| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | March 22, 2005 |
| PATENT TITLE |
Polymerization process and polymer composition |
| PATENT ABSTRACT | Olefin polymerization processes using catalyst systems based on metallocenes and olefin, in particular, propylene polymers obtainable thereby. The metallocenes may be represented by the formula: ##STR1## wherein M.sup.1 preferably is zirconium or hafnium; and R.sup.12 is different from hydrogen |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | June 29, 2001 |
| PATENT REFERENCES CITED |
U.S. Appl. No. 09/620,046, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B039A). U.S. Appl. No. 09/620,359, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B039B). U.S. Appl. No. 09/620,341, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B039C). U.S. Appl. No. 09/619,751, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B039D). U.S. Appl. No. 09/619,757, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B039E). U.S. Appl. No. 09/620,613, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B039F). U.S. Appl. No. 09/620,175, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040A). U.S. Appl. No. 09/619,759, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040B). U.S. Appl. No. 09/619,748, filed Jul. 19, 2001 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040C). U.S. Appl. No. 09/620,304, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040D). U.S. Appl. No. 09/620,522, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040E). U.S. Appl. No. 09/619,752, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040F). U.S. Appl. No. 09/619,750, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040G). U.S. Appl. No. 09/619,749, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040H). U.S. Appl. No. 09/620,303, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040I). U.S. Appl. No. 09/619,764, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040J). U.S. Appl. No. 09/620,302, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040K). U.S. Appl. No. 09/620,198, filed Jul. 19, 2000 (Inventors Mathew C. Kuchta, Udo M. Stehling, Robert T. Li, William T. Haygood, Jr. James R. Hart, James Charles Vizzini & Terry J. Burkhardt), entitled "Metallocene Compositions". (2000B040L). D.P. Krut'ko et al., "Synthesis and photoinduced isomerization of ansa-{.eta..sup.5, .eta..sup. 5,-[1,1'-(1-silacyclopent-3-ene3-1m,1-diyl)bis(indenyl)]}-dichlorozirconiu m. The crystal structure of its meso form"--Russian Chemical Bulletin vol. 47 (11), Nov., 1998--pp. 2280-2285. Woei-Min Tsai et al., "Silolene-Bridged Zirconocenium Polymerization Catalysts" Journal of Polymer Science, Part A: Polymer Chemistry, vol. 32, pp. 149-158 (1994). U.S. Appl. No. Not Yet Assigned, filed Jun. 29, 2001 (Inventors Terry J. Burkhardt, James R. Hart, William T. Haygood, Jr., and Robert T. Li), entitled "Metallocene and Catalyst Compositions". (2001B070). |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A polymerization process comprising contacting, under polymerization conditions, one or more ethylenically unsaturated monomers and a catalyst composition, said catalyst composition comprising the product of a compound represented by formula (I) and a cocatalyst: ##STR11## wherein: M.sup.1 is selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; R.sup.1 and R.sup.2 are selected from chlorine, C.sub.1 -C.sub.6 alkyl groups, C.sub.6 -C.sub.10 aryl groups, C.sub.7 -C.sub.12 arylalkyl groups and C.sub.7 -C.sub.12 alkylaryl groups; R.sup.3 is selected from C.sub.3 -C.sub.6 alkyl groups and phenyl; R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are each independently selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; or two or more adjacent radicals R.sup.5, R.sup.6 and R.sup.7 together with the atoms connecting them may form one or more rings; R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are each independently as defined for R.sup.4, R.sup.5, R.sup.6 and R.sup.7 ; R.sup.12 is selected from halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; R.sup.13 is selected from ##STR12## --B(R.sup.14)--, --Al(R.sup.14)--, --Ge--, --Sn--, --O--, --S--, --SO--, --SO.sub.2 --, --N(R .sup.14)--, --CO--, --P(R.sup.14)-- and --P(O)(R.sup.14); wherein R.sup.14, R.sup.15 and R.sup.16 are each independently selected from hydrogen, halogen, C.sub.1 -C.sub.20 alkyl groups, C.sub.6 -C.sub.30 aryl groups, C.sub.1 -C.sub.20 alkoxy groups, C.sub.2 -C.sub.20 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.8 -C.sub.40 arylalkenyl groups and C.sub.7 -C.sub.40 alkylaryl groups, or R.sup.14 and R.sup.15, together with the atom(s) connecting them, form a ring; and M.sup.3 is selected from carbon, silicon, germanium and tin; or R.sup.13 is represented by the formula ##STR13## wherein: R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are each independently selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.8 -C.sub.40 arylalkenyl groups; or two or more adjacent radicals R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24, including R.sup.20 and R.sup.21, together with the atoms connecting them, form one or more rings; and M.sup.2 represents one or more carbon atoms, or a silicon, germanium or tin atom. 2. The process of claim 1, wherein R.sup.3 is selected from branched C.sub.3 -C.sub.6 alkyl groups. 