Nitrogen substituted phosphinimine ligand

Details Nitrogen substituted phosphinimine ligand Nitrogen substituted phosphinimine ligand

1999-11-15

2001-05-22

Wu, David W. (Department: 1713)

Combinatorial chemistry technology: method, library, apparatus

Library, per se

Library containing only inorganic compounds or inorganic...

C502S103000, C502S117000, C526S127000, C526S161000, C526S172000, C526S901000, C526S943000

Reexamination Certificate

active

06234950

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a catalyst for olefin polymerization. The catalyst is an organometallic complex of a group 4 metal. The catalyst contains a cyclopentadienyl type ligand and a heterosubstituted phosphinimine ligand. The heterosubstituted phosphinimine ligand may be conveniently and inexpensively synthesized and is comparatively non-pyrophoric.
BACKGROUND OF THE INVENTION
Olefin polymerization catalysts having a cyclopentadienyl ligand and a conventional phosphinimine ligand are disclosed in a copending and commonly assigned patent application (Stephen et al). The catalysts of the Stephen et al disclosure are highly active for ethylene (co)polymerization, particularly when used in combination with an alumoxane, or an “ionic activator” (or both).
We have now discovered that heterosubstituted phosphinimine ligands may be easily synthesized and can be used as a component of a highly active ethylene polymerization catalyst system.
SUMMARY OF THE INVENTION
The present invention provides a catalyst component for olefin polymerization comprising an organometallic complex defined by the formula:
wherein Cp is selected from cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl, and substituted fluorenyl; M is a metal selected from titanium, zirconium and hafnium; X is an activatable ligand and n is selected from 1 and 2; said HPI is a heterosubstituted phosphinimine ligand which is bonded to the metal M and wherein said HPI is defined by the formula:
wherein R
1
is independently selected from the group consisting of a hydrogen atom, a halogen atom, C
1-20
hydrocarbyl radicals which are unsubstituted by or further substituted by a halogen atom, a C
1-8
alkoxy radical, a C
6-10
aryl or aryloxy radical, a silyl radical of the formula:
—Si—(R
2
)
3
wherein each R
2
is independently selected from the group consisting of hydrogen, a C
1-8
alkyl or alkoxy radical, C
6-10
aryl or aryloxy radicals, and a germanyl radical of the formula:
Ge—(R
2
)
3
wherein R
2
is as defined above; and H
1
is a heterosubstituent having a nitrogen atom bonded to said phosphorus atom, with the provisos that a=0, 1 or 2, b=1, 2 or 3 and a+b=2 or 3.
Prior art phosphinimines generally involve pyrophoric phosphine precursors in their synthesis. The phosphine precursors of the heterosubstituted phosphinimines used in the present invention mitigate this disadvantage because they may be readily synthesized from less pyrophoric precursors, as illustrated in the examples. This reduces the likelihood of process fires during commercial manufacture of the phosphinimine ligands.
The present catalyst components may be used in combination with an activator to provide an olefin polymerization catalyst system. Alumoxanes, “ionic activators” and/or combinations of the two may be used as activators.
DETAILED DESCRIPTION
1. Description of Catalyst Component
The catalyst components of this invention are defined by the formula:
wherein M is a group 4 metal selected from titanium, zirconium and hafnium; HPI is a heterosubstituted phosphinimine ligand (as described in section 1.2); Cp is a cyclopentadienyl ligand (as described in section 1.3); each X is independently an activatable ligand (and each is preferably a simple monoanionic ligand such as an alkyl or halide—as described in section 1.4); and n is 1 or 2 as defined by the formula, depending upon the valence of the metal M and the anionic ligand(s) as described in section 1.4.
Preferred catalysts are monocyclopentadienyl complexes of titanium (IV) having two, monoanionic activatable ligands (i.e. n is 2).
1.2 Heterosubstituted Phosphinimine Ligand
The catalyst component of this invention must contain a heterosubstituted phosphinimine ligand which is covalently bonded to the metal. This ligand is defined by the formula:
