WO1998000463A1

WO1998000463A1 - Use of platinum complexes particularly as homogeneous and heat activable catalysts for hydrosilylation

Info

Publication number: WO1998000463A1
Application number: PCT/FR1997/001157
Authority: WO
Inventors: Gérard Mignani; John Osborn; Pascal Steffanut
Original assignee: Rhodia Chimie
Priority date: 1996-06-28
Filing date: 1997-06-27
Publication date: 1998-01-08
Also published as: JP2000514849A; EP0907685A1; AU3449597A; CA2259255A1; FR2750349B1; FR2750349A1

Abstract

The invention concerns the sphere of cross-linking and functionalizing reaction catalysis of polymer chains e.g. combined with silicon. In particular the invention discloses the use of novel platinum based catalytic systems that are heat activatable, homogeneous, stable, long lasting and highly efficient as catalysts. The reagents involved are polyorganosiloxanes (POS) SiH and POS SiVi. The platinum complexes employed are, for example, as in (A).

Description

USE OF PLATINUM COMPLEXES, IN PARTICULAR AS HOMOGENEOUS AND THERMOACTIVABLE DEHYDROSILYLATION CATALYSTS

The present invention relates to the field of catalysis of crosslinking or functionalization reactions of polymer chains, e.g. silicones. It is more particularly question, in the present description, of substrates to be crosslinked of polyorganosiloxane type A having, per molecule, at least one reactive radical Si-H, while being free of silicon atoms bonded to more than two atoms of hydrogen. These substrates A are intended to react with substrates of type B having, per molecule, at least one reactive unsaturated aliphatic group and / or at least one reactive function, eg epoxide, in the presence of a catalyst comprising at least one platinum complex, such a reaction being initiated or activated thermally.

More precisely still, the present invention relates, first of all, to the use of thermoactive organoplatinic complexes in crosslinking by hydrosilylation of polyorganosiloxanes A of Si-H type and of compounds B with aliphatic unsaturation and / or with reactive function.

The present invention also relates to a hydrosilylation process in which the above complexes are used, as well as compositions crosslinkable by thermoactivation and containing, inter alia, the substrates A and B as well as the above complexes. In addition to crosslinking, the invention also encompasses the functionalization of silicone oils containing SiH units by terminal unsaturated derivatives. These can include other functions other than unsaturation, for example: epoxide, alcohol, ester, amino, etc.

Among the applications that can be envisaged in the context of the invention, mention may be made, for example, of coatings formed from a mixture of silicone oils which can be crosslinked together and which are intended to form non-stick layers on fibrous supports, such as paper. , dental impressions, adhesives, sealing, jointing materials, etc.

To date, most industrial hydrosilylation reactions are catalyzed by the KARSTEDT solution (US-A-3,775,452), which consists of platinum complexes with a formal and real oxidation state = 0 with tetramethyldivinylesiloxane ( TMDVS), useful as a ligand. The average formula of these complexes can be stated as follows: [Pt ° ₂ (TMDVS) ₃ ]. The source of the platinum in this solution is formed by the catalyst of SPEIER or hexachloroplatinic acid. The activation specific to this KARSTEDT catalyst is thermoactivation. This catalyst however has the major drawback of leading to precipitation of metallic platinum in the reaction medium. This known catalyst is therefore not homogeneous. Its heterogeneous nature has the direct consequence of adversely affecting its catalytic performance in hydrosilylation. In other words, this KARSTEDT catalyst suffers from its too weak activity. During catalysis, the loss of activity is due to the formation of inactive species in catalysis and insoluble in the reaction medium. This catalyst can also be improved, as regards the reaction rate and its effective lifetime in the reaction medium.

Another major defect of the KARSTEDT catalyst is that it has relatively poor storage stability (gel time at 25 ° C less than or equal to 1 min)

In this state of the facts, one of the essential objectives of the present invention is to propose the use of new catalytic systems based on platinum complexes, preferably with a formal oxidation state = 0, said systems being useful, in particular in the hydrosilylation of polyorganosiloxanes of Si-H type and of compounds with aliphatic unsaturation (preferably ethylenic, eg SI-VI) and / or with reactive functions and which must moreover be thermoactivatable, homogeneous, stable in atmosphere and at ambient temperature over long periods of time, and catalytically efficient, (reaction speed / lifetime) without sacrificing the imperatives of industrial feasibility and profitability Another objective of the invention is to provide a hydrosilylation process by thermoactivation of reactive products , and in particular of silicones, in which the abovementioned catalytic systems are used, said process having to be implemented a easy, fast, and inexpensive

Another objective of the invention is to provide compositions of silicone oils crosslinkable by thermoactivation - which comprise the above homogeneous catalytic systems,

- which are stable up to temperatures above room temperature, preferably greater than or equal to 30-40 ° C, and this over long periods,

- and which are very reactive without strong thermal activation Such compositions, stable in storage, can be used, for example, for paper anti-adhesion, dental impressions, sealing or jointing materials, adhesives, or for any other application in which it is advantageous to use performs cross-linking in situ (solvent-free) of silicone elastomers.

These objectives, among others, are achieved by the present invention which relates to the use of platinum complexes with a formal oxidation state = 0 as a heat-activated, homogeneous catalyst, based on platinum and useful in particular in hydrosilylation. between, on the one hand, silanes and / or siloxanes A having, per molecule, at least one reactive radical SiH and free of silicon atom bonded to more than two hydrogen atoms and, on the other hand, compounds B having at least one reactive group and / or at least one reactive function, of at least one platinum complex of formula:

n = 1 or 2

in which: Δ L _α and L _α . are identical or different and are selected from among the binding olefins, preferably from the following olefinic residues, substituted or not: ^• + norbornene

+ (cyclo) hexene,

+ ethylene;

L _α and L _α . can also together form a single diolefin ligand, preferably formed by:

R

R ⁴

(H) in which R ¹ , R ² , R ³ , R ⁴ are different or similar to each other and represent an alkyl and or acyl group, preferably an alkyl having from 1 to 18 carbon atoms, the methyl, ethyl, propyl, pentyl groups , hexyl, allyl, acetyl, propionyie being particularly preferred and especially methyl,

L is chosen from ligands ^, L ₂ defined below

^* L, being a ligand of the following formula ^•

d) in which m Z \ Z ² , Z ³ , Z ⁴ independently represents hydrogen, an aryl, a

alkyl, halogen, hydroxyalkyl or an electron-withdrawing group, preferably selected from the following groups COR, CN, COOR with R = hydrogen, alkyl, aryl, at least one, preferably at least two, of the substituents Z ¹ to Z ⁴ corresponding to an electron-withdrawing group, L ₂ being a ligand constituted by the following residue (2)

Y y-

Y ¹

(2) in which

Y ¹ , Y ² , Y ³ , Y ⁴ independently represents a hydrogen, a halogen, an alkyl, an aryl, an alkoxyl, a hydroxyl, or else Y ¹ and Y ⁴ or Y ² and Y ³ can also form together at least a cyclic group, aromatic or not, and comprising one or more rings, condensed or not, the said cycles being optionally substituted by monovalent radicals corresponding to the definition given above for Y ¹ to Y ⁴ , Δ E ¹ , E ² are identical or different and represent. O, NR ⁵ with R ⁵ = C _r C ₆ alkyl or alkenyl, CR ⁶ R ⁷ with R ⁶ , R ⁷ identical or different and corresponding to C _r C ₆ alkyl, alkoxyl, halogen, oxygen being more particularly preferred for E,, E ₂ . The present invention therefore consists of an advantageous and inventive selection of platinum complexes (I) which are particularly suitable for reaction catalysis, in particular of the hydrosilylation type, and which can be activated thermally.

