FR3108610A1 - Cationic yttrium organometallic complex - Google Patents

Abstract

The present disclosure relates to novel rare earth complexes which may be useful in processes for the polymerization of alkenes, conjugated dienes or mixtures thereof. In particular, the present disclosure relates to a cationic yttrium complex and its preparation process, as well as a catalyst system comprising the cationic yttrium complex.

Description

Organometallic complex of cationic yttrium

FIELD OF THE INVENTION

The present invention relates to novel rare earth complexes which may be useful in processes for the polymerization of alkenes, conjugated dienes or mixtures thereof. In particular, the present invention relates to a cationic yttrium complex and its preparation process, as well as a catalytic system comprising this cationic yttrium complex.

TECHNOLOGICAL BACKGROUND

Transition metal complexes are known to be useful in polymerization reactions of alkenes and conjugated dienes. Thus, US 7,300,903 discloses catalytic systems comprising organometallic complexes, in which the transition metals are chosen from group 3 to 11 of the periodic table, comprising one or more ligands from the salicylaldimine family. These systems can be used in the polymerization of alkenes. Yttrium complexes are not specifically described. FR 2 944 800 discloses, for its part, a catalytic system which can be used in the stereospecific polymerizations of conjugated dienes. The catalyst system may include a rare earth complex such as yttrium tri[N,N-bis-(trimethylsilyl)amide], an alkylating agent such as triisobutyl aluminum and a compound based on an aromatic ring such as N-(2,6-diisopropyl)phenyl-3,5-di-tert-butylsalicylaldimine.

Although a large number of catalytic complexes and systems exist, a need remains to have new organometallic complexes that can be used in catalytic systems that are useful in processes for the polymerization of alkenes, conjugated dienes or their mixtures.

BRIEF DESCRIPTION OF THE INVENTION

In a first aspect, the present invention relates to an organometallic complex of cationic yttrium of formula (I):

[ _YP2 (L) _z ] ⁺ [A] ^- (I)

in which :

Y is an yttrium atom;

P is a ligand represented by the formula (a):

(To)

in which :

n is an integer ranging from 0 to 4 inclusive;

each R represents, independently of one another, a halogen atom, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C ₂₀ cycloaliphatic radical, substituted or unsubstituted, or an aromatic radical C ₆ -C ₂₀ , substituted or unsubstituted;

x is an integer ranging from 0 to 6 inclusive;

y is an integer ranging from 0 to 6 inclusive;

R ¹ and R ² independently represent a hydrogen atom, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C _{20 cycloaliphatic radical,} substituted or unsubstituted, or a C ₆ -C ₂₀ aromatic radical, substituted or unsubstituted;

* denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond;

L represents a Lewis base;

z is a number ranging from 0 to 4 inclusive; And

[A] ^- is a non-coordinating anion.

In a second aspect, the present invention relates to a process for the preparation of an organometallic complex of cationic yttrium as presently described comprising the steps of:

reacting an yttrium halide in the presence of a Lewis base L and a compound of formula MP in which M denotes an alkali metal to give a precursor of formula (II):

Y (L) _z P ₃ (II)

in which :

Y is an yttrium atom,

z denotes an integer or not ranging from 0 to 4, and

P denotes a ligand represented by formula (a) as defined in any one of claims 1 to 6;

reacting the precursor of formula (II) with a cationizing agent to give an organometallic complex of cationic yttrium.

In a third aspect, the present invention relates to a catalyst system comprising a cationic yttrium organometallic complex as presently described and a co-catalyst, in which the molar ratio (co-catalyst) / (yttrium organometallic complex) is greater than or equal to 5.

DEFINITIONS

In this description, the following terms have the following meanings, unless otherwise indicated:

The expression “C _x -C _y ” for a hydrocarbon radical means that said radical comprises x to y carbon atoms.

The terms “radical”, “group” and “grouping” are equivalent and interchangeable.

“aliphatic radical” designates a hydrocarbon radical, linear or branched, saturated or unsaturated, comprising from 1 to 20 carbon atoms. Examples of aliphatic hydrocarbon radicals include C ₁ -C ₂₀ alkyl groups, C ₂ -C ₂₀ alkenyl groups and C ₂ -C ₂₀ alkynyl groups.

"alkyl" denotes a saturated, linear or branched hydrocarbon radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10 carbon atoms, for example the methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl radicals , octyls, nonyls and decyls.

"alkenyl" denotes a hydrocarbon radical comprising at least one double bond, said radical being linear or branched and comprising from 2 to 20 carbon atoms, preferably from 2 to 6 carbon atoms, for example the ethenyl, vinyl, butenyl or 2-propen-1-yl (allyl).

"alkynyl" denotes a hydrocarbon radical comprising at least one triple bond, said radical being linear or branched and comprising from 2 to 20 carbon atoms, preferably from 2 to 6 carbon atoms, for example the ethynyl, propynyl and butynyl radical.

“heteroaliphatic radical” designates an aliphatic radical comprising from 1 to 20 carbon atoms in which one or more carbon atoms can be independently replaced by a heteroatom chosen preferably from oxygen, sulphur, silicon and nitrogen. Examples of heteroaliphatic radicals include heteroalkyls among which ether radicals.

“Cycloaliphatic radical” or “carbocyclic radical” designates a mono- or polycyclic non-aromatic hydrocarbon radical comprising from 3 to 20 atoms, saturated or partially unsaturated. Examples of cycloaliphatic radicals include C ₃ -C ₂₀ cycloalkyl groups and C ₃ -C ₂₀ cycloalkenyl groups.

“Cycloalkyl” designates a monocyclic saturated hydrocarbon radical comprising from 3 to 20 carbon atoms, preferably from 3 to 10 carbon atoms. Examples of cycloalkyl radicals include the cyclopentyl, cyclohexyl and cycloheptyl radical.

"Cycloalkenyl" denotes a monocyclic hydrocarbon radical comprising at least one double bond and comprising from 3 to 20 carbon atoms, preferably from 3 to 10 carbon atoms.

“aromatic radical” designates a mono- or polycyclic aromatic radical comprising from 5 to 20 members which may comprise one or more heteroatoms chosen from nitrogen, oxygen, sulfur and phosphorus. Examples of aromatic radicals include aryl and heteroaryl groups.

“aryl” designates a mono- or polycyclic aromatic hydrocarbon radical comprising from 6 to 20 carbon atoms, preferably from 6 to 10 carbon atoms. Examples of aryl radicals include the phenyl radical and the naphthyl radical.

“heteroaryl” designates a mono- or polycyclic aromatic radical comprising from 5 to 20 members and comprising, in addition to carbon atoms, one or more heteroatoms, identical or different, chosen from nitrogen, oxygen, sulfur, and phosphorus.

"aralkyl" denotes a group comprising an alkyl radical, one hydrogen atom of which is substituted by an aryl radical, the alkyl and aryl radicals being as defined above.

“heteroaralkyl” denotes a group comprising an alkyl radical, one hydrogen atom of which is substituted by a heteroaryl radical, the alkyl and heteroaryl radicals being as defined above.

The notation “(halo)” preceding a radical signifies that the latter includes or does not include a halogen atom. For example, the (halo)aryl radical encompasses the aryl radical and the halogenated aryl radical.

By “halogen atom” is meant an atom chosen from chlorine, bromine, iodine and fluorine.

DETAILED DESCRIPTION OF THE INVENTION

Yttrium organometallic complex

The organometallic yttrium complex according to the present invention is a cationic complex of formula (I):

[ _YP2 (L) _z ] ⁺ [A] ^- (I)

in which :

Y is an yttrium atom;

P is a ligand represented by the formula (a):

(To)

in which :

n is an integer ranging from 0 to 4 inclusive;

each R represents, independently of one another, a halogen atom, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C ₂₀ cycloaliphatic radical, substituted or unsubstituted, an aromatic C ₆ -C ₂₀ , substituted or unsubstituted;

x is an integer ranging from 0 to 6 inclusive;

y is an integer ranging from 0 to 6 inclusive;

R ¹ and R ² independently represent a hydrogen atom, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C _{20 cycloaliphatic radical,} substituted or unsubstituted, or a C ₆ -C ₂₀ aromatic radical, substituted or unsubstituted;

* denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond;

L represents a Lewis base;

z is a number ranging from 0 to 4 inclusive; And

[A] ^- is a non-coordinating anion.

The aliphatic, cycloaliphatic and aromatic radicals defining R, R ¹ and R ² can be substituted by one or more substituents independently chosen from halogen atoms, C 3 -C 6 (halo)cycloalkyls, C ₃ -C ₆ (halo)aryls, C ₆ -C ₁₄ , cyano, nitro, C ₁ -C ₁₀ -alkoxy, oxo, C ₁ -C ₁₀ -alkoxycarbonyl, di-C ₁ -C ₁₀ -alkylcarbamoyl, di-C ₁ -C ₁₀ -alkylamino functional groups and phosphorus radicals not comprising an acid proton.

The cycloaliphatic and aromatic radicals defining R, R ¹ and R ² may additionally or alternatively be substituted by one or more substituents independently chosen from C ₁ -C ₁₀ (halo)alkyls, C ₇ -C (halo)aralkyls ₁₂ , C ₂ -C ₁₀ (halo)alkenyls and C ₂ -C ₁₀ (halo)alkynyls.

In certain embodiments, in formula (a) above, each R independently of one another represents a halogen atom or a C ₁ -C ₂₀ alkyl radical, preferably a C 1 -C 20 alkyl radical ₁ -C _10, for example a methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl or tert-butyl radical.

In certain embodiments, in formula (a) above, n is equal to 0, 1 or 2, more particularly 0.

In certain embodiments, in formula (a) above, n is equal to 1 and R represents a C ₁ -C ₁₀ alkyl radical, for example a methyl, ethyl, n-propyl, iso-propyl, n-butyl or tert-butyl.

In some embodiments, in formula (a) above, x is 0 or 1.

In some embodiments, in formula (a) above, y is 0 or 1.

In certain embodiments, in formula (a) above, x is equal to 0 and y is equal to 0.

In some embodiments, in formula (a) above, R¹represents a hydrogen atom, a C alkyl radical₁-VS₂₀, preferably in C₁-VS₁₀, a C cycloalkyl radical₃-VS₂₀, preferably in C₃-VS₁₀, or an aryl radical at C₆-VS₂₀, preferably in C₆-VS₁₀, said alkyl, cycloaliphatic and aromatic radicals possibly being substituted by one or more substituents as described above, more particularly substituted by one or more substituents independently chosen from among halogen atoms or C alkyl radicals₁-VS₅.

In certain embodiments, R ¹ represents a C ₁ -C ₂₀ , preferably C ₁ -C ₁₀ , or even C ₁ -C ₅ alkyl radical, for example methyl, ethyl, propyl or isopropyl.

In certain embodiments, in formula (a) above, R ¹ represents a C ₆ -C ₁₀ aromatic radical, more particularly a phenyl or naphthyl radical, which may be substituted by one or more substituents as described below. above, more particularly substituted with one or more substituents independently chosen from halogen atoms or C ₁ -C ₅ alkyl radicals.

In certain embodiments, in formula (a) above, R ¹ represents a phenyl, tolyl, mesityl, xylyl, di( o -iso-propyl)phenyl or naphthyl radical, preferably di( o -iso-propyl )phenyl.

