MULTIPLE-METAL COMPLEX-CONTAINING COMFOUJSP AND METAL

COMPLEX, AND MANUFACTURE METHODS THEREFOR, AND EXHAUST GAS

PURIFICATION CATALYST MANUFACTURE METHOD USING THE SAME

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The invention relates to a multiple-metal complex-containing compound ajid a metal complex, and manufacture method therefor as well as an exhaust gas purification catalyst manufacture method using the same, In particular, the invention relates to a method of manufacturing a metal particle having a controlled cluster size through the use of the multiple-metal complex-containing compound and the metal complex.

2, Description of the Related Art

[0002] A size-controlled metal cluster is different from a bulk metal ia chemical characteristics, such as catalytic activity and the like, and physical characteristics, such as magnetism and the like.

[0003] In order to efficiently utilize the peculiar characteristics of the metal cluster, a method for easily synthesizing a size-controlled cluster in. laxgc amount is needed, A known method for obtaining such a cluster is a method in which (i) clusters of various sizes are produced by causing a metal target to evaporates in vacuum, and (ϊi) the thus-obtained clusters are separated according to cluster sizes through the, use of the principle of the mass spectrum. However, this method is not able to easily synthesize a cluster in large amount.

[0004] The peculiar characteristics of the cluster is disclosed in, for example, "Adsorption and Reaction of Methanol Molecule on Nickel Cluster Ions, Ni _n ⁺ (n~3-ll)". M. Ichihashi, X Hanmura, R. T. Yadav and T. Kσndow, J. Phys, Chem- A, 104, 11885 (2000) (non-patent .document). This document discloses that the reactivity between methane molecules and platinum catalyst in the gas phase is greatly affected by the platinum cluster size, and that there exists a particular platinum cluster size that is optimal

fox the reaction, for example, as showa in FIG. 1. . ^•

[0005] Examples of utilization of the catalytic performance of a' noble metal include purification of exhaust gas discharged from an internal combustion engine, such as an

^• automotive engine or the like. At the time of the purification of exhaust gas, exhaust gas components, such as carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (N0χ), etc., are converted into carbon dioxide, nitrogen and oxygen by catalyst components whose main component is a noble metal such as platinum (Ft) ₃ rhodium (Rh), palladium (Pd) ₁ indium (Ir), etc. Generally, the catalyst component that is a noble metal is supported on a support made of an oxide, such as alumina or the like, in order to enlarge the contact area for exhaust gas and the catalyst component.

[0006] In order to support a noble metal on the oxide support, the oxide support is impregnated with a solution of a nitric acid salt of a noble metal or a noble metal complex having one noble metal atom so that the noble metal compound is dispersed on surfaces of the oxide support, and then the support impregnated with the solution is dried and fked. In this method, however, it is not easy to control the size and the number of atoms of the noble metal cluster.

[0007] With regard to such catalysts for exhaust gas purification, too, the supporting of a noble metal in the form of clusters has been proposed in order to further improve the exhaust gas purification capability, For example, Japanese Patent Application Publication No. JP-A-11-285644 discloses a technology in which a catalytic metal is supported in the form of ultrafine particle directly on a support through the use of a metal cluster complex that has a caibonyl group as a ligand.

[0008] Furthermore, Japanese Patent Application Publication No. JP-A-2003-181288 discloses a technology in which a noble metal catalyst having a controlled cluster size is manufactured by introducing a noble metal into pores of a hollow carbon material ^, such as carbon nanotube or the like, and fixing the carbon material with the noble metal introduced therein to an oxide support, and then firing it

[0009] Still further, Japanese Patent Application Publication No. JP-A-9-253490 discloses a technology in which a metal cluster made up of an alloy of rhodium and

, platinum dissolved in the solid state is obtained by ^" adding a reductant. to a solution containing rhodium' ions and platinum ions. . ^' ' ^•

[0010] With regard to the metal complex, obtaining a polymer having an infinite number of metal atoms through the use of a polydentate ligand is known. For example, Japanese Patent Application Publication No, JP-A-2000-109485 discloses a technology for obtaining a diearboxylic acid metal complex polymer having a giant three-dimensional structure through the use of a dicarboxylic acid.

SUMMARY OF IHE INVENTION [0011] The invention provides a novel multiple-metal complex-containing compound that allows easy synthesis of large amount of a size-controlled cluster, and a metal complex that can be used for the synthesis of the compound. The invention also provides methods for manufacturing the multiple-metal complex-containing compound and the complex, and methods of using the multiple-metal complex-containing compound and the complex. [00121 A first aspect of the invention relates to a multiple-metal complex-containing compound including two or more metal complexes in each of which a ligand is coordinated to one metal atom or a plurality of metal atoms of the same kind, wherein the two or more metal complexes are bound to each other via a pαlydentate ligand that substitutes partially the Hgands of the two or more metal complexes, and have 2 to 1000 metal atoms. [0013] According to the foregoing .aspect, if the ligands. are removed from the multiple-metal complex-containing compound by firing or the like, a metal or metal oxide cluster having the same number of metal atoms as contained in the compound can be obtained _*

[0014] A second aspect of the invention relates to a manufacture method for a metal or metal oxide cluster that has 2 to 1000 metal atoms, which includes (a) providing a solution containing the multiple-metal complex-containing compound of the invention, and (b) drying and firing the solution.

[0015] A third aspect of the invention relates to a manufacture method for a ^■ multiple-metal complex-containing compound, which includes; ^• providing ^• a metal

complex; providing a polydentate ligand or a pαlydentate ligand source; and dissolving the metal complex and the polydentate ligand or the polydentate ligand source in a solvent. [0016] According to the foregoing aspect, a multiple-metal complex-containing compound having a controlled number of metal atoms can be obtained by substituting at least only partially the ligands coordinated in the metal complexes, with a polydentate ligand. It is to be noted herein that the term "polydentate ligand source or iigand source" in this specification means a polydentate ligand or a compound (precursor) that provides or a ligand when dissolved in a solvent,

[0017] A fourth aspect of the invention relates to a metal complex in which ligands are coordinated to one metal atom or a plurality of metal atoms of the same kind, and at least one of the ligands has an, uncoordinated functional group that is not coordinated, to a metal atom and that is selected from the group consisting of: -COOH, -COOR ⁸ , -CR ⁸ R^OH,

-NR ⁸ {C(>O)R ⁹ } _? -NR ⁸ R ⁹ , -CR ⁸ =N-R ⁹ _? -CO-R ⁸ , -PR ⁸ R ⁹ , ^(-O)R ⁸ R ⁹ , -P(OR ⁸ )(OR ⁹ ),

-S(=O) ₂ R ^S , -S ⁺ (-COR ^s ₃ -SR ⁸ , -CR ⁸ R ⁹ -SH, -CR ⁸ R ⁹ -SR ¹⁰ , and -CR ⁸ =R ⁹ R ¹⁰ (R ⁸ to R ^1Q each independently are hydrogen, or a monovalent organic group).