More specifically, specific iigands L _α , L _α -, L., and L ₂ were isolated in accordance with the invention. They confer to the platinum complexes to which they belong quite attractive catalytic properties. Indeed, the catalysts comprising these complexes platinics (I) are homogeneous and stable in the reaction medium, are endowed with a high activity for example in hydrosilylation and are also stable in storage

This homogeneous nature is a remarkable advantage for the platinum catalysts (I) used in the context of the use according to the invention. This gives them in particular an undeniable superiority in terms of, eg, the reaction speed and the duration. compared to known KARSTEDT catalysts which can also be activated thermally

These heat-activated catalysts envisaged in the context of the use according to the invention are particularly advantageous in the context of crosslinking or functionalization, for example of silicones of the SiH and SIVI type, by hydrosilylation.

They make it possible to obtain a homogeneous and stable reaction medium, formed by a solution of the catalyst and of the reagents in at least one organic solvent. At no time does precipitation of metallic platinum occur, liable to hinder the reaction considered.

This improvement in performance leads to control of the crosslinking conditions and therefore of the final mechanical properties targeted for the crosslinked elastomeric compositions. It is thus possible to adapt the latter to the intended application. According to a preferred arrangement of the invention, the ligands L platinum complexes (I) are selected from the following L ₁ and L ₂ subgroups → L,

NC CN NC H

> = <> = <

(11) NC CN (12) H CN

EtOOC COOEt EtOOC H (13) EtOOC COOEt ₍₁₄ ) H COOEt PhOC H

(15) H COPh

-2 ^•

→ and mixtures of ligands L, and / or L ₂

All the platinum complexes (I) of which the ligands L consist of one or more of the compounds (11) to (15) and (21) to (26) fall within the scope of the invention as heat-activatable catalysts, in particular of hydrosilylation. According to a preferred arrangement of the invention, let L _α = L _α . = nbn, let L _α and L _α . together form (II). Given the homogeneous nature of these platinum complexes (I), it is expected in the context of the use according to the invention, that the catalyst is advantageously used in a reaction medium consisting of a stable solution of said catalyst and of the reactants , in at least one organic solvent.

In practice, this organic solvent can for example be an alkane such as hexane, cyclohexane, methylcyclohexane or their mixtures. The solvent can also be chosen from the following products: toluene, xylene, chlorobenzene, and mixtures thereof, eg

In accordance with an advantageous characteristic of the invention, the catalyst contains, in the free state, at least one stabilizing agent formed by at least one ligand Ls of formula L, or L ₂ as defined above.

In the same catalyst, the ligand Ls forming the stabilizing agent can be identical or different to the ligands (L ,, L ₂ ) of the complexes (I).

Among the preferred Ls radical ligands, mention may be made of naphthoquinone, methylnaphthoquinone, chloronaphthoquinone or tetracyanoethylene. According to the invention, it is advantageous to use the compound Ls in the catalytic system in an excess of 1 to 30, preferably 10 to 20 molar equivalents relative to the platinum present.

This Ls compound can in fact be considered as a catalyst inhibitor. It is moreover possible to use in combination or as a replacement for Ls other conventional inhibitors of hydrosilylation catalysts. These inhibitors also known under the name of thermal blockers make it possible to increase the "pot life" of the compositions considered (stabilities greater than 3-5 days) without harming the kinetics of hydrosililation.

As examples of such compounds, mention may be made of certain polyolefinic siloxanes, pyridine, organic phosphines and phosphites, unsaturated amides, alkylated maleates and acetylenic alcohols (Cf FR-B-1 528 464 and FR-A -2 372 874).

These acetylenic alcohols, which are part of the preferred hydrosilylation reaction thermal blockers, have the formula: R - (R ') C (OH) - C s CH formula in which,

. R is a linear or branched alkyl radical, or a phenyl radical; . R 'is H or a linear or branched alkyl radical, or a phenyl radical; the radicals R, R ¹ and the carbon atom located at α of the triple bond which can optionally form a ring; the total number of carbon atoms contained in R and R ¹ being at least 5, preferably from 9 to 20.

Said alcohols are preferably chosen from those having a boiling point above 250 ° C. Mention may be made, by way of examples:. ethynyl-1-cyclohexanol 1;

. 3-methyl-dodecy-1 ol-3; . trimethyl-3,7,11 dodécyne-1 ol-3; . diphenyl-1, 1 propyne-2 ol-1; 3-ethyl-6-ethyl nonyne-1 ol-3, 3-methyl pentadecyne-1 ol-3 These α-acetylenic alcohols are commercial products In the case where L _α and L _α . form (II) together, the synthesis of the platinum complexes (I) according to the invention, consists in reacting a ligand L with products of average formula [Pt ₂ ] [Vι e ₂ Si - O - Si Me ₂ Vι] ₃ These products are preferably formed by a KARSTEDT catalyst solution. This reaction can be carried out in bulk or in a solvent, such as toluene, ethanol or isopropanol.

In the other particular case prefers where L _α = L _α = nbn =

, the complexes (I) are prepared by reacting (nbn) ₃ Pt with the ligand L This process is described by DREW & COLL in Iπorg Synth, 13 (1972) p 148

These syntheses are simple and involve products which are neither toxic nor expensive A priori, they meet all the criteria required to be considered as industrially feasible, especially since they are characterized by good isolated yields, which can be greater than or equal to 50%

The invention also relates to new platinum complexes of formula (I) as defined above, in which L _α and L _α are identical or different and are selected from binding olefins, preferably from the following olefin residues, substituted or not + norbornene

+ (cyclo) hexene,

+ ethylene,

According to another of these aspects, the present invention also relates to a heat-activatable catalyst based on platinum and useful in particular in hydrosilylation between, on the one hand, silanes and / or siloxanes A having, per molecule, at least a reactive radical SiH and free of silicon atom bonded to more than two hydrogen atoms and, on the other hand, compounds B having at least one reactive group and / or at least one reactive function, characterized

- in that it comprises at least one platinum complex (I) as defined above,

- and in that it is homogeneous

This catalyst can be one of those suitable for use in accordance with the invention and set out above. One of the forms of presentation of the above heat-activated catalyst can be, in accordance with the invention, a stable and homogeneous solution of said catalyst in at least one organic solvent, preferably chosen from alkanes, for example hexane, cyclohexane or methylcyclohexane and their mixtures or even among the following products: toluene, xylene, chlorobenzene, eg and their mixtures.