In some embodiments, in formula (a) above, R²represents a hydrogen atom, a C alkyl radical₁-VS₂₀, preferably in C₁-VS₁₀, a C cycloalkyl radical₃-VS₂₀, preferably in C₃-VS₁₀, or an aryl radical at C₆-VS₂₀, preferably in C₆-VS₁₀, said alkyl, cycloaliphatic and aromatic radicals possibly being substituted by one or more substituents as described above, more particularly substituted by one or more substituents independently chosen from among halogen atoms or C alkyl radicals₁-VS₅.

In certain embodiments, R ² represents a C ₁ -C ₂₀ , preferably C ₁ -C ₁₀ , or even C ₁ -C ₅ alkyl radical, for example methyl, ethyl, propyl or isopropyl.

In certain embodiments, R ¹ and R ² represent a C ₁ -C ₂₀ , preferably C ₁ -C ₁₀ , or even C ₁ -C ₅ alkyl radical, for example methyl, ethyl, propyl or isopropyl.

In certain embodiments, the ligand P is a ligand of formula (a-1):

(a-1)

in which :

- R ¹ , R ² , R and n are as described above;

- * denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond.

In certain embodiments, the ligand P is a ligand of formula (a-2):

(a-2)

in which :

R and n are as described above;

* denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond.

In certain embodiments, the ligand P is a ligand of formula (a-2) in which n is equal to 0.

In formula (I) above, L represents a Lewis base. The Lewis base can be chosen from ethers, amines, phosphates and thioethers. Examples of ethers include diethyl ether, 1,2-diethoxyethane, 1,2-di-n-propoxyethane, 1,2-di-n-butoxyethane, tetrahydrofuran, dioxane, and tetrahydropyran. Examples of amines include compounds of the family of trialkylamines and aromatic amines such as pyridine or piperazine and its derivatives. An example of a phosphate includes tri-n-butylphosphate. Examples of thioethers include compounds of the dialkyl sulfide family, such as dimethyl sulfide.

In certain embodiments, in formula (I) above, L represents an ether, more particularly tetrahydrofuran.

Those skilled in the art will understand that the number z, corresponding to the number of L present in the complex, depends on the method of preparation of the yttrium compound used during the synthesis of the complex according to the invention. This number can be an integer, or not, and varies from 0 to 4.

In formula (I) above, [A] ^- is a non-coordinating anion. By non-coordinating anion is meant a counter-ion of the cationic organometallic complex of yttrium. The non-coordinating anion is typically large and sufficiently labile to allow displacement by a monomer to be polymerized.

In some embodiments, the non-coordinating anion has the following formula:

B(Ri) ₄ ^-

in which B is the boron atom and each Ri represents, independently of one another, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C ₂₀ cycloaliphatic radical, substituted or unsubstituted, or a C ₆ -C ₂₀ aromatic radical, substituted or unsubstituted.

In certain embodiments, the aliphatic radical, the cycloaliphatic radical and the C ₆ -C ₂₀ aromatic radical may be substituted by one or more substituents independently chosen from halogen atoms, C ₁ -C ₅ alkyl groups or C ₁ -C ₅ perfluoroalkyl groups.

In certain embodiments, R represents an aryl group which may be substituted by one or more substituents independently chosen from halogen atoms, C ₁ -C ₅ alkyl groups or C ₁ -C ₅ perfluoroalkyl groups.

In certain embodiments, R 1 independently represents a phenyl, tolyl, mesityl, xylyl or pentafluorophenyl group.

In certain embodiments, the four Ri are pentafluorophenyl groups.

Examples of non-coordinating anions include alkyltris(pentafluorophenyl) borate, tetrakis(pentafluorophenyl)borate and tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

In certain embodiments, in formula (I) above, [A] ^- is tetrakis(pentafluorophenyl)borate.

In certain embodiments, the organometallic yttrium complex according to the present invention is a cationic complex of formula (I):

[ _YP2 (L) _z ] ⁺ [A] ^- (I)

in which :

Y is an yttrium atom;

P is a ligand of formula (a-1):

(a-1)

in which :

- R ¹ , R ² , R and n are as described above;

- * denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond;

- L is a Lewis base which can be chosen from ethers, amines, phosphates and thioethers, preferably L is tetrahydrofuran;

- z is as described above;

-[A] ^- is as described above, preferably [A] ^- is tetrakis(pentafluorophenyl)borate.

In certain embodiments, the organometallic yttrium complex according to the present invention is a cationic complex of formula (I):

[ _YP2 (L) _z ] ⁺ [A] ^- (I)

in which :

- Y is an yttrium atom;

- P is a ligand represented by the formula (a-2):

(a-2)

in which :

R and n are as described above, more particularly n is 0;

* denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond;

L is a Lewis base which can be chosen from ethers, amines, phosphates and thioethers, preferably L is tetrahydrofuran;

z is as described above;

[A] ^- is as described above, preferably [A] ^- is tetrakis(pentafluorophenyl)borate.

Preparation of the organometallic complex of yttrium

The organometallic complex of cationic yttrium of formula (I) can be prepared according to a process comprising the following steps:

reacting an yttrium halide, for example yttrium chloride, in the presence of a Lewis base L and a compound of formula MP in which M denotes an alkali metal (for example Li or K) to give a precursor of formula (II):

Y (L) _z P ₃ (II)

in which Y is an yttrium atom and z denotes a number ranging from 0 to 4;

reacting the precursor of formula (II) in the presence of a Lewis base L with a cationizing agent to give an organometallic complex of cationic yttrium of formula (I).

The cationizing agent employed in step (b) of the processes reacts with the yttrium compound to form an ion pair. Ionic compounds are preferred as cationizing agent.

The cationizing agent can be a compound of the formula [A] ^- [Q] ⁺ in which the anion [A] ^- is as described above and the cation [Q] ⁺ is a proton, a carbonium cation and its substituted derivatives (primary, secondary or tertiary carbocation), an ammonium cation and its substituted derivatives (primary, secondary, tertiary, quaternary ammonium), an oxonium cation and its substituted derivatives, a phosphonium cation, a cycloheptyltrienyl cation, a ferrocenium cation having a transition metal, or the like.

Examples of carbonium cations include but are not limited to tri-substituted carbonium cations, such as triphenylcarbonium cation, tri(methylphenyl)carbonium cation and tri(dimethylphenyl)carbonium cation.

Examples of ammonium cations include but are not limited to primary, secondary and tertiary ammonium cations. Examples of secondary ammonium cations include dialkylammonium and diarylammonium, for example dimethylammonium, diethylammonium, di(isopropyl)ammonium cation, dicyclohexylammonium cation and diphenylammonium cation. Examples of ternary ammonium cations include trialkyl ammonium, for example trimethylammonium cation, triethylammonium cation, tripropylammonium cation and tributylammonium (especially tri(n-butyl)ammonium) cation. Examples of ammonium cations also include anilinium cations and their derivatives, such as anilinium cation, N-alkylanilinium and N,N-dialkylanilinium cations, such as N-methylanilinium cation, N,N-dimethylanilinium cation, N, N-diethylanilinium, the N,N-2,4,6-pentamethylanilinium cation, the p-bromo-N,N-dimethylanilinium cation and the p-nitro-N,N-dimethylanilinium cation.

Examples of phosphonium cations include but are not limited to triarylphosphonium cations, such as triphenylphosphonium cation, tri(methylphenyl)phosphonium cation and tri(dimethylphenyl)phosphonium cation.

In certain embodiments, the cation [Q] ⁺ is a carbonium cation or an ammonium cation as described above, preferably [Q] ⁺ is the triphenylcarbonium cation, the N,N-dimethylanilinium cation or the N cation, N-diethylanilinium.

In certain embodiments, the cationizing agent may therefore be a trialkyl-substituted ammonium salt, an N,N-dialkylanilinium salt, a dialkylammonium salt or a tri-substituted carbonium salt.

In certain embodiments, the cationizing agent may be a compound of the following formula (IV):

[Q] ⁺ [B(Ri) ₄ ] ^- (IV)

wherein [Q] ⁺ and R1 are as described above, preferably [Q] ⁺ is the triphenylcarbonium cation, the N,N-dimethylanilinium cation or the N,N-diethylanilinium cation.

Examples of cationizing agent of formula (IV) include triethylammoniumtetra(phenyl)borate, tripropylammoniumtetra(phenyl)borate, tri(n-butyl)ammoniumtetra(phenyl)borate, trimethylammoniumtetra(p-tolyl)borate, trimethylammoniumtetra (o-tolyl))borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl) borate, tripropylammoniumtetrakis(o,p-dimethylphenyl)borate, tri(n-butyl)ammoniumtetrakis(m,m-dimethylphenyl)borate, tri(n-butyl)ammoniumtetrakis(p-trifluoromethylphenyl)borate, tri(n-butyl)ammoniumtetrakis(3,5-ditrifluoromethylphenyl)borate, tri(n-butyl)ammoniumtetra(o-tolyl)borate, N, N-dimethylaniliniumtetra(phenyl)borate, N,N-dimethylanilinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, N,N-diethylaniliniumtetra(phenyl) borate, N,N-2,4,6- pentamethylaniliniumtetra(phenyl)borate, di(1-propyl)ammoniumtetrakis(pentafluorophenyl)borate, dicyclohexylammoniumtetra(phenyl)borate, triphenylcarboniumtetrakis(pentafluorophenyl)borate, triphenylcarboniumtetrakis[3,5-bis(trifluoromethyl)-phenyl]borate, N,N-dimethylaniliniumtetrakis(pentafluorophenyl)borate, ferroceniumtetrakis(pentafluorophenyl)borate, triphenylcarbeniumpentaphenylcyclopentadienyl complex, N,N-diethylaniliniumpentaphenylcyclopentadienyl complex.

The cationizing agent is preferably an N,N-dialkylanilinium salt, more preferably N,N-dimethylanilinium tetrakis(pentafluorophenyl) borate.

The cationizing agents mentioned above can be used singly or in a mixture of two or more.

More particularly, the organometallic complex of cationic yttrium of formula (I) in which P is a ligand of formula (a-2) and L is tetrahydrofuran can be prepared according to a process comprising the steps of:

reacting YX ₃ (THF) _z , X being a halogen atom, preferably the chlorine atom, and z ranging from 0 to 4, and MCH ₂ Ph-o-NMe _2, M being an alkali metal, from preferably Li, to give a precursor of formula (II'):

Y(CH ₂ -Ph-o-NMe ₂ ) ₃ (II')

reacting the precursor of formula (II') with a cationizing agent, for example N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, to give the organometallic complex of cationic yttrium.

The operating conditions of such a process and their optimization, in particular in terms of duration, solvent, reaction time and temperature, fall within the general knowledge of those skilled in the art and their know-how in this field.

Catalytic system

The yttrium complex of formula (I) can advantageously be used in combination with a co-catalyst in order to carry out the polymerization of alkenes or conjugated dienes.

Thus, the present invention also relates to a catalytic system comprising at least one cationic yttrium complex of formula (I) as described above and a co-catalyst.

In the catalytic system, the molar ratio (co-catalyst)/(yttrium organometallic complex) is greater than or equal to 5.

Those skilled in the art will understand that there is no upper limit to the range of values of this molar ratio. Indeed, there is no maximum value, even preferential, for this molar ratio (co-catalyst) / (cationic organometallic complex of yttrium) which is imposed by a deactivation of the catalytic system in the polymerization processes of alkenes, conjugated dienes or mixtures thereof.

The co-catalyst can be any co-catalyst commonly employed in the technical field. More particularly, the co-catalyst can be an organometallic alkylating agent of metals from groups 1, 2, 12 and 13 of the periodic table according to IUPAC (December 2018).

Examples of co-catalysts include co-catalysts belonging to the group consisting of magnesium alkyls, lithium alkyls, zinc alkyls, aluminum alkyls, Grignard reagents and mixtures of these constituents.

Co-catalysts belonging to the group of aluminum alkyls can be represented by the following formula (V):

(Ra) _m' Al (ORb) _n' H _p' X _q' (V)

in which :

Ra and Rb are identical or different and each represents a hydrocarbon group of 1 to 15 carbon atoms, preferably a hydrocarbon group of 1 to 4 carbon atoms;

X is a halogen atom; And

m', n', p' and q' are numbers satisfying the following conditions:

0 < m’ ≦ 3,

0 ≦ n' <3,

0 ≦ p' <3,

0 ≦ q’ <3 and

m' + n' + p' + q' = 3.

Very particularly, the aluminum alkyls of formula (V) can be compounds represented by the following formulas:

(a) (Ra) _m' Al(ORb) _3-m'

in whichRa AndRb are identical or different and each represents a hydrocarbon group of 1 to 15 carbon atoms, preferably a hydrocarbon group of 1 to 4 carbon atoms; Andmeis preferably a number satisfying the condition of 1.5 ≦me≦ 3;

(b) (Ra) _m' AlX _3-m'

wherein Ra is a hydrocarbon group of 1 to 15 carbon atoms, preferably a hydrocarbon group of 1 to 4 carbon atoms; X is a halogen atom; and m' is preferably a number satisfying the condition of 0 <m'<3;

(c) (Ra) _m AlH _3-m'
wherein Ra is a hydrocarbon group of 1 to 15 carbon atoms, preferably a hydrocarbon group of 1 to 4 carbon atoms; and m' is preferably a number satisfying the condition of 2≦ m' <3;

(d) (Ra) _m' Al(ORb) _n' X _q'

in which Ra and Rb can be identical or different and each represent a hydrocarbon group of 1 to 15 carbon atoms, preferably a hydrocarbon group of 1 to 4 carbon atoms; X is a halogen atom; and m' , n' and q' are numbers satisfying the conditions of 0 <m' ≦ 3, 0 ≦ n' < 3, 0 ≦ q' < 3 and m' + n' + q' = 3.

Specific examples of alkylaluminum compounds include:

- tri-n-alkylaluminums, such as trimethylaluminum, triethylaluminum, tri-n-butylaluminum, tripropylaluminum, tripentylaluminum, trihexylaluminum, trioctylaluminum and tridecylaluminum;

- branched-chain trialkylaluminums, such as triisopropylaluminum, triisobutylaluminum, tri-sec-butylaluminum, tri-tert-butylaluminum, tri-2-methylbutylaluminum, tri-3-methylbutylaluminum, tri-neopentylaluminum, tri-2-methylpentylaluminum, tri-3 -methylpentylaluminum, tri- 4-methylpentylaluminum, tri-2-methylhexylaluminum, tri-3-methylhexylaluminum and tri-2-ethylhexylaluminum;

- tricycloalkylaluminums, such as tricyclohexylaluminum and tricyclooctylaluminum;

- triarylaluminum, such as triphenylaluminum and tritolylaluminum;

- trialkenylaluminums represented by the formula (iC ₄ H ₉ ) _x Al _y (C ₅ H ₁₀ ) _z (where x, y and z are positive numbers and z≧2x), such as isoprenylaluminum;

- alkylaluminum alcoholates, such as isobutylaluminum methoxide, isobutylaluminum ethoxide and isobutylaluminum isopropoxide;

- dialkylaluminum alcoholates, such as dimethylaluminum methoxide, diethylaluminum ethoxide and dibutylaluminum butoxide;

- alkylaluminum sesquialkoxides, such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide;

- partially alkoxylated aluminum alkyls having an average composition represented by R ^a _2.5 Al(OR ^b ) _0.5; also called aluminoxanes, for example methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, triisobutylaluminoxane;

- dialkylaluminum aryloxides, such as diethylaluminum phenoxide, diethylaluminum (2,6-di-t-butyl-4-methylphenoxide), ethylaluminumbis (2,6-di-t-butyl-4-methylphenoxide), diisobutylaluminum (2,6-di-t-butyl-4-methylphenoxide) and isobutylaluminumbis (2,6-di-t-butyl-4-methylphenoxide);

- dialkylaluminum halides, such as dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diethylaluminum bromide and diisobutylaluminum chloride;

- alkylaluminum sesquihalides, such as ethylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide;

- partially halogenated aluminum alkyls, such as ethylaluminum dichloride, propylaluminum dichloride and butylaluminum dibromide;

- dialkylaluminum hydrides, such as diethylaluminum hydride and diisobutylaluminum hydride;

- partially hydrogenated aluminum alkyls, for example alkylaluminum dihydrides, such as ethylaluminum dihydride and propylaluminum dihydride; And

- partially alkoxylated and halogenated aluminum alkyls, such as ethylaluminum ethoxychloride, butylaluminum butoxychloride and ethylaluminum ethoxybromide.

Co-catalysts belonging to the group of magnesium alkyls, zinc alkyls or Cd alkyls (group 2 or group 12) can be represented by the following formula:

RaRbM ₃

wherein Ra and Rb may be the same or different and each represents a hydrocarbon group of 1 to 15 carbon atoms, preferably a hydrocarbon group of 1 to 4 carbon atoms; and M ₃ is Mg, Zn or Cd.

