JP7647233B2 - Method for producing olefin copolymer - Google Patents

Description

The present invention relates to a novel catalyst composition containing a complex having a specific structure, and more specifically, to a catalyst composition containing a low-spin transition metal complex as an essential component, and a method for producing an olefin copolymer using the catalyst composition.

Among resin materials, olefin polymers have excellent properties such as physical properties and moldability, and are also highly economical and environmentally friendly, making them a very versatile and important industrial material. However, because olefin polymers do not have polar groups, they present many challenges, such as the difficulty of using them in applications that require physical properties such as adhesion to other materials, printability, or compatibility with fillers.

In recent years, methods for producing olefin polymers having polar groups that use polar monomers in the polymerization stage have been attracting attention. For this purpose, late transition metal complex catalysts, known as postmetallocenes, have been developed and the physical properties of olefin polymers have been controlled using them. As postmetallocene catalysts for olefin polymerization, for example, paramagnetic iron complex catalysts such as tridentate iron complexes with a diiminopyridine skeleton and bisaryliminopyridine iron are used, and the results of ethylene polymerization using these catalysts are known (Patent Documents 1 to 3, Non-Patent Document 1). In addition, ethylene polymerization using paramagnetic iron complexes and cobalt complexes is known (Patent Documents 4, 5, Non-Patent Documents 2, 3). In addition, group 10 complexes known as SHOP catalysts are known as catalyst design using ligands (Patent Document 6).

Special Publication No. 2006-501067 Patent No. 4108141 Special Publication No. 2002-513823 JP 2018-172644 A JP 2020-056021 A Patent No. 5292059

Campora et al. Organometallics, 2005, 24, 4878-4881 Britovsek et al. Chem. Commun. 1998, 849. Britovsek et al. J. Am. Chem. Soc. 1999, 121, 8728.

As mentioned above, ethylene polymerization using metal complex catalysts has been reported, but in the evaluation of polymerization, it is necessary to properly evaluate the catalytic activity, and using a catalyst with high purity is important for accurate catalyst evaluation. However, in the case of 8-9 group complex catalysts, Patent Documents 1, 2, 3, 4, 5 and Non-Patent Documents 1, 2, 3 use transition metal complexes in a high spin state, and it is not possible to identify the catalyst or evaluate its purity, etc., using commonly used techniques such as NMR. Proper evaluation of the purity of the catalyst not only leads to a proper evaluation of its function as a polymerization catalyst, but also has an impact on the reproducibility of olefin polymerization. Thus, there is a need for the development of a catalyst that can be used as an olefin polymerization catalyst to produce polyethylene, and that allows easy and accurate evaluation of purity, etc. after production.

The object of the present invention is to create a catalyst composition that can be easily evaluated for purity and functions effectively as an olefin polymerization catalyst. As a result of intensive research aimed at solving the above problems, the inventors have found that a composition containing a specific iron complex functions as a component of a polymerization catalyst that meets the above objectives, and have created the present invention.

In a first aspect of the present invention, a method for producing an olefin polymer is provided, which includes a step of polymerizing an olefin monomer using a catalyst containing a complex having a metal atom of Group 8 or 9 of the periodic table in a low spin state as a polymerization catalyst component.

In a second aspect of the present invention, there is provided a method for producing an olefin polymer according to the first aspect, characterized in that the complex has a tridentate or tetradentate ligand having a phosphorus atom at the coordination site.

［一般式（１）中、
Ｍは、酸化数が＋２の鉄、酸化数が＋２のルテニウム、酸化数が＋１のコバルト又は酸化数が＋１のロジウムであり、
ｎは、０又は１の整数を表し、
Ｒ^１ａ、Ｒ^１ｂ、Ｒ^１ｃ及びＲ^１ｄは、それぞれ独立して、炭素数３～１２の炭化水素基を表し、
Ｒ^２ａ及びＲ^２ｂは、それぞれ独立して、水素原子又は炭素数１～３の炭化水素を表し、
Ｒ^３ａ、Ｒ^３ｂ、Ｒ^３ｃ、Ｒ^３ｄ、Ｒ^３ｅ、Ｒ^３ｆ、Ｒ^３ｇ及びＲ^３ｈは、それぞれ独立して、水素原子、ハロゲン原子、炭素数１～３０の炭化水素基、炭素数１～４のアルコキシ基、ハロゲン原子で置換された炭素数１～３０の炭化水素基、アルコキシ基で置換された炭素数２～３０の炭化水素基、及び炭素数１～３０の炭化水素基で置換されたシリル基からなる群より選択される置換基を表し、
Ｒ^４ａ及びＲ^４ｂは、それぞれ独立して、水素原子又は炭素数１～４の炭化水素基を表すか、あるいはＲ^４ａ及びＲ^４ｂは、互いに連結して環を形成し、
Ｌは、各登場においてそれぞれ独立して、中性の単座配位子、又はアニオン性の単座配位子から選択される金属の補助配位子を表し、
Ｘは、存在しないか、又は、－１価若しくは２価のカウンターアニオン種である。］ In a third aspect of the present invention, there is provided the method for producing an olefin polymer according to the first or second aspect, wherein the complex is represented by the following general formula (1):

[In the general formula (1),
M is iron with an oxidation state of +2, ruthenium with an oxidation state of +2, cobalt with an oxidation state of +1, or rhodium with an oxidation state of +1;
n represents an integer of 0 or 1;
R ^1a , R ^1b , R ^1c and R ^1d each independently represent a hydrocarbon group having 3 to 12 carbon atoms;
R ^2a and R ^2b each independently represent a hydrogen atom or a hydrocarbon having 1 to 3 carbon atoms;
R ^3a , R ^3b , R ^3c , R ^3d , R ^3e , R ^3f , R ^3g and R ^3h each independently represent a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydrocarbon group having 1 to 30 carbon atoms substituted with a halogen atom, a hydrocarbon group having 2 to 30 carbon atoms substituted with an alkoxy group, and a silyl group substituted with a hydrocarbon group having 1 to 30 carbon atoms;
R ^4a and R ^4b each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, or R ^4a and R ^4b are bonded to each other to form a ring;
L, at each occurrence, independently represents a metal ancillary ligand selected from a neutral monodentate ligand or an anionic monodentate ligand;
X is absent or a counter anion species having a valence of −1 or 2.

In a fourth aspect of the present invention, there is provided a method for producing an olefin polymer according to the third aspect, characterized in that M in formula (1) is iron with an oxidation number of +2 or ruthenium with an oxidation number of +2.

In a fifth aspect of the present invention, there is provided a method for producing an olefin polymer according to any one of the first to fourth aspects, characterized in that the weight average molecular weight of the resulting olefin polymer is 100,000 or more and 10,000,000 or less.

The catalyst composition of the present invention provides a novel catalyst for olefin polymerization. The purity of the metal complex of the catalyst can be determined by NMR measurement, and a catalyst containing a high-purity metal complex can be used as a polymerization catalyst component. The polyolefin polymerization catalyst using the metal complex of the present invention and the olefin polymerization method using the same are extremely useful from an industrial point of view.