In any event, whether they are understood from the point of view of their use in thermal catalysis or from the point of view of heat-activated catalysts taken as such, the platinum complexes (I) are homogeneous and have a high efficiency in hydrosilylation. olefins. They generate a high reaction speed and are endowed with a long effective life which results in their capacity for catalysis for a large number of cycles.

These complexes (I) are moreover easily obtainable, stable in air. They are easy to handle, because they come either in the form of a solution or in the form of a powder. According to a variant of the invention, the catalyst can comprise a precursor of the complexes (I). Such a precursor is advantageously constituted by a composition of the starting materials for the synthesis of the complexes (I), namely: catalyst of KARSTEDT and ligand L in excess for (I) and for example (nbn) ₃ Pt for ( II). In this case, the formation of the platinum complexes takes place in situ, before and / or during the use of the crosslinkable composition containing the precursor composition. This greatly simplifies the preparation.

According to another of its aspects, the present invention relates to a hydrosilylation process between, on the one hand, silanes and / or siloxanes such as polyorganosiloxanes A having, per molecule, at least one reactive radical Si-H and free silicon atoms linked to more than two hydrogen atoms, and on the other hand, compounds B preferably chosen from polyorganosiloxanes and having, per molecule, at least one reactive unsaturated aliphatic group and / or at least one function reactive, process in which at least one platinum complex is used as catalyst.

This process differs from its similar in that it consists essentially in reacting compounds A and B in the presence of a catalytic system of the type of that according to the invention described above, and / or by using simultaneously a synthesis of either complexes (I) in which a precursor is formed, as described above, formed by a composition of the starting materials (excess ligand + KARSTEDT catalyst or (nbn) ₃ Pt, the initiation of the reaction being carried out by thermoactivation. Advantageously, the compounds A are chosen from polyorganohydrogensiloxanes comprising: * units of the following formula:

H _a W _b SiO ₄ . _{(a + b)} (1) ² in which: the symbols W are similar or different and representing a monovalent hydrocarbon group, free from any adverse action on the activity of the catalyst and preferably chosen from (cyclo) alkyl groups having from 1 to 18 carbon atoms inclusive and, advantageously, from methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl groups and also from C ₆ -C ₁₂ aryl or aralkyl groups and, advantageously, among the xylyl and totyl and phenyl radicals, all of these groups being optionally halogenated (eg fluorine) and / or hydroxylated and / or alkoxylated. a is 1 or 2, b is 0, 1 or 2, the sum (a + b) has a value between 1 and 3, * and possibly other units of average formula: W _c SiQ ₄ . _c (2)

2 in which W has the same meaning as above and c has a value between 0 and 3.

Organopolysiloxane A can only be formed of units of formula (1) or additionally comprise units of formula (2)

Organopolysiloxane A can have a linear, branched or unbranched, cyclic or network structure. The degree of polymerization is greater than or equal to 2. More generally, it is less than 5,000.

Examples of units of formula (1) are: H (CH ₃ ) Si0 _1/2 , HCH ₃ Si0 _2/2 , H (C ₆ H ₅ ) Si0 _2/2 ,

When linear polymers are involved, these essentially consist of "D" W ₂ Si0 _2/2 , WHSi0 _2/2 , and "M" W ₃ Si0 _1/2 or W ₂ HSi0 _{1/2 units.} , WH ₂ Si0 _1/2 ; the blocking terminal "M" units can be trialkylsiloxy, dialkylarylsiloxy groups.

By way of example of terminal "M" units, mention may be made of trimethylsiloxy, dimethylphenylsiloxy, dimethylethoxysiloxy, dimethylethyltriethoxy-silylsiloxy groups, etc.

As examples of units "D", mention may be made of dimethylsiloxy, methylphenylsiloxy groups. Said linear polyorganosiloxanes A can be oils of dynamic viscosity at 25 ° C of the order of 1 to 100,000 mPa.s at 25 ° C, generally of the order of 10 to 5,000 mPa.s at 25 ° C, or gums having a molecular mass of the order of 1,000,000. When it is cyclic polyorganosiloxanes, these consist of units

"D" W ₂ Si0 _2/2 , and WHSi0 _2/2 , which may be of the dialkylsiloxy or alkylarylsiloxy type

Said cyclic polyorganosiloxanes have a viscosity of the order of 1 to 5000 mPa.s

The dynamic viscosity at 25 ° C all the silicone polymers considered in this presentation can be measured using a BROOKFIELD viscometer, according to AFNOR standard NFT 76 102 of February 1972

The viscosity in question in this presentation is the dynamic viscosity at 25 ° C called "Newtonian", that is to say the dynamic viscosity which is measured, in a manner known per se, at a shear rate gradient low enough for the viscosity measured to be independent of the speed gradient

Examples of organopolysiloxanes A are

- dimethylpolysiloxanes with hydrogenodimethylsilyl ends,

- dimethylhydrogenomethylpolysiloxane copolymers with tπmethyl-silyl ends,

- dimethylhydrogenomethylpolysiloxane copolymers with hydrogenodimethylsilyl ends,

- hydrogenomethylpolysiloxanes with tπmethylsilyl ends,

- cyclic hydrogenethylpolysiloxanes

As regards compounds B, they are selected from polyorganosiloxanes comprising similar or different units of formula W ′ _d X _e YfSiθ4. (d + e + f) (3)

2 in which ^•

Δ The symbols W correspond to the same definition as that given above for

W, Δ The symbols X are similar or different and represent a hydrogen atom or a reactive function, preferably epoxyfunctional, linked to silicon by a divalent radical eg C ₁ -C ₂₀ optionally comprising at least one heteroatom, the radicals X more particularly preferred being 3-glycιdoxypropyl, 4-éthanedιyle

(1,2-epoxycylohexyl)? Δ The symbols Y are similar or different and represent a linear or branched alkenyl residue at C., - C ₁₂ , and having at least one ethylenic unsaturation at the chain end and / or in the chain and optionally at least one heteroatom, Δ d , e and f are 0, 1, 2 or 3, Δ d + e + f = 0- 1, 2 or 3. the rate of SiO _{4/2 units} being less than 30% by moles;

As regards the Y residues, they are advantageously chosen from the following list vinyl, propenyl, 3-butenyl, 5-hexenyl, 9 decenyl, 10-undecenyl, 5.9 - decadienyl, 6-11-dodecadιenyl

Organopolysiloxanes B can have a linear (branched or not) cyclic or network structure. Their degree of polymerization is preferably between 2 and 5000