3. The process of claim 1, wherein R.sup.3 is an isopropyl group. 4. The process of claim 1, wherein R.sup.12 is selected from C.sub.1 -C.sub.6 alkyl groups and C.sub.6 -C.sub.10 aryl groups. 5. The process of claim 3, wherein R.sup.12 is phenyl. 6. The process of claim 4, wherein each of R.sup.4 and R.sup.8 is hydrogen. 7. The process of claim 1, wherein R.sup.3 is selected from isopropyl, isobutyl, sec-butyl, tert-butyl and phenyl groups, and R.sup.12 is selected from n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, phenyl, tolyl, benzyl and naphthyl groups. 8. The process of claim 1, wherein the compound of formula (I) comprises not more than 2% of the meso form. 9. The process of claim 1, wherein the cocatalyst is selected from compounds comprising noncoordinating anion, alumoxanes and mixtures thereof. 10. The process of claim 1, wherein the cocatalyst comprises methylalumoxane. 11. The process of claim 1, wherein the cocatalyst comprises a noncoordinating anion. 12. The process of claim 11, wherein the noncoordinating anion comprises at least one unit of the formula --B(C.sub.6 F.sub.5).sub.3. 13. The process of claim 1, wherein the catalyst composition further comprises a support material. 14. The process of claim 1, wherein the catalyst composition further comprises an inorganic support material. 15. The process of claim 13, wherein the support material is selected from silica, alumina, silica-alumina, magnesium chloride and mixtures thereof. 16. The process of claim 1, wherein said one or more ethylenically unsaturated monomers are selected from monoolefins, diolefins and mixtures thereof. 17. The process of claim 16, wherein said monoolefins comprise compounds of the formula R.sup.a CH.dbd.CHR.sup.b wherein R.sup.a and R.sup.b are each independently selected from hydrogen, alkyl and alkenyl radicals having 1 to 14 carbon atoms or, together with the carbon atoms to which they are connected, form a ring having 4 to 8 carbon atoms. 18. The process of claim 16, wherein said monoolefins are selected from ethylene and .alpha.-olefins having from 3 to 12 carbon atoms. 19. The process of claim 18, wherein said .alpha.-olefins are selected from propylene, 1-butene, 4-methyl-1pentene, 1-hexene, 1-octene and mixtures thereof. 20. The process of claim 1, wherein said ethylenically unsaturated monomers consist essentially of ethylene and propylene. 21. The process of claim 1, wherein said process is carried out at a temperature ranging from 30.degree. C. to 80.degree. C. 22. The process of claim 21, wherein said process is carried out at a pressure ranging from 5 to 64 bar. 23. The process of claim 1, wherein R.sup.1 and R.sup.2 are selected from chlorine, C.sub.1 -C.sub.6 alkyl groups, C.sub.6 -C.sub.10 aryl group, C.sub.7 -C.sub.12 arylalkyl groups and C.sub.7 -C.sub.12 alkylaryl groups, R.sup.3 is selected from C.sub.3 -C.sub.6 alkyl groups and phenyl, each of R.sup.4 and R.sup.8 is hydrogen, R.sup.12 is selected from n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, phenyl, tolyl, benzyl and naphthyl groups, the cocatalyst comprises noncoordinating anions, alumoxanes or mixtures thereof, wherein the catalyst composition further comprises a support material selected from silica, alumina, silica-alumina, magnesium chloride and mixtures thereof, and wherein said one or more ethylenically unsaturated monomers comprise at least ethylene and propylene. 24. A polymerization process comprising contacting, under polymerization conditions, one or more ethylenically unsaturated monomers and a catalyst composition, said catalyst composition comprising the product of a compound represented by formula (I) and a cocatalyst: ##STR14## wherein: M.sup.1 is selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; R.sup.1 and R.sup.2 are selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.7 -C.sub.40 arylalkenyl groups; or R.sup.1 and R.sup.2 are joined together to form an alkanediyl group or a conjugated C.sub.4 -C.sub.40 diene ligand which is coordinated to M.sup.1 in a metallacyclopentene fashion; or R.sup.1 and R.sup.2 represent a conjugated diene, optionally substituted with one or more groups independently selected from hydrocarbyl, trihydrocarbylsilyl and trihydrocarbylsilylhydrocarbyl groups, said diene having a total of up to 40 atoms not counting hydrogen and forming a .pi. complex with M.sup.1 ; R.sup.3 is selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OsiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are each independently selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; or two or more adjacent radicals R.sup.5, R.sup.6 and R.sup.7 together with the atoms connecting them may form one or more rings; R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are each independently as defined for R.sup.4, R.sup.5, R.sup.6 