1 is a ³¹ P-NMR chart of Fe(II) complex A of Example 1. 1 is a ¹ H-NMR chart of Fe(II) complex A of Example 1. 3 is a ³¹ P-NMR chart of Fe(II) complex B of Example 2. 1 is a ¹ H-NMR chart of Fe(II) complex B of Example 2.

The polymerization catalyst component of the present invention and the method for producing an olefin polymer using the same will be described in detail below.

<Transition metal complex>
The polymerization catalyst component used in the method of the present invention contains a transition metal complex containing a metal atom of Group 8 or 9 of the periodic table in a low spin state as the polymerization catalyst component. The transition metal complex is not particularly limited in type as long as it is a Group 8 or 9 metal complex and can be identified by NMR measurement. The NMR measurement is preferably one that observes nuclei that are highly sensitive and result in simple peaks. Specific NMR measurement methods include ¹ H-NMR and ³¹ P-NMR, and NMR that measures these nuclei is preferred because the peaks appear clearly and the measurement environment is often uniform. When the ligand contains a phosphorus atom, ³¹ P-NMR is particularly preferred. In ³¹ P-NMR, the position of the signal changes depending on the atoms and functional groups around the phosphorus atom, but in order to make the peak observed in the NMR measurement simple, the type of signal of the phosphorus atom may be one or two. In addition, since a characteristic peak is observed by coordination with a metal atom, it is preferable that the phosphorus atom is at a coordination site and is coordinately bonded to the metal atom. More preferably, the transition metal complex has a tridentate or tetradentate ligand having at least one phosphorus atom at a coordination site.

When the ligand is a tridentate ligand, examples thereof include a ligand having a structure (hereinafter referred to as PNP) in which a phosphorus atom, a nitrogen atom, and a phosphorus atom are arranged clockwise as shown in the following general formula (2), or a ligand having a structure (hereinafter referred to as PNN) in which a phosphorus atom, a nitrogen atom, and a nitrogen atom are arranged clockwise as shown in the following general formula (3).When the ligand is a tetradentate ligand, a representative example thereof includes a tetradentate ligand having a structure (hereinafter referred to as PNNP) in which a phosphorus atom, a nitrogen atom, a nitrogen atom, and a phosphorus atom are arranged clockwise as shown in the above general formula (1).Such ligands are generally considered to be prone to forming a regular octahedral complex structure, and as a result, the 8th or 9th group metal complex is prone to being in a paramagnetic, low spin state. In general formulas (2) and (3), R ^1a , R ^1b , R ^2a , R ^3a , R ^3b , R ^3c , R ^3d , R ^4a , R ^4b and n are as defined in general formula (1), and R ⁵ is the same as R ^1a .

In terms of sensitivity, it is desirable that the sample in the NMR measurement is in the form of a solution. Therefore, it is preferable that the transition metal complex used in the method of the present invention is soluble in an organic solvent. In particular, it is preferable that the transition metal complex is soluble in any one of deuterated benzene, deuterated toluene, deuterated acetone, deuterated acetonitrile, deuterated methylene chloride, and deuterated chloroform. It is preferable that the solubility of the transition metal complex is at least the level required for ³¹ P-NMR measurement (1 g/L).

The transition metal complexes used in the method of the present invention contain metal atoms of Group 8 or 9 of the periodic table in a low spin state. Group 8 or 9 transition metals have 6 or 7 electrons in five d orbitals, with the number of unpaired electrons varying depending on the mode of orbital filling. "Low spin" refers to a state in which the number of unpaired electrons is zero. Examples of metal species that can be employed include iron, ruthenium, or osmium with a valence of +2, and cobalt, rhodium, or iridium with a valence of +1.

［一般式（１）中、
Ｍは、酸化数が＋２の鉄、酸化数が＋２のルテニウム、酸化数が＋１のコバルト又は酸化数が＋１のロジウムであり、
ｎは、０又は１の整数を表し、
Ｒ^１ａ、Ｒ^１ｂ、Ｒ^１ｃ及びＲ^１ｄは、それぞれ独立して、炭素数３～１２の炭化水素基を表し、
Ｒ^２ａ及びＲ^２ｂは、それぞれ独立して、水素原子又は炭素数１～３の炭化水素を表し、
Ｒ^３ａ、Ｒ^３ｂ、Ｒ^３ｃ、Ｒ^３ｄ、Ｒ^３ｅ、Ｒ^３ｆ、Ｒ^３ｇ及びＲ^３ｈは、それぞれ独立して、水素原子、ハロゲン原子、炭素数１～３０の炭化水素基、炭素数１～４のアルコキシ基、ハロゲン原子で置換された炭素数１～３０の炭化水素基、アルコキシ基で置換された炭素数２～３０の炭化水素基、及び炭素数１～３０の炭化水素基で置換されたシリル基からなる群より選択される置換基を表し、
Ｒ^４ａ及びＲ^４ｂは、それぞれ独立して、水素原子又は炭素数１～４の炭化水素基を表すか、又はＲ^４ａ及びＲ^４ｂは、互いに連結して環を形成し、
Ｌは、各登場においてそれぞれ独立して、中性の単座配位子、又はアニオン性の単座配位子から選択される金属の補助配位子を表し、
Ｘは、存在しないか、又は、－１価若しくは２価のカウンターアニオン種である。］ Specific examples of the transition metal complexes used in the method of the present invention include transition metal complexes represented by the following general formula (1).

[In the general formula (1),
M is iron with an oxidation state of +2, ruthenium with an oxidation state of +2, cobalt with an oxidation state of +1, or rhodium with an oxidation state of +1;
n represents an integer of 0 or 1;
R ^1a , R ^1b , R ^1c and R ^1d each independently represent a hydrocarbon group having 3 to 12 carbon atoms;
R ^2a and R ^2b each independently represent a hydrogen atom or a hydrocarbon having 1 to 3 carbon atoms;
R ^3a , R ^3b , R ^3c , R ^3d , R ^3e , R ^3f , R ^3g and R ^3h each independently represent a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydrocarbon group having 1 to 30 carbon atoms substituted with a halogen atom, a hydrocarbon group having 2 to 30 carbon atoms substituted with an alkoxy group, and a silyl group substituted with a hydrocarbon group having 1 to 30 carbon atoms;
R ^4a and R ^4b each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, or R ^4a and R ^4b are bonded to each other to form a ring;
L, at each occurrence, independently represents a metal ancillary ligand selected from a neutral monodentate ligand or an anionic monodentate ligand;
X is absent or a counter anion species having a valence of −1 or 2.

"Hydrocarbon group" means a structure consisting of a carbon skeleton having a specific number of carbon atoms, and includes linear or branched alkyl groups, alkenyl groups, alkynyl groups, cycloalkyl groups, cycloalkenyl groups, cycloalkynyl groups, aryl groups, and structures in which two or more of these groups are bonded together, such as benzyl and biphenyl. In addition, in this specification, "hydrocarbon group" generally refers to a monovalent group, but when it is specifically stated that the "hydrocarbon group" has a valence of two or more, the "hydrocarbon group" indicates a structure in which at least one hydrogen atom in the above group or structure is replaced with a bond depending on the valence.