When linear polymers are concerned, these essentially consist of units "D" W ₂ Sι0 _2/2 , XSiO _2/2 , YSiO _2/2 , and "M" W ₃ Si0 _1/2 , W ₂ YSiO _1/2 , W ₂ XSιO _1/2 , the terminal blocking "M" units can be tπalkylsiloxy, dialkylarylsiloxy, dialkylvinylsiloxy, dialkylalkenylsiloxy groups

As examples of terminal "M" units, mention may be made of tnmethylsiloxy, dimethylphenylsiloxy, dimethylvinylsiloxy, dimethylhexenylsiloxy, dimethylethoxysiloxy, dimethylethyltnethoxysilylsiloxy groups

As examples of units "D", mention may be made of dimethylsiloxy, methylphenylsiloxy, methylvinylsiloxy, methylbutenylsiloxy, methylhexenylsiloxy, methyldecenylesiloxy, methyldecadienylsiloxy, methyl-3-hydroxypropylsιloxy, methyl-3-glycidoxypropyl , 4'-epoxycyclohexyl) ethylsiloxy, methyl-butoxysiloxy, methyl-β-tnmethoxysilylethylsiloxy, methyl-β-tπethoxysilylethylsiloxy

Said linear polyorganosiloxanes B can be oils of dynamic viscosity at 25 ° C of the order of 1 to 100,000 mPa s at 25 ° C, generally of the order of 10 to 5,000 mPa s at 25 ° C, or gums with a molecular mass of the order of 1,000,000 When cyclic polyorganosiloxanes B are used, these consist of "D" units W ₂ Sι0 _2/2 , WSι0 _2/2 , WYSι0 _2/2 , which may be of the dialkylsiloxy, alkylarylsiloxy, alkylvinylsiloxy, alkylYsiloxy, alkylXsiloxy type, examples of such units have already been mentioned above

Said cyclic polyorganosiloxanes B have a viscosity αe of the order of 1 to 5000 mPa s

Having this large variety of polyorganosiloxanes B, it is perfectly conceivable to use a mixture of different products of formula (3), as defined above

The aliphatic unsaturated compounds B useful in the context of the process according to the invention are, for example, those with olefinic or acetylenic unsaturation well known in the technical field under consideration In this regard, reference may be made to American patents Nos ^. 3,159,662 , 3,220,272 and 3,410,886, which describe the above compounds According to an advantageous embodiment of the invention, the reaction mixture comprises compounds A and compounds B in an amount such that the molar ratio Si-H / unsaturated groups and / or reactive function eg epoxy, ie between 0.4 and 10 preferably between 1 and 4 and, more preferably still, of the order of 1.7 The catalyst being present in an amount of 1 to 400, preferably from 10 to 300 and, more preferably, from 20 to 200 ppm of platinum metal, expπmés by weight relative to the compounds A and B present

The technical literature of the field considered gives all the other useful information, as for the reaction conditions of hydrosilylation by thermoactivation.

The crosslinking reactions of silicone oils, in particular hydrosilylation (e g SI-H / SI-VI), catalyzed by heat-sensitive platinum complexes, in accordance with the invention, obey a process of homogeneous catalysis

A final aspect of the invention, which is mentioned in a nonlimiting manner in the present description, relates to a thermoreticutable composition, characterized in that it comprises the compounds A and B and a catalyst and / or a precursor thereof, as defined above The weight quantities of compounds A and B and of the catalyst are also given above

These compositions according to the invention are prepared either before (or even long before) or even immediately before the implementation of the hydrosilylation process

It should be noted that these compositions are particularly stable on storage and that, in accordance with the process of the invention, they offer rapid crosslinking kinetics. In addition, they offer great ease of handling, application or placement. on different supports or other shaping molds

Conventionally, the compositions and / or the process according to the invention can incorporate different additives, chosen according to the intended final application. II can be, for example, mineral fillers or not and / or pigments such as fibers. crushed or natural (polymers) calcium carbonate, talc, titanium dioxide clay or fumed silica This can improve eg the mechanical characteristics of the final materials

Soluble dyes, oxidation inhibitors and or any other material which does not interfere with the catalytic activity of the platinum complex can also be added to the composition or used in the context of the process according to the invention Once prepared by mixing all the compounds referred to above, the composition can be applied, for vanity purposes, on the surface of any solid substrate. These solid supports can be paper, cardboard, wood, plastic (eg polyester, nylon, polycarbonate), fibrous supports woven or not made of cotton, polyester, nylon etc, or a metal, glass or ceramic

The applications, more particularly, targeted by the catalyst, the process and the compositions according to the invention are, in particular, those of crosslinkable silicone oils, useful for the preparation of non-stick coatings on fibrous supports of any kind and in particular on paper In this application, the above compositions make it possible to achieve very high coating speeds, due to their very rapid crosslinking kinetics

Other possible applications are, for example, dental impression materials, adhesives, sealants, sealants, adhesion primers

The examples which follow, of catalytic systems, of compositions and of implementations of the process according to the invention, will allow a better understanding of the latter and will provide an illustration of its numerous advantages and of its variants.

EXAMPLES

EXAMPLE I: PREPARATION OF ORGANOMETALLIC COMPLEXES OF

PLATINUM (O) IMPLEMENTED IN THE CONTEXT OF USE ACCORDING TO THE INVENTION.

- 1 - COMPLEXES OF FORMULA (I) WITH L _α AND L _α = TMDVS

The operating method used consists in reacting a ligand of type π on the KARSTEDT complex of ideal formula Pt ₂ (VιMe ₂ Sι-0-SιMe ₂ Vι) ₃ This reaction can be carried out in bulk or in a solvent such as toluene, ethanol or isopropanol,

R ₂ (VιSiMe -0-S.Ms ₂ V.) ₃ + 2

+ VιMe2Si-OSi e ₂ i

1.1. PROCEDURE: 1, 1 equivalent of a Karstedt catalyst solution at 12% by mass of platinum in hexane is evaporated under vacuum. After volatilization of the solvent, 1 equivalent of the ligand olefin (L, or L ₂ ) complexing agent is added to the oil obtained. The mixture is then brought to a temperature varying between 50 and 90 ° C for a period of 15 to 90 minutes. After cooling to room temperature, the precipitate formed is washed successively with 2 x 5 ml of TetraMethylDiVinylSiloxane TMDVS, 2 x 10 ml of HexaMethylDisiloxane HMDS and 2 x 10 ml of pentane. After filtration, the powder is dried under vacuum.

Additional purification can be carried out by chromatography on silica using a diethyl ether / hexane mixture as eluent. The crystals of the various products are obtained by slow evaporation of a hexane solution.