[0018] According to the foregoing aspect, the characteristics of a functional group that is not coordinated to a metal atom can be utilized. Concretely, through the use of such functional groups, it is possible to stably adsorb the metal complex to a substrate, bind metal complexes to each other, bind the metal complex and another compound, etc [0019] A fifth aspect of the invention Mates to a manufacture method for an exhaust gas purification catalyst, which includes: providing a solution containing the metal complex according to the foregoing aspects; impregnating a catalyst support with the solution; and drying and firing the solution.

[0020] According to this aspect, a metal complex is adsorbed to a catalyst support due to the affinity between a functional group not coordinated to a metal atom and the catalyst support, so that when the metal complex is fired or the l&e, the metal contained in the metal complex can be supported on the catalyst support with high degree of dispersion.

[0021] A sixth aspect of the invention relates to a manufacture ^' method for a multiple-metal comples-containing compound, which includes: providing a metal

complex that has a ligand that has an uncoordinated carbon-carbon double bond; and dissolving lhe metal complex in a solvent and substituting an alkylidene group of an uncoordinated carbon-carbon double bond through a cross-mctathcsis reaction, of the carbon-carbon double bond. [0022] According to the foregoing aspect, a multiple-metal complex-containing compound can be manufactured from a metal complex that has an uncoordinated carbon-carbon double bond, through the cross-metathesis reaction of a carbon-carbon double bond (olefin).

BRIEF DESCRIPTION OF THE DRAWINGS

[0023J The foregoing and/or further objects, features and advantages of the invention will become more apparent from the following description of preferred embodiment with reference to the accompanying drawings, in which like numerals are used to represent like elements and wherdn: FIG. 1 is a graph showing a relationship between the Pt cluster size and the reactivity extracted from the aforementioned non-patent document;

FlG. 2 shows a TEM photograph in which the appearance of Pt on MgO prepared by a method of Comparative Example was observed;

FIG 3 shows a scheme for synthesizing a compound y\ accordance with Example 1; FIG. 4 shows a TEM photograph m which the appearance of Pt on MgO prepared by a method of Example 1 was observed;

FlG. 5 shows a scheme for synthesizing a compound in accordance with Example 2; FIG. 6 shows a scheme for synthesizing the compound in accordance with Example 2; FIG. 7 shows a TEM photograph m which the appearance of Pt on MgO prepared by a method of Example 2 was observed; and

FIG. S shows a scheme for synthesizing a compound in accordance with Example 3,

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0024] Bo. the following description, the present invention will be described in more

detail in terms of exemplary embodiments.

[0025] (Multiple-Metal Complex-Containing Compound)

A multiple-metal complex-containing compound in accordance with an embodiment of the invention has a plurality of metal complexes in each of which a ligand is coordinated to one metal atom or a plurality of metal atoms of the same load. In this compound, a plurality of metal complexes are bound to each other via a polydentate ligand that substitutes partially the ligands, and have 2 to 1000 metal atoms. The number of the metal atoms may be 2 to 100, for example, 2 to 50, or 2 to 20, or 2 to 10. [0026) (Ligand of a Metal Complex) The ligands of the metal complexes of the multiple-metal complex-containing compound in accordance with the embodiment can be arbitrarily selected, laldng into consideration the properties of the multiple-metal complex-containing compound obtained, the steric hindrance between metal complexes to be bound, etc. The ligand may be either a unidentate ligand or a polydentate ligand such as a chelate ligand. [0027] This ligand may be a hydrogen group bound with one functional group selected from the group of functional groups mentioned below, or an organic group bound with one or more functional groups selected from the group of functional groups mentioned below, particularly an organic group bound with one Ot more functional groups of the same kind selected from the group consisting of; -COO ^" (carboxy group), -CR ¹ R ² ^O ^" (alkoxy group), -NR ¹ - (amide group), -NR ¹ R ² (amine group), -CR ¹ ^N-R ² (imine group), -CO-R ¹ (carbonyl group), -PR ¹ R ² (phosphine group), -P(=O)R ¹ R ² (phosphine oxide group), -P(OR ¹ XOR ² ) (phosphite group), -S(=O) ₂ R* (sulfone group), -S ⁺ (-O)R* (sulfoxide group), -SR ¹ (sulfide group), and -CR ¹ R^-S ^" (thiolato group); and particularly -COO ^' (carboxy group), -CR ¹ R^O ^" (alkoxy group), -NR ^1" (amide group), and -NR ¹ R ² (amine group) (R ¹ and R ² each independently are hydrogen or a monovalent organic group),

[0028] The organic group bound with a functional group may be a substituted or non-substituted hydrocarbon group, particularly a substituted or non-substituted hydrocarbon group of Ci to C ₃₀ (Le _n whose carbon atom number is 1 to 30; this will be applied in the following description as well), that may have a hetrøatonx, an ether bond or

an ester bond. In particular, this organic group may be an alkyl group; an alkenyl group, an alkynyl group, an aryl group, an aralkyl group or a monovalent alicydic group of Cj to C ₃ 0, particularly C ₁ to C ₁₀ More particularly, this organic group may be an alkyl group, an alkenyl group, an alkynyl group of C1 to C5, particularly Ci to C ₃ . [0029] R ¹ and R ² may each independently be hydrogen, or a substituted or non-substituted hydrocarbon group, particularly a substituted or non-substituted hydrocarbon group of Ci to C ₃₀ , that may have a hetroatom, an ether bond or an ester bond. Particularly, R* and R ² may be hydrogen, or an alkyl group, an alkenyl group, an atbynyl group, an aryl group, an aralkyl group or a monovalent alicydic group of C ₁ to C ₃₀ , particularly C1 to C ₁₀ , More particularly, R ¹ and R ² may be hydrogen, or an alkyl group, an alkenyl group or an alkynyl group of Ci to C ₅ , particularly Ci to Qj.

