Polymerization catalyst system comprising heterocyclic fused...

Details Polymerization catalyst system comprising heterocyclic fused... Polymerization catalyst system comprising heterocyclic fused...

1997-12-29

2002-09-17

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S132000, C526S134000, C526S160000, C526S943000, C502S117000, C502S152000, C502S155000

Reexamination Certificate

active

06451938

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to polymerization catalysts. More particularly, the invention relates to a polymerization catalyst system comprising a catalytic complex formed by activating transition metal compounds comprising cyclopentadienide anions which bear fused heterocyclic rings as substituents, and to a process for the polymerization or copolymerization of monomers and comonomers using the catalyst system.
BACKGROUND OF THE INVENTION
Transition metal compounds which function as catalysts are well known in the art. Some of the more successful ligands for such transition metal compounds are derived from a cyclopentadienide anion. Indeed, pi-bonded cyclopentadienide metal compounds, commonly referred to as “metallocenes,” have found a broad range of applications including the catalysis of industrially important processes, the use as catalysts or synthetic intermediates in the synthesis of pharmaceuticals and other fine chemicals, and the use as precursors to inorganic materials.
Metallocenes are often used as components of “single-sited” polymerization catalyst systems. As discussed in U.S. Pat. No. 5,502,124, characteristics thought to impart catalytic activity to known metallocene catalysts include: a coordinatively unsaturated, electrophilic, metal center in a trigonal geometry; an active sigma bound substituent, preferably an alkyl or hydride radical; and a least a single vacant orbital cis to the sigma bound substituent. In addition to the active sigma bound substituent, the metal is bound to an inert ancillary ligand set, the purpose of which is to establish and maintain the proper electronic and steric environment of the metal center throughout the polymerization. Ancillary ligands may be defined as ligands which do not directly participate in the monomer insertion reaction, but which are covalently bound to the metal center by single or multiple bonds. Ancillary ligands are typically composed of organic and/or inorganic moieties in a discrete and well defined manner and generally have a molecular weight greater than about 50 amu (atomic mass units). The cyclopentadienide anion is prototypical of the ancillary ligands generally found in single-sited catalysts.
Neutral metallocenes which have the above characteristics, i.e., a coordinatively unsaturated electrophilic metal center, an active sigma bound substituent, and a least a single vacant orbital cis to the sigma bound substituent, are also active polymerization catalysts, often used to polymerize olefins. However, such neutral metallocene catalysts suffer from a propensity to dimerize to form inactive species. This tendency to deactivate by dimerization can be attenuated by using sterically demanding ancillary ligand sets, thus inhibiting the dimerization, but this approach is only partially successful. Moreover, the use of sterically demanding ancillary ligand sets may inhibit the polymerization of larger monomers or comonomers.
On the other hand, charged cationic complexes formed from metallocenes do not readily deactivate by dimerization and do not require the use of extremely sterically demanding ligand sets. In these cases, the repulsion due to like electrostatic forces prevents dimerization, thereby obviating the need for sterically demanding ligands and allowing for much greater reactivity of larger monomer substrates.
Despite the forgoing, only a relatively narrow range of ancillary ligands has been investigated. Known ancillary ligands often comprise a cyclopentadienyl moiety substituted with one or more substituents which are chosen primarily from alkyl, aryl, and fused aromatic groups. Frequently, a number of structural variants is examined in which both the steric and electronic properties are changed simultaneously. Efforts to directly determine the relative contributions of electronic and steric effects have to date met with only limited success, and access to a broader range of systematically variable ancillary ligands is therefore highly desirable.
Further, despite the ubiquity of heterocycles in nature, extremely few examples of such compounds suitable as cyclopentadienyl ligands can be found in the literature. Two reports of transition metal complexes of azaindenylide ligands have appeared in the literature. Basolo and coworkers reported a manganese pyrindinyl complex in 1985 (Basolo, F. J. et al., J. Organomet. Chem. 1985, 296, 83). More recently, Fu has reported an iron pyrindinyl complex and a dimethylamino substituted iron pyrindinyl complex (Fu, G. C. et al., J. Org. Chem. 1996, 61, 7230).
U.S. Pat. No. 5,434,116 and PCT publication WO 95/04087 discuss catalyst compositions comprising heterocyclopentadienyl ligands, where one of the carbon atoms in a cyclopentadienyl ligand has been replaced with a group 15 heteroatom.
U.S. Pat. No. 5,489,659 discusses metallocenes which comprise two bridged cyclopentadienyl groups, each of which is bonded to the metal, wherein at least one of the cyclopentadienyl groups is substituted with a ring system which comprises a silicon-containing hydrocarbon group.
Several heteroatom-substituted cyclopentadienide ligands have been reported. For example, aminocyclopentadienyl complexes of iron, a group 8 metal (see Nesmeyanov, A. N. et al. Dokl. Acad. Nauk. SSSR 1963, 150, 102; Herberhold, M. et. al, .J. Organomet. Chem. 1983, 241, 227), and cobalt, a group 9 metal (see El Murr, N.Conpt. Rend. 1971, C272, 1989), have been disclosed. In these instances the amino substituent was incorporated by substitution on the cyclopentadienyl ring of the pre-formed metallocene. Use of an amino cyclopentadiene or dienyl precursor to synthesize iron and titanium complexes has also be reported by Stahl, K. P. et al.(J. Organomet. Chem. 1984, 277, 113). More recently, Plenio et. al (Angew. Chem. Int. Ed. Engl. 1995, 34, 800) have disclosed the formation of aminocyclopentadiene and dienyl precursors to their corresponding ferrocene complexes. This report also disclosed the use of the related 2-dimethylaminoindene and indenyl precursors. In all of these examples, however, the nitrogen heteroatom is exocyclic to the cyclopentadienyl ring and is not a part of a heterocyclic ring system.
Because ligands are so important in determining the polymerization behavior of catalysts for the reasons discussed above, the development of new transition metal catalyst systems exhibiting enhanced activities and selectivities frequently requires the synthesis of new organic compounds to serve as ligands for the transition metal centers of the active catalysts or their precursors. A need thus exists for transition metal compounds, and catalysts formed therefrom, which have ligands bearing a greater range of substituents and which span a greater range of electronic properties.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a polymerization catalyst system comprising a catalytic complex formed by activating for polymerization a transition metal compound which comprises a metal selected from groups 3 through 10 of the periodic table, preferably from groups 4, 5, or 6 of the periodic table, and a group 13, 15, or 16 heterocyclic fused cyclopentadienide ligand. In one embodiment, the transition metal compounds used in the invention are represented by the formula:
[L]
m
M[A]
n
(D′)
o
wherein:
M is a transition metal selected from groups 3 through 10 of the periodic table, preferably from groups 4, 5, and 6, and more preferably from group 4;
L is a cyclopentadienide-containing ligand which may be the same as or different from any other L, but at least one L is a group 13, 15, or 16 heterocyclic fused cyclopentadienide ligand;
A is a monatomic or polyatomic ligand, other than a cyclopentadienide-containing ligand, which bears a formal negative charge and can be the same as or different from any other A;
D′ is an optional donor ligand which may or may not be present;
m is an integer which has a value of 1, 2, or 3;
n is an integer which has a value of 1, 2, or 3; and
o is an integer representing the number of optional donor

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