The ¹ H NMR spectral analyzes (300 MHz, CDCI ₃ ), ¹³ C NMR (200 MHz, CβDβ), ¹⁹⁵ Pt { ¹ H} NMR (85 MHz, CDCI3) and FT-IR (nujol) are in agreement with the proposed structures, diene: tetramethyldivinylsiloxane: TMDVS

(DBE) Pt (diene)

DBE: Dibenzoyl ethylene

PhOC H

H COPh ₍ i 5)

YId: 57%

Melting Point: 156.1 ° C (decomposition)

Elementary analysis, found (calculated); C: 46, 81 (47.08); H: 4, 95 (5, 08) → (TETCE) Pt (diene)

TETCE: Tetra-ethyl tetra-carboxylato ethylene

EtOOC COOEt

EtOOC COOEt ₁₃ ) Yield: 69%

Melting Point: 138.4 ° C (decomposition)

Elementary analysis, found (calculated); Pt: 22, 05 (23, 56)

→ (DCNQ) Pt (diene)

DCNQ: Dichloro naphthoquinone

Yield: 69.5% Melting Point: 152.0 ° C (decomposition)

Elementary analysis, found (calculated); C: 36, 18 (35, 53); H: 3.65 (3.64)

→ (NQ) Pt (diene) NQ: naphthoquinone

YId: 47% Melting Point: 138.4 ° C (decomposition)

→ (MeNQ) Pt (diene)

MeNQ: Methyl-naphthoquinone

YId: 64.8%

Melting Point: 144.3 ° C (decomposition)

Elementary analysis, found (calculated); C: 41, 81 (41, 95); H: 4.77 (4.76); Pt: 33, 70 (33, 83)

-> (P1) Pt (diene)

P1: 1,2,3,4 tetramethyl-4a, 8a dihydro-en-1,4-methylmethanonaphthalene-5,8-dione

YId: 59.7%

IR (nujol) n (cm- ¹ ): 1672 fs (CO), 1258 Fs, 839 Fs, 794 Fs (Me ₂ Si-0), 1654 Fs, 1007 Fs

(CH ₂ = CH-Si).

Melting Point: 152 ° C (decomposition)

→ (BAD) Pt (diene)

ADB 9.10 dihydro-9, 10-ortho-benzenoanthracene-1, 4-dione (dihydro 9, 10 triptycenequinone)

YId: 68.4%

Melting Point: 202.7 "C (decomposition)

- 2 - COMPLEXES OF FORMULA (I) L _α = L _α . = nbn modification of the diene ligand with an L ₂ ligand = (21)

(nbn) 2 Pt (MeNQ) nbn = norbomylene or bicyclo [2.2.1] hept-2-ene

In a glove box, 200 mg of Pt (nbn) 3 (0.42 mmol) and 72 mg of Methyl naphthoquinone (0.42 mmol) are dissolved in 20 ml of toluene. The mixture is stirred for 3 hours while maintaining a slight heating. Thereafter, the solvent is slowly evaporated to yield a yellowish-brown powder. The product obtained is washed with 2 x 10 ml of pentane and dried under vacuum. 152 mg of complex are obtained. Yield: 65% Melting Point: 135.9 ° C (decomposition)

EXAMPLE II: EVALUATION OF CATALYSTS (I) AND (II) IN HYDROSILYLATION.

"High temperature" hydrosilylation procedure All hydrosilylation reactions are carried out on the same operating model. The assembly is a three-necked flask fitted with a dropping funnel and a coolant. It is passed through an oven (180 ° C) and conditioned under argon before each handling. Heating is done by oil bath and stirring by magnetic bar.

The temperature is regulated by reflux of a solvent. This removes the calories generated during the reaction and allows greater reproducibility of the catalysis.

The solvent chosen is hexane. Its boiling point is 72 ° C. Following various tests carried out in the laboratory and in industry, the optimum alkene / silane ratio has a value of 2. The quantity of catalyst will be fixed at 6, 6. 10 " ⁶ mole of platinum for 3. 10 ^_ 3 _mo | _e All the catalysts will be monitored by CPG, except the mechanistic studies followed by ¹ H NMR. A small amount of aliphatic tertiary amine will be added to each sample taken, which will be used to stifle your reaction at the time of sampling. The amine used will be trihexylamine

"Low temperature" hydrosilylation procedure

These hydrosilylations are carried out in Schlenck tubes under an inert atmosphere.

The temperature is regulated at 30 ° C. The substrates are introduced at the same time.

The concentration of silane in the reaction medium is therefore maximum from the start of the reaction. The stoichiometric conditions are identical to those of high temperature handling. EXAMPLE III: TESTS

The substrates used are models for hydrosilylation, namely trimethylvinylsilane and triethylhydrogenosilane. The catalysts tested will be: (MeNQ) Pt (diene), (TCNE) Pt (diene), (FN) Pt (diene), (TETCE) Pt (diene), (NQ) Pt (diene), (DCNQ) Pt ( diene) and (P1) Pt (diene). The manipulations are carried out protected from light. Solvents and reagents are degassed before use. A comparison to the Karstedt catalyst is made. For the nomenclature, see example 1.

111.1. TESTS 1 TO 3: HYDROSILYLATION SPEED: ///. 1. 1. Hydrosilylation of trimethylvinylsilane by triethylhydrogenosilane:

OPERATING CONDITIONS:

T ° C = 30 "C, [Si-H] o = 0.5 [C = C] o: 0.15 mole. L ^'1 solvent: hexane 20 ml, catalysts (TCNE) R (diene), (NQ ) Pt (diene), (FN) Pt (diene), (TCNE) Pt (diene). [Si-H] o R] θ = 500, diene = tetramethyldivinylsiloxane Fig. 1 appended shows a curve of the% of SiH consumed as a function of time.

The most effective catalyst is the platinum complex carrying Naphtoquinone. The ligand reactivity orders, thereafter, are TETCE> TCNE> FN. Several derivatives of this type have been synthesized and complexed.

3. 1.2. Hydrosilylation of trimethylvinylsilane by triethylhydrogenosilane: OPERATING CONDITIONS:

T "C = 30" C, [Si-H] o = 0.5, [C = C] o: 0.15 mole. ¹ solvent: 20 ml hexane, catalysts

(MeNQ) Pt (diene), (NQ) Pt (diene), (DCNQ) Pt (diene), (P1) R (diene), [Si-H] o / [R] θ =

500. diene = tetramethyldivinylsiloxane.

Fig. 2 appended shows a curve of the% of SiH consumed as a function of time. The various catalysts used have proven to be very effective in catalyzing the hydrosilylation of trimethylvinylsilane by triethylsilane. The most reactive is the complex (MeNQ) Pt (diene).

///.1.3. Half reaction time:

They are shown in Table 1 below. They correspond to the consumption of 50% of the silane introduced. Table 1: Hydrosilylation of trimethyl vinyl silane with triethylhydrogenosilane: T ° C = 30 "C, [Si-HJo - 0.5 [C = CJo: 0.15 mol. The ¹ _t solvent: hexane 20 ml. Complexes more as effective as the Karstedt catalyst.

