Binuclear metal hydride complexes as catalysts for the...

Details Binuclear metal hydride complexes as catalysts for the... Binuclear metal hydride complexes as catalysts for the...

1999-08-12

2001-09-18

Nazario-Gonzalez, Porfirio (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Rare earth containing

C502S152000, C502S158000, C502S155000, C526S160000, C526S943000, C534S011000

Reexamination Certificate

active

06291655

ABSTRACT:

The present invention relates to binuclear metal hydride complexes of the formula (I)
where the substituents and indices have the following meanings:
M is scandium, yttrium, lanthanum or a lanthanide metal,
R is hydrogen, halogen, C
l
-C
20
-alkyl, C
3
-C
10
-cycloalkyl, C
6
-C
15
-aryl or C
3
-C
30
-organosilyl, where two adjacent radicals R can also form a saturated or unsaturated, cyclic or heterocyclic group having from 4 to 18 carbon atoms,
z is —SiR′
2
—, —CR′
2
—, —GeR′
2
—, —SnR′
2
—, —BR′— or —O—,
R′ is C
1
-C
20
-alkyl, C
3
-C
10
-cycloalkyl, C
6
-C
15
-aryl or alkylaryl having from 1 to 10 carbon atoms in the alkyl part and from 6 to 10 carbon atoms in the aryl part,
m is 1 or 2,
X is —O—, —S—, —NR″—, —PR″—, —OR″, —SR″, —NR″
2
or —PR″
2
,
R″ is hydrogen, C
1
-C
20
-alkyl, C
3
-C
10
-cycloalkyl, C
6
-C
15
-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl part and from 6 to 10 carbon atoms in the aryl part or C
3
-C
30
-organosilyl and
L is a low molecular weight, Lewis-basic, organic compound.
The invention also provides a process for preparing said binuclear metal hydride complexes and provides for their use as catalysts for the (co)polymerization of polar monomers. In addition, the invention relates to a process for preparing (co)polymers from polar monomers.
In recent times, complexes based on rare earth metals have been increasingly examined for suitability as catalysts for the coordinatively controlled polymerization of both nonpolar and polar, olefinically unsaturated monomers (cf. H. Yasuda, E. Ihara, Bull. Chem. Soc. Jpn. 1997, 70, pp. 1745-1767). Polar monomers such as acrylates or acrylonitrile have, however, hitherto still been polymerized by free-radical methods, particularly in industrial processes. However, free-radical polymerization processes are frequently difficult to control and lead to polymer products having a broad molecular weight distribution. First indications are that selected catalysts based on rare earth metals can also be polymerization-active for polar monomers.
For example, Jiang et al., Eur. Polym. J., 1997, 33 (4), pp. 577-578, use multicomponent catalyst systems based on lanthanides substituted by 2-ethylhexyl phosphonate for the polymerization of acrylonitrile. Further necessary catalyst constituents are dibutylmagnesium and N,N,N′,N′-tetramethyl-ethylenediamine, in each case in excess based on the rare earth metal. To obtain an active catalyst species, the catalyst mixture has to be additionally subjected to an aging process. The monomer conversion achieved is generally not above 50%.
Similarly to the case of metallocene compounds based on the early transition metals, it is possible to prepare polymerization-active sandwich complexes of the rare earth metals. U.S. Pat. No. 5,312,881 describes bridged mononuclear biscyclopentadienyl complexes of the lanthanides by means of which &agr;-substituted acrylates can be copolymerized. A Lewis-acid cocatalyst such as methylaluminoxane may have to be added to the catalyst system to obtain a satisfactory polymerization result. In EP-A 0 634 429, it is stated that block copolymers can be obtained from polar and nonpolar monomers with the aid of bridged mononuclear sandwich complexes of samarium (cf. Yasuda et al., Macromolecules, 1992, 25, pp. 5115-5116). However, the metallocene complex to be used is extremely sensitive or unstable and can essentially not be analyzed spectroscopically. Accordingly, the preparation of bridged sandwich complexes is generally more complicated than the preparation of sandwich or semisandwich complexes.
U.S. Pat. No. 5,464,906 describes binuclear, amido-bridged cyclopentadienyl complexes based on metals of transition group III of the Periodic Table of the Elements. These complexes are suitable for the homopolymerization of &agr;-olefins, in particularly ethene. The polymerization of polar monomers is not discussed.