The hydrocarbon group having 1 to 30 carbon atoms is preferably an alkyl group, a cycloalkyl group, an alkenyl group, or an aryl group. Examples of the alkyl group and the cycloalkyl group include a methyl group, an ethyl group, a 1-propyl group, an isopropyl group, a 1-butyl group, an isobutyl group, a t-butyl group, a 1-pentyl group, a 1-hexyl group, a 1-heptyl group, a 1-octyl group, a 1-nonyl group, a 1-decyl group, a tricyclohexylmethyl group, a 1,1-dimethyl-2-phenylethyl group, a 1-dimethylpropyl group, a 1,1,2-trimethylpropyl group, a 1,1-diethylpropyl group, a 1-phenyl-2-propyl group, a 1,1-dimethylbutyl group, a 2-pentyl group, a 3-pentyl group, a 2-hexyl group, a 3-hexyl group, a 2-ethyl ... Examples of the substituent include cyclopropyl, 2-heptyl, 3-heptyl, 4-heptyl, 2-propylheptyl, 2-octyl, 3-nonyl, cyclopropyl, cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl, methylcyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, 1-adamantyl, 2-adamantyl, exo-norbornyl, endo-norbornyl, 2-bicyclo[2.2.2]octyl, nopinyl, decahydronaphthyl, menthyl, neomenthyl, neopentyl, and 5-decyl. Among these, preferred substituents are isopropyl, isobutyl, and cyclohexyl.

Alkenyl groups include vinyl groups, allyl groups, butenyl groups, cinnamyl groups, and styryl groups.

Examples of aryl groups include phenyl, naphthyl, anthracenyl, and fluorenyl groups, and the aromatic rings of these aryl groups may have a substituent. Examples of the substituent that may be present include alkyl groups, aryl groups, fused aryl groups, phenylcyclohexyl groups, phenylbutenyl groups, tolyl groups, xylyl groups, and p-ethylphenyl groups. Among these, preferred aryl groups are phenyl groups and substituted phenyl groups, and preferred specific examples of the substituents of the substituted phenyl groups are methyl groups, ethyl groups, and phenyl groups, and more particularly preferred is the methyl group.

"Halogen" refers to an element belonging to Group 17 of the periodic table, specifically fluorine, chlorine, bromine, and iodine, preferably chlorine and bromine. A hydrocarbon group having 1 to 30 carbon atoms substituted with a halogen atom is preferably a structure in which one or more hydrogen atoms in the aforementioned hydrocarbon group having 1 to 30 carbon atoms are substituted with a halogen atom. Specific preferred examples include a trifluoromethyl group or a pentafluorophenyl group.

An "alkoxy group" refers to a hydrocarbon group having an oxygen atom bonded to the end thereof, but the oxygen is not bonded to an aromatic ring. An alkoxy group having 1 to 4 carbon atoms is preferred, and specific examples include a methoxy group, an ethoxy group, an isopropoxy group, a 1-propoxy group, a 1-butoxy group, and a t-butoxy group. Among these, more preferred substituents are a methoxy group, an ethoxy group, or an isopropoxy group, and a methoxy group is particularly preferred.

The hydrocarbon group having 2 to 30 carbon atoms substituted with an alkoxy group preferably has a structure in which the aforementioned hydrocarbon group having 1 to 30 carbon atoms is substituted with an alkoxy group. Specific preferred examples include a methoxymethyl group or a methoxyethyl group.

"Silyl group" means a substituent having silicon at the end, and the silyl group substituted with a hydrocarbon group having 1 to 30 carbon atoms is preferably a silyl group having 3 to 18 carbon atoms, and preferred examples are a trimethylsilyl group, a dimethylphenylsilyl group, a diphenylmethylphenylsilyl group, and a triphenylsilyl group. Among these, more preferred substituents are a trimethylsilyl group or a dimethylphenylsilyl group, and particularly preferred is a trimethylsilyl group.

In general formula (1), M is a transition metal of Group 8 or 9, and is particularly selected from the group consisting of iron with an oxidation number of +2, ruthenium with an oxidation number of +2, cobalt with an oxidation number of +1, or rhodium with an oxidation number of +1. Preferably, M is iron with an oxidation number of +2 or cobalt with an oxidation number of +1.

In the portion corresponding to the tetradentate ligand in general formula (1), n represents an integer of 0 or 1. When the value of n is 0, the carbon to which R ^4a is bonded and the carbon to which R ^4b is bonded are directly bonded. Since there are a wide variety of types of raw materials for ligand synthesis, it is preferable that the value of n is 0.

R ^1a , R ^1b , R ^1c and R ^1d each independently represent a hydrocarbon group having 3 to 12 carbon atoms. R ^1a , R ^1b , R ^1c and R ^1d may be the same or different, but are preferably the same group from the viewpoints of availability of raw material compounds, ease of synthesis of ligands, and control of the steric environment of the metal complex. Examples of R ^1a to R ^1d include alkyl groups having 3 to 12 carbon atoms, particularly isopropyl and t-butyl groups; cycloalkyl groups having 3 to 12 carbon atoms, particularly cyclohexyl groups; and aryl groups having 6 to 12 carbon atoms, particularly phenyl, toluyl and naphthyl groups. Among these, alkylaryl groups such as phenyl, toluyl and naphthyl groups are preferred, alkylaryl groups not having substituents at the 2- and 6-positions are more preferred, and phenyl groups are particularly preferred. It is desirable that R ^1a , R ^1b , R ^1c and R ^1b have an appropriate size from the viewpoints of the molecular weight of the polymer, polymerization activity and ease of synthesis.

R ^2a and R ^2b each independently represent a hydrogen atom or a hydrocarbon having 1 to 3 carbon atoms. The groups R ^2a and R ^2b can control the electronic state of the metal M via the nitrogen atom and can be selected without being limited within the above range. From the viewpoint of increasing the yield of the ligand synthesis, it is desirable to select a hydrogen atom.

R ^3a , R ^3b , R ^3c , R ^3d , R ^3e , R ^3f , R ^3g and R ^3h each independently represent a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, a hydrocarbon group having 1 to 30 carbon atoms substituted with a halogen atom, an alkoxy group substituted with a hydrocarbon having 1 to 4 carbon atoms, a hydrocarbon group having 2 to 30 carbon atoms substituted with an alkoxy group, and a silyl group substituted with a hydrocarbon group having 1 to 30 carbon atoms. A hydrogen atom is preferable in terms of suppressing the steric bulkiness of the entire ligand. In particular, it is preferable that R ^3d and R ^3e are hydrogen atoms, since it is possible to easily control the steric state by R ^1a to R ^1d . It is also preferable that R ^3a and R ^3e are hydrogen atoms, since it is possible to easily perform ligand synthesis. When any of R ^3a to R ^3h has a group other than a hydrogen atom as a substituent, those having substituents in R ^3b and R ^3g are preferred in terms of ease of availability, etc. Furthermore, from the viewpoint of improving the solubility of the entire complex, it is desirable for R ^3b , R ^3c , R ^3g and R ^3h to be a hydrogen atom, an alkoxy group having 1 to 4 carbon atoms or a halogen atom.

R ^4a and R ^4b each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, or R ^4a and R ^4b may be linked together to form a ring. They can be selected without being limited within the above range depending on the synthesis raw materials of the ligand. When R ^4a and R ^4b are linked together to form a ring, the ring structure may be any of an alicyclic, heterocyclic, and aromatic ring. The number of ring members is preferably 5 to 8. From the viewpoint of synthesis cost, it is advantageous to procure raw materials when R ^4a and R ^4b are both hydrogen atoms or both methyl groups.

L, independently in each occurrence, represents a metal auxiliary ligand selected from a neutral monodentate ligand or an anionic monodentate ligand. An example of a neutral monodentate ligand is a ligand that is electrically neutral and can form a coordinate bond by coordinating an unpaired electron to a central metal M, such as a molecule having a nitrogen atom, a phosphorus atom, an arsenic atom, an oxygen atom, a sulfur atom, or a selenium atom having an unpaired electron. Another example is a molecule such as ethylene that forms a π-donor bond by donating a π-electron. Examples of neutral monodentate ligands that can be used as L include those known as neutral ligands for metal complexes, such as acetonitrile, isonitrile, carbon monoxide, ethylene, and tetrahydrofuran. An example of an anionic monodentate ligand is a ligand that can formally donate an even number of electrons to a metal atom, such as a halogen, an alkyl group, an aryl group, an alkoxide, an amide, or a silyl group. Among these, neutral monodentate ligands with weak coordinating power are desirable because they tend to lead to high catalytic activity. Acetonitrile and ethylene are particularly desirable.

X is absent or a -1- or 2-valent counter anion species. When M is +2-valent iron or ruthenium and both L are anionic monodentate ligands, or when M is +1-valent cobalt or rhodium and one of L is an anionic monodentate ligand, X is absent. When X is present, its valence and the type of anion species are selected according to the valence of the complex portion composed mainly of metal M. Examples of -1-valent anion species include halide ions, NO ₃ ^- , SbF ₆ ^- , PF ₆ ^- , BF ₄ ^- , B(C ₆ F ₅ ) ₄ ^- , and the like. Examples of -2-valent anion species include SO ₄ ^2- , SO ₃ ^2- , CO ₃ ^2- , FeCl ₄ ^{2- ,} and the like. Among these, SbF ₆ ^- , PF ₆ ^- , BF ₄ ^- , B(C ₆ F ₅ ) ₄ ^- and the like, which have weak coordination to metals, are preferred from the standpoint of catalytic activity.

Specific preferred examples of the transition metal complex having a tetradentate ligand represented by general formula (1) include the following compounds. These are merely examples, and it is self-evident that the invention is not limited to these.

<Synthesis of Metal Complexes>
(1) Basic synthesis route The synthesis of the transition metal complex used in the method of the present invention can be carried out using a method known to those skilled in the art. That is, the transition metal complex can be obtained by reacting a compound that is a ligand with a complex precursor containing a transition metal. Conditions such as reaction temperature, reaction solvent, atmosphere, and time can be appropriately selected from known conditions depending on the ligand and complex precursor used. Since many of them are unstable to water and oxygen, it is preferable to carry out the reaction in a dehydrated and deoxygenated atmosphere. The synthesis method of the ligand can also be a method known to those skilled in the art. As a specific example, when the structure of the ligand includes a phosphine and an imine, a method of condensing an amine compound with an aldehyde having a phosphine as a raw material can be mentioned. The synthesis route of the metal complex obtained by reacting a complex precursor with a ligand can be arbitrarily determined from the structure of the target compound.

(2) Complex Precursor The complex precursor is a compound of a transition metal of Group 8 to 9. Preferred specific examples are compounds or complexes of divalent iron or ruthenium, monovalent or trivalent cobalt or rhodium, and in particular, metal halides such as iron chloride, cobalt chloride, and ruthenium chloride; acetates such as iron acetate and cobalt acetate; and complexes having ligands such as carbonyl, triphenylphosphine, acetylacetone, η4-cyclooctadiene, acetonitrile, and pyridine.

(3) Reaction with Complex Precursor The amount of the complex precursor used in the preparation of the transition metal complex used in the method of the present invention is usually in the range of 0.5 mol to 3 mol, preferably 0.7 mol to 1.5 mol, per mol of the ligand. The reaction between the ligand and the complex (complex synthesis reaction) may be carried out in a reactor used for copolymerization with the α-olefin, or in a vessel separate from the reactor. After the complex synthesis reaction, the complex may be isolated and extracted before use as a catalyst, or may be used as a catalyst without being isolated. In either case, it is desirable to determine the purity of the complex by NMR measurement.

<Second Component>
In a further embodiment, the olefin polymerization catalyst of the present invention may be a composition containing, as component (A), a transition metal complex represented by the general formula (1) or a transition metal complex having a ligand represented by the general formula (2) or (3), and, as component (B), a compound that reacts with component (A) to form an ion pair or an ion-exchangeable layered silicate.

(1) Compound that reacts with component (A) to form an ion pair An example of a compound that is one of the components (B) and that reacts with component (A) to form an ion pair is an organoaluminum oxy compound. The organoaluminum oxy compound has an Al-O-Al bond in the molecule, and the number of bonds is usually in the range of 1 to 100, preferably 1 to 50. Such an organoaluminum oxy compound is usually a product obtained by reacting an organoaluminum compound with water.
The reaction of organoaluminum with water is usually carried out in an inert hydrocarbon (solvent), which may be an aliphatic hydrocarbon, an alicyclic hydrocarbon, or an aromatic hydrocarbon such as pentane, hexane, heptane, cyclohexane, methylcyclohexane, benzene, toluene, or xylene, but is preferably an aliphatic or aromatic hydrocarbon.

The organoaluminum compound used in the preparation of the organoaluminum oxy-compound may be any of the compounds represented by the following general formula, but trialkylaluminum is preferably used.
(R ₁ ) _t Al(X ₃ ) _(3-t)
(In the above formula, _R1 represents a hydrocarbon group having 1 to 18 carbon atoms, preferably 1 to 12 carbon atoms, such as an alkyl group, an alkenyl group, an aryl group, or an aralkyl group, _X3 represents a hydrogen atom or a halogen atom, and t represents an integer satisfying 1≦t≦3.)
The alkyl group of the trialkylaluminum may be any of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, octyl, decyl, and dodecyl groups, with methyl and isobutyl being preferred, and methyl being particularly preferred. The above organoaluminum compounds may also be used in combination of two or more kinds.

The reaction ratio of water to the organoaluminum compound (water/Al molar ratio) is preferably 0.25/1 to 1.2/1, particularly 0.5/1 to 1/1, and the reaction temperature is usually in the range of -70°C to 100°C, preferably -20°C to 20°C. The reaction time is usually selected in the range of 5 minutes to 24 hours, preferably 10 minutes to 5 hours. As the water required for the reaction, not only simple water but also crystal water contained in copper sulfate hydrate, aluminum sulfate hydrate, etc., or a component that can generate water in the reaction system can be used. Among the above-mentioned organoaluminum oxy compounds, those obtained by reacting alkylaluminum with water are usually called aluminoxanes, and in particular, methylaluminoxane (including those substantially composed of methylaluminoxane (MAO)) is suitable as an organoaluminum oxy compound. Dry methylaluminoxane (DMAO) in a solid form obtained by distilling off the solvent from the MAO solution is also suitable.
Of course, as the organoaluminum oxy-compound, two or more of the above-mentioned organoaluminum oxy-compounds may be used in combination, and a solution in which the organoaluminum oxy-compound is dissolved or dispersed in the above-mentioned inert hydrocarbon solvent may be used.