and R.sup.7, provided that two or more adjacent radicals R.sup.8, R.sup.9, R.sup.10 and R.sup.11 together with the atoms connecting them may form one or more rings; R.sup.12 is selected from halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; R.sup.13 is selected from groups of the formula ##STR15## wherein R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are each independently selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.8 -C.sub.40 arylalkenyl groups; or two or more adjacent radicals R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24, including R.sup.20 and R.sup.21, together with the atoms connecting them, form one or more rings; and M.sup.2 represents a carbon, silicon or germanium atom. 25. The process of claim 24, wherein R.sup.3 is selected from C.sub.3 -C.sub.6 alkyl groups and phenyl. 26. The process of claim 25, wherein R.sup.3 is an isopropyl group. 27. The process of claim 25, wherein R.sup.12 is selected from C.sub.1 -C.sub.6 alkyl groups and C.sub.6 -C.sub.10 aryl groups. 28. The process of claim 26, wherein R.sup.12 is phenyl. 29. The process of claim 27, wherein each of R.sup.4 and R.sup.8 is hydrogen. 30. The process of claim 24, wherein the cocatalyst comprises noncoordinating anions, alumoxanes or mixtures thereof. 31. The process of claim 30, wherein the noncoordinating anion comprises at least one unit of the formula --B(C.sub.6 F.sub.5).sub.3. 32. The process of claim 24, wherein the catalyst composition further comprises a support material. 33. The process of claim 24, wherein said one or more ethylenically unsaturated monomers are selected from monoolefins, diolefins and mixtures thereof. 34. The process of claim 33, wherein said monoolefins comprise compounds of the formula R.sup.a CH.dbd.CHR.sup.b wherein R.sup.a and R.sup.b are each independently selected from hydrogen, alkyl and alkenyl radicals having 1 to 14 carbon atoms or, together with the carbon atoms to which they are connected, form a ring having 4 to 8 carbon atoms. 35. The process of claim 33, wherein said monoolefins are selected from ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and mixtures thereof. 36. The process of claim 30, wherein said ethylenically unsaturated monomers consist essentially of ethylene and propylene. |
| PATENT DESCRIPTION |
FIELD This invention relates to metallocene compounds and their use in the preparation of catalyst compositions for olefin polymerization, particularly propylene homo- and copolymerization. The present invention also relates to polymerisation processes using such catalyst compositions and polymer compositions obtainable by these processes. BACKGROUND The use of metallocene compositions in olefin polymerization is well known. Metallocenes containing substituted, bridged indenyl derivatives are noted for their ability to produce isotactic propylene polymers having high isotacticity and narrow molecular weight distribution. Considerable effort has been made toward obtaining metallocene produced propylene polymers having ever-higher molecular weight and melting point and, thus, ever better strength (impact) properties, while maintaining suitable catalyst activity. Toward this end researchers have found that there is a direct relationship between the way in which a metallocene is substituted and the molecular structure of the resulting polymer. For the substituted, bridged indenyl type metallocenes, it is now well established that the type and arrangement of substituents on the indenyl groups, as well as the type of bridge connecting the indenyl groups, determines such polymer attributes as molecular weight and melting point. For example, U.S. Pat. Nos. 5,840,644 and 5,770,753, incorporated herein by reference in their entireties, describe certain metallocenes containing aryl-substituted indenyl derivatives as ligands, which are said to provide propylene polymers having high isotacticity, narrow molecular weight distribution and very high molecular weight. Likewise, U.S. Pat. No. 5,936,053, incorporated herein by reference in its entirety, describes certain metallocene compounds said to be useful for producing high molecular weight propylene polymers. These metallocenes have a specific hydrocarbon substituent at the 2 position and an unsubstituted aryl substituent at the 4 position on each indenyl group of the metallocene compound. WO 98/40419 and WO 99/42497 both describe certain supported catalyst systems for producing propylene polymers having high melting point. Metallocene compositions and their activators are often combined with a support material in order to obtain a catalyst system that is less likely to cause reactor fouling. However, it is known that supported metallocene catalyst systems tend to result in a polymer having lower melting point than would otherwise be obtained if the metallocene were not supported. Much of the current research in this area has been directed toward using metallocene catalyst systems under commercially relevant process conditions, to obtain propylene polymers having melting points higher than known metallocene catalyst systems and close to, or as high as, propylene polymers obtained using conventional, Ziegler-Natta catalyst systems. The present inventors have discovered metallocene compounds that not only have this capability, but retain it upon supportation. Additionally, it would be desirable to have available metallocenes which not only afford propylene homopolymers having high melting points of (i.e., high stereotacticity), but also elastomeric copolymers having the high molecular weights required for the production of, e.g., impact copolymers, thereby making possible the production of satisfactory in situ blends of, e.g., propylene homopolymer and ethylene-propylene rubbers (EPR's) with a single catalyst composition in a single reactor or in a series of two or more reactors. The present inventors have found metallocene compounds which in combination with a cocatalyst (activator) make both propylene homopolymers having high melting points and elastomeric copolymers that are suitable for the production of impact copolymers in combination with these propylene homopolymers. SUMMARY OF THE INVENTION The present invention relates to novel metallocene compounds capable of providing propylene homo- and copolymers having high melting point and high molecular weight. The present invention further relates to metallocene catalyst compositions comprising one or more of these compounds and one or more activators or cocatalysts, and optionally, support material, and to the use of such catalyst compositions in polymerization, in particular propylene polymerization. In one aspect, the present invention provides metallocene compounds represented by formula (I): ##STR2## wherein: M.sup.1 is selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; R.sup.1 and R.sup.2 are selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.7 -C.sub.40 arylalkenyl groups; or R.sup.1 and R.sup.2 are joined together to form a C.sub.4 -C.sub.40 alkanediyl group or a conjugated diene ligand which is coordinated to M.sup.1 in a metallacyclopentene fashion; or R.sup.1 and R.sup.2 represent a conjugated diene, optionally substituted with one or more groups independently selected from hydrocarbyl, trihydrocarbylsilyl and trihydrocarbylsilylhydrocarbyl groups, said diene having a total of up to 40 atoms not counting hydrogen and forming a .pi. complex with M.sup.1 ; R.sup.3 is selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; provided that if R.sup.1 and R.sup.2 both are halogen and R.sup.13 is dimethylsilanediyl, R.sup.3 is different from methyl and ethyl; R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are each independently selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; or two or more adjacent radicals R.sup.5, R.sup.6 and R.sup.7 together with the atoms connecting them may form one or more rings; R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are each independently as defined for R.sup.4, R.sup.5, R.sup.6 and R.sup.7, provided that two or more adjacent radicals R.sup.8, R.sup.9, R.sup.10 and R.sup.11 together with the atoms connecting them may form one or more rings; R.sup.12 is selected from halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; R.sup.13 is selected from ##STR3## --B(R.sup.14)--, --Al(R.sup.14)--, --Ge--, --Sn--, --O--, --S--, --SO--, --SO.sub.2 --, --N(R.sup.14)--, --CO--, --P(R.sup.14)-- --P(O)(R.sup.14)--, --B(NR.sup.14 R.sup.15)-- and --B[N(SiR.sup.14 R.sup.15 R.sup.16).sub.2 ]--; wherein: R.sup.14, R.sup.15 and R.sup.16 are each independently selected from hydrogen, halogen, C.sub.1 -C.sub.20 alkyl groups, C.sub.6 -C.sub.30 aryl groups, C.sub.1 -C.sub.20 alkoxy groups, C.sub.2 -C.sub.20 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.8 -C.sub.40 arylalkenyl groups and C.sub.7 -C.sub.40 alkylaryl groups, or R.sup.14 and R.sup.15, together with the atom(s) connecting them, form a ring; and M.sup.3 is selected from carbon, silicon, germanium and tin; or R.sup.13 is represented by the formula ##STR4## wherein: R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are each independently selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.8 -C.sub.40 arylalkenyl groups; or two or more adjacent radicals R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24, including R.sup.20 and R.sup.21, together with the atoms connecting them, form one or more rings; and M.sup.2 represents one or more carbon atoms, or a silicon, germanium or tin atom. In preferred embodiments of the above compound, M.sup.1 is selected from titanium, zirconium and hafnium and R.sup.1 and R.sup.2 are selected from chlorine, C.sub.1 -C.sub.6 alkyl groups, C.sub.6 -C.sub.10 aryl groups, C.sub.7 -C.sub.12 arylalkyl groups and C.sub.7 -C.sub.12 alkylaryl groups. R.sup.3 may be a C.sub.3 -C.sub.6 alkyl group such as, e.g., a branched C.sub.3 -C.sub.4 alkyl group and, in particular, an isopropyl group, or may be a phenyl group. Preferably at least one of R.sup.4 and R.sup.8, and most preferred both of them, represent hydrogen atoms. In the above formula, M.sup.3 may be selected