[0030] Examples of the ligand of the metal complex include a caiboxylic acid ligand (R-COO ^" ), an alkoxy ligand (R-CR ¹ R^CO, an amide ligand (R-NR ^1" ), an amine ligaod (R-NR ¹ R ² ), an imine ligand (R-CR^N-R ² ), a carbonyl ligand (R-CO-R ¹ ), a phosphine ligand (R-PR ¹ R ² ), a phosphine oxide ligaad (R-P(O)R ¹ R ² ), a phosphite ligand (R-P(OR ¹ XOR ² )), a sulfone ligand (R-S(=O) ₂ K ¹ ), a sulfoxide Ugand (R-S ⁺ O-O)R ¹ ), a sulfide ligand (R-SR ¹ ), and a thiolato ligand (R-CR ¹ R^-SO (R is hydrogen or an organic group, aud R ¹ and R ² are as mentioned above).

[0031] Concrete examples of the carboxylic acid ligand include a formic acid (formato) ligand, an acetic acid (acetato) ligand, a propionic acid (propionate) ligand _* and an ethylenediaminetetraacetic acid ligand.

[0032] Concretes examples of the alkoxy ligand include a methanol (methoxy) ligand, an ethanol (ethoxy) ligaxid, a propanol (propoxy) ligand, a butanol (butoxy) ligand, a pentanol (pentoxy) ligand, a dodecanol (dodecyl oxy) ligaad, and a phenol (phcnoxy) ligand.

[0033] Concrete examples of the amide ligand include a dimethyl amide ligand, a diethyl amide ligand, a di-n-propyl amide ligand, a disopropyl amide ligand, a di-n-butyl amide ligand, a di-t-butyl amide ligand, and a nicotine amide.

[0034] Concrete examples of the maine ligand include methyl amine, ethyl amine,

methyl ethyl amine, trimetbyl amine, triethyl amine, ethylene diamine, tributyl amine, hexamethylene diamine, aniline, ethylene diamine, propylene diamine, trimethylene diamine, diethylene triafπine, Methylene tetraamme, tris(2-ammoethyl)arnmc, ethanol amine, triethanol amine, ethaπol amine, triethanol amine, diethanol amine, ttimethylene diamine, piperidine, Methylene tetracaine, and triethylene diamine.

[0035] Concrete examples of the imine ligand include diimme, ethyleneimine _} propyleneimine _} hexamethyϊeneimitie, benzophenoneimine, methyl ethyl ketone imine, pyridine, pyra2θle _s imidazole, and benzoimidazole.

[0036] Concrete examples of the carbonyl ligand include carbon monoxide, acetone, be.izophen.oae, acetyl acetone, acenaphthoquinone, hexafluoroacetyl acetone, benzoyl acetone, triiluoroacelyl acetone, and dibenzoyl methane,

[0037] Concrete examples of the phosphide Ugaαd include phosphorus hydride, methyl phosphine, dimethyl phosphine, trimethyl phospbine, and diphosphine.

[003S] Concrete examples of the phosphine oxide ligand include tributyl phosphine oxide, triphenyl phosphine oxide, and tri-n-octyl phosphine oxide.

[0039] Concrete examples of the phosphite ligand include triphenyl phosphite, tritolyl phosphite, tributyl phosphite, and triethyl phosphite.

[0040] Concrete examples of the sulføne ljgand include hydrogen sulfide, dimethyl suifone, and dibutyl sulfone. [0041] Concrete examples of the sulfoxide ligand include a dimethyl sulfoxide Hgaud, and a dibutyl sulfoxide ligand.

£0042] Concrete examples of the sulfide ligand include ethyl sulfide, butyl sulfide, etc.

[0043] Concrete examples of the thiolato ligand include a methanethiolato ligaod, and a benzenethiolato ligand. [0044] (Polydentate Ligand)

As the polydentate ligand that substitutes partially the Iigands of a plurality metal complexes and that binds the metal complexes to each other, an arbitrary polydentate ligand that can play the aforementioned role may be used. It is considered preferable that the polydentate Jjgatid have a certain length in order to avoid destabilϊzation of the

multiple-metal complex-containing compound due- to the steric hindrance between metal complexes. Particularly, in the case where the multiple-metal complex-containing compound in accordance with the embodiment of the invention is subjected ¹ to firing or the like so as to obtain a cluster that has the same number of metal atoms as contained in this compound, an excessively great length of the polydentate ligand may possibly make it difficult to obtain a single kind of cluster from the compound,

[0045] The polydentate ligand that substitutes partially the ligands of the metal complexes may be represented by the following formula:

(L ^l )~R^(L ² ) (where R ³ is a bond or a bivalent organic group, and L ¹ and L ² are either the same or different functional groups selected from the group constituting of: -COO ^" (caibσxy group), -CR ⁴ R ⁵ -O ^" (alfcoxy group), -NK ^4* (amide group), -NR ⁴ R ³ (amine ^' group), -CR ⁴ =N-R ⁵ (iraine group), -CO-R ⁴ (carbonyl group), -PR ⁴ R ⁵ (phosphme group), -P(=O)R ⁴ R ⁵ (phosphine oxide group), ^P(OR ⁴ XOR ⁵ ) (phosphite group), ~S(=O) ₂ R ⁴ (sulfone group), -S ⁺ (-O')R ⁴ (sulfoxide group), -SR ⁴ (sulfide group), and -CR ^l R ⁴ -S ^' (thiolato group) (R ⁴ and R ⁵ each independently are hydrogen or a monovalent organic group)).

[0046] In particular, L ¹ and L ² may represent the same functional group selected from the group consisting of: -COO ^" (carboxy group), -CR ⁴ R ⁵ -O ^~ (alkαxy group), -NR ^4" (amide group), and -NR ⁴ R ⁵ (amine group) (R ⁴ and R ⁵ each independently are hydrogen or a monovalent organic group).

[0047] R ³ may be a bond, or a substituted or non-substituted bivalent hydrocarbon group, particularly a substituted or non-substituted bivalent hydrocarbon group of Ci to C ₃₀ , that may have a heteroatom, an ether bond or an ester bond. Particularly, R ³ may be an alkylene group, an alkenylene group, an alkynylene group, an arylene group, an aralkylen group or a bivalent alicycHc group of Ci to C ₃₀ and, particularly Ci to do.

