JP7638511B2 - Methylenebis(dialkoxysilanol) and its production method, metal complex having methylenebis(dialkoxysilanolate) as ligand and its production method, supported metal complex and its production method, and supported metal catalyst production method - Google Patents

Description

The present invention relates to methylene bis(dialkoxysilanols) and their production methods, metal complexes having methylene bis(dialkoxysilanolates) as ligands and their production methods, supported metal complexes and their production methods, and supported metal catalysts.

Supported metal complexes in which a metal complex is supported on an inorganic oxide such as silica gel, and supported metal catalysts obtained by heat-treating a supported metal complex in an oxygen atmosphere, etc., are widely used as heterogeneous catalysts.
In general, when a metal complex is supported on an inorganic oxide, a ligand exchange reaction between an anionic ligand on the metal complex and a hydroxyl group on the surface of the inorganic oxide is utilized (Non-Patent Document 1). Therefore, a large structural change occurs around the central metal of the metal complex before and after support, and it is difficult to predict the properties of the supported metal complex from the properties of the metal complex before support.
Therefore, Tilley et al. have developed a method using a metal complex having a tris(tert-butoxy)siloxy ligand (Non-Patent Document 2). Since the central metal of a metal complex having a tris(tert-butoxy)siloxy ligand is adjacent to an oxygen atom, adjacent to that is a silicon atom, and adjacent to that is an oxygen atom, even if the loading proceeds by a ligand exchange reaction between the tris(tert-butoxy)siloxy ligand and the surface hydroxyl groups of the silica gel, the structure around the central metal of the metal complex before loading and the loaded metal complex does not change significantly (see the chemical reaction formula below).

However, the supported metal complex produced by the above method is supported on the inorganic oxide surface via a single bond, and therefore has low stability. In addition, even during the process of heat-treating this supported metal complex to obtain a supported metal catalyst, there is a possibility that the complex will be supported on the inorganic oxide as large metal particles due to its low stability.

The present inventors have therefore developed a method of using a metal complex having a disiloxane ligand as a method of supporting a metal complex on an inorganic oxide while maintaining the skeletal structure before support (Patent Document 1). With a metal complex having a disiloxane ligand, a substitution reaction with the surface hydroxyl group of the inorganic oxide proceeds on the silicon atom of the disiloxane ligand, rather than a ligand exchange reaction. Therefore, not only does the structure around the central metal not change before and after support, but the chelate structure of the disiloxane ligand is maintained, and the supported metal complex produced can be expected to be highly stable compared to the case of using a metal complex having a tris(tert-butoxy)siloxy ligand supported by a single bond. Patent Document 1 discloses a metal complex and a supported metal complex having disiloxane as a ligand, a method for producing the same, and a supported metal catalyst prepared using the same.

Patent No. 6090759

Chem. Rev. ,2016,116,323 Chem. Mater. ,2008,20,6517

（上記式中Ｍはパラジウムまたは白金、Ｌは一酸化炭素、オレフィン化合物、アミン化合物、ホスフィン化合物、Ｎ－複素環式カルベン化合物、ニトリル化合物、イソシアニド化合物から選ばれる配位子、ｎは配位子の個数を表す０から２の整数、Ｒ^１～Ｒ^４はそれぞれ独立に、アルコキシ基、アミノ基から選択される有機基を表す。）
本発明の課題は、ジシロキサンおよびそれを配位子として有する金属錯体よりも取り扱いが簡便であり、かつ、当該金属錯体と同様に金属触媒等として利用可能な化合物の提供にある。 In the above-mentioned Patent Document 1 (JP Patent No. 6090759), disiloxane in which two silicon atoms are crosslinked with oxygen is used as a ligand of a metal complex. Specifically, a compound represented by the following general formula is disclosed. In this compound, the Si-O bond of disiloxane and the metal complex having it as a ligand is highly hydrolyzable, so it is necessary to handle them with care.

(In the above formula, M is palladium or platinum, L is a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n is an integer of 0 to 2 representing the number of ligands, and R ¹ to R ⁴ each independently represent an organic group selected from an alkoxy group and an amino group.)
An object of the present invention is to provide a compound which is easier to handle than disiloxanes and metal complexes having disiloxanes as ligands, and which can be used as metal catalysts, etc., like the metal complexes.

（式（１）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す）
また本発明の別の態様は、
〔２〕上記〔１〕に記載の化合物を製造する方法であって、
（ｉ）メチレンビス（トリクロロシラン）と金属アルコキシドとを反応させて、下記一般式（２）で示される化合物を得る工程と

（式（２）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す）
（ｉｉ）前記一般式（２）で示される化合物を塩基存在下、水と反応させる工程と
を含む、製造方法に関する。
また本発明の別の態様は、
〔３〕下記一般式（２）で示される化合物に関する：

（式（２）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す） The present inventors came up with the idea of using methylene bis(dialkoxysilanolate), in which two silicon atoms are bridged with a methylene carbon (CH ₂ ), as a ligand for a metal complex. As a result of intensive research, the present inventors succeeded in newly synthesizing methylene bis(dialkoxysilanol) and in producing a metal complex having methylene bis(dialkoxysilanolate) as a ligand from the methylene bis(dialkoxysilanol). The present invention was completed based on the above findings and includes the following aspects:
One aspect of the present invention is
[1] A compound represented by the following general formula (1):

(In formula (1), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
Another aspect of the present invention is
[2] A method for producing the compound according to the above [1], comprising the steps of:
(i) reacting methylenebis(trichlorosilane) with a metal alkoxide to obtain a compound represented by the following general formula (2);

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
(ii) reacting the compound represented by the general formula (2) with water in the presence of a base.
Another aspect of the present invention is
[3] A compound represented by the following general formula (2):

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

（式（２）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す）
また本発明の別の態様は、
〔６〕下記一般式（３）または（３）’で示される金属錯体に関する：

（式（３）および（３）’中、Ｍは白金またはロジウム、Ｌは一酸化炭素、オレフィン化合物、アミン化合物、ホスフィン化合物、Ｎ－複素環式カルベン化合物、ニトリル化合物、イソシアニド化合物から選ばれる配位子、ｎは配位子の個数を表す０から２の整数、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を表す。） Another aspect of the present invention is
[4] A method for producing the compound according to [3] above, comprising the steps of:
(i) The present invention relates to a production method comprising the step of reacting methylenebis(trichlorosilane) with a metal alkoxide.
Another aspect of the present invention is
[5] A method for producing the compound according to the above [1], comprising the steps of:
(ii) A production method comprising a step of reacting a compound represented by the following general formula (2) with water in the presence of a base:

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
Another aspect of the present invention is
[6] A metal complex represented by the following general formula (3) or (3)':

(In formulas (3) and (3)', M represents platinum or rhodium, L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n represents an integer of 0 to 2 representing the number of ligands, and R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

（式（３）および（３）’中、Ｍは白金またはロジウム、Ｌは一酸化炭素、オレフィン化合物、アミン化合物、ホスフィン化合物、Ｎ－複素環式カルベン化合物、ニトリル化合物、イソシアニド化合物から選ばれる配位子、ｎは配位子の個数を表す０から２の整数、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を表す。） Another aspect of the present invention is
[7] A method for producing the metal complex according to [6] above, comprising the steps of:
The present invention relates to a method for producing a metal complex, comprising the steps of: (a) reacting the compound according to the above item [1] with a base; and (b) reacting the compound obtained in the above item (a) with a metal complex LnMX ₂ (wherein M is platinum or rhodium, L is a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n is an integer of 0 to 2 representing the number of ligands, and X is a halogen or a hydroxyl group).
Another aspect of the present invention relates to [8] a method for producing a supported metal complex, comprising the step of supporting the metal complex on an inorganic oxide by contacting an organic solvent solution of a metal complex represented by the following general formula (3) or (3)′ with an inorganic oxide:

(In formulas (3) and (3)', M represents platinum or rhodium, L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n represents an integer of 0 to 2 representing the number of ligands, and R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

Another aspect of the present invention is
[9] The present invention relates to a supported metal complex comprising the metal complex according to [6] above and an inorganic oxide, the supported metal complex being supported on the inorganic oxide.
Another aspect of the present invention is
[10] The present invention relates to a method for producing a supported metal catalyst, which comprises a step of heat-treating the supported metal complex according to [9] above at a temperature of 80° C. to 600° C.
Another aspect of the present invention is
[11] The present invention relates to a supported metal catalyst obtained by heat-treating the supported metal complex according to the above [9].
Another aspect of the present invention is
[12] The present invention relates to a method for producing a catalyst for hydrogenation of olefins, comprising a step of heat-treating the supported metal complex according to [9] above at a temperature of 80° C. to 600° C. in an oxygen, air, nitrogen, argon or hydrogen atmosphere.
Another aspect of the present invention is
[13] A catalyst for hydrosilylation of olefins, comprising the metal complex according to the above [6].
Another aspect of the present invention is
[14] The present invention relates to a catalyst for hydrosilylation reaction of olefins, comprising the supported metal complex according to the above [9].

The methylenebis(dialkoxysilanol) provided by the present application is less prone to hydrolysis than disiloxane. This makes it possible to stably handle metal complexes with methylenebis(dialkoxysilanol) and methylenebis(dialkoxysilanolate) as ligands.

FIG. 1 is a graph showing a TEM image and average particle size distribution of a platinum catalyst supported on mesoporous silica (MCM-41) synthesized in Example 8 below. FIG. 2 is a graph showing a TEM image and average particle size distribution of a platinum catalyst supported on mesoporous silica (MCM-41) synthesized in Example 9 below. FIG. 3 is a graph showing a TEM image and average particle size distribution of the amorphous silica-supported platinum catalyst synthesized in Example 10 below. 4 is a graph showing the reaction time (horizontal axis) and yield (vertical axis) when cyclooctene was subjected to a hydrogenation reaction using each supported platinum complex in the following Examples 16 to 18. In FIG. 4, (1) shows the results for a platinum catalyst supported on mesoporous silica, (2) shows the results for a platinum catalyst supported on amorphous silica, and (3) shows the results for a platinum catalyst supported on fumed silica.

（式（１）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す） 1-1. Methylenebis(dialkoxysilanol)
In one aspect of the present invention, there is provided a compound represented by the following general formula (1):

(In formula (1), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

In this specification, an alkoxy group having 1 to 20 carbon atoms may be a linear, branched, or cyclic alkoxy group. Specific examples of the alkoxy group having 1 to 20 carbon atoms in this specification include, but are not limited to, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentoxy group, an isopentoxy group, a tert-pentoxy group, a neo-pentoxy group, an n-hexyloxy group, an n-cyclohexyloxy group, an n-dodecyloxy group, and a phenoxy group. A tert-butoxy group or a tert-pentoxy group is preferable.
In this specification, an alkoxy group having 1 to 20 carbon atoms can be represented by ^-OR5 . ^R5 is, for example, a substituted or unsubstituted alkyl group or aryl group having 1 to 20 carbon atoms. Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms such as fluorine, bromine, or chlorine.