1 1/2 ligands (min)

Methylnaphthoquinone 22.5

Dichloronaphthoquinone 30

Ligand P1 (diels help) 44

HEAD 58.5

Naphtoquinone 61

Karstedt 65 catalyst

III.1.4. Conclusion

In conclusion, it should be noted that the new synthesized catalysts are more effective than the Karstedt catalyst. The most reactive seem to be the quinone complexes. Their average half-reaction time is of the order of 35 minutes. The tetraethyl-tetracarboxylato-ethylene complex is also of comparable reactivity.

Table 2 below gives the efficiencies of the various catalysts tested. Board

III.2. REACTION SPEED / LIFETIME: COMPARISON TO KARSTEDT 11132 CATALYST. 1. Introduction

It is necessary to compare these new catalytic systems with the catalyst already used industrially. Two studies were carried out mainly based on the reaction rate and the lifetime of the catalyst. The catalyst chosen to carry out this comparison is (MeNQ c (21)) Pt (diene), It 1.2.2. Reaction speed

The platinum complex (MeNQ) Pt (diene) was compared under the same operating conditions to the existing Karstedt catalyst in diméπque type Pt2 (TMDVS) 3 Two tests were carried out at identical platinum concentration on the substrates previously used. The results are shown in the attached FIG. 3, which shows the curve of the% of silane SiH consumed as a function of time.

OPERATING CONDITIONS Hydrosilylation of tnmethyl vmyl silane by tnethylhydrogenosilane T ° C = 30 "C,

[Si-HJo = 0.5 [C = C] o 0.15 mole L ^'1 ₁ hexane solvent 20 ml, catalysts (MeNQ) Pt (diene), Karstedt Pt∑ catalyst (TMDVS) 3 [Sι-H] o / [Pt] o = 500 diene = tetramethyldivinylsiloxane Twice, the complex carrying methylnaphthoquinone proved to be more effective than the Karstedt catalyst Finally, the color of the solution at the end of the reaction is lighter in our case This indicates , that in opposition to the Karstedt catalyst, much less decomposition into inactive colloids appears at the end of the reaction /// 2 3 lifetime of the catalyst The lifetime of the catalyst is characteristic of the evolution of the active species in the medium In hydrosilylation, from the Speier catalyst, platinum is considered active in catalysis after reduction to the degree of (0) monometallic oxidation This reduction also generally leads to the precipitation of inactive metal at the end of the reaction. study is often to push this point lim ite The experiment carried out, in parallel, on the Karstedt catalyst and on that according to the invention, was to add a large amount of silane and olefin and to measure their disappearance Each time that a fraction is converted into all, another is added Table 3 below gives the results obtained

OPERATING CONDITIONS Hydrosilylation of tnmethyl vinylsilane by tnethylhydrogenosilane in the presence of (MeNQ) Pt (diene) or of the Karstedt catalyst Method of the successive additions Reaction conditions, Initial concentrations alkene = 6 W ³ mole, silane = 3 10 ^{~ 3} mole, catalyst = 6 10 ^'6 mole Hexane solvent, 20 ml, T 30' C, diene = tetramethyldivinylsiloxane Table 3

Cat. (MeNQ) Pt (diene) Pt2fTMDVS) 3 addition atcene number * silane ^* alkene * silane *

1 1000 500 1000 500

2 +1000 +500 +1000 +500

3 +500 +500 +500 +500

4 +500 +500 +500 +500

5 + 1000 + 1000 +1000 +1000

6 + 1000 + 1000 stop * ^*

7 +1000 + 1000 stop ^**

Conversion 4200 ^* 2900 ^*

* The quantities are expnm according to the number of equivalents compared to platinum. The conversion is given relative to the silane introduced ** The handling is stopped when there is no longer any observed variation in the concentration of silane in the medium after 2 hours. In the case of the Karstedt complex, a maximum rotation of approximately 3000 equivalents was obtained. This conversion is obtained after 5 successive additions of substrate. The catalyst becoming inactive at time t = 2880 minutes, it is then impossible to continue the addition. The color of the solution is brown-black, indicating a total decomposition On the other hand, by using (MeNQ) Pt (diene), the maximum conversion on the same substrate is 4200 equivalents in 7 successive additions. The color may be brown but the lifespan is increased by 50%. The complex according to the invention, by the coordination of methylnaphthoquinone, undergoes much less quickly than the Karstedt catalyst, degradation to metallic platinum.

Thus, the catalyst according to the invention has a longer lifespan than that of its known counterparts. In other words, this catalyst is recyclable

III.3. INFLUENCE OF AN EXCESS IN LIGAND L ₂ = (21) = METHYL-NAPHTOQUINONE

The coordination of quinone therefore seems to weaken at the end of the reaction. An excess of ligand is added to the medium, in order to stabilize the active species and avoid this degradation. Several experiments are carried out with this in mind. The reaction mixture is added to: a) 50 equivalents of MeNQ relative to platinum b) 100 equivalents of MeNQ relative to platinum c) 150 equivalents of MeNQ relative to platinum To these three different mixtures, 2000 equivalents of substrates are added successively. After addition, the percentage converted is checked every hour. When 100% of the silane has disappeared, another 2000 equivalent is added. Table 4 below gives the results obtained in terms of average hydrosilylation rate.

OPERATING CONDITIONS:

Hydrosilylation of trimethyl vinyl silane by triethylhydrogenosilane: TC = 30'C, [Si-HJo = 0.5 [C = CJo: 0.15 mole. L ¹ ₁ solvent: hexane 20 ml. Values of the Average Vm Hydrosilylation Speeds in the Presence of 50, 100, 150 MeNQ Equivalents. diene = tetramethyldivinylsiloxane.

Table 4 nb equivalent V mean V2moy ^* ^* ^* V3moy

2000 1040 820 760

4000 684 480 475

6000 470 395 390

12000 330 280 270

16000 266 220 200

26,000 166 125 110

^* V avg: average hydrosilylation speed in the presence of n = 50, 100, 150 equivalents of MeNQ relative to platinum When the alkene concentration decreases, the solution remains clear, the reaction resumes when 2000 equivalents of silane. Industrial handling of the Karstedt catalyst involves very slow addition of the silane, which fixes a very low concentration of Si-H in solution. When this concentration increases, the catalyst gradually dies. In the case of the invention, the addition is very important at the initial time, but no abrupt degradation of the platinum complex is observed. In addition, it can be seen that the lifespan is greatly increased by the addition of 50, 100, 150 equivalents of Methylnaphthoquinone. The reaction rate decreases slightly with the increase in the concentration of quinone in the medium. In conclusion, even after 26,000 equivalents of Si-H converted, the catalyst according to the invention is still active (comparison with Table 3).