[0048] R ⁴ and R ⁵ may be Organic groups mentioned in conjunction with R ¹ and R ² . [0049] (Combination of a Polydentate Ligand and a Ligand of a Metal Complex) The ligands of the metal complexes, and the polydentate ligand substituting partially the

ligands of the metal complexes may have the same functional group. For example, the ligands of the metal complexes and the polydentate ligand may each have a carboxy group, an alkoxy group, an amide group, or an amine group.

[0050] (Metal That Becomes a Nucleus of a Metal Complex) The metal that becomes a nucleus of the metal complex may be either a mam group metal or a transition, metal. This metal may be particularly a transition metal, and more particularly fourth to eleventh group transition metals, for example, a metal selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt,, nickel, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and gold.

[0051] Furthermore, in the case where a catalyst is provided through the use of a multiple-metal complex-containing compound in accordance with the embodiment, the metal to be used may be a metal beneficial for the use of the catalyst, for example, elements of the iron family (iron, cobalt, nickel), copper, platinum group elements (ruthenium, rhodium, palladium, osmium, iridium, and platinum), gold, or silver. [0052] (Metal Complex)

As for the multiple-metal complex-containing compound in accordance with the embodiment, the metal complexes each may be an arbitrary metal complex m which a ligand is coordinated to one metal atom or a plurality of metal atoms of the same kind. That is, the metal complex may be a polynudear complex, for example, a complex that has

2 to 10 metal atoms, particularly 2 to 5 metal atoms.

[0053] This metal complex may be an arbitrary metal complex. Concrete examples of the metal complex include [Pt ₄ (CH ₃ COO)S], [Pt(acac) ₂ ] ("acac" is an acetyl acetoiiato ligaud), [Pt(CH ₃ CH ₂ NHz) ₄ ]Cl ₂ , [RlIz(C ₅ H ₅ COO) ₄ ], [Rh ₂ (Qi ₃ COO) ₄ ], [Rh ₂ (OOCC ₆ H ₄ COO) ₂ ], [Pd(acac) ₂ ], [Ni(aCac) ₂ ], [Cu(CuH ₂₃ COO) ₂ ]Z,

[CU ₂ (OOCC ₆ H ₄ COO) ₂ ], [CU ₂ (OOCC ₅ H4CH ₃ ) ₄ 3, [MO ₂ (OOCC ₆ H ₄ COO) ₂ ],

[Mo ₂ (CH ₃ COO) ₄ ], and [N(n-C ₄ H ₉ ) ₄ ][Fe ^π Fe ^m (ox) ₃ 3 fox" is an oxalic acid ligand).

[0054] (Form in Which the Multiple-Metal Complex-Coataining Compound Has Carbo^ylic Acid Ligands)

The multiple-metal complex-containing compound in accordance with the embodiment may be in a form in which the metal complexes ate metal complexes that have carboxylic acid ligands, particularly acetic acid ligands, for example, octaacetatotetraplatinum

([Pt(μ-CH ₃ COO) _S ]), and in which the polydentate ligand substituting partially the ligands of the metal complexes is a dicarboxylic acid ligand.

[0055] The dicarboxylic acid ligand may be represented, by the following formula:

OOC-R ⁶ 'COO-

(R ^δ is an alkylene group, an alkenylcnε group, an alkynylene group, an arylene group, an aralkylen group or a. bivalent alicyclic group of C ₁ to Cjo and, particularly, C ₁ to C ₁ O). [0056] R ⁶ may be selected from the group consisting of p-phenyϊene groups, and alkenylene groups represented by the following formula:

-(CH ₂ ) _n C=C(CH ₂ ) _il - (n is an integer of 1 to 5).

[0057] (Form in Which the Metal Complexes Are Octaacetatotetraplatinum) The multiple-metal complex-contamiag compound in accordance with the embodiment may be represented by the following formula:

[Pt ₄ (CH ₃ COO) ₁ (O ₂ C-R ⁷ -CO ₂ I (CH ₃ COO) ₇ Pt ₄ ]

(R ⁷ is an alfcylene group, ΆΆ alkenylene group, an alky&ylene group, an arylene group, an aralkylen group or a bivalent alicyclic group of Ci to C30, particularly Q to Qo). [0058] R ⁷ may be selected from the group consisting of p-ρhenylene groups, and ^■ alkenylerte groups represented by the following formula:

IB2007/000533

12

-(CHa) _n C=C(CH ₂ )^ (n is an integer of 1 to 5).

[0059] (Manufacture Method ttor a Metal or Metal Oxide Cluster) In the manufacture method for a metal αr metal oxide cluster having 2 to 1000 metal atoms in accordance with the embodiment, (a) a solution containing the multiple-metal complex-containing compound of the invention is provided, and (fa) the solution is dried and fired.

[0060] The drying and firing of the solution containing the multiple-metal complex-containing compound can be performed in a condition, of a temperature and a time that are sufficient to obtain a metal or metal oxide cluster. For example, the drying may be performed at a temperature of 120 to 250 ^β C for 1 to 2 hours, and then the firing may be performed at a temperature of 400 to 600 ⁰ C for 1 to 3 hours. The solvent of the solution to be used in this method may be an arbitrary solvent that is capable of stably maintaining the muMple-mctal coraplex-containirig compound of the invention, for example, an aqueous solvent, or an organic solvent such as dichloroethane, or the like.

[0061] This method may further include impregnating a porous support with the solution before drying and firing the solution in the step (b).

[0062] In the case where a catalyst, particularly, an exhaust gas purification catalyst, is to be manufactured by using this method, the porous support to be used may be a porous metal oxide support, for example, a porous metal oxide support selected from the group consisting of alumina, ceria, zirconia, silica, titania, atxd their combinations.

[0063] (Manufacture Method for a Multiple-Metal Complex-Containing Compound of the Invention)

In the manufacture method for the multiple-metal complex-containing compound in accordance with the embodiment, (a) a xnetal complex is provided, and (b) a polydentate ligand or a polydentate Hgand source is provided, and (c) the metal complex and the polydentate Ugand or the polydentate ligand source are mixed in. a solvent.

[0064] The polydentate ligand to be used in this method is selected so that the selected polydentate ligand can substitute ligands coordinated in the metal complex for use as a raw

material. Therefore, in general, it is possible to use a polydentate ligand that Has stronger coordinating power than the ligands coordinated in the metal complex for use as a raw material, particularly a polydentate ligand that has stronger coordinating power than the ligands coordinated m the metal complex for use as a raw material and that has the same number of functional groups as the ligands.

[0065] The polydentate ligand may be used in relatively large amount in order to accelerate the substitution of the ligaads of the metal complex with the polydentate ligand. However, the amount of the polydentate ligand to be used in this method may be less than the amount that is needed in order to substitute entirely the ligands coordinated in the metal complex. The amount of the polydentate ligand to be used in. this method may be 1/2 or less, or 1/4 or less, or 1/8 or less of the amount that is needed in order to substitute entirely the Hgands coordinated in the metal complex, from the viewpoint of binding controlled numbers of metal complexes to each other.

[0066] The solvent to be used In this method may be an arbitrary solvent capable of stably maintaining the multiple-metal complex-containing compound of the invention, for example _; , an aqueous solvent, or an organic solvent such as dichloroethane or the like. [0067] (Metal Complex)

The metal complex of the invention, is a metal complex in which ligands are coordinated to one metal atom or a plurality of metal atoms of the same kind, and at least one of the ligands has an uncoordinated functional group that is not coorjdnated to a metal atom and that is selected from the group consisting of: -COOH (carboxy group), -COOR ⁸ (ester group), -CR ⁸ R ⁹ OH (alcohol group), -NR ^S {C(=O)R ^!> } (amide group), -NR ⁸ R ⁹ (amine group), -CR ⁸ -N-R ⁹ (imine group), -CO-R ⁸ (carbonyl group), -PR ⁸ R ⁹ (phosphine group),

.p(=O)R ⁸ R ^? (phosphine oxide group), -P(OR ³ )(OR ⁹ ) (phosphite group), -S(=O) ₂ R ^δ (sulfone group), -S ⁺ (-O ^" )R ^s (sulfoxide group), *SR ⁸ (sulfide group), -CR ⁸ R ⁹ ^SH (thiol group), -CRV-SR ¹⁰ (thioether group), and -CR ^S =R ⁹ R ¹⁰ (ethylene bond) (R* to R ¹⁰ each independently are hydrogen or a monovalent organic group).

[0068] Independently for each of R ^s to R ¹⁰ , the organic groups mentioned above in conjunction with R ¹ and R ² may be cited as examples.

[0069] The ligand of the metal complex of the invention may be a hydrogen group bound with a functional group of the following functional groups which is coordinated to a metal atom, or an organic group bound with one or more of the following functional groups which are coordinated to a metal atom: -COO ^" , -CR ¹¹ R ¹² O'. -KR ^11" , -NR ^U R ¹² , ~CR ^U =N-R ¹² , -CO-R ¹¹ , -PR ¹¹ R ¹² , -FC=O)R ¹¹ R ¹² , -P(OR ¹¹ XOR ¹² ), ^=O) ₂ R ¹¹ , -S ⁺ (-O )R ⁿ , -SR ^U , and -CR ^U R ¹² -S ^~ (R ¹¹ and R ¹² each independently are hydrogen or a monovalent organic group).

[0070] Examples the ligand of the metal complex of the invention include the ligands cited above in conjunction with the metal complexes of the multiple-metal complex-containing compound of the invention. Therefore, independently for each of K, ¹¹ and R ²² , the organic groups mentioned above in conjunction with R ¹ and R ² may be cited as examples.

[0071] It is possible that each lϊgand of the metal complex of the invention have only one functional group coordinated to a metal atom. [0072] (Form in Which the Metal Complex in Accordance with the Embodiment Has a Carboxy Group as an Uncoordinated Functional Group)

Ia the case where the metal complex in accordance with the embodiment has a carboxy group as an uncoordinated functional group, a ligand of the metal complex may have a carboxy group that is coordinated to a metal atom. For example, the metal complex may be in a form in which the ligand having an uncoordinated functional group is a dicarboxylic acid ligand and the ligand not having an uncoordinated functional group is an acetic acid ligand,

[0073] Therefore, the metal complex may be an octaacetatotetraplatimira ([Pt(CH ₃ COO) ₈ ]) in which at least one acetic acid lϊgand (acetato ligand) is substituted with a dicarboxylic acid ligand.

[0074] The dicarboxylic acid ligand may be represented by the following formula;

O0C-R ¹³ ~C00H

(R ¹³ is an, alkylεne group, an alkenylene group, an alkynylene group, an aiylene group, an aralkylen group or a bivalent alicyclic group of Ci to C ₃₀ , particularly C _x to Qo).

[0075] (Form in Which the Metal Complex in Accordance with the Embodiment Is Dicarboxylic Acid-Substituted Octaacetatotetr aplatinum)

The metal complex may be represented by the following formula:

[PU (CH ₃ COO) ₇ IO ₂ CR ¹ MCOOH) ] ]

(R ¹⁴ is an alkylene group, an alkenylene group, an alkynylene group, an arylene group, an aralkylen group or a bivalent alicyclic group of Ci to C30, particularly Ci to Cχ ₀ ). [0076] R ¹⁴ may be, for example, a ρ-ρhenylene group.

[00771 (Form in Which the Metal Complex hi Accordance with the Embodiment Has a Carbon-Carbon Double Bond as an Uncoordinated Functional Group) In the case where the metal complex in accordance with the embodiment has a carbon-carbon double bond as a uncoordinated functional group, a, ligand of the metal complex; may have a, carboxy group that is coordinated to a metal atom. For example, the metal complex may be in a form in which the ligand having an uncoordinated functional group is a carboxylic acid ligand that has a carbon-carbon double bond, namely, an unsaturated carboxylic acid, and in which the ligand not having an uncoordinated functional group is an acetic acid lig-Uid.

[0078] Therefore, the metal complex may be an octaacetatαtetraplatmum (JPt(CB ₃ COO) _S ]) in which at least one acetic acid ligand is substituted with a carboxylic acid Hgartd that has a carbon-caibon double bond, [0079] The carboxylic acid ligand having a carbon-carbon double bond may be represented by the following formula:

OOOR ¹⁵ (R ¹⁵ is an, alkenyl group of Q to C ₃₀ , particularly Ci to Cio)-

[0080] (Form in Which the Metal Complex in Accordance with the Embodiment Is Octaacetatotetraplatinuiϊi Substituted With a Carboxylic Acid That Has a Carbon-Carbon Double Bond)

The metal complex of the invention may be represented by the following formula:

[Pt ₄ (CH ₁ COO) ₇ (O ₂ CR ^{1 5} ) ]

(R ¹⁶ is a linear chain or branched chain alkenyl group of Ci to C^, particularly Ci to Cio).

[0081] (Manufacture Method for an Exhaust Gas Purification Catalyst through the Use of a Metal Complex in Accordance with the Embodiment)

In a manufacture method for an exhaust gas purification catalyst in accordance with the embodiment, (a) a solution containing a metal complex of the invention, particularly a metal complex having., as a nucleus, a metal atom that is preferable for use as a catalyst, is provided, (b) a catalyst support is impregnated with the solution, and (c) the solution is dried and fired,

[0082] The catalyst support may be a porous metal oxide support, for example, a porous raetal oxide support selected from the group consisting of alumina, ceria, zirconia, silica, tϊtania, and combinations thereof.

[0083] The drying and firing of the solution containing the metal complex may be performed in a condition of a temperature and a time that are sufficient to obtain a metal or metal oxide cluster. For example,, the drying may be performed at a temperature of 120 to 25O ⁰ C for 1 to 2 hours, and then the firing may be performed at a temperature of 400 to 600 ⁰ C for 1 to 3 hours. The solvent of the solution to be used in this method may be an arbitrary solvent that is capable of stably maintaining the metal complex of the invention, for example, an aqueous solution, or an organic solution such as dichlαroetha&e or the like.

[00S4] (Manufacture Method for a Mtiltiple-Metal Complex-Containing Compound through, the Use of a Metal Complex in Accordance with the Embodiment That Has a . CarboxyUc Acid ligand That Has a Carbon-Carbon Double Bond)

In a manufacture method for a multiple-metal complex-containing compound through , the use of a metal complex in accordance with the embodiment, (a) a metal complex having a carboxylic acid ligajαd having a carbon-carbon double bond is provided, and (b) the metal complex is dissolved in a solvent and an alkylidene group of an uncoordinated carbon-carbon double bond is substituted through a cross-metathesis reaction of the carbon-carbon double bond. [0QS5J The cross-metathesis reaction of the carbon-carbon double bond (olefin) is as follows;

RVC=CR ⁵ R ¹¹ + R ⁼ R ^f OCR ^β R ^h

-* R^C=CR ⁵ R ¹¹ + R ^e R ^f C=CR ^c R ^d

(R ^a to R ^h each independently are an organic group such as a alkyl group or the like). [00S6] The cross-metathesis reaction and the catalyst to be used in this reaction are disclosed in, for example, Japanese Patent Application Publication No. JF-A-2004423925, Japanese Patent Application Publication No. JP-A-2004-043396, and Published Japanese Translation of PCT Application, JP-T-2004-510699. The catalyst for the cross-metathesis reaction may be a fourth-generation Grubbs catalyst. Therefore, the reaction can be caused to progress undei mild conditions. [0087] COMPARATIVE EXAMPLE (Synthesis of [Pt ₄ (CH ₃ COO) ₈ ])

The synthesis of the compound was performed using a procedure described in "Jikken Kagaku Kouza (Experimental Chemistry Course)", 4th ed., Vol. 17, p.452, Maruzen, 1991. That is, the synthesis was performed as follows. 5 g of K ₂ PtCl ₄ was dissolved in 20 ml of warm water, and 150 ml of glacial acetic acid was added to the solution, At this time, K ₂ FtCIt begaa precipitating. Without minding this, S g of silver acetate was added. This slurry-like material was refluxed for 3 to 4 hours while being stirred by a stirrer. After the material was let to cool, black precipitation was filtered out. Through the use of

a rotary evaporator, acetic acid was removed by concentrating a brown precipitation, as much as possible. This concentrate was combined with 50 ml of acetonitrile, and the mixture was left standing. The produced precipitation was filtered out, and the filtrate was concentrated again. Substantially the same operation was performed on the concentrate three times. The final concentrate was combined with 20 ml of dichloromethane, and was subjected to adsorption on a silica gel column. The elution was performed with dichloromemane-acetonitrile (S ;1), and a red extract was collected and concentrated to obtain a crystal.

[0088] (Supporting) 10 g of magnesium oxide (MgO) was dispersed in 200 g of acetone. While this MgO dispersal solution was being stirred, a solution obtained by dissolving 16.1 rng of [Ft ₄ (CH ₃ COO) ₈ ] in 100 g of acetone was added. The mixture was stirred for 10 min. When the stirring was stopped, MgO precipitated and a pale red supernatant was obtained (Le., [Pt ₄ (CHaCOO) ₈ ) did not adsorb to MgO). This mixed solution was concentrated and dried by using a rotary evaporator. The dried powder was fired at 400 ⁰ C in air for 1.5 hours. The supported concentration of Pt was 0.1 wt%.

[0089] (TFM Observation of Clusters)

The appearance of the Pt on the MgO prepared by the foregoing method was observed by TEM. Using an HD-2000 type electron microscope of Hitachi, STEM images were observed at an acceleration voltage of 200 kV. An STEM image of Reference Example 1 is shown in FIG 2. In this image, Pt particles having a spot diameter of 0,6 nm estimated from the structure of 4-platϊnurα atom clusters can be seen, demonstrating that, by the foregoing technique, 4-platfnum atom clusters can be supported on an oxide support ^,

[0090] EXAMPLE l (Synthesis of [Pt ₄ (CH ₅ COO) ₄ {o-C6H4(COO)(COOH)}43)

The synthesis of this compound was performed in a scheme shown in FIG 3.

[0091] Concretely, this compound was synthesized as follows. After [Pt ₄ (CHsCOO) ₈ ] (460 rag, 369 μmol) synthesized in the method of Comparative Example and (1.5Og, 9.00 mmol) were placed in an argon-substituted Schlenk

device of 50 ml, 10 ml of CH ₂ Cl ₂ and 10 ml of MeOH were added in that order. Immediately, the solution changed into an orange-red solution. After the solution was stirred at room temperature for 2 hours, the solvent was removed by evaporation under reduced pressure, so that a solid was obtained. This solid was dissolved in CH ₂ Cl ₂ , and was filtered. The filtrate was dried under reduced pressure to obtain a yellow solid,

[0092] The spectral data of the compound, and results of the elementary analysis thereof are shown below.

[0093] ¹ H NMR (300 MHz, CDCl ₃ , 308K) δr 1.96 (s, 12H, CH ₃ ), 7.55^7.67 (m, 12H, aromatic H), 840-8.43 (m, 4H _S aromatic H), 12.3 (br s', wi _/2 =32.4Hz, 4H, -CO ₂ H). [0094] ¹³ C( ¹ H) NMR (TS MHz, CDCI ₃ , 30SK) δ: 21-3 (O ₂ CCH ₃ ), 126.3, 129.1,

129.8, 131.1, 132.1, 135,8 (aromatic C), 176.9 (CO ₂ H) ₅ 180,1 (O ₂ CCH ₃ ).