（式（２）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す）
（ｉｉ）前記一般式（２）で示される化合物を塩基存在下、水と反応させる工程
とにより合成することができる。
下記にメチレンビス（ジアルコキシシラノール）の製造方法の一実施の形態における合成スキームを記載する。

1-2. Synthesis of methylenebis(dialkoxysilanol) The methylenebis(dialkoxysilanol) provided by the present invention is
(i) reacting methylenebis(trichlorosilane) with a metal alkoxide to obtain a compound represented by the following general formula (2);

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
(ii) reacting the compound represented by the general formula (2) with water in the presence of a base.
A synthesis scheme of one embodiment of the method for producing methylenebis(dialkoxysilanol) is shown below.

(i) In the step of reacting methylenebis(trichlorosilane) with a metal alkoxide to obtain a compound represented by the above general formula (2), the metal alkoxide is preferably an alkali metal alkoxide, and specific examples thereof include, but are not limited to, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, lithium tert-pentoxide, sodium tert-pentoxide, potassium tert-pentoxide, and the like.
The amount of metal alkoxide used (charged amount) is 3 to 6 equivalents in terms of substance amount relative to methylenebis(trichlorosilane).

Examples of the base used in step (ii) include nitrogen-containing organic bases such as pyridine, 2,6-lutidine, 3,5-lutidine, 2,4,6-collidine, 4-dimethylaminopyridine, triethylamine, tributylamine, diisopropylamine, diisopropylethylamine, piperidine, 2,2,6,6-tetramethylpiperidine, 1-methylimidazole, 1,5-diazabicyclo[4.3.0]-5-nonene, and 1,8-diazabicyclo[5.4.0]-7-undecene.
The amount of the base used (charged amount) is 1.5 to 2.5 equivalents in terms of the amount of substance based on the compound represented by the general formula (2).

Examples of the solvent used in step (i) include hexane, heptane, cyclohexane, benzene, and toluene. The reaction is preferably carried out under an inert atmosphere such as nitrogen or argon. The reaction temperature can be −80° C. to 25° C. The reaction time can be 4 hours to 48 hours.
After the reaction, the reaction solution is preferably subjected to filtration or distillation under reduced pressure to remove volatile components, if necessary.

（式（２）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す） By the step (i), a compound represented by the following general formula (2) can be obtained as an intermediate in the synthesis of methylenebis(dialkoxysilanol).

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

After the compound represented by the above general formula (2) is obtained by the step (i), the step (ii) of reacting the compound represented by the general formula (2) with water in the presence of a base is carried out.
Examples of the solvent used in step (ii) include diethyl ether, cyclopentyl methyl ether, tert-butyl methyl ether, or a mixture thereof. The reaction is preferably carried out under an inert atmosphere such as nitrogen or argon. The reaction temperature can be 0° C. to 30° C. The reaction time can be 12 hours to 48 hours.
The amount of water used (charged amount) in the step (ii) is 2 to 5 equivalents in terms of the amount of substance of the compound represented by the general formula (2).
After the reaction, the reaction solution is preferably separated by column chromatography, and then volatile components are distilled off under reduced pressure.

（式（３）および（３）’中、Ｍは白金またはロジウム、Ｌは一酸化炭素、オレフィン化合物、アミン化合物、ホスフィン化合物、Ｎ－複素環式カルベン化合物、ニトリル化合物、イソシアニド化合物から選ばれる配位子、ｎは配位子の個数を表す０から２の整数、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基表す。） 2-1. Metal Complex Having Methylenebis(dialkoxysilanolate) Ligand As another embodiment of the present invention, there is provided a metal complex represented by the following general formula (3) or (3)′:

(In formulas (3) and (3)', M represents platinum or rhodium, L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n represents the number of ligands and is an integer of 0 to 2, and R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

The ligand L in the general formulae (3) and (3)' is not particularly limited as long as it can substantially form a coordinate bond with the central metal. Examples of such ligands include carbon monoxide, olefin compounds such as 1,5-cyclooctadiene (COD), 1,3-cyclopentadiene, 1,2,3,4,5-pentamethylcyclopentadiene, 2,5-norbornadiene, ethylene, and dibenzylideneacetone, and amine compounds such as 2,2'-bipyridyl, 1,10-phenanthroline, ethylenediamine, 1,2-bis(dimethylamino)ethane, 1,2-diphenylethylenediamine, 1,2-diphenylethylenediamine, and 1,3-diphenylethylenediamine. , 2-cyclohexanediamine, and the like. Examples of the phosphine compound include trimethylphosphine, triethylphosphine, triisopropylphosphine, tri-tert-butylphosphine, tricyclohexylphosphine, triphenylphosphine, dimethylphenylphosphine, trimethylphosphite, triethylphosphite, triisopropylphosphite, tri-tert-butylphosphine, triphenylphosphine, methyldiphenylphosphite, 1,2-bis(dimethylphosphino)ethane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(dimethylphosphino)ethane, 1,4-bis(dimethylphosphino)ethane, 1,5-bis(dimethylphosphino)ethane, 1,6-bis(dimethylphosphino)ethane, 1,7-bis(dimethylphosphino)ethane, 1,8-bis(dimethylphosphino)ethane, 1,9-bis(dimethylphosphino)ethane, 2,10-bis(dimethylphosphino)ethane, 2,11-bis(dimethylphosphino)ethane, 2,2-bis(dimethylphosphino)ethane, 2,3-bis(dimethylphosphino)ethane, 2,4-bis(dimethylphosphino)ethane, 2,5-bis(dimethylphosphino)ethane, 2,6-bis(dimethylphosphino)ethane, 2,7-bis(dimethylphosphino)ethane, 2,8-bis(dimethylphosphino)ethane, 2,9-bis(dimethylphosphino)ethane, 2,11-bis(dimethylphosphino)ethane, 2,12-bis(dimethylphosphino)ethane, 2,13-bis(dimethylphosphino)ethane, 2,14-bis(dimethylphosphino)ethane, 2,15-bis(dimethylphosphino)ethane, 2,16-bis(dimethylphosphino)ethane, 2,17-bis Examples of the N-heterocyclic carbene compounds include 1,3-bis(2,6-diisopropylphenyl)imidazolidine-2-ylidene, 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, 1,3-di-tert-butylimidazol-2-ylidene, 1,3-bis(2,4,6-trimethylphenyl)imidazolidine-2-ylidene, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, 1,3-di(1-adamantyl)imidazolidine ... Examples of the nitrile compound include benzonitrile and acetonitrile. Examples of the isocyanide compound include tert-butylisocyanide and 1,1,3,3-tetramethylbutylisocyanide. Of these, 1,5-cyclooctadiene, dibenzylideneacetone, trimethylphosphine, triethylphosphine, tri-tert-butylphosphine, triphenylphosphine and the like are preferred, and 1,5-cyclooctadiene and trimethylphosphine are more preferred.
In addition, n in the general formulae (3) and (3)′ represents the number of ligands and is an integer of 0 to 2. When the ligand L is a bidentate ligand such as 1,5-cyclooctadiene, n is usually 1, and when it is a monodentate ligand such as trimethylphosphine, n is usually 2.
From the viewpoint of enabling immobilization on an inorganic oxide, the organic groups R ¹ to R ⁴ are preferably each independently a hydrolyzable alkoxy group having 1 to 20 carbon atoms.