III.4. MAXIMUM CONVERSION

It is possible to know the maximum amount of silane that the catalytic system according to the invention could convert. Using the same stabilizer, an additional test was performed to assess the maximum number of cycles. To do this, a much larger amount of substrate is introduced at the initial time. We chooses stoichiometric reaction conditions to minimize the effects of an excess of alkene and a methyl naphthoquinone ratio of 50 equivalents / Platinum. The catalyst is dissolved in toluene FIG. 4 appended gives the number of SiH equivalents converted as a function of time. OPERATING CONDITIONS

Hydrosilylation kinetics of tnmethylvmylsilane by triethylhydrogenosilane in the presence of (MeNQ) R (diene) and 50 equivalents of Methylnaphthoquinone Determination of the maximum number of rotations. [Si-HJo = [C = CJo = 1, 2 10 ^{~ 2} mole L ' ¹ Hexane: 20 ml. diene = tetramethyldivinylsiloxane Table 5 below gives the value of the Maximum speed V _m ax of hydrosilylation of methyl vinylsilane by methyl hydrogenosilane in the presence of (MeNQ) Pt (diene) and 50 equivalents of MeNQ Table 5

Initial speed 1400 equ / hr

Maximum speed 2800 equ / hr

Maximum number of rotations 38,000 equ

Under stoichiometric conditions, a maximum conversion of

38,000 equivalents per platinum atom The contribution of quinone to the medium is considerable and makes it possible to increase the tolerance of the active species In fact, when 20,000 equivalents of silane are added at one time, the catalyst remains active and n is not affected by the high concentration of Si-H functionalities unlike the Karstedt complex

III.5 INFLUENCE OF MERCURY

The use of mercury as a heterogeneous catalysis inhibitor was first proposed by G Whitesides (J. Am Chem Soc, 110 (1988) 3164) and by T Miller, (J Am. Chem. Soc, 110 (1988) , 3156-3163) It seems obvious that the amalgam caused by the addition of Hg makes the heterogeneous catalyst totally ineffective by having only a weak effect on the homogeneous catalyst

L. Boardman arrives at the same observation when he performs a similar experiment on his photochemical catalyst CpPtMe3 (Organometallics, 11, 1992, 4194). Hydrosilylation is completely inhibited Prigano and Trogler note that only the colloidal platinum catalyst supported on silica is sensitive to the addition of Hg, that consisting of Monoméπque platinum phosphme not being influenced (Organometallics, 4,

1985, 647-657), (Organometallics, 1, 1982, 768-770) Mercury poisoning is therefore proof of a heterogeneous type of catalysis, which L. Lewis observed during a study on the Karstedt catalyst (Am. Chem. Soc, 108, 1986, 7228). This experiment was therefore carried out using the catalyst according to the invention and, it was compared, under the same conditions, to the Karstedt catalyst.

111.5.1. Fig. 5 appended gives the curve of% of SiH consumed as a function of time, with (Δ) and without Hg (+) for the MeNQ Pt diene catalyst.

OPERATING CONDITIONS:

Influence of mercury on the hydrosilylation of trimethylvinyl silane by triethylhydrogenosilane: (+) without Hg, (D) with Hg, T "C = 30" C, [Si-HJo = 0.5 [C = CJo: 0.15 mole. L ¹ ₁ solvent: hexane 20 ml. diene = tetramethyldivinylsiloxane. catalyst (MeNQ) Pt (diene), volume of Mercury: 0.1 ml.

111.5.2. Fig. 6 appended gives the curve of% of SiH consumed as a function, with (Δ) and without Hg (+) for the KARSTEDT catalyst OPERATING CONDITIONS:

Influence of mercury on the hydrosilylation of trimethyl vinyl silane by triethylhydrogenosilane: (+) without Hg, (D) with Hg, T ° C = 30 ° C,

[Si-HJo = 0, 5 [C = CJo: 0, 15 mole. L ¹ ₁ solvent: hexane 20 ml, catalyst Pt2 (TMDVS) 3 (Karstedt), volume of Mercury: 0.1 ml. ///.5.3. Conclusion

No effect of mercury could be demonstrated when using the system according to the invention. However, the effect is dramatic on Karstedt's catalyst. In this case, the hydrosilylation is stopped. We can say that our system keeps its homogeneous nature over time unlike the Karstedt complex which evolves towards a heterogeneous system much less active.

111.6. EFFECT OF THE NATURE OF LIGAND DIENE - PLATINUM COMPLEXES TYPE I WITH

L _α = L _α . = nbn

The complex (I) prepared according to Example I.2 is compared with the Karstedt catalyst and the

(TMDVS) Pt (MeNQ). It can be seen that the rate of reaction in catalysis is greater in this case. We can deduce that the ligand L _α = L _α p = nbn makes the compound more effective.

Fig. 7 appended gives the% of SiH consumed as a function of time.

OPERATING CONDITIONS:

Kinetics of trimethylvinylsilane hydrosilylation by heptamethyltrisiloxane (MD'M) in the presence of (MeNQ) Pt (diene) Δ, (MeNQ) Pt (nbn) 2 o, Karstedt + catalyst. T'C = 30 ° C, [Si-HJo = 0, 5 [C = CJo: 0.15 mole. ¹ solvent: hexane 20 ml.

111.7. The striking fact is that the catalyst of the invention works in homogeneous mode.

Claims

CLAIMS: 1 - Use, as a heat-activated, homogeneous catalyst, based on platinum and useful in particular in hydrosilylation between, on the one hand, silanes and / or siloxanes A having, per molecule, at least one reactive radical SiH and free of silicon atom linked to more than two hydrogen atoms and, on the other hand, of compounds B having at least one reactive group and / or at least one reactive function, of at least one platinum complex of formula :

n - l or 2

in which Δ L _α and L _α . are identical or different and are selected from among the binding olefins, preferably from the following olefinic residues, substituted or not: + norbornene

+ (cyclo) hexene, + ethylene; Δ L _α and L _α . can also form together a single diolefin ligand, preferably formed by ^•

Yes

/

R '

R ⁴

(II)

in which R ¹ , R ² , R ³ , R ⁴ are different or similar to each other and represent an alkyl and / or acyl group, preferably an alkyl having from 1 to 18 carbon atoms, methyl, ethyl, propyl, pentyl, hexyl, allyl, acetyl, propionyie being particularly preferred and especially methyl, Δ L is chosen from ligands L.,, L ₂ defined below L., being a ligand of the following formula:

(D in which: m Z ¹ , Z ² , Z ³ , Z ⁴ , independently represents hydrogen, an aryl, an alkyl, a halogen, a hydroxyalkyl or an electron-withdrawing group, preferably selected from the following groups: COR, CN, COOR with R = hydrogen, alkyl, aryl; at least one, preferably at least two, of the substituents Z ¹ to Z ⁴ corresponding to an electron-withdrawing group; * L ₂ being a ligand consisting of the following residue (2):

(2) in which:

Y ¹ , Y ² , Y ³ , Y ⁴ independently represents a hydrogen, a halogen, an alkyl, an aryl, an alkoxyl, a hydroxyl, or else Y ¹ and Y ⁴ or Y ² and Y ³ can also form together at least a cyclic group, aromatic or not, and comprising one or more rings, condensed or not; said cyles being optionally substituted by monovalent radicals corresponding to the definition given above for Y ¹ to Y ⁴ ;