In some embodiments, the co-catalyst is an aluminum alkyl. Examples of preferred aluminum alkyls include:

- aluminoxanes, such as methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, triisobutylaluminoxane;

- tri-alkyaluminums of formula Al(C ₁ -C ₁₀ -alkyl) ₃ , such as trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-isopropylaluminum, tri-n-butylaluminum, tri-isobutylaluminum (TiBA), tri -t-butylaluminum, tri-n-pentylaluminum, tri-neopentylaluminum, tri-n-hexyl-aluminum, tri-cyclohexylaluminum, tri-n-octylaluminum, preferably tri-isobutylaluminum;

- dialkylaluminum hydrides of formula (Al(C ₁ -C ₁₀ -alkyl) ₂ H), such as diethylaluminum hydride, diisopropylaluminum hydride, di-n-propylaluminum hydride, di-isobutylaluminum, di-n-butylaluminum hydride, di-n-octylaluminum hydride, preferably diisobutylaluminum hydride;

- alkylaluminum monohalides, such as diethylaluminum chloride (CDEA).

In some embodiments, the co-catalyst is a tri-alkyl aluminum of formula Al(C ₁ -C ₁₀ -alkyl) ₃ , such as trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-isopropylaluminum, tri-n -butylaluminum, tri-isobutylaluminum (TiBA), tri-t-butylaluminum, tri-n-pentylaluminum, tri-neopentylaluminum, tri-n-hexyl-aluminum, tri-cyclohexylaluminum, tri-n-octylaluminum, preferably tri-isobutylaluminum .

In certain embodiments, the co-catalyst is a dialkylaluminum hydride of formula (Al(C ₁ -C ₁₀ -alkyl) ₂ H), such as diethylaluminum hydride, diisopropylaluminum hydride, di-n-propylaluminum, di-isobutylaluminum hydride, di-n-butylaluminum hydride, di-n-octylaluminum hydride, preferably diisobutylaluminum hydride.

The co-catalyst according to the invention can be a mixture of at least two co-catalysts as described above.

Preparation of the catalytic system

Preparation in situ

The catalytic system according to the invention can be prepared by adding the constituents of the catalytic system directly to the polymerization solvent containing the monomer(s) to be polymerized ( in situ preparation). The constituents of the catalytic system can be added at the same time or one after the other. Typically the co-catalyst is added first. The cationic yttrium complex of formula (I) is then added.

Premix

The constituents of the catalytic system can be pre-mixed before being brought into contact with the solvent containing the monomer(s) to be polymerized, by introducing the constituents of the catalytic system into an inert hydrocarbon solvent, for a time between 0 and 120 minutes, at a temperature ranging from 10° C. to 80° C., optionally higher than ambient temperature, generally ranging from 18° C. to 60° C., so as to obtain a premixed catalyst. The premixed catalyst thus obtained is then brought into contact with the solvent containing the monomer(s) to be polymerized.

The preparation of the catalytic system is typically carried out in a low molecular weight hydrocarbon solvent, such as for example cyclohexane, methylcyclohexane, n-heptane, or a mixture of these solvents, preferably in n-heptane, or else in an aromatic solvent such as toluene. It should be noted that non-aromatic solvents are particularly preferred.

The constituents of the catalytic system can be added as follows. In a first step, the co-catalyst is added in the solvent. In a second step, the cationic yttrium complex of formula (I) is added.

The constituents of the catalytic system can alternatively be added as follows. In a first step, the cationic yttrium complex of formula (I) is added in the solvent. In a second step, the co-catalyst is added.

Preparation in situ in two steps

The co-catalyst can initially be mixed with the monomers to be polymerized. The cationic yttrium complex of formula (I) is then added to drive the polymerization reaction.

Polymerization

The catalytic system of the present invention can be used in processes for the polymerization of olefins, more particularly alkenes, conjugated dienes or their mixtures. The monomers to be polymerized can then be brought into contact with the catalytic system according to the present invention. In certain embodiments, the monomers to be polymerized are brought into contact with the cocatalyst before addition of the organometallic complex of cationic yttrium of formula (I).

The monomers to be polymerized are preferably chosen from the group of monomers consisting of conjugated dienes, ethylene, α-monoolefins and mixtures thereof.

The conjugated diene used as monomer is preferably a 1,3-diene having 4 to 8 carbon atoms, among which mention may be made of 1,3-butadiene or isoprene.

More particularly, the catalytic system of the present invention can be used in processes for the polymerization of monomers chosen from ethylene,
1,3-butadiene, isoprene and mixtures thereof.

The aforementioned characteristics of the present invention, as well as others, will be better understood on reading the following description of several embodiments of the present invention, given by way of indication and not limitation.

EXAMPLES

1. Preparation of the [Y(CH ₂ VS ₆ H ₄ -o-NMe ₂ ) ₂ (THF) ₂ ][B(C ₆ F ₅ ) ₄ ]

Definition of abbreviations:

THF = tetrahydrofuran

Me = methyl

nBuLi = n-butyllithium

TiBA = tri-isobutylaluminum

BHT = 2,6-di-tert-butyl-4-methylphenol

Synthesis of the Y(CH) complex ₂ VS ₆ H ₄ -o-NMe ₂ ) ₃

Li-CH synthesis protocol ₂ VS ₆ H ₄ -o-NMe ₂

In a Schlenk tube under argon, N,N- o -dimethyl- o -toluidine (9.3 g, 68.8 mmol) is diluted in 71 mL of diethyl ether. 29 mL (2.5 M) of n BuLi are added to this solution at room temperature (about 20° C.-23° C.). Let it react overnight. The solution is filtered. Washed with 4×20 mL of pentane. The precipitate is dried and 2.3 g of product are recovered. The solution is evaporated to 2/3. Leave to stir over the weekend at room temperature. It is filtered again and the powder is washed with pentane. 5.2 g of solid are obtained. Finally, 7.5 g (53 mmol) of Li-CH ₂ C ₆ H ₄ -o-NMe ₂ are isolated, ie a yield of 77%.