（式（１）中、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を示す）
（ｂ）上記工程（ａ）で得られた化合物と金属錯体ＬｎＭＸ_２（式中Ｍは白金またはロジウム、Ｌは一酸化炭素、オレフィン化合物、アミン化合物、ホスフィン化合物、Ｎ－複素環式カルベン化合物、ニトリル化合物、イソシアニド化合物から選ばれる配位子、ｎは配位子の個数を表す０から２の整数を表す。Ｘはハロゲンまたは水酸基を表す）とを反応させる工程。 2-2. Synthesis of metal complex having methylenebis(dialkoxysilanolate) ligand The metal complex having a methylenebis(dialkoxysilanolate) ligand provided by the present invention can be produced by the following steps (a) and (b):
(a) reacting a compound represented by the following general formula (1) with a base:

(In formula (1), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
(b) A process for reacting the compound obtained in the above process (a) with a metal complex LnMX ₂ (wherein M is platinum or rhodium, L is a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n is an integer of 0 to 2 representing the number of ligands, and X is a halogen or a hydroxyl group).

A synthesis scheme in one embodiment of the method for producing a metal complex having a methylenebis(dialkoxysilanolate) ligand is shown below.

Examples of the base that can be used in step (a) include, but are not limited to, alkali metal hydrides such as lithium hydride, sodium hydride, and potassium hydride, alkyl lithiums such as n-butyllithium, sec-butyllithium, and tert-butyllithium, lithium amides such as lithium diisopropylamide, and alkali metal disilazides such as lithium hexamethyldisilazide, sodium hexamethyldisilazide, and potassium hexamethyldisilazide, etc. Preferred examples include potassium hydride and sodium hydride.
The amount of the base used (charged amount) is 1.5 to 2.5 equivalents in terms of the amount of substance based on the compound represented by the general formula (1).

Examples of the solvent used in step (a) include tetrahydrofuran, diethyl ether, cyclopentyl methyl ether, tert-butyl methyl ether, or a mixture thereof. The reaction in step (a) is preferably carried out in an inert atmosphere such as nitrogen or argon. The reaction temperature can be 0 to 30°C. The reaction time can be 1 to 6 hours.

The metal complex used in step (b) can be represented by _LnMX2 . M represents platinum or rhodium. L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, and can be selected from the same compounds as the ligand L in the above general formula (3) or (3)'. n represents an integer of 0 to 2 representing the number of ligands, and X represents a halogen or a hydroxyl group.
The amount of the metal complex used (charged amount) is 0.5 to 1.5 equivalents in terms of the amount of substance based on the compound represented by the general formula (1).

Examples of the solvent used in step (b) include tetrahydrofuran, diethyl ether, cyclopentyl methyl ether, tert-butyl methyl ether, and a mixture thereof. The reaction in step (b) is preferably carried out under an inert atmosphere such as nitrogen or argon. The reaction temperature can be −80 to 80° C. The reaction time can be 1 to 24 hours.
After the reaction, the reaction solution is preferably subjected to filtration or distillation under reduced pressure to remove volatile components, if necessary.

3. Synthesis of Supported Metal Complexes In another aspect of the present invention, there are provided a method for producing a supported metal complex comprising a metal complex having a methylenebis(dialkoxysilanolate) ligand and an inorganic oxide, and a supported metal complex produced by said method. The supported metal complex has a structure in which the constituent metal complex is supported on an inorganic oxide.

（式（３）および（３）’中、Ｍは白金またはロジウム、Ｌは一酸化炭素、オレフィン化合物、アミン化合物、ホスフィン化合物、Ｎ－複素環式カルベン化合物、ニトリル化合物、イソシアニド化合物から選ばれる配位子、ｎは配位子の個数を表す０から２の整数、Ｒ^１～Ｒ^４はそれぞれ独立に、炭素原子数１～２０のアルコキシ基を表す。） The method for producing a supported metal complex according to the present invention includes a step of supporting the metal complex on an inorganic oxide by contacting an organic solvent solution of a metal complex represented by the following general formula (3) or (3)′ with an inorganic oxide:

(In formulas (3) and (3)', M represents platinum or rhodium, L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n represents an integer of 0 to 2 representing the number of ligands, and R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)

The supported metal complex can be obtained by contacting an organic solvent solution of the metal complex having the methylene bis(dialkoxysilanolate) ligand of the present invention with an inorganic oxide as described above. The alkoxy groups on the methylene bis(dialkoxysilanolate) ligand are substituted with hydroxyl groups on the surface of the inorganic oxide to achieve the supporting. As long as the metal complex is supported on the inorganic oxide, the supported metal complex of the present invention may have one to four alkoxy groups substituted at any one of the four alkoxy groups (i.e., the substitution may occur in any one of the following patterns (a) to (e) or a combination thereof).

Inorganic oxides that can be used to produce supported metal complexes include, but are not limited to, single oxides of silicon, titanium, aluminum, zirconium, magnesium, etc., or composite oxides containing them. Preferably, silica, which is an oxide of silicon, such as amorphous silica, or composite oxides containing silicon, such as aluminosilicate, are used from the viewpoint that they have many silanol groups as hydroxyl groups on the surface and can form strong covalent bonds between organic leaving groups and inorganic oxides. Furthermore, it is also preferable to use regular mesoporous silica or regular mesoporous metallosilicates such as MCM-41 and SBA-15, zeolites such as crystalline aluminosilicates, metallosilicates, aluminophosphates, and silica aluminophosphates, porous glass, clay minerals, etc., because they can be introduced in a large amount per unit weight by utilizing a large surface area. The inorganic oxides used in the present invention may be synthesized by a known method or may be commercially available products.

The inorganic oxide preferably has an average pore diameter of 0.5 to 500 nm, more preferably 1 to 100 nm. In order to bond the metal complex to the inorganic oxide at high density, the inorganic oxide preferably has a large surface area, for example, a specific surface area of 100 to 1500 ^{m 2} /g.
Examples of organic solvents for dissolving the metal complex include aliphatic hydrocarbons such as pentane and hexane, aromatic hydrocarbons such as toluene and xylene, and ethers such as diethyl ether and dibutyl ether. These may be used alone or in combination.
The step of contacting an inorganic oxide with an organic solvent solution containing a metal complex of the above general formula (3) or (3)' may be carried out by suspending the inorganic oxide in the organic solvent solution in which the metal complex has been dissolved, and stirring the suspension at room temperature or under heating. The solid is then collected by filtration, washed, and dried to obtain a supported metal complex.
The amount of supported metal in the resulting supported metal complex can be determined by analysis such as ICP-OES.

In the supported metal complex of the present invention, the metal complex supported on the carrier maintains the framework structure of the metal complex before being supported, and therefore can maintain the catalytic activity of the metal complex before being supported.
For example, as confirmed in Examples 13 to 18 described below, the supported metal complex of the present invention has catalytic activity for the hydrosilylation reaction of olefins, such as the hydrosilylation reaction of norbornene, similar to the corresponding metal complex before being supported. In addition, the supported metal catalyst of the present invention has catalytic activity for the hydrogenation reaction of olefins, such as the hydrogenation reaction of cyclooctene.

The supported metal catalyst of the present invention can be obtained by heat treating the supported metal complex of the present invention at a temperature of 80 to 600°C in an oxygen, air, nitrogen, argon or hydrogen atmosphere. The amount of supported metal in the obtained supported metal catalyst can be determined by analysis such as ICP-OES.

The present invention will be described in detail below using specific examples, but the present invention is not limited to the following embodiments.

Example 1. Synthesis of methylenebis(di-tert-butoxysilanol)
In this example, methylenebis(di-tert-butoxysilanol) was synthesized using methylenebis(trichlorosilane), as shown in the following chemical reaction formula.

Specifically, under an inert atmosphere, 15 mL of n-hexane was added to 0.50 g of methylenebis(trichlorosilane) in a flask, and the mixture was cooled to -50°C. 0.79 g of potassium tert-butoxide was added thereto, and the mixture was mixed and stirred for 19 hours while slowly raising the temperature to room temperature to obtain a reaction solution. The reaction solution was then filtered, and the volatile components of the filtrate were distilled off under reduced pressure to obtain a colorless oily product in a yield of 87% (0.67 g). The colorless oily product was confirmed to be methylenebis(di-tert-butoxychlorosilane) by ¹ H-NMR and ²⁹ Si-NMR.
¹ H NMR (600 MHz, C ₆ D ₆ ); δ1.34 ((CH ₃ )C), 0.73 (Si-CH ₂ -Si)
^29Si NMR (600MHz, C ₆ D ₆ ); δ-49.5

0.30 g of this methylenebis(di-tert-butoxychlorosilane), 8 mL of diethyl ether, and 0.12 mL of pyridine were added to a flask, and then 0.06 mL of water was added at room temperature and mixed and stirred for 28 hours to obtain a reaction solution. This reaction solution was passed through a column packed with diol silica (eluent: diethyl ether), and the resulting solution was distilled under reduced pressure to obtain a colorless oily product in a yield of 73% (0.2 g). The colorless oily product was confirmed to be methylenebis(di-tert-butoxysilanol) by ¹ H-NMR and ²⁹ Si-NMR.
¹ H NMR (600 MHz, C ₆ D ₆ ); δ3.78 (Si-OH), 1.39 ((CH ₃ )C), 0.15 (Si-CH ₂ -Si)
^29Si NMR (600MHz, C ₆ D ₆ ); δ-49.5

Example 2. Synthesis of platinum complexes having methylenebis(dialkoxysilanolate) ligands.
In this example, as shown in the following chemical reaction formula, a platinum complex having a methylenebis(di-tert-butoxysilanol) ligand was synthesized using the methylenebis(di-tert-butoxysilanol) obtained in Example 1.

Specifically, under an inert atmosphere, 25 mL of THF was added to 0.26 g of potassium hydride in a flask, and cooled to 0° C. A 15 mL THF solution containing 1.24 g of methylenebis(dialkoxysilanol) was added thereto at 0° C. After mixing and stirring for 2 hours at 0° C., the mixture was mixed and stirred at room temperature for 0.5 hours to obtain a reaction solution. Then, this reaction solution was added to a 15 mL THF suspension containing 1.15 g of platinum dichloro(cyclooctadiene) complex at −80° C. Then, the suspension was mixed and stirred while being gradually heated to room temperature over 3 hours. After further stirring at room temperature for 0.5 hours, the volatile components were distilled off under reduced pressure. 50 mL of diethyl ether was added to the obtained solid, and the solution was filtered. The obtained filtrate was distilled off under reduced pressure, and recrystallized from hexane to obtain a white solid with a yield of 50% (1.10 g). The white solid was identified as a platinum complex having a methylenebis(dialkoxysilanolate) ligand by ¹ H-NMR, ¹³ C-NMR and ²⁹ Si-NMR.
^1H NMR (600MHz, C ₆ D ₆ ); δ4.73 (m, 4H, HC=CH (COD)), 1.81 (m, 4H, H ₂ C=CH ₂ (COD)), 1.60 (s, 36H, (CH ₃ )C), 1.19 (m, 4H, H ₂ C=CH ₂ (COD)), 0.53 (s, 2H, Si-CH ₂ -Si)
^13C NMR (600MHz, _C6D6 ) _; δ91.0, 71.5, 32.6, 29.8, 8.1
^29Si NMR (600MHz, C ₆ D ₆ ); δ-50.3

Example 3. Synthesis of rhodium complexes having methylenebis(dialkoxysilanolate) ligands.
In this example, as shown in the following chemical reaction formula, a rhodium complex having a methylenebis(di-tert-butoxysilanol) ligand was synthesized using the methylenebis(di-tert-butoxysilanol) obtained in Example 1.

Specifically, 10 mL of THF was added to 0.08 g of potassium hydride in a flask under an inert atmosphere, and cooled to 0° C. A 10 mL solution of methylene bis(dialkoxysilanol) containing 0.40 g was added thereto at 0° C. After mixing and stirring at 0° C. for 2 hours, the mixture was mixed and stirred at room temperature for 0.5 hours. Then, this reaction solution was added to a 10 mL solution of THF containing 0.49 g of rhodium chloro(cyclooctadiene) dimer complex at −60° C. After this, the reaction solution was mixed and stirred while being gradually warmed to room temperature over 4 hours. After further stirring at room temperature for 0.5 hours, the volatile components were distilled off under reduced pressure. 50 mL of diethyl ether was added to the obtained solid, and the solution was filtered. The obtained filtrate was distilled off under reduced pressure, and recrystallized from hexane to obtain a yellow solid with a yield of 42% (0.3 g). The yellow solid was identified as a dinuclear rhodium complex having a methylenebis(dialkoxysilanolate) ligand by ¹ H-NMR and ²⁹ Si-NMR.
^1H NMR (600MHz, C ₆ D ₆ ); δ4.41 (m, 8H, HC=CH (COD)), 2.57 (m, 8H, H ₂ C=CH ₂ (COD)), 1.71 (m, 8H, H ₂ C=CH ₂ (COD)), 1.51 (s, 36H, (CH ₃ )C), 0.63 (s, 2H, Si-CH ₂ -Si)
^29Si NMR (600MHz, C ₆ D ₆ ); δ-59.2

Example 4. Synthesis of mesoporous silica-supported platinum complex
In this example, the platinum complex having the methylenebis(dialkoxysilanolate) ligand synthesized in Example 2 was supported on mesoporous silica (MCM-41) to synthesize a supported platinum complex. Specifically, the supported platinum complex was synthesized as follows.

Mesoporous silica MCM-41 (0.3 g) was dried at 120° C. under reduced pressure for 1 hour. After cooling to room temperature, the reaction system was replaced with an inert atmosphere, 15 mL of toluene was added thereto, and mechanical stirring was performed at room temperature for 2 hours. A solution of 8 mL of toluene containing 0.01 g of a platinum complex having a methylene bis(dialkoxysilanolate) ligand was added thereto, and the mixture was mixed and stirred at room temperature for 24 hours. The obtained solid was filtered and washed with toluene. It was then dried under reduced pressure to obtain a platinum complex supported on mesoporous silica (MCM-41). It was confirmed by ²⁹ Si CP/MAS NMR that the platinum complex was supported on the surface of the mesoporous silica.
²⁹ Si CP/MAS NMR (400MHz); δ-47.2

(Example 5. Synthesis of amorphous silica-supported platinum complex)
In this example, the platinum complex having a methylenebis(dialkoxysilanolate) ligand synthesized in Example 2 was supported on amorphous silica (CARiACT Q-10, manufactured by Fuji Silysia Chemical Ltd.) to synthesize a supported platinum complex. Specifically, the supported platinum complex was synthesized as follows.

Amorphous silica (Fuji Silysia Co., Ltd., CARiACT Q-10) (0.5 g) was dried under reduced pressure at 120° C. for 1 hour. After cooling to room temperature, the atmosphere was replaced with an inert atmosphere, 12 mL of toluene was added, and mechanical stirring was performed at room temperature for 2 hours. A solution of 0.02 g of a platinum complex having a methylene bis(dialkoxysilanolate) ligand and 5 mL of toluene was added thereto, and the mixture was stirred at room temperature for 24 hours. The obtained solid was filtered and washed with toluene. It was then dried under reduced pressure to obtain a platinum complex supported on amorphous silica (CARiACT Q-10). It was confirmed by ²⁹ Si CP/MAS NMR that the platinum complex was supported on the surface of the amorphous silica.
²⁹ Si CP/MAS NMR (400MHz); δ-51.6.

Example 6. Synthesis of fumed silica supported platinum complex.
In this example, the platinum complex having a methylenebis(dialkoxysilanolate) ligand synthesized in Example 2 was supported on fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) to synthesize a supported platinum complex. Specifically, the supported platinum complex was synthesized as follows.

Fumed silica (Aerosil 200, Nippon Aerosil Co., Ltd.) (2 g) was dried at 120° C. for 1 hour under reduced pressure. After cooling to room temperature, the reaction system was replaced with an inert atmosphere, 163 mL of toluene was added, and mechanical stirring was performed at room temperature for 2 hours. A solution of 0.07 g of a platinum complex having a methylene bis(dialkoxysilanolate) ligand and 25 mL of toluene was added thereto, and the mixture was mixed and stirred at room temperature for 24 hours. The obtained solid was filtered and washed with toluene. It was then dried at room temperature under reduced pressure to obtain a platinum complex supported on fumed silica (Aerosil 200). It was confirmed by ²⁹ Si CP/MAS NMR that the platinum complex was supported on the surface of the fumed silica.
²⁹ Si CP/MAS NMR (400MHz); δ-51.6, -59.3

Example 7. Synthesis of fumed silica supported rhodium complex
In this example, the rhodium complex having a methylenebis(dialkoxysilanolate) ligand synthesized in Example 3 was supported on fumed silica (Aerosil 200, Nippon Aerosil Co., Ltd.) to synthesize a supported rhodium complex. Specifically, the supported rhodium complex was synthesized as follows.

Fumed silica (Aerosil 200, Nippon Aerosil Co., Ltd.) (2 g) was dried at 120° C. for 1 hour under reduced pressure. After cooling to room temperature, the reaction system was replaced with an inert atmosphere, 95 mL of toluene was added, and mechanical stirring was performed at room temperature for 2 hours. A solution of 0.9 g of a rhodium complex having a methylene bis(dialkoxysilanolate) ligand and 18 mL of toluene was added thereto, and the mixture was mixed and stirred at room temperature for 24 hours. The obtained solid was filtered and washed with toluene. It was then dried at room temperature under reduced pressure to obtain a rhodium complex supported on fumed silica (Aerosil 200). It was confirmed by ²⁹ Si CP/MAS NMR that the rhodium complex was supported on the surface of the fumed silica.
²⁹ Si CP/MAS NMR (400MHz); δ-61.9

Example 8. Synthesis of mesoporous silica-supported platinum catalyst.
In this example, the mesoporous silica-supported platinum complex synthesized in Example 4 was heat-treated to synthesize a mesoporous silica-supported platinum catalyst.
Specifically, 0.5 g of the mesoporous silica (MCM-41)-supported platinum complex synthesized in Example 4 was heat-treated at 300°C for 2 hours under an oxygen stream to obtain 0.49 g of mesoporous silica (MCM-41)-supported platinum catalyst. The amount of platinum supported on the obtained mesoporous silica (MCM-41)-supported platinum catalyst was determined by ICP-OES and was found to be 0.95 wt%. The average particle size was evaluated by TEM observation and was found to be 2.8 nm (Figure 1).

Example 9. Synthesis of mesoporous silica-supported platinum catalyst.
In this example, the mesoporous silica-supported platinum complex synthesized in Example 4 was heat-treated to synthesize a mesoporous silica-supported platinum catalyst.
Specifically, 0.5 g of the mesoporous silica (MCM-41) supported platinum complex synthesized in Example 4 was heat-treated at 300° C. for 2 hours under an argon stream to obtain 0.49 g of mesoporous silica (MCM-41) supported platinum catalyst. The average particle size was evaluated from a TEM observation image and was found to be 1.1 nm (FIG. 2).

Example 10. Synthesis of amorphous silica supported platinum catalyst.
In this example, the amorphous silica-supported platinum complex synthesized in Example 5 was heat-treated to synthesize an amorphous silica-supported platinum catalyst.
Specifically, 0.49 g of amorphous silica (CARiACT Q-10)-supported platinum catalyst was obtained by carrying out the same procedure as in Example 8, except that 0.5 g of the amorphous silica (CARiACT Q-10)-supported platinum complex synthesized in Example 5 was used. The amount of platinum supported on the obtained amorphous silica (CARiACT Q-10)-supported platinum catalyst was determined by ICP-OES and was found to be 1.04 wt %. The particle size was evaluated by TEM observation and was found to be 1.5 nm (Figure 3).

Example 11. Synthesis of fumed silica supported platinum catalyst.
In this example, the fumed silica-supported platinum complex synthesized in Example 6 was heat-treated to synthesize a fumed silica-supported platinum catalyst.
Specifically, 0.48 g of a platinum catalyst supported on fumed silica (Aerosil 200) was obtained by carrying out the same operation as in Example 8, except that 0.5 g of the platinum complex supported on fumed silica (Aerosil 200) synthesized in Example 6 was used. The amount of platinum supported on the obtained platinum catalyst supported on fumed silica (Aerosil 200) was determined by ICP-OES and was found to be 1.04 wt %.