Δ E ¹ , E ² are identical or different and represent: O, NR ⁵ with R ⁵ = CC ₆ alkyl or alkenyl, CR ⁶ R ⁷ with R ⁶ , R ⁷ identical or different and corresponding to CC ₆ alkyl, alkoxyl, halogen, oxygen being more particularly preferred for E-., E ₂ . 2 - Use according to claim 1 characterized in that the ligands L of the platinum complexes (I) are selected from the following subgroups L, and L ₂ : → L,:

NC CN NC H

> = <= <

(11) NC CN (12) H CN

EtOOC COO and EtOOC H

> = <

(13) EtOOC COOEt (14) H COOEt

PhOC H = <

(15) H COPh

- "and mixtures of L ₁ and / or L ₂ ligands 3 - Use according to claim 1 or claim 2, characterized in that the catalyst is used in a reaction medium consisting of a stable solution of said catalyst and reagents, in at least one organic solvent.

4 - Use according to any one of claims 1 to 3, characterized in that the catalyst contains, in the free state, at least one stabilizing agent formed by at least one ligand Ls of formula L _α , L _α ., L , or L ₂ as defined in claim 1.

5 - Use according to any one of claims 1 to 4, characterized in that the catalyst comprises at least one thermal blocker present, preferably, chosen from acetylenic alcohols of formula:

R - (R ') C (OH) - C --- CH formula in which,

. R is a linear or branched alkyl radical, or a phenyl radical; . R 'is H or a linear or branched alkyl radical, or a phenyl radical; the radicals R, R ¹ and the carbon atom located at α of the triple bond which can optionally form a ring; the total number of carbon atoms contained in R and R ¹ being at least 5, preferably from 9 to 20, said alcohols being more preferably selected from those having a boiling point above 250 ° C., such as :. ethynyl-1-cyclohexanol 1; . 3-methyl-dodecy-1 ol-3; . trimethyl-3,7,11 dodécyne-1 ol-3; . diphenyl-1,1 propyne-2 ol-1;

. 3-ethyl-6-ethyl nonyne-1 ol-3; . 3-methyl-pentadecyne-1 ol-3.

6 - Platinum complex of formula (I) as defined in claim 1 or 2 and in which L _α and L _α . are identical or different and are selected from among the binding olefins, preferably from the following olefinic residues, substituted or not: + norbornene

+ (cyclo) hexene, + ethylene. 7 - Process for the synthesis of complexes (I) in which L _α and L _α . together form a single diolefinic ligand (II) according to claim 1, characterized in that it consists in reacting at least one ligand L as defined in claim 1 with products of average formula. [Pt °] ₂ [ViMe ₂ Si-O-Si-Me ₂ -Vi] ₃ .

8 - Process for the synthesis of complexes (I) according to claim 1 or 2, in which L _α = L _α -, = nbn, characterized in that it consists in reacting at least one ligand

L as defined in claim 1, with starting materials of the type [nbn] ₃ Pt

9 - Heat-activatable catalyst based on platinum and useful in particular in hydrosilylation between, on the one hand, silanes and / or siloxanes A having, per molecule, at least one reactive radical SiH and free of silicon atom bonded to more than two hydrogen atoms and, on the other hand, compounds B having at least one reactive group and / or at least one reactive function, characterized

- in that it comprises at least one platinum complex (I) as defined in claim 1, 2 or 6,

- and in that it is homogeneous

10 - Catalyst according to claim 9, characterized in that it is in the homogeneous form of a solution in at least one organic solvent

11 - Hydrosilylation process between, on the one hand, silanes and / or siloxanes A having, per molecule, at least one reactive radical Si-H and free of silicon atom bonded to more than two hydrogen atoms , and on the other hand, compounds B having, per molecule, at least one reactive unsaturated aliphatic group and / or at least one reactive polar function, in which at least one complex of platinum is used as catalyst, characterized in that it is based on thermoactivation and in that it consists essentially in reacting compounds A and B in the presence of the catalyst defined in any one of claims 1 to 6, 9 or 10, and / or obtained in implementing the synthesis method according to claim 7 12 - Process according to claim 11, characterized in that the compounds A are chosen from polyorganohydrogensiloxanes comprising:

* reasons for the following formula:

H _a W SiO ₄ . Q + b) 0)

2 in which: the symbols W are similar or different and represent monovalent hydrocarbon groups, free from any adverse action on the activity of the catalyst and preferably chosen from (cyclo) alkyl groups having from 1 to 18 carbon atoms included and, advantageously, among the methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl groups as well as among the C ₆ -C ₁₂ aryl or aralkyl groups and, advantageously, among the xylyl and totyl and phenyl radicals, all these groups possibly being halogenated (fluorine eg) and / or hydroxylated and / or alkoxylated. - a is 1 or 2, b is 0, 1 or 2, the sum (a + b) has a value between 1 and 3,

* and, possibly, other reasons of medium formula:

W _c SiO ₄ _ _J ç (2)

2 in which W has the same meaning as above and c has a value between 0 and 3.

13 - Process according to claim 11, characterized in that the compounds B are selected from polyorganosiloxanes comprising similar or different units of formula: W ' _d X _e Y _f SiO ₄ . _(d + _e + f) (3)

2 in which:

Δ The symbols W are similar or different and represent monovalent hydrocarbon groups, free from any unfavorable action on the activity of the catalyst and preferably chosen from (cycio) alkyl groups having from 1 to 18 carbon atoms inclusive and, advantageously, among the methyl, ethyl, propyl, octyl and 3,3,3-trifluoropropyl groups as well as among the C ₆ -C ₁₂ aryl or aralkyl groups and, advantageously, among the xylyl and totyl and phenyl radicals, all these groups being optionally halogenated (fluorine eg) and / or hydroxylated and / or alkoxylated, Δ The symbols X are similar or different and represent a hydrogen atom or a reactive, preferably epoxyfunctional, function linked to silicon by a divalent radical eg in

C _r C ₂₀ optionally comprising at least one heteroatom, the more particularly preferred radicals X being:

3-glycidoxypropyl, 4-ethanediyl, (1, 2-epoxycylohexyl) ... Δ The symbols Y are similar or different and represent a linear or branched alkenyl residue in C _r C ₁₂ , alkenyl residue having at least one ethylenic unsaturation at the end chain and / or in the chain and optionally at least one heteroatom;

Δ d, e and f are 0, 1, 2 or 3;

Δ d + e + f = 0, 1, 2 or 3; of Si0 _4/2 patterns being less than 30% by mole

14 - thermosetting composition characterized in that it comprises: compounds A according to claims 11 or 12, compounds B according to any one of claims 11 or 13, and a catalyst as defined in any one of claims 1 to 10 and / or a precursor thereof