Synthesis of Y(CH ₂ VS ₆ H ₄ -o-NMe ₂ ) ₃

2.54 g of YCl ₃ (13 mmol) are suspended in 52 mL of THF. The 2-(dimethylamino)benzyl-lithium (5.5 g, 39 mmol) is dissolved in 52 mL of THF (brown solution). This solution is added dropwise to the YCl ₃ solution at ambient temperature. The solution turns green over time. After 2 hours of reaction, the THF is evaporated. 58 mL of toluene are added and the mixture is filtered through celite. The salt is washed with 3×20mL of toluene. The volume of the solution is reduced to 20 mL. This solution is again filtered through celite. Allowed to crystallize at -20°C. The supernatant is removed through a filter cannula. The solid is dried under vacuum. The volume of the supernatant is reduced and allowed to crystallize. The supernatant is removed, the two solids are combined. 2.51 g (5.1 mmol) of Y(CH ₂ C ₆ H ₄ -o-NMe ₂ ) ₃ are obtained, ie a yield of 39%.

Synthesis of [Y(CH ₂ VS ₆ H ₄ NMe ₂ ) ₂ (THF) ₂ ][B(C ₆ F ₅ ) ₄ ] (1)

A solution containing [PhNMe ₂ H][B(C ₆ F ₅ ) ₄ ] (326 mg, 0.4 mmol) and 7 mL of THF is added to a solution containing 4 mL of THF and Y(CH ₂ C ₆ H ₄ NMe ₂ ) ₃ (200 mg, 0.4 mmol). The solution is stirred for 30 minutes at room temperature. Three quarters of the solution are evaporated and 8 mL of pentane are added. Two phases then appear. The upper phase is removed and 8 mL of pentane are again added. The medium is cooled for one hour at
-30°C, the top phase is removed and the orange oil/solid is dried under vacuum to give [Y(CH ₂ C ₆ H ₄ NMe ₂ ) ₂ (THF) ₂ ][B(C ₆ F ₅ ) ₄ ] (318 mg, 0.27 mmol, 68% yield).

Control of the elementary composition of the complex obtained:

Elemental analysis of the Complex obtained in %:

C 50.61, H 3.44, Y 7.90.

Theoretical calculation for [Y(CH ₂ C ₆ H ₄ NMe ₂ ) ₂ (THF) ₂ ][B(C ₆ F ₅ ) ₄ ]:

C 50.87, H 3.42, Y 7.53

Control by NMR spectroscopy of the complex obtained:

¹ H NMR (400 MHz, THF d ₈ , 298K): 7.42 ppm (d, J = 8 Hz, 2H), 7.16-7.07 ppm (br, 4H, H-Ar), 6.95 (m, 2H, H-Ar), 3.65 ppm (m, 8H, THF), 2.89 ppm (s, 12H, NMe ₂ ), 1.81 ppm (m, 8H, THF), 1.76 ppm (s, THF & YCH ₂ )

¹³ C NMR (75.4 MHz, THF d ₈ , 298K): 149.4 ppm (C ₆ F ₅ ), 147.0 ppm (C ₆ F ₅ ), 144.2 ppm (C ₆ F ₅ ), 140 .4 ppm (CN, Ar), 139.4 ppm (C ₆ F ₅ ), 138.1 ppm (C, Ar), 137.2 ppm (C ₆ F ₅ ), 134.9 ppm (C ₆ F ₅ ), 130.4 ppm (CH Ar), 128.1 ppm (CH Ar), 121.1 ppm (C Ar), 121.0 ppm (C, Ar), 67.2 ppm (THF), 48.3 ppm (d, J _CY = 25 Hz, YCH ₂ ), 44.3 ppm (NMe ₂ ), 25.4 ppm (THF)

¹⁹ F NMR (THF d ₈ , 298K): -132.8 ppm (br ,2F), -165.0 ppm (t, J = 20 Hz, 1F), -168.5 ppm (t, J = 18 Hz , 2 F)

¹¹ B NMR (THF d ₈ , 298K): -16.5 ppm

⁸⁹ Y NMR (19.6 MHz, THF d ₈ , 328K): 440.4 ppm

2. Examples of polymerization of isoprene using the previously prepared complex

For examples 1 to 4:

2 mL of a TiBA solution (50 mM) are added in 38 mL of toluene, then 2 g (30 mmol) of isoprene are added. The solution is stirred overnight. This solution is poured into a Schlenk tube containing 16.5 mg (0.01 mmol) of [Y(CH ₂ C ₆ H ₄ NMe ₂ ) ₂ (THF) ₂ ][B(C ₆ F ₅ ) ₄ ]. The mixture is stirred at 30° C. for a time varying between 5 minutes and one hour depending on the tests. The reaction is stopped by adding methanol and the polymer is precipitated in a large volume of methanol containing BHT (approximately 200 mg/L). The polymer is dried under dynamic vacuum at 70° C. for 3 hours.

For counterexample 5:

The isoprene polymerization process is identical to examples 1 to 4, except that it uses a catalytic system based on a noncationic complex Y (CH ₂ C ₆ H ₄ NMe ₂ ) ₃ synthesized previously.

Isoprene Polymerization Results

^a Determined by size exclusion chromatography ^b Determined by ¹ H and ¹³ C NMR spectroscopy of polyisoprene. ^c Kg _PI mol _Y ^-1 h ^-1

Results :

It emerges from the above results that the catalytic system comprising a cationic yttrium complex according to the invention and a co-catalyst of the alkylaluminum type allows polymerization of isoprene with increased efficiency in view of a catalytic system comprising a non-cationic yttrium complex.

3. Characterization techniques

Conversion:

The conversion is calculated using the ratio between the mass of polymer isolated at the end of the reaction and the mass of isoprene introduced into the reactor.

m _isoprene which represents the mass of isoprene introduced into the reactor,
m _polyisoprene which represents the mass of polyisoprene obtained,

Elemental analysis

Elemental analyzes were carried out at Mikroanalytisches Labor Pascher, Remagen (Germany).