from carbon and silicon, and R.sup.14, R.sup.15 and R.sup.16 may independently be selected from C.sub.1 -C.sub.4 alkyl groups and C.sub.6 -C.sub.10 aryl groups. Moreover, when R.sup.13 is represented by the formula ##STR5## R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 may each be hydrogen, with M.sup.2 representing a silicon atom. R.sup.12 may be selected from C.sub.1 -C.sub.6 alkyl groups and C.sub.6 -C.sub.10 aryl groups, a preferred meaning being phenyl. In another embodiment, R.sup.11 is different from hydrogen and may represent, e.g., a C.sub.1 -C.sub.4 alkyl group. Particularly preferred compounds of the above formula include those wherein R.sup.1 and R.sup.2 are selected from chlorine, methyl, neopentyl and benzyl, R.sup.3 is selected from C.sub.3 -C.sub.4 alkyl groups, each of R.sup.4 and R.sup.8 is hydrogen, and R.sup.12 is selected from C.sub.1 -C.sub.4 alkyl groups and C.sub.6 -C.sub.10 aryl groups; wherein R.sup.3 is selected from branched C.sub.3 -C.sub.4 alkyl groups and R.sup.12 is selected from C.sub.6 -C.sub.10 aryl groups; wherein R.sup.3 is selected from isopropyl isobutyl, sec-butyl, tert-butyl and phenyl groups, and R.sup.12 is selected from n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, phenyl, tolyl, benzyl and naphthyl groups; and wherein M.sup.1 is selected from zirconium and hafnium; R.sup.1 and R.sup.2 are selected from chlorine, C.sub.1 -C.sub.3 alkyl groups and C.sub.6 -C.sub.10 aryl groups; R.sup.3 is selected from C.sub.3 -C.sub.6 alkyl groups and C.sub.6 -C.sub.10 aryl groups; R.sup.4 and R.sup.8 are hydrogen; R.sup.5, R.sup.6, R.sup.7, R.sup.9, R.sup.10 and R.sup.11 are each independently selected from hydrogen, halogen and C.sub.1 -C.sub.3 alkyl groups; R.sup.12 is selected from C.sub.3 -C.sub.6 alkyl groups and C.sub.6 -C.sub.10 aryl groups; and R.sup.13 is selected from di(C.sub.1 -C.sub.4 alkyl)silanediyl, diphenylsilanediyl, (C.sub.1 -C.sub.4 alkyl)phenylsilanediyl, diphenylmethanediyl and C.sub.2 -C.sub.4 alkanediyl and alkenediyl radicals, and groups of the formula R ##STR6## wherein: R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are each independently selected from hydrogen, halogen and C.sub.1 -C.sub.3 alkyl groups, and M.sup.2 represents a carbon or silicon atom. In another aspect R.sup.13 may selected from di(C.sub.1 -C.sub.4 alkyl)silanediyl, diphenylsilanediyl, (C.sub.1 -C.sub.4 alkyl)phenylsilanediyl, C.sub.2 -C.sub.4 alkanediyl and alkenediyl, di(C.sub.1 -C.sub.4 alkyl)amidoborane and bis[tri(C.sub.1 -C.sub.4 alkyl)silyl]amidoborane radicals. Other preferred compounds of the above formula may comprise not more than 2% of the meso isomer. In another aspect the metallocenes of this invention are represented by the above formula (I), wherein: M.sup.1 is selected from titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten; R.sup.1 and R.sup.2 are selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.7 -C.sub.40 arylalkenyl groups; or R.sup.1 and R.sup.2 are joined together to form an alkanediyl group or a conjugated C.sub.4 -C.sub.40 diene ligand which is coordinated to M.sup.1 in a metallacyclopentene fashion; or R.sup.1 and R.sup.2 represent a conjugated diene, optionally substituted with one or more groups independently selected from hydrocarbyl, trihydrocarbylsilyl and trihydrocarbylsilylhydrocarbyl groups, said diene having a total of up to 40 atoms not counting hydrogen and forming a .pi. complex with M.sup.1 ; R.sup.3 is selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; R.sup.4, R.sup.5, R.sup.6 and R.sub.7 are each independently selected from hydrogen, halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; or two or more adjacent radicals R.sup.5, R.sup.6 and R.sup.7 together with the atoms connecting them may form one or more rings; R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are each independently as defined for R.sup.4, R.sup.5, R.sup.6 and R.sup.7 provided that two or more adjacent radicals R.sup.8, R.sup.9, R.sup.10 and R.sup.11 together with the atoms connecting them may form one or more rings; R.sup.12 is selected from halogen, C.sub.1 -C.sub.10 alkyl groups, C.sub.6 -C.sub.14 aryl groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups, C.sub.8 -C.sub.40 arylalkenyl groups, and --NR'.sub.2, --SR', --OR', --SiR'.sub.3, --OSiR'.sub.3 and --PR'.sub.2 radicals wherein each R' is independently selected from halogen, C.sub.1 -C.sub.10 alkyl groups and C.sub.6 -C.sub.14 aryl groups; R.sup.13 is selected from di(C.sub.6 -C.sub.12 aryl))silanediyl, (C.sub.1 -C.sub.6 alkyl)(C.sub.6 -C.sub.12 aryl)silanediyl, and groups of the formula ##STR7## wherein: R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21, R.sup.22, R.sup.23 and R.sup.24 are each independently selected from hydrogen, halogen, hydroxy, C.sub.1 -C.sub.10 alkyl groups, C.sub.1 -C.sub.10 alkoxy groups, C.sub.6 -C.sub.14 aryl groups, C.sub.6 -C.sub.14 aryloxy groups, C.sub.2 -C.sub.10 alkenyl groups, C.sub.7 -C.sub.40 arylalkyl groups, C.sub.7 -C.sub.40 alkylaryl groups and C.sub.8 -C.sub.40 arylalkenyl groups; or two or more