Example 12: Hydrosilylation of olefins using platinum complexes having methylenebis(dialkoxysilanolate) ligands
In this example, the hydrosilylation of norbornene, an olefin, was examined using the platinum complex having the methylenebis(dialkoxysilanolate) ligand synthesized in Example 2.

Specifically, 0.20 mL of a toluene solution containing 0.02 g of a platinum complex having a methylenebis(dialkoxysilanolate) ligand was added to 4 mL of a toluene solution containing 0.16 g of dimethylphenylsilane, 0.11 g of norbornene, and 0.1 mL of the reference substance 1,3,5-trimethylbenzene, and the mixture was stirred at room temperature for 20 minutes. The product yield (67%) was then determined by gas chromatographic analysis.

(Examples 13 to 15. Hydrosilylation reaction of olefins using supported platinum complexes)
In this example, the hydrosilylation reaction of norbornene, an olefin, was investigated using each of the supported platinum complexes synthesized in Examples 4 to 6 (mesoporous silica-supported platinum complex, amorphous silica-supported platinum complex, and fumed silica-supported platinum complex).

45 mg of any of the supported metal complexes synthesized in Examples 4 to 6, which had been dried under vacuum at 80°C for 1 hour, was weighed out and placed in a flask, and 1 mL of toluene was added. 4 mL of a toluene solution containing 0.16 g of dimethylphenylsilane, 0.11 g of norbornene, and 0.1 mL of the reference substance 1,3,5-trimethylbenzene was added, and the mixture was mixed and stirred at room temperature for 20 minutes. The yield of the hydrosilylation product was then determined by gas chromatographic analysis (Table 1).

(Examples 16 to 18. Hydrogenation of olefins using platinum catalyst supported on silica)
In this example, the hydrogenation reaction of cyclooctene, which is an olefin, was examined using each of the supported platinum catalysts synthesized in Examples 8, 10, and 11 (mesoporous silica-supported platinum catalyst, amorphous silica-supported platinum catalyst, and fumed silica-supported platinum catalyst).

In a 50 mL Schlenk flask, 20 mg of the supported platinum catalyst obtained in Examples 8, 10, and 11 was weighed out and reduced at 300° C. for 1 hour under a hydrogen stream of 40 mL min ⁻¹ . After cooling the Schlenk flask to room temperature, the inside of the Schlenk flask was replaced with argon gas, and 4 mL of isopropanol, 0.32 mL (2.45 mmol) of cyclooctene, and 0.12 mL of mesitylene as a reference substance were added. Thereafter, the inside of the Schlenk flask was replaced with hydrogen gas, and the mixture was stirred at 25° C. under 1 atmosphere of hydrogen. After a predetermined time had elapsed, the reaction solution was sampled, and the yield of cyclooctane was determined by gas chromatography analysis (FIG. 4; (1) mesoporous silica-supported platinum catalyst, (2) amorphous silica-supported platinum catalyst, and (3) fumed silica-supported platinum catalyst are shown).

Claims (13)

A compound represented by the following general formula (1):

(In formula (1), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.) A method for producing the compound of claim 1, comprising the steps of:
(i) reacting methylenebis(trichlorosilane) with a metal alkoxide to obtain a compound represented by the following general formula (2);

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
(ii) reacting the compound represented by the general formula (2) with water in the presence of a base. A method for producing a compound represented by the following general formula (2):

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.)
(i) A method for producing a compound comprising the step of reacting methylenebis(trichlorosilane) with a metal alkoxide . A method for producing the compound of claim 1, comprising the steps of:
(ii) A production method comprising the step of reacting a compound represented by the following general formula (2) with water in the presence of a base:

(In formula (2), R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.) A metal complex represented by the following general formula (3) or (3)':

(In formulas (3) and (3)', M represents platinum or rhodium, L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n represents an integer of 0 to 2 representing the number of ligands, and R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms.) A method for producing the metal complex of claim 5, comprising the steps of:
A method for producing a metal complex, comprising: (a) reacting the compound according to claim 1 with a base; and (b) reacting the compound obtained in the above step (a) with a metal complex LnMX ₂ (wherein M is platinum or rhodium, L is a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n is an integer of 0 to 2 representing the number of ligands, and X is a halogen or a hydroxyl group). A method for producing a supported metal complex, comprising the step of supporting the metal complex on an inorganic oxide by contacting an organic solvent solution of a metal complex represented by the following general formula (3) or (3)' with an inorganic oxide:

(In formulas (3) and (3)′, M represents platinum or rhodium, L represents a ligand selected from carbon monoxide, an olefin compound, an amine compound, a phosphine compound, an N-heterocyclic carbene compound, a nitrile compound, and an isocyanide compound, n represents an integer of 0 to 2 representing the number of ligands, and R ¹ to R ⁴ each independently represent an alkoxy group having 1 to 20 carbon atoms. A supported metal complex comprising the metal complex according to claim 5 and an inorganic oxide, the metal complex being supported on the inorganic oxide. A method for producing a supported metal catalyst, comprising a step of heat treating the supported metal complex according to claim 8 at a temperature of 80°C to 600°C. A supported metal catalyst obtained by heat-treating the supported metal complex according to claim 8. A method for producing a catalyst for hydrogenation of olefins, comprising a step of heat-treating the supported metal complex according to claim 8 at a temperature of 80°C to 600°C in an oxygen, air, nitrogen, argon or hydrogen atmosphere. A catalyst for hydrosilylation reactions of olefins comprising the metal complex according to claim 5. A catalyst for hydrosilylation reactions of olefins comprising the supported metal complex according to claim 8.

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