Other specific examples of component (B) include borane compounds and borate compounds. More specific examples of the borane compounds include triphenylborane, tri(o-tolyl)borane, tri(p-tolyl)borane, tri(m-tolyl)borane, tris(o-fluorophenyl)borane, tris(p-fluorophenyl)borane, tris(m-fluorophenyl)borane, tris(2,5-difluorophenyl)borane, tris(3,5-difluorophenyl)borane, tris(4-trifluoromethylphenyl)borane, tris(3,5-ditrifluoromethylphenyl)borane, tris(2,6-ditrifluoromethylphenyl)borane, tris(pentafluorophenyl)borane, tris(perfluoronaphthyl)borane, tris(perfluorobiphenyl)borane, tris(perfluoroanthryl)borane, and tris(perfluorobinaphthyl)borane.

Among these, tris(3,5-ditrifluoromethylphenyl)borane, tris(2,6-ditrifluoromethylphenyl)borane, tris(pentafluorophenyl)borane, tris(perfluoronaphthyl)borane, tris(perfluorobiphenyl)borane, tris(perfluoroanthryl)borane, and tris(perfluorobinaphthyl)borane are more preferred, and even more preferred examples of the compounds include tris(2,6-ditrifluoromethylphenyl)borane, tris(pentafluorophenyl)borane, tris(perfluoronaphthyl)borane, and tris(perfluorobiphenyl)borane.

A first example of the borate compound is a compound represented by the following general formula:
[L1-H] ⁺ [B(R2)(R3)(X4)(X5)] ^-
In the above formula, L1 is a neutral Lewis base, and [L1-H] is a Bronsted acid such as ammonium, anilinium, or phosphonium.
Examples of ammonium include trialkyl-substituted ammonium such as trimethylammonium, triethylammonium, tripropylammonium, tri(t-butyl)ammonium, and tri(n-butyl)ammonium, and dialkylammonium such as di(n-propyl)ammonium and dicyclohexylammonium. Examples of anilinium include N,N-dialkylanilinium such as N,N-dimethylanilinium, N,N-diethylanilinium, and N,N-dimethyl-2,4,6-pentamethylanilinium.
Further, examples of the phosphonium include triarylphosphonium and trialkylphosphonium, such as triphenylphosphonium, tributylphosphonium, tri(methylphenyl)phosphonium, and tri(dimethylphenyl)phosphonium.

In the above general formula, R2 and R3 are the same or different aromatic or substituted aromatic hydrocarbon groups containing 6 to 20, preferably 6 to 16, carbon atoms, which may be linked to each other by a bridging group, and the substituent of the substituted aromatic hydrocarbon group is preferably an alkyl group such as a methyl group, an ethyl group, a propyl group, or an isopropyl group, or a halogen such as fluorine, chlorine, bromine, or iodine. Furthermore, X4 and X5 are a hydride group, a halide group, a hydrocarbon group containing 1 to 20 carbon atoms, or a substituted hydrocarbon group containing 1 to 20 carbon atoms in which one or more hydrogen atoms are replaced by a halogen atom.

Specific examples of compounds represented by the above general formula include tributylammonium tetra(pentafluorophenyl)borate, tributylammonium tetra(2,6-ditrifluoromethylphenyl)borate, tributylammonium tetra(3,5-ditrifluoromethylphenyl)borate, tributylammonium tetra(2,6-difluorophenyl)borate, tributylammonium tetra(perfluoronaphthyl)borate, dimethylanilinium tetra(pentafluorophenyl)borate, dimethylanilinium tetra(2,6-ditrifluoromethylphenyl)borate, dimethylanilinium tetra(3,5-ditrifluoromethylphenyl)borate, dimethylanilinium tetra(2,6-difluorophenyl)borate, dimethylanilinium tetra(perfluoronaphthyl)borate, triphenylphosphonium tetra(pentafluorophenyl)borate, triphenylphosphonium tetra(2,6-ditrifluoromethylphenyl)borate, Examples of such compounds include triphenylphosphonium tetra(3,5-ditrifluoromethylphenyl)borate, triphenylphosphonium tetra(2,6-difluorophenyl)borate, triphenylphosphonium tetra(perfluoronaphthyl)borate, trimethylammonium tetra(2,6-ditrifluoromethylphenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(2,6-ditrifluoromethylphenyl)borate, triethylammonium tetra(perfluoronaphthyl)borate, tripropylammonium tetra(pentafluorophenyl)borate, tripropylammonium tetra(2,6-ditrifluoromethylphenyl)borate, tripropylammonium tetra(perfluoronaphthyl)borate, tripropylammonium tetra(pentafluorophenyl)borate, and dicyclohexylammonium tetraphenylborate.

Among these, tributylammonium tetra(pentafluorophenyl)borate, tributylammonium tetra(2,6-ditrifluoromethylphenyl)borate, tributylammonium tetra(3,5-ditrifluoromethylphenyl)borate, tributylammonium tetra(perfluoronaphthyl)borate, dimethylanilinium tetra(pentafluorophenyl)borate, dimethylanilinium tetra(2,6-ditrifluoromethylphenyl)borate, dimethylanilinium tetra(3,5-ditrifluoromethylphenyl)borate, and dimethylanilinium tetra(perfluoronaphthyl)borate are preferred.

A second example of the borate compound is represented by the following general formula:
[L2] ⁺ [B(R2)(R3)(X4)(X5)] ^-
In the general formula, L2 is a carbocation, a methyl cation, an ethyl cation, a propyl cation, an isopropyl cation, a butyl cation, an isobutyl cation, a t-butyl cation, a pentyl cation, a tropinium cation, a benzyl cation, a trityl cation, a sodium cation, a proton, etc. R2, R3, X4, and X5 are as defined above.

Specific examples of the above compounds include trityl tetraphenylborate, trityl tetra(o-tolyl)borate, trityl tetra(p-tolyl)borate, trityl tetra(m-tolyl)borate, trityl tetra(o-fluorophenyl)borate, trityl tetra(p-fluorophenyl)borate, trityl tetra(m-fluorophenyl)borate, trityl tetra(3,5-difluorophenyl)borate, trityl tetra(pentafluorophenyl)borate, trityl tetra(2,6-ditrifluoromethylphenyl)borate, trityl tetra(3,5-ditrifluoromethylphenyl)borate, trityl tetra(perfluoronaphthyl)borate, and tropinium tetraborate. tropinium tetra(o-tolyl)borate, tropinium tetra(p-tolyl)borate, tropinium tetra(m-tolyl)borate, tropinium tetra(o-fluorophenyl)borate, tropinium tetra(p-fluorophenyl)borate, tropinium tetra(m-fluorophenyl)borate, tropinium tetra(3,5-difluorophenyl)borate, tropinium tetra(pentafluorophenyl)borate, tropinium tetra(2,6-ditrifluoromethylphenyl)borate, tropinium tetra(3,5-ditrifluoromethylphenyl)borate, tropinium tetra(perfluoronaphthyl)borate, NaBPh ₄ , NaB(o- _CH3 -Ph) ₄ , NaB(p- _CH3 -Ph) ₄ , NaB(m- _CH3 -Ph) ₄ , NaB(o-F-Ph) ₄ , NaB(p-F-Ph) ₄ , NaB(m-F-Ph) ₄ , NaB(3,5- _F2 - _Ph ) ₄ , NaB( _C6F3 ) ₄ , NaB(2,6-( _CF3 ) ₂ -Ph) ₄ , NaB( _3,5- ( _CF3 ) ₂ -Ph) ₄ , NaB( _C10F7 ) ₄ , HBPh _4.2 diethyl ether, HB(3,5- _F2 -Ph) _4.2 diethyl ether, HB _{( C6F5} ) Examples of the HB(C 10 H 7 ) _4.2 diethyl ether include HB(2,6-(CF ₃ ) ₂ -Ph) _4.2 diethyl ether, HB(3,5-(CF ₃ ) ₂ -Ph) _4.2 diethyl ether, and HB(C ₁₀ H ₇ ) _4.2 diethyl ether.

