1′ are each independently a linear or branched C 1 -C 6 -alkyl group, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl;

R 5 is a linear C 1 -C 4 -alkyl group; and

R 6 is tert butyl.

11. The process of claim 1 , wherein the complex is of formula (VII):

wherein

M is Hf;

X is a hydrogen atom, a halogen atom, C 1-6 alkoxy group, C 1-6 alkyl, phenyl, or benzyl group;

L is —SiMe 2 ;

each n is independently 1 or 2;

R 1 and R 1′ are each independently a linear or branched C 1 -C 4 -alkyl group, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl;

R 5 is methyl; and

R 6 is tert butyl.

12. The process of claim 1 , wherein the complex is of formula (VIII):

wherein

M is Hf;

X is Cl;

L is —SiMe 2 ;

each n is independently 1 or 2;

R 1 and R 1′ are each independently methyl or tert butyl, with the proviso that when there are four R 1 and R 1′ groups present, then one or more of R 1 and/or R 1′ is not tert butyl,

R 5 is methyl; and

R 6 is tert butyl.

13. The process of claim 1 , wherein at least one of the C(4) or C(4′) phenyl rings is 3,5-dimethyl phenyl.

14. The process of claim 1 , wherein at least one of the C(4) or C(4′) phenyl rings is 4-(tert-butyl)-phenyl.

15. The process of claim 1 , wherein R 1 , R 1′ , and each value of n are selected such that the C(4) or C(4′) phenyl rings are 3,5-dimethyl phenyl, 3,5-ditertbutylphenyl, and/or 4-(tert-butyl)-phenyl.

16. The process of claim 1 , wherein the catalyst is in solid form.

17. The process of claim 1 , wherein the catalyst is supported on an external carrier or is in solid particulate form free from an external carrier.

18. A process for the manufacture of the catalyst of claim 1 , said process comprising:

contacting complex (i), cocatalyst (ii), and cocatalyst (iii) to provide a catalyst solution;

forming a liquid/liquid emulsion system by dispersing the catalyst solution in a solvent in the form of dispersed droplets; and

solidifying said dispersed droplets to form solid particles of said catalyst.

19. The process of claim 1 , wherein the cocatalyst (ii) of an aluminum compound is an aluminoxane; wherein the cocatalyst (iii) of a boron compound is a borate; or a combination thereof.

20. The process of claim 1 , wherein each X is independently a hydrogen atom, halogen atom, C 1-6 alkoxy group, C 1-6 alkyl, phenyl, or benzyl group.