[0095] IR (KBr disk, v/cm ⁴ ): 1715 (C=O), 1557, 1386 (CO ₂ -).

[009S] Anal, Calcd. for C ₄₀ H ₃₂ O ₂₄ Pt ₄ : C, 28-65; H, 1.92. Found: C, 28.63; H ₁ 215. [0097] (Structural Confirmation of the Compound)

The structure of the compound was determined through the X-ray structure analysis of the single crystal of the compound obtained in a CH ₂ C ₁₂ solution.

[0098] (Supporting)

10 g of MgO was dispersed in 20Og of acetone. While this MgO dispersal solution was being stirred, ■ a solution obtained by dissolving 21.5 mg of

[Pt ₄ (CH ₃ COO) ₄ (O-CgH ₄ (COOXCOOH)),*] in lOOg of acetone was added. This mixture was stirred for 10 min. When the stirring was stopped, MgO precipitated and the supernatant became transparent (i.e., [Pt ₄ (CH ₃ COO)4{o-C ₆ H ₄ (COO)(COOH)} ₄ ] adsorbed to MgO). This mixed solution was concentrated and dried by using a rotary evaporator. The dried powder was fired at 4OD ⁰ C in air for 1.5 hours. The supported concentration of

Pt was 0.1 wt%,

[0099] (IEM Observation of Clusters)

The appearance of Pt on MgO prepared in the foregoing method was observed by TEM. Using an H.D-20Q0 type electron microscope of Hitachi, STEM images were observed at

an acceleration voltage of 200 kV. An STEM image of Example 1 is shown in FIG, 4. In this image, Pt particles having a spot diameter of 0.6 nm estimated from the structure of 4-platinum atom clusters can be seen, demonstrating that, by the foregoing technique, 4-platinum atom clusters can be supported on an oxide support, [0100] EXAMPLE 2

(Synthesis of [Pt4(CH ₃ COO)7{0 ₂ qCH2)3CH CH(CH ₂ )3C0 ₂ }(CH ₃ COO) ₇ Pt4])

The synthesis of this compound was performed in a scheme shown in FIG 5 and FIG. 6.

[0101] Concretely, this compound was synthesized as follows.

CH ₂ =CH(CHa) ₃ CO ₂ H (19.4 μL, 18.6 mg) was added to a CH ₂ Cl ₂ solution (10 mL) of the octaacetatσtetraplatinum [Pt ₄ (CH ₃ COO) ₈ ] (0.204 g, 0λ63 mmol) obtained by the procedure shown above in conjunction with Comparative Example 1. This changed the color of the solution from orange to red-orange. After the solution was stirred at room temperature for 2 hours, the solvent was removed by evaporation under reduced pressure, and the remaining substance was washed with diethyl ether (S mJL) twice. As a result, ao orange solid of [Pt ₄ (CH ₃ COO) ₇ (O ₂ C(CHa) ₃ CH=CH ₂ )] was obtained.

[0102] [Pt ₄ (CH ₃ COO) ₇ {O ₂ C(CH2) ₃ CH=CH2}] (362 mg, 0.277 mraol) synthesized as described above and a first-generation Grubbs catalyst (6.7 mg, 8,1 μmol, 2.9 mol%) were placed in an argon-substituted Schlenk device, and were dissolved in CH2CI ₂ (30 mL). A cooling pipe was attached to the Schlenk device, and a heated reflux was performed in an oil bath. After the solution was refluxed for 60 hours, the solvent was removed by evaporation under reduced pressure, and the remaining substance was dissolved in CH ₂ Cl ₂ .

After that, filtration via a glass filter was performed. The filtrate was concentrated under reduced pressure to obtain a solid. The solid was washed with diethyl ether (10 mL) three times to obtain an orange solid of [Ft ₄ (CH ₃ COO) ₇ {0 ₂ C(CH ₂ ) ₃ CH^CH(CH ₂ ) ₃ C0 ₂ }(CH3COO)7Ft4] as an E/Z type mixture.

[0103] (Spectral Data)

[Pt ₄ (CH3COO) ₇ {O _z C(CH2)3CH~CHa}]

¹ H NMR (300 MHz, CDCl ₃ , 308K) 5; 1.89 (tt/ ³ J _HH =^ 7.5HZ, 2H _> OZCCHZCHZ'), 1.99 (s, 3H, ³¹ O ₂ CCH ₃ X 2.00 (s, 3H ₁ ^O ₂ CCH ₃ ), 2.01 (s, 6H, "OaCCH ₃ ), 2,10 (q like, 2H ₅

-CH ₂ CH=CH ₂ ), 2.44 (s, 6H, ^∞ OjCCHj), 2.45 (s, 3H, ⁶⁹ O ₂ CCH ₃ ), 2.70 (t, ³ J _tm =7.5Hz ₇ 2H, O ₂ CCH ₂ CH ₂ "), 4.96 (ddt, ³ JHH=10.4HZ, ^Z JHH=1.8HZ, ⁴ J_*a=?Hz, IH, -CH=C (Hf ⁸ H), 5.01 (ddζ ³ JHH=17,3HZ, ² JHH=1-8HZ, ⁴ Jm=IEz, IH, -CH=C (H) ^tøλS H), 5.81 (ddt, ³ JHH^7.3, 10.4, 6.6Hz, IH, -CH-CH ₂ ). [0X04] ^l3 C{ ^λ H} NMR (75 MHz, CDCl ₃ , 30SK) δ; 21.2, 21.2 C ³ O ₂ CCH ₃ ), 22.O ₁ 22.0 (^O ₂ CCH ₃ ), 25.8 (O ₂ CCH ₂ CH ₂ -), 33.3 (-CH ₂ CH=CH ₂ ), 35.5 (O ₂ CCH ₂ CH ₂ -), 115.0 (XH=CH ₂ ), 137,9 ("CH=CH ₂ ), 187.5, 193.0» 193λ (O ₂ CCH ₃ ), 189.9 (O ₂ CCH ₂ CH ₂ -).

[0105] MS (ESI+, CH ₃ CN solution) ro/z: 1347 ([M+soL] ⁺ ).

[01061 IR (KBr disk, v/αn ¹ ): 2931, 2855 (V _C -H), 1562, 1411 (vcoo-), 1039, 917 (V^o).