Among these, trityl tetra(pentafluorophenyl)borate, trityl tetra(2,6-ditrifluoromethylphenyl)borate, trityl tetra(3,5-ditrifluoromethylphenyl)borate, trityl tetra(perfluoronaphthyl)borate, tropinium tetra(pentafluorophenyl)borate, tropinium tetra(2,6-ditrifluoromethylphenyl)borate, tropinium tetra(3,5-ditrifluoromethylphenyl)borate, tropinium tetra(perfluoronaphthyl)borate, NaB(C ₆ F ₃ ) ₄ , NaB(2,6-(CF ₃ ) ₂ -Ph) ₄ , NaB(3,5-(CF ₃ ) ₂ -Ph) ₄ , NaB(C ₁₀ F ₇ ) ₄ , HB(C ₆ F ₅ ) _4.2 diethyl ether, HB(2,6-(CF ₃ ) ₂ Of _these , HB(3,5-(CF ₃ ) ₂ -Ph) _4.2 diethyl ether, HB(C ₁₀ H ₇ ) _4.2 diethyl ether are preferred.

Among these, trityl tetra(pentafluorophenyl)borate, trityl tetra(2,6-ditrifluoromethylphenyl)borate, tropinium tetra(pentafluorophenyl)borate, tropinium tetra(2,6-ditrifluoromethylphenyl)borate, NaB(C ₆ F ₃ ) ₄ , NaB(2,6-(CF ₃ ) ₂ -Ph) ₄ , HB(C ₆ F ₅ ) _4.2 diethyl ether, HB(2,6-(CF ₃ ) ₂ -Ph) _4.2 diethyl ether, HB(3,5-(CF ₃ ) ₂ -Ph) _4.2 diethyl ether, and HB(C ₁₀ H ₇ ) _4.2 diethyl ether are more preferable.

Among the above-listed compounds, it is preferable that component (B) is an aluminoxane or a boron compound.

(2) Ion-exchangeable layered silicate Further, a specific example of component (B) is ion-exchangeable layered silicate (hereinafter, sometimes abbreviated as "silicate"). Ion-exchangeable layered silicate refers to a silicate compound that has a crystal structure in which faces formed by ionic bonds are stacked in parallel with each other by binding force, and the ions contained therein are exchangeable. Various types of silicate are known, and specific examples are described in "Clay Mineralogy" by Haruo Shiramizu, Asakura Publishing (1995).
In the present invention, the ion-exchangeable layered silicate of component (B) is preferably one belonging to the smectite group, and specific examples thereof include montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, etc. Among these, montmorillonite is preferred from the viewpoint of increasing the polymerization activity and molecular weight of the copolymer portion.

Most silicates are naturally produced as the main component of clay minerals, and therefore often contain impurities other than ion-exchangeable layered silicates (such as quartz and cristobalite), and the smectite group silicates used in the present invention may contain impurities.
The silicate may be treated with an acid and/or a salt, in which case the corresponding acid and base may be mixed to form a salt in the reaction system.

As component (B), a mixture of the above-mentioned organoaluminum oxy compound with a borane compound, a borate compound, or an ion-exchangeable layered silicate can also be used. Furthermore, each of them may be used alone, or two or more of them may be used.

<Third Component>
Yet another embodiment of the present invention contains an alkylaluminum compound as component (C) in addition to the components (A) and (B). An example of the alkylaluminum compound used as component (C) is represented by the following general formula:
Al(R4) _a X _(3-a)
In the general formula, R4 is a hydrocarbon group having 1 to 20 carbon atoms, X is a hydrogen atom, a halogen atom, an alkoxy group, or a siloxy group, and a is a number greater than 0 and equal to or less than 3.
Specific examples of the organoaluminum compound represented by the general formula include trialkylaluminums such as trimethylaluminum, triethylaluminum, tripropylaluminum, and triisobutylaluminum, and halogen- or alkoxy-containing alkylaluminums such as diethylaluminum monochloride and diethylaluminum monomethoxide.

Of these, triisobutylaluminum is preferred. Two or more of the above organoaluminum compounds may be used in combination. The above aluminum compounds may be modified with alcohol, phenol, or the like. Examples of these modifying agents include methanol, ethanol, 1-propanol, isopropanol, butanol, phenol, 2,6-dimethylphenol, and 2,6-di-t-butylphenol, with preferred examples being 2,6-dimethylphenol and 2,6-di-t-butylphenol.

<Method of preparing catalyst composition>
In one embodiment of the present invention, the method for preparing an olefin polymerization catalyst includes, for example, contacting component (A) with, if necessary, components (B) and (C). The specific method, such as the contacting order, is not particularly limited, but the following methods can be exemplified.
(i) A method of contacting component (A) with component (B) and then adding component (C). (ii) A method of contacting component (A) with component (C) and then adding component (B). (iii) A method of contacting component (B) with component (C) and then adding component (A). (iv) A method of simultaneously contacting components (A), (B), and (C).
Furthermore, among the components, different kinds of components may be used as a mixture, or may be contacted separately in a different order. This contact may be carried out not only during catalyst preparation, but also during prepolymerization with olefins or during polymerization of olefins. Also, the components may be divided and contacted with each component, for example, by contacting component (B) with component (C) and then adding a mixture of component (A) and component (C).

The contact of the above components (A), (B), and (C) is preferably carried out in an inert gas such as nitrogen and in an inert hydrocarbon solvent such as pentane, hexane, heptane, toluene, or xylene. The contact can be carried out at a temperature between -20°C and the boiling point of the solvent, and is particularly preferably carried out at a temperature between room temperature and the boiling point of the solvent.

<Polymerization method>
(1) Monomer The olefin polymerization catalyst containing the above-mentioned Group 8 or Group 9 complex can be used for homopolymerization of an α-olefin or copolymerization of two or more kinds of α-olefins. α-olefins include those having 2 to 30 carbon atoms, preferably 2 to 8 carbon atoms, and specific examples thereof include ethylene, propylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene. More preferred are ethylene and propylene. Two or more kinds of α-olefins can also be copolymerized as the α-olefins. The copolymerization may be any of alternating copolymerization, random copolymerization, and block copolymerization. Of course, it is also possible to use a small amount of a comonomer other than an α-olefin. In this case, examples of the comonomer include compounds having a polymerizable double bond, such as styrenes such as styrene, 4-methylstyrene, and 4-dimethylaminostyrene; dienes such as 1,4-butadiene, 1,5-hexadiene, 1,4-hexadiene, and 1,7-octadiene; cyclic compounds such as norbornene and cyclopentene; and oxygen-containing compounds such as hexenol, hexenoic acid, methyl octenoate, methyl acrylate, methyl methacrylate, methoxystyrene, and vinyl acetate.