The binuclear rare earth metal complex [SmH(C
5
Me
5
)
2
]
2
allows, as Yasuda et al., Bull. Chem. Soc. Jpn., 1997, 70 (8), pp. 1745-1767, were able to show, the polymerization of polar monomers. However, only alkyl methacrylates can be polymerized using this catalyst, albeit in high yield and over a relatively wide temperature range. The binuclear metal complex [Y(OMe)(C
5
Me
5
)
2
]
2
again displays no polymerization activity in respect of polar monomers. In contrast, Ren et al., Chin. J. Appl. Chem., 1995, 12, p. 105, were able to polymerize acrylonitrile in small yields using binuclear neodymium complexes of the type [NdMe(t-BuCp)
2
]
2
(t-Bu=tert-butyl, Cp=cyclopentadienyl).
Mu et al., Organometallics, 1996, 15, pp. 2720-2726, synthesized binuclear scandium hydride semisandwich complexes using a multidentate cyclopentadienyl ligand and used the complexes obtained for the polymerization of nonpolar olefins such as 1-hexene. However, no reaction at all was found at room temperature while at elevated temperatures small amounts of a rubber-like product which was not analyzed further were obtained. The polymerization of polar monomers is not discussed at any point in Mu et al.
Schaverien, Organometallics, 1994, 13 (1), pp. 69-82, were able to prepare the binuclear yttrium hydride semisandwich complex [Y(C
5
Me
5
)(OAr)(&mgr;-H)]
2
(Ar=−2,6-C
6
H
3
-(t-Bu)
2
), but this is obtained only in a moderate yield. Longer reaction times (>3h) lead to formation of a by-product in not inconsiderate amounts. The binuclear yttrium hydride semisandwich complex obtained proved to be moderately polymerization-active toward nonpolar olefinically unsaturated monomers. The polymerization of polar monomers was not studied.
According to Duchateau et al., Organometallics, 1997, 16, pp. 3511-3522, the binuclear yttrium hydride complex {[(O-t-Bu)Me
2
Si(N-t-Bu)]
2
Y(&mgr;-H)}
2
obtained from [(O-t-Bu)Me
2
Si(N-t-Bu)]Y[CH(SiMe
3
)
2
] by hydrogenation can, owing to insufficient stability, be detected only by
1
H-NMR spectroscopy but cannot be isolated. It is not suitable as a catalyst for the polymerization of nonpolar or polar monomers. Furthermore, in the case of the binuclear yttrium hydride complex of the formula [(C
5
H
4
R)
2
Y(&mgr;-H)(THF)]
2
(R═H or Me), insertion was observed in the presence of acetonitrile as polar monomer to give the corresponding imido complex, but polymerization to polyacrylonitrile was not observed (cf. Evans et al., J. Am. Chem. Soc., 1984, 106, p. 1291).
It would therefore be desirable to find stable complexes of the rare earth metals which are suitable for the polymerization of a broad range of polar monomers and at the same time can be obtained simply, unproblematically and inexpensively.
It is an object of the present invention to find stable, readily obtainable metal complexes of the rare earth metals by means of which a variety of monomers can be coordinatively polymerized in a satisfactory manner.
We have found that this object is achieved by the binuclear metal hydride complexes described at the outset. We have also found a process for preparing said binuclear metal hydride complexes, which are suitable, for example, as catalysts for the (co)polymerization of polar monomers. In addition, a process for preparing (co)polymers from polar monomers has been found.
Preferred binuclear metal hydride complexes are compounds of the formula (I) in which
M is yttrium,
R is C
1
-C
10
-alkyl or C
3
-C
21
--organosilyl, where two adjacent radicals R can also form a fused aromatic ring,
Z is —SiR′
2
— or —CR′
2
—,
R′ is C
1
-C
10
-alkyl or C
6
-C
10
-aryl,
m is 1,
X is —NR″— or —PR″—,
R″is C
1
-C
10
-alkyl, C
6
-C
10
-aryl or alkylaryl having from 1 to 6 carbon atoms in the alkyl part and from 6 to 10 atoms in the aryl part and
L is tetrahydrofuran, 2,5-dialkyltetrahydrofuran, dioxane, dialkyl ether, acetonitrile, triarylphosphine or halogenated triarylphosphine.
In the binuclear com

Affiliated with

Also associated with

Rating

Binuclear metal hydride complexes as catalysts for the... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Binuclear metal hydride complexes as catalysts for the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Binuclear metal hydride complexes as catalysts for the... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2540595