adjacent radicals R .sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.22, R.sup.22, R.sup.23 and R.sup.24, including R.sup.20 and R.sup.21, together with the atoms connecting them, form one or more rings; and M.sup.2 represents a carbon, silicon or germanium atom. Preferred embodiments of these compounds are those already given above. The present invention also provides a catalyst composition which comprises the product of a compound of at least one of the above metallocene compounds of the present invention and a cocatalyst. The cocatalyst may be a compound comprising a noncoordinating anion (e.g., a noncoordinating anion comprising at least one unit of the formula --B(C.sub.6 F.sub.5).sub.3) and/or may be an alumoxane, e.g., methylalumoxane. The catalyst composition may comprises a support material, e.g., an inorganic material such as silica, alumina, silica-alumina and magnesium chloride. Preferred support materials include silica having a surface area ranging from 10 to 700 m.sup.2 /g, a total pore volume ranging from 0.1 to 4.0 cc/g and an average particle size ranging from 10 to 500 .mu.m. Another aspect of the present invention is a polymerization process which comprises contacting, under polymerization conditions, one or more ethylenically unsaturated monomers and a catalyst composition as defined above. The ethylenically unsaturated monomers preferably are selected from monoolefins, diolefins and mixtures thereof. Illustrative and non-limiting examples of suitable monoolefins are compounds of the formula R.sup.a CR.dbd.CHR.sup.b wherein R.sup.a and R.sup.b are each independently selected from hydrogen, alkyl and alkenyl radicals having 1 to 14 carbon atoms or, together with the carbon atoms to which they are connected, form a ring having 4 to 8 carbon atoms. Preferred monoolefins include ethylene and .alpha.-olefins having from 3 to 12 carbon atoms such as, e.g., propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and mixtures thereof. In a preferred embodiment, the ethylenically unsaturated monomers consist essentially of ethylene and propylene. In one aspect of the above process the temperature ranges from about 30.degree. C. to about 80.degree. C. In another aspect, the process is carried out at a pressure ranging from about 5 to about 64 bar. The present invention also provides a polymer composition comprising: (a) propylene polymer comprising at least about 99% by weight of units derived from propylene and having a melting point of at least about 155.degree. C.; and (b) olefin copolymer comprising from about 40 to about 70% by weight of units derived from propylene and having an intrinsic viscosity of at least about 1.8; the composition made with a single catalyst composition. Component (a) may be a homopolypropylene or a copolymer of propylene and at least one monoolefin selected from ethylene and .alpha.-olefins having from 4 to 12 carbon atoms, the copolymer containing at least about 99.5% by weight of units derived from propylene. Component (b) may contain from about 30 to about 60% by weight of ethylene and/or components (a) and (b) together may contain a total of about 1.5 to about 20% by weight of ethylene. In a preferred composition of the present invention component (a) has a melting point of at least about 156.degree. C., more preferred at least about 157.degree. C., and/or component (b) has an intrinsic viscosity of at least about 2.0, more preferred at least about 2.2. The composition preferably has a molecular weight distribution, M.sub.w /M.sub.n, of not higher than about 3.5, more preferably not higher than about 3.0. In another preferred embodiment the catalyst composition used to make the polymer composition is based on a bridged zirconocene compound. DETAILED DESCRIPTION In the following detailed description, unless otherwise stated, all percentages, parts, ratios, etc., are by weight. Also, unless otherwise stated, a reference to a compound or component includes the compound or component by itself, its individual stereoisomers and any mixtures thereof, of as well as any combination with other compounds or components, such as mixtures of compounds. Further, when an amount, concentration, or other value or parameter, is given as a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of an upper preferred value and a lower preferred value, regardless whether ranges are separately disclosed. Additionally, as utilized herein, the following terms have the meanings indicated below. The term "product" in connection with the catalyst composition of the present invention includes any species that is different in any respect from the completely independent and individual materials, i.e., the metallocene compound (catalyst precursor) and the cocatalyst (activator). By way of illustrative, non-limiting example, these individual materials may have interacted or even reacted, giving rise to a contact product and/or reaction product. The term "alkyl", means a straight-chain, branched-chain or cyclic alkyl radical. Examples of such radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, iso-amyl, hexyl, 2-ethylhexyl, octyl, cyclopentyl, cyclohexyl and the like. The cyclic alkyl radicals may be substituted with one or more straight-chain and/or branched-chain alkyl radicals (i.e., may be alkylcycloalkyl radicals such as, e.g., methylcyclohexyl etc.). Conversely, the straight-chain and branched-chain alkyl radicals may be substituted with one or more cyclic alkyl radicals (i.e., may be cycloalkylalkyl radicals such as cyclohexylmethyl etc.). Moreover, unless indicated otherwise, the above alkyl radicals may be substituted by one or more groups preferably and independently selected from halogen (e.g., F, Cl, Br), alkoxy (e.g., methoxy, ethoxy, propoxy, butoxy and the like), hydroxy, amino, monoalkylamino (e.g., methylamino, ethylamino, propylamino and the like) and dialkylamino (e.g., dimethylamino, diethylamino, dipropylamino, diisopropylamino, piperidino and the like) and trihydrocarbylsilyl (e.g., trimethylsilyl, triphenylsilyl and the like). The term "alkenyl" means "alkyl" as defined above having one or more double and/or triple bonds. Examples of alkenyl radicals include, but are not limited to, ethenyl, propenyl, allyl, butenyl, propargyl, 1,4-butadienyl, isopropenyl, cyclopentenyl, cyclohexenyl, cyclooctenyl, cyclopentadienyl, cyclohexadienyl, cyclooctadienyl and the like. The term "alkoxy" means an alkyl or alkenyl ether radical wherein the terms "alkyl" and "alkenyl" are as defined above. Examples of suitable alkyl ether radicals include, but are not limited to, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, iso-butoxy, sec-butoxy, tert-butoxy, allyloxy, trifluoromethoxy and the like. The term "aryl" means an aromatic radical, for example, a phenyl, naphthyl, azulenyl, phenanthryl or anthracenyl radical and the like which optionally contains one or more (e.g., 2 or 3) heteroatoms (preferably selected from N, O and S and combinations thereof) in the ring and/or carries one or more identical or different substituents, for example, alkoxy, aryl, halogen, hydroxy, amino, monoalkylamino, dialkylamino, nitro, trihydrocarbylsilyl, alkyl-CO, alkylsulfonyl, alkyl-OCO etc., these terms being as defined herein. Illustrative, non-limiting examples of aryl radicals are phenyl, naphthyl, fluorenyl, chlorophenyl, dichlorophenyl, fluorophenyl, perfluorophenyl, hydroxyphenyl, anisyl, biphenyl, nitrophenyl, acetylphenyl, aminophenyl, pyridyl, pyridazyl, quinolyl, and the like. When carbon numbers are given herein for aryl radicals, ring heteroatoms are counted as carbon atoms. The term "aryloxy" means an aryl ether radical wherein the term "aryl" is as defined above. The term "alkylaryl" means an aryl radical carrying at least one alkyl and/or alkenyl radical as ring substituent, the terms "aryl", "alkyl" and "alkenyl" being as defined above. Illustrative, non-limiting examples of alkylaryl groups are tolyl, xylyl, mesityl, ethylphenyl, trifluoromethylphenyl, vinylphenyl, cumyl, methylpyridyl and the like. The term "arylalkyl" means an alkyl radical carrying at least one aryl group wherein the terms "aryl" and "alkyl" are as defined above, provided that the aryl radical may have one or more alkyl substituents. Illustrative, non-limiting examples of arylalkyl groups are benzyl, phenethyl, diphenyl methyl, tolyl methyl, naphthylmethyl and the like. The term "arylalkenyl" means an alkenyl radical carrying at least one aryl substituent wherein the terms "aryl" and "alkenyl" are as defined above, provided that the aryl radical may have one or more alkyl substituents. Illustrative, non-limiting examples of arylalkenyl groups are styryl, methylstyryl, phenylpropenyl, 1-phenyl-1,4-butadienyl and the like. The term "halogen" means fluorine, chlorine, bromine and iodine. The term "hydrocarbyl" encompasses alkyl, alkenyl, arylalkyl, arylalkenyl and alkylaryl groups as defined above. Preferred hydrocarbyl groups comprise 1 to 20, more preferred 1 to 10, and most preferred 1 to 6 carbon atoms. Illustrative, non-limiting examples are methyl, ethyl, propyl and phenyl. Unless specified otherwise herein, preferred meanings of the various groups defined above are: Alkyl: linear and branched alkyl groups having 1 to 8, particularly 1 to 6, and even more preferred, 1 to 4 carbon atoms (such as, e.g., methyl, ethyl, propyl and isopropyl). If present, substituents are preferably selected from halogen and alkoxy, more preferred from F, Cl, methoxy and ethoxy, most preferred from F and Cl. Alkoxy: the preferred alkyl groups connected to an oxygen atom, more preferred methoxy and ethoxy. Alkenyl: linear and branched alkenyl groups having 2 to 8, particularly 2 to 6, and even more preferred, 2 to 4 carbon atoms (such as, e.g., vinyl, allyl, and 2-butenyl). If present, substituents are preferably selected from halogen and alkoxy, more preferred from F, Cl, methoxy and ethoxy, most preferred from F and Cl. Aryl: aryl groups containing 6 to 12, more preferred 6 to 10 carbon atoms, such as, e.g., phenyl, naphthyl and biphenyl. Preferably no heteroatoms are present in the ring system. If