Nuclear Magnetic Resonance analyzes

NMR spectra were performed on a Brucker Avance III HD 400 Mz spectrometer in NMR tubes with Teflon valves (Young). The ¹ H NMR spectra were calibrated by the residual protons of the deuterated solvents. ¹³ C NMR spectra were calibrated by residual carbons of deuterated solvents and reported in ppm relative to TMS. We used Bruker's pulse programs without further modification. The spectrometer probe is a Bruker gradient Z BBFO.

Size Exclusion Chromatography (SEC)

Polyisoprene

The analyzes were carried out on a Viscotek system (from Malvern Instruments) equipped with a column (PLgel Olexis Guard 7.5x50mm) followed by three columns (PLgel Olexis Guard 7.5x300mm ie from Agilent Technologies). The detectors are composed of a refractometer, a RALS (Right-Angle Light Scattering), a 7° LALS (Low Angle Light Scattering) and a viscometer. The analysis is carried out at 35°C. The volume taken is 100 µL. The concentration of the sample is 3 mg mL ^-1 . The solvent used is THF (stabilized with 2,6-di-tert-butyl-4-methylphenol). The flow rate in the column is 1 mL min ^-1 , the temperature in the apparatus is 35°C. The data processing and analysis software is OmniSEC. The average molar masses were calculated using a triple calibration.

Claims (15)

Organometallic complex of cationic yttrium of formula (I):
[ _YP2 (L) _z ] ⁺ [A] ^- (I)
in which :
Y is an yttrium atom;
P is a ligand represented by the formula (a):

(To)
in which :
n is an integer ranging from 0 to 4 inclusive;
each R represents, independently of one another, a halogen atom, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C ₂₀ cycloaliphatic radical, substituted or unsubstituted, or an aromatic radical C ₆ -C ₂₀ , substituted or unsubstituted;
x is an integer ranging from 0 to 6 inclusive;
y is an integer ranging from 0 to 6 inclusive;
R ¹ and R ² independently represent a hydrogen atom, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C _{20 cycloaliphatic radical,} substituted or unsubstituted, or a C ₆ -C ₂₀ aromatic radical, substituted or unsubstituted;
* denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond;
L represents a Lewis base;
z is a number ranging from 0 to 4 inclusive; And
[A] ^- is a non-coordinating anion. The organometallic complex according to claim 1 in which P represents a ligand of formula (a-1):

(a-1)
in which R ¹ , R ² , R and n are as defined in claim 1 and * denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond. The organometallic complex according to claim 2 in which R ¹ and R ² represent a methyl group and n is equal to 0. The organometallic complex according to any one of claims 1 to 3 in which L represents an ether, preferably tetrahydrofuran. The organometallic complex according to any one of claims 1 to 4 in which the non-coordinating anion [A] ^- has the following formula:
B(Ri) ₄ ^-
in which B is the boron atom and each Ri represents, independently of one another, a C ₁ -C ₂₀ aliphatic radical, substituted or unsubstituted, a C ₃ -C ₂₀ cycloaliphatic radical, substituted or unsubstituted, or a C ₆ -C ₂₀ aromatic radical, substituted or unsubstituted, preferably an aryl group, which may be substituted by one or more substituents independently chosen from halogen atoms, C ₁ -C ₅ alkyl groups or perfluoroalkyl groups in C ₁ -C ₅ . The organometallic complex according to claim 5 wherein the non-coordinating anion is tetrakis(pentafluorophenyl)borate. Process for the preparation of an organometallic complex of cationic yttrium according to any one of claims 1 to 6 comprising the steps of:
(a) reacting an yttrium halide in the presence of a Lewis base L and a compound of formula MP in which M denotes an alkali metal to give a precursor of formula (II):
Y(L)_zP₃(II)
in which :
Y is an yttrium atom,
z denotes an integer or not ranging from 0 to 4, and
P denotes a ligand represented by formula (a) as defined in any one of claims 1 to 6;
(b) reacting the precursor of formula (II) with a cationizing agent to give an organometallic complex of cationic yttrium. The process according to claim 7 wherein P denotes a ligand represented by the formula (a-1):

(a-1)
in which R ¹ , R ² , R and n are as defined in claim 1 and * denotes the atoms of the ligand P establishing a bond with the yttrium atom, which bond is a covalent bond or a dative bond. The process according to claim 8 in which P denotes a ligand represented by the formula (a-1) in which R ¹ and R ² represent a methyl group and n is equal to 0. The process according to any one of claims 7 to 9, wherein the cationizing agent is a compound of formula [A] ^- [Q] ⁺ wherein [A] ^- is as described in claim 1 or 5 and [ Q] ⁺ is a proton, a carbonium cation and its substituted derivatives, an ammonium cation and its substituted derivatives, an oxonium cation and its substituted derivatives, a phosphonium cation, a cycloheptyltrienyl cation or a ferrocenium cation having a transition metal. The process according to claim 10 wherein the cationizing agent is a trialkyl-substituted ammonium salt, an N,N-dialkylanilinium salt, a dialkylammonium salt or a tri-substituted carbonium salt. The process according to claim 11 wherein the cationizing agent is dimethylanilinium tetrakis(pentafluorophenyl)borate. Catalyst system comprising a cationic yttrium organometallic complex according to any one of claims 1 to 6 and a co-catalyst, in which the molar ratio (co-catalyst) / (yttrium organometallic complex) is greater than or equal to 5 . The catalytic system according to claim 13 wherein the co-catalyst is selected from the group consisting of magnesium alkyls, lithium alkyls, zinc alkyls, aluminum alkyls, Grignard reagents and mixtures of these constituents. The catalytic system according to claim 14, in which the cocatalyst is an aluminum alkyl chosen from aluminoxanes, tri-alkylaluminums of formula Al(C ₁ -C ₁₀ -alkyl) ₃ , dialkylaluminum hydrides of formula (Al(C ₁ -C ₁₀ -alkyl) ₂ H) and alkylaluminum monohalides.