wherein each R
1
is independently selected from the group consisting of a hydrogen atom, a halogen atom, C
1-20
hydrocarbyl radicals which are unsubstituted by or further substituted by a halogen atom, a C
1-8
alkoxy radical, a C
6-10
aryl or aryloxy radical, a silyl radical of the formula:
—Si—(R
2
)
3
wherein each R
2
is independently selected from the group consisting of hydrogen, a C
1-8
alkyl or alkoxy radical, C
6-10
aryl or aryloxy radicals, and a germanyl radical of the formula:
Ge—(R
2
)
3
wherein R
2
is as defined above; and H
1
is a heterosubstituent.
H
1
is a heterosubstituent which is characterized by having a nitrogen atom that is bonded to the phosphorus atom via a single covalent bond. The nitrogen atom is then substituted either with two substituents (which are bonded to the nitrogen via single bonds) or one substituent (bonded to the nitrogen via a double bond). The substituents on the nitrogen atom are not particularly critical to the success of this invention. However, for reasons of cost and convenience, it is preferred that each R
1
substituent on the nitrogen atom is independently selected from hydrocarbyl and silyl (and, as will be appreciated by those skilled in the art, the hydrocarbyl and/or silyl substituents may also be substituted). Hydrocarbyl groups, especially tertiary butyl, are particularly preferred R
1
substituents. There must be at least one heterosubstituent H
1
(i.e. b must be at least 1). The sum of a+b is 3 when all three substituents on the phosphorus atoms are singly bonded to it. Alternatively, the sum of a+b is 2 when one of the substituents is doubly bonded to the phosphorus atom. It is preferred that there are three, singly bonded substituents on the phosphorus atom. It is particularly preferred that a=2 and b=1 (i.e. two of the R
1
substituents and one H
1
substituent).
1.3 Cyclopentadienyl-type Ligands
As used herein, the term cyclopentadienyl-type ligand is meant to convey its conventional meaning, namely a ligand having a five carbon ring which is bonded to the metal via eta-5 bonding. Thus, the term “cyclopentadienyl-type” includes unsubstituted cyclopentadienyl, substituted cyclopentadienyl, unsubstituted indenyl, substituted indenyl, unsubstituted fluorenyl and substituted fluorenyl. An exemplary list of substituents for a cyclopentadienyl ligand includes the group consisting of C
1-10
hydrocarbyl radical (which hydrocarbyl substituents are unsubstituted or further substituted); a halogen atom, C
1-8
alkoxy radical, a C
6-10
aryl or aryloxy radical; an amido radical which is unsubstituted or substituted by up to two C
1-8
alkyl radicals; a phosphido radical which is unsubstituted or substituted by up to two C
1-8
alkyl radicals; silyl radicals of the formula —Si—(R
2
)
3
wherein each R
2
is independently selected from the group consisting of hydrogen, a C
1-8
alkyl or alkoxy radical C
6-10
aryl or aryloxy radicals; germanyl radicals of the formula Ge—(R
2
)
3
wherein R
2
is as defined directly above. It is preferred to use an unsubstituted cyclopentadienyl ligand for reason of cost and convenience.
1.4 Activatable Ligand
The term “activatable ligand” refers to a ligand which may be activated by a cocatalyst (also known as an “activator” to facilitate olefin polymerization). Exemplary activatable ligands are independently selected from the group consisting of a hydrogen atom, a halogen atom, a C
1-10
hydrocarbyl radical, a C
1-10
alkoxy radical, a C
5-10
aryl oxide radical; each of which said hydrocarbyl, alkoxy and aryl oxide radicals may be unsubstituted by or further substituted by a halogen atom, a C
1-8
alkyl radical, a C
1-8
alkoxy radical, a C
6-10
aryl or aryl oxy radical, an amido radical which is unsubstituted or substituted by up to two C
1-8
alkyl radicals; a phosphido radical which is unsubstituted or substituted by up to two C
1-8
alkyl radicals.
The number of activatable ligands depends upon the valency of the metal and the valency of the activatable ligand. The preferred catalyst metals are group 4 metals in their highest oxidation state (i.e. 4+) and the preferred activatable ligands are monoanionic. Thus, the preferred catalyst com

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