present, substituents are preferably selected from halogen and alkoxy, more preferred from F, Cl, methoxy and ethoxy, most, preferred from F and Cl. Aryloxy: the preferred aryl groups attached to an oxygen atom. Most preferred are phenoxy and naphthoxy. Arylalkyl and alkylaryl: the preferred aryl groups in combination with the preferred alkyl groups, the total number of carbon atoms being 7 to 20, more preferred 7 to 12. Particularly preferred examples include benzyl, phenethyl, tolyl and xylyl. Arylalkenyl: the preferred aryl groups in combination with the preferred alkenyl groups, the total number of carbon atoms being 8 to 20, more preferred 8 to 12. Particularly preferred examples include styryl and chlorostyryl. Halogen: F, Cl and Br, more preferred F and Cl. Preferred meanings of the various constituents of the compounds of formula (I) above are as follows, it being understood that these preferred meanings are defined as above, including the preferred embodiments of a particular meaning. For example, "alkyl" means an alkyl group as defined above, preferred meanings thereof being also as defined above. M.sup.1 : titanium, zirconium, hafnium; more preferred are zirconium and hafnium, with zirconium being most preferred. R.sup.1 and R.sup.2 : halogen (more preferred Cl and Br), alkyl (more preferred methyl and neopentyl), aryl (more preferred phenyl), alkylaryl (more preferred tolyl) and arylalkyl (more preferred benzyl); or R.sup.1 and R.sup.2 are joined together to form a C.sub.4-6 alkanediyl group or a conjugated C.sub.4 -C.sub.6 diene ligand which is coordinated to M.sup.1 in a metallacycloalkane or -cycloalkene fashion; or R.sup.1 and R.sup.2 represent a conjugated diene, optionally substituted with one or more groups independently selected from alkyl, aryl, trialkylsilyl and trialkylsilylalkyl groups, said diene having a total of up to 30, e.g., up to 24 atoms not counting hydrogen and forming a .pi. complex with M.sup.1. Illustrative, non-limiting examples of conjugated dienes are 1,4-diphenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 2,4-hexadiene, 1-phenyl-1,3-pentadiene, 1,4-dibenzyl-1,3-butadiene, 1,4-ditolyl-1,3-butadiene, 1,4-bis(trimethylsilyl)-1,3-butadiene, and 1,4-dinaphthyl-1,3-butadiene. While R.sup.1 and R.sup.2 may be different, they are preferably the same. The most preferred meanings of R.sup.1 and R.sup.2 are Cl and methyl. R.sup.3 : alkyl, aryl, alkylaryl and arylalkyl. More preferred meanings are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, phenyl, naphthyl, tolyl and benzyl, even more preferred isopropyl, benzyl and phenyl. Most preferred is isopropyl. R.sup.4, R.sup.5, R.sup.6 and R.sup.7 : hydrogen, alkyl and aryl (particularly phenyl), more preferred hydrogen and alkyl. Illustrative, non-limiting examples are hydrogen, methyl and ethyl. For R.sup.4 a particularly preferred meaning is hydrogen. In another preferred embodiment, all of R.sup.4, R.sup.5, R.sup.6 and R.sup.7 are hydrogen. R.sup.8, R.sup.9, R.sup.10 and R.sup.11 : hydrogen, alkyl, arylalkyl (particularly benzyl) and aryl (particularly phenyl), more preferred hydrogen and alkyl. Illustrative, non-limiting examples are hydrogen, methyl and ethyl. For R.sup.8 a particularly preferred meaning is hydrogen. In another preferred embodiment, all of R.sup.8, R.sup.9, R.sup.10 and R.sup.11 are hydrogen. While in still another preferred embodiment at least one of R.sup.9 and R.sup.11 is different from hydrogen, it is particularly preferred for R.sup.11 to be different from hydrogen when R.sup.12 represents methyl or ethyl. R.sup.12 : alkyl, aryl, alkylaryl, arylalkyl and trialkylsilyl. More preferred meanings are methyl ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, phenyl, naphthyl, (o-, m- and p-)tolyl, benzyl and trimethylsilyl, in particular, isopropyl and phenyl. Most preferred is phenyl. R.sup.13 : dialkylsilanediyl, diarylsilanedlyl, (aryl)(alkyl)silanediyl, amidoborane, alkylene, arylalkylene and arylene, the latter groups being derived from the defined alkyl, arylalkyl and aryl radicals. More preferred as alkyl and aryl groups are methyl, ethyl, propyl, butyl and phenyl. More preferred alkylene, arylalkylene and arylene radicals are ethylene, propylene, butylene, phenylmethylene and diphenylmethylene as well as phenylene. More preferred dialkylsilanediyl, diarylsilanediyl and (aryl)(alkyl)silanediyl radicals are dimethylsilanediyl, diethylsilanediyl, dipropylsilanediyl, dibutylsilanediyl, methylphenylsilanediyl and diphenylsilanediyl. More preferred amidoborane radicals are dialkylamidoborane, diarylamidoborane and bis(trialkylsilyl)amidoborane radicals. Illustrative, non-limiting examples thereof are dimethylamidoborane, diethylamidoborane, diisopropylamidoborane, diphenylamidoborane and bis(trimethylsilyl)amidoborane. Other preferred meanings of R.sup.13 are 9-fluorenyl and 9-silafluorenyl. R.sup.13 is usually connected to the 1-positions of the indenyl ring systems. The following are particularly preferred metallocenes: |
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