[0107] (Spectral Data)

[Pt4(CH3COO)7{0 ₂ qCH ₂ )3CH CH(CH ₂ ) ₃ CO _z }(CH ₃ COO) ₇ Pt4] Major(E type);

¹ H NMR (300 MHz ₅ CDCl ₃ , 30SK) δ: 1.83 (like, I=IJBz, 4H, O ₂ CCH ₂ CH ₂ -), 2.00 (s, 6H, ^O ₂ CCH ₃ ), 2.01 (s, 18H ₅ ¹¹³ O ₂ CCH ₃ ), 2,02-2.10 (m, 4H ₅ -CH ₂ CH=CH-), 2.44 (s, ISH, ⁵¹¹ O ₂ CCH ₃ ), 2.67 (t, ³ .T _H -H=7.2HZ, 4H ₃ O ₂ CCH ₂ CH ₂ -), 5.37-5.45 (m _? 2H, -CH=).

[0108] ¹³ C NMR (75 MHz ₅ CDCl ₃ , 308K) 6; 21.I ₇ (q, ¹ JaH=ISO^Hz, ^O ₂ CCH ₃ ),

21.2 ₂ (q, ¹ Jc _-H =ISl ₁ IHz, ^M OjCCH ₃ ), 21.9 (q, ¹ J _C- κ=129.4Hz, ^O ₂ CCH ₃ ), 22.0 (q,

4^=129.4^ ^Eq O ₂ CCH ₃ ), 26.4 (t, 40^127.3Hz, O ₂ CCH ₂ CH ₂ '), 32.0 (t _> ¹ J^H= 127.3HZ, -CH ₂ CH=CH-), 3S.5 (t, ¹ JoH-ISO^Hz, O ₂ CCH ₂ CH ₂ -), 130.1 (d _? ¹ J _C .H=148.6HZ, -CH-),

187.3, 187.4, 193,0 (O ₂ CCH ₃ ), 189.9 (O ₂ CCH ₂ CH ₂ -), .

[0109] Minor (Z type);

¹ H NMR (300 MHz, CDCl ₃ , 308K) 6: 1.83 (like, J=7.7Hz, 4H, O ₂ CCH ₂ CH ₂ -), 2.00 (β, 6H _> " ³¹ O ₂ CCH ₃ ), 2.01 (s, 18H, ⁸³⁵ O ₂ CCH ₃ ), 2.02-2.10 (m, 4H, -CH ₂ CH=CH-), 2.44 (s, 18H, ^O ₂ CCH.), 2.69 (t, ³ J _H . _H =7,2Hz, 4H, OzCCH ₂ CH ₂ -), 5.37-5.4S (m, 2H, -OH-

[0110] ¹³ C ^fMR (75 MHz, CDCl ₃ , 308K) δ: 21.I ₇ (q, ^=130.9^, ³¹ O ₂ CCH ₃ ), 2L2 ₂ (q, ¹ Jc- _H =Wl-IHz, ⁸³ O ₂ CCH ₃ ), 21.9 (q, ^=129.4^, " ¹ O ₂ CCH ₃ ), 22.0 (q, ¹ Jc^nMHz, ^eq O ₂ CCH ₃ ), 26.5 (t, ¹ J^H=IaTSHz, O ₂ CCE ₂ CH ₂ -), 26.7 (t, *J _C - _H =127.3HZ, -CHiCH=CH-). 35.5 (t, ¹ Jc-H=BO^Hz, O ₂ CCH ₂ CH ₂ -), 129.5. (d,

¹ J _c-H =154:3Hz _! -CH=), 187.3, 1874, 193,0 (O ₂ CCH ₃ ), 189.9 (O ₂ CCHzCH ₂ -).

[0111] MS (ESI+, CH ₃ CN solution) m/z: 2584 ([M] ⁺ ).

[0112] (Supporting)

10 g of MgO was dispersed fa, 200 g of acetone. While this MgO dispersal solution was being stirred, a solution obtained by dissolving 16.6 mg of [Pt ₄ (CH ₃ COO) ₇ {θ ₂ C(α-ϊ ₂ ) ₃ CH=CH(CH ₂ ) ₃ Cθ ₂ }(CH ₃ COO) ₇ Pt4] in 100 g of acetone was added. The mixture was stirred for 10 min. This mixed solution was concentrated and dried by using a rotary evaporator. The dried powder was fired at 400 ^D C in air for 1.5 hours. The supported concentration of Pt was 0.1 wt%- [0113] (TEM Observation of Clusters)

The appearance of the Pl on the MgO prepared by the foregoing method was observed by TEM, Using an HD-2000 type electron microscope of Hitachi, STEM images were observed at an acceleration voltage of 200 kV. An STEM image of Example 2 is shown in FIG; 7. In this image, Pt particles having a spot diameter of 0.9 nm estimated from the structure of 8-ρlatmum atom clusters can be seen, demonstrating that, by fte foregoing technique, 8-platimim atom clusters can be supported on an oxide support.

[0114] EXAMPLE 3

(Synthesis of [Pt ₄ (C^COO) ₇ {θ ₂ C-(>C ₆ H ₄ )-CO _z χci^COO) ₇ Pt43)

The synthesis of this compound was performed in a scheme shown in FIG 8. [0115] Concretely, this compound was synthesized as follows. A CH ₂ CIs solution (10 mL) of [Pt ₄ (CH ₃ COO) ₈ ] (0.204g, 0-163 mmol) obtained by substantially the same procedure as in Comparative Example was combined with an amount of terephtiialic acid (HOzC-(p-C _< sH ₄ >CO _z H) (0.0135g, 0.0815 mmol) that was half the amount of [Pt ₄ (CH ₃ COO)s]. As a result, a black precipitation was produced. This precipitation was washed twice with CH ₂ Cl ₂ (10 mL) to obtain crystal of [Pt ₄ (CH ₃ COO) ₇ {0 ₂ C^(p^C _f iH ₄ )-C0 ₂ }(CH3COO) ₇ Ft4].

[0116] (Identification)

The compound was identified by elementary analysis since the crystal of the compound did not dissolve in solvents. Results were as shown, below.

Anal. CaICd IOr C ₃₆ H ₄₆ O ₃₂ Pt ₆ : C, 16.95; H, 1.82. Found; C, 20.10; H, IJS.

[0117] While the invention has been described with reference to exemplary embodiments thereof, it should be understood that the invention is not limited to the exemplary embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the exemplary embodiments are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.