JPH07247360A - Production of high-molecular-weight polysilane - Google Patents

Abstract

PURPOSE:To produce a high-molecular-weight polysilane in high yields by reacting a hydrosilane with silane(SiH4)or disilane (Si2H6)in the presence of a specified metal complex. CONSTITUTION:A hydropolysilane [desirably a poly(alkylsilylene) or poly(arylenesilylene) having 5 or more Si atoms] is reacted with silane(SiH4)or disilane(Si2H6) in the presence of a group IIIa metal complex [e.g. an organoneodymium complex of the formula (wherein Cp* is pentamethylcyclopentadienyl; and Me is methyl)] or a group IVa metal complex (e.g. a complex having titanium as the central atom) to produce a polysilane. According to the above process, a high-molecular-weight polysilane can be produced in high yields.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing polysilanes. Polysilanes are useful as photoconductors, photoreactive materials such as photoresists, and raw materials for silicon carbide ceramics.

[0002]

2. Description of the Related Art Polysilanes have hitherto been produced mainly by a method using the following reactions. 1) Polycondensation reaction of Wurtz reaction of dichlorosilanes. 2) Group IVa metal complexes or IIIa of trihydrosilanes
Dehydrogenative polycondensation reaction in the presence of group metal complexes.

However, each of these methods has the following problems. That is, in the reaction of 1) above,
In addition to the use of halosilanes, which are sensitive to moisture and corrosive, they also handle alkali metals, i.e. flammable reagents, which are dangerous and naturally limit the synthesis of functional groups. In the dehydrogenative polycondensation polymerization of 2), the reaction conditions are mild, but it is generally difficult to produce high molecular weight polysilanes. The present inventors also reported a method for obtaining polysilanes by reacting hydrosilanes as a raw material in the presence of a lanthanoid complex (JP-A-5-32785).
Issue). However, this method has a limit in increasing the molecular weight of the obtained polysilane.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for further increasing the molecular weight of polysilanes having a relatively low molecular weight such as hydropolysilanes obtained by dehydrogenative condensation. .

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have made use of a Group IIIa metal complex or a Group IVa metal complex and hydropolysilanes and silane SiH ₄ or It has been found that higher molecular weight polysilanes can be obtained by reacting disilane Si ₂ H ₆ . The present invention has been completed based on these findings.

That is, the present invention provides a Group IIIa metal complex or
The present invention provides a method for producing polysilanes, which comprises treating hydropolysilanes with silane SiH ₄ or disilane Si ₂ H ₆ in the presence of a Group IVa metal complex.

IIIa used as a catalyst in the present invention
The central metal of the group metal complex includes scandium, yttrium, lanthanoid elements (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium) and actinide elements. Any selected one can be used. Of these, lanthanum, neodymium, samarium, ytterbium, and lutetium are preferably used, and neodymium is particularly preferably used.

IVa used as a catalyst in the present invention
Examples of the central metal of the group metal complex include titanium, zirconium, hafnium and the like.

Examples of the ligand of the metal complex used as a catalyst in the present invention include halogen, hydrogen, alkyl, aralkyl, aryl, alkylsilyl, arylsilyl, olefin, diene, triene and tetraene.
Cyclodiene, cyclotriene, cyclotetraene, allyl, alkoxy, aryloxy, alkylthio, arylthio, cyclopentadienyl, methylcyclopentadienyl, dimethylcyclopentadienyl, pentamethylcyclopentadienyl, alkylamine, arylamine, Pyridyl, alkylphosphine, arylphosphine, alkylarylphosphine, alkylisocyanide, arylisocyanide, ether and the like can be used. These ligands also include those having a substituent. Among these, preferred ligands are hydrogen, alkyl [preferably an alkyl group having 1 to 10 carbon atoms, for example, methyl, trimethylsilylmethyl, bis (trimethylsilyl) methyl, ethyl, i-propyl,
t-butyl, neopentyl, hexyl], cyclopentadienyl, pentamethylcyclopentadienyl, tetrahydrofuran and the like.

The structure of the metal complex used as a catalyst in the present invention is represented by the following general formula (I), (II) or (II
The organometallic complex represented by I) and its associated product are particularly preferable, but not limited thereto. Cp ′ ₂ MR (I) Cp ′ ₂ M ′ (II) Cp ′ ₂ M ″ R ₂ (III) (In the formula, Cp ′ represents a cyclopentadienyl group or a substitution product thereof, and M is any IIIa group. Represents a metal, M ′ represents any one of samarium, europium and ytterbium, M ″ represents titanium, zirconium or hafnium, R represents hydrogen, an alkoxy group, a monovalent organic group or a monovalent silyl group. Represent)

Among the groups represented by R in the above general formula (I), preferred groups include hydrogen, methyl, trimethylsilylmethyl, bis (trimethylsilyl) methyl, neopentyl, phenyl and benzyl. In the present invention, a group IIIa metal complex is preferable as a catalyst, and an organic neodymium complex is particularly preferable. Further, the organic neodymium complex is represented by the above formula (I), wherein R
Is particularly preferably a bis (trimethylsilyl) methyl group.