(2) Polymerization Method The polymerization reaction can be carried out in the presence of the above-mentioned olefin polymerization catalyst, preferably by slurry polymerization, bulk polymerization, or gas phase polymerization. In the case of slurry polymerization, ethylene or the like is polymerized in the presence of an inert hydrocarbon solvent selected from aliphatic hydrocarbons such as isobutane, hexane, and heptane, aromatic hydrocarbons such as benzene, toluene, and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, in a state substantially free of oxygen and water. Bulk polymerization in which liquid monomers such as liquid ethylene and liquid propylene are also used as a solvent is also one of the preferred modes.

The polymerization conditions are generally as follows: temperature: 0°C to 250°C, preferably 20°C to 110°C, more preferably 60°C to 100°C; pressure: normal pressure to 10 MPa, preferably normal pressure to 4 MPa, more preferably 0.5 MPa to 2 MPa; polymerization time: 5 minutes to 10 hours, preferably 5 minutes to 5 hours.

A component for removing water, i.e., a scavenger, may be added to the polymerization system without any problems. Examples of such scavengers include organoaluminum compounds such as trimethylaluminum, triethylaluminum, triisobutylaluminum, and tri-n-octylaluminum, the organoaluminum oxy compounds, modified organoaluminum compounds containing a branched alkyl, organozinc compounds such as diethylzinc and dibutylzinc, organomagnesium compounds such as diethylmagnesium, dibutylmagnesium, and ethylbutylmagnesium, and Grignard compounds such as ethylmagnesium chloride and butylmagnesium chloride.
Of these, triethylaluminum, triisobutylaluminum, ethylbutylmagnesium, and tri-n-octylaluminum are preferred, with triethylaluminum and triisobutylaluminum being particularly preferred.

The olefin polymerization catalyst of the present invention can be used without problems in multi-stage polymerization methods with two or more stages in which the polymerization conditions are different from each other.

The present invention will be specifically explained below using examples to demonstrate the rationality and significance of the configuration of the present invention and its superiority over the prior art.

<Evaluation method>

(1) NMR measurement of metal complexes
[Sample preparation]
In a nitrogen-substituted glove box, 20 mg of the complex sample, 0.7 ml of deuterated acetonitrile, and 5.0 mg of tris(orthotoluyl)phosphine as an arbitrary internal standard were placed in an NMR sample tube with an inner diameter of 5 mm, sealed, and then stirred at room temperature for 10 minutes to dissolve uniformly. The resulting solution was used for ³¹ P-NMR and ¹ H-NMR measurements.
[ ^31P -NMR measurement]
NMR measurements were performed using an AV400 NMR instrument from Bruker Japan Ltd. equipped with a normal probe of 5 mmφ. The measurement conditions for ³¹ P-NMR were a sample temperature of 30°C, a pulse angle of 45°, a pulse interval of 2.76 seconds, and an accumulation count of 256. The chemical shift was determined based on the external standard of the instrument. The purity of the complex was determined by calculating the molar concentration of the complex from the peak area ratio with respect to the internal standard substance, and converting this into the complex concentration in 20 mg of sample. However, when there was only one peak derived from the target complex, the purity was determined to be 100%.
[ ^1H -NMR Measurement]
The NMR measurements were performed using an AV400 NMR instrument from Bruker Japan Ltd., equipped with a normal probe of 5 mmφ. ^{The 1} H-NMR measurement conditions were a sample temperature of 30° C., a pulse angle of 45°, a pulse interval of 2.76 seconds, and an accumulation count of 16. The chemical shift was determined based on the acetonitrile peak in deuterated acetonitrile.
(2) Molecular weight and molecular weight distribution (Mw, Mn, Q value)
(Measurement conditions) Model used: Waters 150C Detector: FOXBORO MIRAN1A IR detector (measurement wavelength: 3.42 μm) Measurement temperature: 140° C. Solvent: orthodichlorobenzene (ODCB) Column: Showa Denko AD806M/S (3 columns) Flow rate: 1.0 mL/min Injection volume: 0.2 mL
(Preparation of Samples) A 1 mg/mL solution of the sample was prepared using ODCB (containing 0.5 mg/mL BHT (2,6-di-t-butyl-4-methylphenol)) and dissolved at 140° C. for about 1 hour.
(Calculation of molecular weight) The standard polystyrene method was used, and the conversion from retention volume to molecular weight was performed using a calibration curve of standard polystyrene that had been prepared in advance. All of the standard polystyrenes used were brands manufactured by Tosoh Corporation, and were F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, and A1000. 0.2 mL of a solution dissolved in ODCB (containing 0.5 mg/mL BHT) was injected so that each was 0.5 mg/mL, and a calibration curve was created. The calibration curve used a cubic equation obtained by approximating with the least squares method. The viscosity equation [η] = K × M ^α used for conversion to molecular weight was the following value.
PS: K=1.38×10 ⁻⁴ , α=0.7
PE: K=3.92×10 ⁻⁴ , α=0.733
PP: K=1.03×10 ⁻⁴ , α=0.78

The synthesis route of the transition metal complex in the present invention is shown below. For the synthesis, reference was made to the non-patent literature: Sui-Seng et al. Angew. Chem. Int. Ed. 2008, 47, 930. In the following synthesis examples, unless otherwise specified, the operations were performed under an inert gas atmosphere, and the solvents used were dehydrated and deoxygenated.

シュレンク管に（Ｓ，Ｓ）－Ｎ，Ｎ－ビス［２－（ジフェニルホスフィノ）ベンジリデン］シクロヘキサン－１，２－ジアミンを３００ｍｇ（０．４５５ｍｍｏｌ）量り取り、アセトニトリルを１０ｍL加えた。ここに、アセトニトリル２ｍLに溶解させた塩化鉄（２）１１５ｍｇ（０．９１ｍｍｏｌ）を室温で加え、１時間撹拌した。その後溶媒を２ｍL程度残して留去し、残留物をエーテル２０ｍLで洗浄した。洗浄後、溶媒を完全に留去してからクロロホルムを１５ｍL加え、不溶物をガラスフィルターで除去した。回収した溶液を完全に乾固し、クロロホルム５ｍLとヘキサン２０ｍLで再結晶することで２１１ｍｇの固体を得た。
この錯体Ａの^３１Ｐ－ＮＭＲ（^３１Ｐ－ＮＭＲ（１６２ＭＨｚ、ＣＤ_３ＣＮ））のチャートを図１に、^１Ｈ－ＮＭＲのチャートを図２に示した。５２．４ｐｐｍに鋭利なシングレットピークが観測できた。純度は１００％であった。 Example 1
(1) Synthesis Example 1: Complex A

300 mg (0.455 mmol) of (S,S)-N,N-bis[2-(diphenylphosphino)benzylidene]cyclohexane-1,2-diamine was weighed out in a Schlenk flask, and 10 mL of acetonitrile was added. 115 mg (0.91 mmol) of iron(2) chloride dissolved in 2 mL of acetonitrile was added at room temperature and stirred for 1 hour. After that, the solvent was distilled off leaving about 2 mL, and the residue was washed with 20 mL of ether. After washing, the solvent was completely distilled off, and 15 mL of chloroform was added, and insoluble matter was removed with a glass filter. The collected solution was completely dried and recrystallized with 5 mL of chloroform and 20 mL of hexane to obtain 211 mg of solid.
^{The 31} P-NMR ( ³¹ P-NMR (162 MHz, CD ₃ CN)) chart of this complex A is shown in FIG. 1, and the ¹ H-NMR chart is shown in FIG. 2. A sharp singlet peak was observed at 52.4 ppm. The purity was 100%.

(2) Polymerization Example Homopolymerization of Ethylene Complex A (18 mg) was dissolved in 10 mL of toluene, and 20 mL of MMAO-3A/hexane solution (Al = 5.9 wt%) was added thereto, and the mixture was stirred at 25 ° C for 5 minutes to prepare a complex solution. 1000 mL of toluene was introduced into a stirring autoclave with an internal volume of 3 L, and then 20 mL of MMAO-3A/hexane solution was added. The inside of the reactor was replaced with ethylene, and the temperature was raised to 60 ° C. The pressure was raised to 2.5 MPa with ethylene. The complex solution previously prepared was injected therein with N _2. The ethylene pressure was maintained at 2.5 MPa for 60 minutes, and ethanol was injected to stop the polymerization. The obtained slurry was poured into hydrochloric acid/ethanol, filtered, washed with ethanol, and dried to obtain 0.2 g of polymer. The melting point of the obtained polymer was 135.1 ° C, and the weight average molecular weight was 2,477,000.

シュレンク管にＮ，Ｎ－ビス［ｏ－（ジフェニルホスフィノ）ベンジリデン］エチレンジアミンを３００ｍｇ（０．５０ｍｍｏｌ）量り取り、アセトニトリルを１１ｍＬ加えた。ここに、アセトニトリル３ｍＬに溶解させた塩化鉄（２）１２７ｍｇ（１．０ｍｍｏｌ）を室温で加え、３時間撹拌した。その後溶媒を１ｍＬ程度残して留去し、残留物にエーテル３０ｍＬを加えて沈殿物を析出させ、ガラスフィルターを用いて沈殿物を回収した。沈殿物をクロロホルム１５ｍＬで洗浄した後、クロロホルム１．２ｍＬとヘキサン６ｍＬで再結晶することで１１４ｍｇの固体（錯体Ｂ）を得た。
この錯体Ｂの^３１Ｐ－ＮＭＲ（^３１Ｐ－ＮＭＲ（１６２ＭＨｚ、ＣＤ_３ＣＮ））のチャートを図３に、^１Ｈ－ＮＭＲのチャートを図４に示した。^３１Ｐ－ＮＭＲからは５３．５ｐｐｍに鋭利なシングレットピークが観測された。錯体以外のピークが観測されないことから、今回準備された錯体が高純度であることが確認できた。純度は１００％であった。 Example 2
(1) Synthesis Example 2: Complex B

300 mg (0.50 mmol) of N,N-bis[o-(diphenylphosphino)benzylidene]ethylenediamine was weighed out in a Schlenk flask, and 11 mL of acetonitrile was added. 127 mg (1.0 mmol) of iron chloride (2) dissolved in 3 mL of acetonitrile was added at room temperature and stirred for 3 hours. The solvent was then distilled off leaving about 1 mL, and 30 mL of ether was added to the residue to precipitate a precipitate, which was then collected using a glass filter. The precipitate was washed with 15 mL of chloroform and then recrystallized with 1.2 mL of chloroform and 6 mL of hexane to obtain 114 mg of a solid (complex B).
^{The 31} P-NMR ( ³¹ P-NMR (162 MHz, CD ₃ CN)) chart of this complex B is shown in FIG. 3, and the ¹ H-NMR chart is shown in FIG. 4. A sharp singlet peak was observed at 53.5 ppm from ^{the 31} P-NMR. Since no peaks other than those of the complex were observed, it was confirmed that the complex prepared this time was of high purity. The purity was 100%.

(2) Polymerization Example Ethylene Homopolymerization Ethylene polymerization was carried out in the same manner as in Polymerization Example 1 (2) except that the complex used was changed to Complex B. The amount of polyethylene obtained was 0.84 g. The weight average molecular weight of the obtained polymer was 539,000.

(Comparative Example 1)
An Fe(II) complex having a pyridyldiimine ligand described in Non-Patent Document 2 was synthesized according to Non-Patent Document 2. An attempt was made to measure ¹ H-NMR on the obtained complex, but this was not possible due to magnetism, and the purity of the complex could not be determined by NMR measurement.
(Comparative Example 2)
An Fe(III) complex having a bisoxazolidylphenylamine ligand described in Example 1 of Patent Document 4 was synthesized according to Patent Document 4. An attempt was made to measure ¹ H-NMR of the obtained complex, but this was not possible due to magnetism, and the purity of the complex could not be determined by NMR measurement.

Claims (3)

A method for producing an olefin polymer, comprising a step of polymerizing an olefin monomer using a catalyst containing a complex represented by the following general formula (1) having a low-spin metal atom of Group 8 or 9 of the periodic table as a polymerization catalyst component:

[In the general formula (1),
M is iron with an oxidation state of +2, ruthenium with an oxidation state of +2, cobalt with an oxidation state of +1, or rhodium with an oxidation state of +1;
n represents an integer of 0 or 1;
R ^1a , R ^1b , R ^1c and R ^1d each independently represent a hydrocarbon group having 3 to 12 carbon atoms;
R ^2a and R ^2b each independently represent a hydrogen atom or a hydrocarbon having 1 to 3 carbon atoms;
R ^3a , R ^3b , R ^3c , R ^3d , R ^3e , R ^3f , R ^3g and R ^3h each independently represent a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a hydrocarbon group having 1 to 30 carbon atoms substituted with a halogen atom, a hydrocarbon group having 2 to 30 carbon atoms substituted with an alkoxy group, and a silyl group substituted with a hydrocarbon group having 1 to 30 carbon atoms;
R ^4a and R ^4b each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, or R ^4a and R ^4b are bonded to each other to form a ring;
L represents a metal auxiliary ligand, and when M is iron having an oxidation number +2 or ruthenium having an oxidation number +2, one of them is a neutral monodentate ligand and the other is an anionic monodentate ligand, or both are neutral monodentate ligands, when M is cobalt having an oxidation number +1 or rhodium having an oxidation number +1, both are neutral monodentate ligands;
X is a counter anion species having a valence of −1 or 2. 2. The method for producing an olefin polymer according to claim 1 , wherein M is iron having an oxidation number of +2 or ruthenium having an oxidation number of +2. 3. The process for producing an olefin polymer according to claim 1 or 2 , wherein the weight average molecular weight of the obtained olefin polymer is 100,000 or more and 10,000,000 or less.