The group IIIa metal complex (rare earth metal complex) used in the present invention may be one which forms a complex, but in the form of a precursor or a raw material for generating these complexes in the reaction system. It may be charged into the reaction system.

There are no particular restrictions on the hydropolysilanes used in the present invention, but if this is given as an example, 1,1,2,2
-Tetramethyldisilane, 1,1,2,2,3,3,3
4,4,5,5,6,6-dodecamethylhexasilane,
Examples thereof include poly (alkylsilylene) s such as poly (methylsilylene) and poly (hexylsilylene), and poly (arylsilylenes) such as poly (phenylsilylene). Among these, poly (alkylsilylene) s and poly (arylsilylenes) are preferable, and particularly, the number of silicon atoms is 5
Poly (alkylsilylene) s and poly (arylsilylenes) having more than one group are preferable.

In the method of the present invention, the reaction temperature is usually -50.
-300 degreeC, Preferably it is 20-200 degreeC, More preferably, it is 20-160 degreeC.

The reaction pressure of the method of the present invention is not particularly limited, but it is usually carried out in the range of atmospheric pressure to 100 atm.

When carrying out the method of the present invention, a solvent is not always necessary for the reaction, but it is also essential to dilute the reaction system with the solvent, thereby preventing the viscosity of the reaction mixture from increasing with the progress of the reaction. This is one of the advantageous aspects of the invention. Examples of the solvent used here include aromatic compounds such as toluene and benzene, ethers such as diethyl ether, tetrahydrofuran and dioxane, and aliphatic hydrocarbons such as pentane, hexane and decane.

In the method of the present invention, the amount of silane SiH ₄ or disilane Si ₂ H ₆ used with respect to the hydropolysilane is not particularly limited, but preferably 0.01 mol of SiH ₄ or Si ₂ H ₆ per mol of hydropolysilane.
It is used in an amount of about 2 mol. In the method of the present invention, the treatment with silane or disilane can be carried out by using a gas of silane or disilane by a conventional method. For example, the inside of the reactor can be replaced with these gases.

The amount of the group IIIa metal complex or the group IVa metal complex used as a catalyst may be a so-called catalytic amount, but preferably about 0.001 to 0.1 mol per mol of hydropolysilane. Used.

The polysilanes obtained by the method of the present invention are hydropolysilanes themselves, but have a higher molecular weight than the hydropolysilanes used as a raw material. Further, since silane SiH ₄ or disilane Si ₂ H ₆ is incorporated, the H / Si atomic ratio is usually higher than that in the raw material.

The reaction product can be easily separated by reprecipitation, preparative GPC, etc., after removing the solvent and unreacted raw materials by usual means such as filtration and concentration.

[0021]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a high molecular weight polysilane having a high yield from a hydropolysilane, and its industrial significance is great.

[0022]

The present invention will be described in more detail based on the following examples, but the invention is by no means limited to these examples.

EXAMPLE 1 Bis (pentamethylcyclopentadienyl) was added to a stainless steel autoclave (with 37 ml glass insert).
[Bis (trimethylsilyl) methyl] neodymium (0.0
1 mmol), poly (hexylsilylene) (Mw = 86
No. 5, 354 mg of Mw / Mn = 1.03) was added. Here, Mw represents a weight average molecular weight and Mn represents a number average molecular weight, respectively. Silane SiH ₄ was purged under pressure up to 10 atm three times to replace the inside of the apparatus with silane SiH ₄ (1.5 mmol), and then reacted at 80 ° C. for 48 hours. Unreacted silane was removed from the reaction mixture by nitrogen purge to obtain 384 mg of polysilane. The yield was quantitative. According to GPC analysis, the product was Mw 46,
000 (Mw / Mn = 5.00) and Mw 1100 (M
w / Mn = 1.07).

¹ H-NMR (C ₆ D ₆ ) of the product is
0.7-1.8 ppm (m, hexyl group), and 3.
It showed a resonance of 5 to 4.5 ppm (m, Si-H), and was Si-Hex / Si-H = 1: 1.78 by integration.

Comparative Example 1 A stainless steel autoclave (with 37 ml glass insert) was charged with bis (pentamethylcyclopentadienyl).
[Bis (trimethylsilyl) methyl] neodymium (0.0
1 mmol), poly (hexylsilylene) (Mw 86
5, 353 mg of Mw / Mn = 1.03) was added. 80
After reacting at 48 ° C for 48 hours, the raw material hydropolysilane 3
53 mg was recovered. The recovered polysilane is Mw 1
It was 300 (Mw / Mn = 1.12).

Claims (4)

[Claims] 1. A method for producing polysilanes, which comprises reacting hydropolysilanes with silane SiH ₄ or disilane Si ₂ H ₆ in the presence of a Group IIIa metal complex or a Group IVa metal complex. 2. The method of claim 1, wherein the hydropolysilanes are poly (alkylsilylenes) or poly (arylsilylenes). 3. The method according to claim 1, wherein the Group IIIa metal complex is an organic neodymium complex. 4. The organic neodymium complex formula ^{_{Cp * 2 NdCH (SiMe 3)}} 2 ( wherein, Cp ^* is a pentamethylcyclopentadienyl group, Me represents a methyl group.) Is a complex represented by The method according to claim 3, wherein: