US3625755A

US3625755A - Supported metal salt/phosphine complexes and metallized products therefrom

Info

Publication number: US3625755A
Authority: US
Inventors: Earle M Potrafke
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1969-04-14
Filing date: 1969-04-14
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07

Abstract

Metal salt/phosphine complexes deposited within and/or on a metallic or nonmetallic support or substrate, said complexes being derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table, for example, gold or palladium chloride, and 1 to 4 moles of a triorganophosphine, for example, a trihydrocarbyl or tridihydrocarbylamino phosphine such as a trialkylphosphine, and metallized metallic and nonmetallic substrates prepared therefrom.

Description

United States Patent Earle M. Potralke Wilmington, Del.

Apr. 14, 1969 Dec. 7, 1971 E. 1. du Pont de Nemours and Company Wilmington, Del.

Continuation-impart of application Ser. No. 540,517, Apr. 6, 1966, now Patent No. 3,438,805, dated Apr. 15, 1969. This application Apr. 14, 1969, Ser. No.

inventor Appl. No. Filed Patented Assignee SUPPORTED METAL SALT/PHOSPHINE COMPLEXES AND METALLIZED PRODUCTS THEREFROM OTHER REFERENCES Jensen et al., Acta Chemica Scand. 3 (1949) 474- 480 Primary ExaminerRalph S. Kendall Attorney-Louis H. Rombach ABSTRACT: Metal salt/phosphine complexes deposited within and/or on a metallic or nonmetallic support or substrate, said complexes being derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table, for example, gold or palladium chloride, and l to 4 moles of a triorganophosphine, for example, a trihydrocarbyl or tridihydrocarbylamino phosphinc such as a trialkylphosphine, and metallized metallic and nonmetallic substrates prepared therefrom.

SUPPORTED METAL SALT/PHOSPHINE COMPLEXES AND METALLIZED PRODUCTSTHEREFROM CROSSREFERENCE TO RELATED APPLICATION This is a continuation-in-part of copending application Ser. No. 540,517 filed Apr. 6, 1966 and issued Apr. 15, 1969 as US. Pat. No. 3,438,805.

Metal-coated articles are presently enjoying wide utility. They are often conveniently obtained by chemical or nonelectroyltic methods, starting with a compound of the coating metal and converting it to the metal under controlled conditions. In general, however, the known methods are not entirely satisfactory; they each have one or more disadvantages such as requiring exceedingly high temperatures or preformed organometallic compounds, or are limited to aqueous plating baths or to the use of active metal substrates in accordance with the electromotive series, or are otherwise not readily adapted to plating a wide variety of substrates. Of particular interest at the present time is the coating of nonmetallic substrates such as plastics.

[t is an object of this invention to provide supported metal salt/phosphine complexes which are useful in a variety of applications, including the preparation of metallized metallic nonmetallic substrates. A further object is to provide a method for producing said supported complexes by depositing the complex within and/or on either a metallic or a nonmetallic substrate. A still further object is to provide metallized metallic or nonmetallic substrates.

It has now been discovered that a wide variety of substrates can be chemically metallized by the process which comprised heating a metal salt/phosphine complex derived from 1 mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table and about 1 to 4 moles of a trimgano phosphine in which each organo group is a hydrocarbyl or dihydrocarbylamino radical in the presence of the substrate to be metallized at a temperature of about 25 to 350 C., but below the decomposition temperature of the substrate and the heavy metal salt alone, provided that when the substrate is not a heavy metal of the Deming Periodic Table other then the plating metal, the metal salt/phosphine complex is in substantially pure form in direct contact with the substrate. By metallized" is meant metal coated or metal impregnated. By normally solid heavy metals is meant heavy metals which are solid at nonnal ambient temperatures, thereby excluding metals such as Hg and Ga which are liquid at temperatures as low as about 30 C. By plating metal is meant the heavy metal of the salt from which the complex is derived. By substantially pure form is meant undiluted by any substantial amount of solvent, diluent or carrier. Minor amounts of impurities and additives are readily tolerated.

When the substrate is a normally solid heavy metal of the Deming Periodic Table other than the plating metal, the substrate may be immersed in a bath containing the metal salt/phosphine complex dissolved in an inert solvent and the bath is heated for a time sufiicient to provide an adherent coating of the plating metal on the substrate.

When the substrate is not a heavy metal of the Deming Periodic Table other than the plating metal, the metal salt/phospine complex is heated in substantially pure form in direct contact with the substrate. When direct contact between the complex is substantially pure form and the substrate is required, it is most conveniently provided by coating the substrate with the complex alone, especially in the case of a liquid complex, or by mixing the complex with a volatile carrier such as a solvent or diluent, coating the substrate with the mixture, evaporating the volatile carrier and heating the coated substrate, thereby metallizing the substrate.

Because the metal salt/phosphine complexes are soluble in a wide variety of solvents, metal impregnates as well as coatings can be produced with a wide variety of polymeric substrates that are also soluble in such solvents and can be recovered and reconstituted by solvent evaporation. For impregnating a substrate such as plastic the metal salt/phosphine complex and a soluble polymer are dissolved in a mutual inert volatile solvent, the solvent is evaporated to form an intimate metal salt/phosphine-polymer mixture which is heated to produce the impregnated plastic. A solvent is chosen which softens, swells or dissolves the plastic substrate thereby allowing the plating components to penetrate the surface or to become completely and intimately associated therewith. Solutions of the metal salt/phosphine complex and the substrate polymer can be cast as films, spun into fibers or molded into any desired shape and, with evaporation of the solvent and heating, converted into a metallized product.

Broadly, the method of this invention comprises heating the metal salt/phosphine complex in the presence of the substrate to be metallized at the temperature required to effect the metal salt/phosphine to metal transformation in the particular case. The required temperature, which may be as high as 350 C., but usually is in the range of 25 to 250 C., is significantly lower than that required to decompose the metal salt alone to the free metal.

When the substrate is a normally solid heavy metal of the Deming Periodic Table other than the plating metal, plating temperatures generally range from about 25 to 150 C. When the substrate is other than the specified heavy metals, somewhat higher temperatures in the range of about to 250 C. are generally required. In other words, metal plating with the same metal salt/phosphine complex may require different temperatures depending depending whether upon not the substrate is one of the specified heavy metals.

While the exact nature of this phenomenon is not definitely known, it is believed that the specified heavy metals may enter into an exchange reaction with the heavy metal of the complex. Although it is not intended that this invention be limited to any particular theory, these exchange reactions could account for the lower temperatures encountered with heavy metal substrates.

However, these exchange reactions do not follow the normal relationships encountered in the electromotive series of the metals as shown for example by Lange in Handbook of Chemistry, 10 the Edition, page 1,218, McGraw-Hill Book Co. In accordance with this invention, metals such as aluminum, manganese, zinc, chromium, iron, cobalt, nickel and tin are readily plated on a substrate such as copper, which is lower down in the electromotive series than these plating metals. Such exchange reactions are contrary to the accepted rules of the electromotive series.

It is possible that the presence of the phosphine in the complex may alter the normal forces in the electromotive series. It has been found that by proper selection of the phosphine and solvent, any of the heavy metals can be plated on any other heavy metal at substantially reduced temperatures.

The complexes used in accordance with this invention are derived in part from salts of the normally solid heavy metals of the Deming Periodic Table. These heavy metals are defined in the Deming Periodic Table as shown by H. G. Deming in F undamental Chemistry, 2nd Edition (1947), page 255, John Wiley & Sons, Inc. and by Lange in Handbook of CHemistry, 10th Edition, pages 56 and 57. Suitable heavy metals which may be used in accordance with this invention include: Cu, Ag and Au (Group I B);Zn and Cd (Group 11 B); A1, TI and In (Group 111); Sn, Pb, Ti and Zr (Group IV); Sb, V, Nb, Ta and Bi (Group V); Cr, Mo and W (Group Vl); Mn and Re (Group Vll;); Fe, Ru, Co, Rh, Ni, Pd, Pt, Os and Ir (Group VIII).

The heavy metal salts from which the metal salt/phosphine complexes are derived are nonorganometallic salts. By nonorganometallic salt" is meant a salt which is free of carhon-metal bonds. In other words, this invention is directed to the utilization of heavy metal compounds in their commonly available, essentially inorganic salt forms and does not require that the metal salts first be activated by conversion to an intermediary organometallic form. The heavy metals are commonly available and conveniently used as the chlorides, bromides, iodides, cyanides, nitrites, nitrates, perchlorates, fluoroborates, carbonates or carboxylates such as acetates and trifiuoroacetates.

Preferred plating metals are the ductile, noble and precious metals of Groups I B, and VIII, especially the salts of silver, copper, gold, nickel, cobalt, palladium and platinum. Still other preferred plating metals are titanium, chromium, zinc and tin. These are preferably employed as the readily available chlorides, bromides and iodides, but sometimes, as in the case of silver, are more advantageously used as the nitrites, nitrates or perchlorates.

The complexes are also derived in part from triorgano phosphines in which each organo group is a hydrocarbyl or dihydrocarbylamino radical. Each of the hydrocarbyl groups, including those in the dihydrocarbylamino radical, may be aliphatic, cycloaliphatic or aromatic and, for reasons of availability and economy, normally contain from about one to carbon atoms, but may contain up to about 18 carbon atoms. These groups may be straight-chain, branchedchain, saturated or unsaturated including ethylenic and acetylenic unsaturation. Exemplifying such groups are methyl, ethyl, npropyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, amyl, hexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl, propenyl, allyl, butenyl, propargyl, octadecenyl, cyclopentyl, cyclohexyl, cyclohexenyl, phenyl, totyl, xylyl, ethylphenyl, styryl and dodecylphenyl. The trialkyl phosphines are preferred, particularly the tri-lower alkyl phosphines having from about one to five carbon atoms in each alkyl group.

The hydrocarbyl secondary amino groups are preferably, for reasons of availability and economy, di-lower alkylamino groups where each alkyl has from about one to five carbon atoms such as dimethylamino, diethylamino, methylethylamino,'dibutylamino, methyl amylamino and diamylamino. Suitable homologs and analogs include dioctylamino, methyl octadecylarnino, ethyloctadecenylamino, methyl cyclopentylamino, methyl cyclohexylamino, octyl cyclohexylamino, dicyclohexylamino, N-methylanilino, N- ethylanilino and N-methyl toluidino. The hydrocarbyl group may also constitute a single divalent radical such as the pyrrolidino and piperidino radicals.

The process of this invention may be carried out using a preformed metal salt/phosphine complex, or the complex may be prepared in situ by adding the metal salt and phosphine separately to a solvent in which the complex is soluble. In either case, the complex is formed and acts as a necessary component in the process. When the complex is formed in situ small excesses of metal salt or phosphine may be present. These do not interfere with the metallization process.

As is well known in the art, phosphines and heavy metal salts generally form definite coordination complexes involving from 1 to 4 moles of the phosphine per mole of the salt. For efficient utilization of the heavy metal salt in forming the complex in situ, the phosphine is normally present in amounts corresponding to at least about I mole per mole of heavy metal salt. More than about 4 moles of the phosphine per mole of salt is generally not needed, but may be used, if desired. The optimum amount of the phosphine may vary depending on the particular heavy metal salt and the substrate to be coated. Usually, however, only about 2 moles of the phosphine are needed per mole of salt and sometimes only about 1, particularly in the case of Group I B metals. The formation of definite metal salt/phosphine complexes constitutes an important practical advantage since the complexes are easily obtained pure and can be conveniently stored and handled at ordinary temperatures.

In general the metal salt/phosphine complexes decompose to form metal at or slightly above their melting points and in general this is completed at temperatures below about 350 C. As a class, the triaryl phosphine complexes are thermally more stable than the trialkyl phosphine complexes and require higher metallization temperatures. This may be advantageously used where enhanced thermal stability of a complex is needed as in controlled and stepwise metal deposition. Thus, the wide variety of phosphines that are available enables one to control or. vary the temperature of metallization to suit the particular processing need.

The metal salt/phosphine complexes, in contrast to the metal salts from which they are derived, are highly soluble in a wide variety of organic solvents making possible the formulation of a wide range of plating compositions. The solvent of course should be substantially inert to the plating ingredients and the substrate. Suitable solvents include alcohols such as methanol, ethanol, 2-propanol and 2-methyl-l-propanol; ethers such as diethyl ether, furan, tetrahydrofuran and dioxane; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as pentane, hexane, isooctane, tetradecane, benzene, xylene and toluene; halogenated hydrocarbons such as chloroform, methylene chloride, carbon tetrachloride, chlorobenzene, dichlorobenzene, trichloroethylene, l, l ,2,2-tetrachlorol ,2-difluoroethane, l l ,2-trichloro-l ,2,2-trifluoroethane, trichlorofluoromethane, chlorotrifluoromethane and mixtures and azeotropes thereof; nitriles such as acetonitrile, butyronitrile and benzonitrile; amines such as triethylamine, tributylamine, pryridine and picoline; amides such as dimethylformamide, dimethylacetamide, hexamethylphosphoramide and hexaethylphosphoramide; and esters such as ethyl acetate, butyl acetate and amyl acetate.

The main function of the solvent is to provide liquid, easily handled compositions which can effectively bring the metal salt/phosphine complex in intimate contact with the substrate to be metallized. The solvent may also serve to transfer heat to the metallizing components and as a vehicle for other ingredients having beneficial effects such as plating promoters and surface conditioners. Volatile solvents are preferred, particularly those which can be evaporated from the metallizing compositions at temperatures at or below the temperature at which metallization occurs.

The method of this invention can be applied to a wide variety of substrates, including metallic and nonmetallic materials. The metals may be any of those normally used for decorative, structural or electrical purposes. These are usually the normally solid heavy metals of the Deming Periodic Table and alloys thereof. For practical reasons the substrate metal is generally different from the plating metal except where special effects such as relief are desired. Besides the heavy metals, other metals may alsoserve as substrates including the rare earths such as cerium and actinides such as uranium. As pointed out above the substrate metal may be higher or lower than the plating metal in the electromotive series of the metals.

There may also be used as substrates siliceous solids such as glass, Pyrex glass, spun glass, and asbestos; carbonaceous materials such as graphite and the various amorphous carbon blacks; refractory materials such as carborundum, ceramics and cermets; natural and synthetic cellulosic materials such as cotton, hemp, jute, paper, parchment, wood, cellulose acetate, and rayon; proteineous materials such as silk, wool, leather, mohair and fur. Still other important substrates are the synthetic polymeric compositions exemplified by the polyvinyls such as polyacrylonitrile, polyvinyl chloride, polytrifluorochloroethylene, polytetrafluoroethylene, polystyrene, polyethylene, polypropylene, polyvinyl acetate, polyvinylidene fluoride, poly(alkyl methacyclates) and copolymers thereof; polybutadiene, poly(diallyl esters) such as poly(diallyl phthalate); polyamides such as nylon, polyimides, polyesters, polyurethanes, polyacetals, melamine-formaldehyde, ureaformaldehyde, phenol-formaldehyde and epoxies. When the substrate is a polymeric material, the metallization temperature should be below the deformation temperature of the polymer.

The substrate may be particulate, for example powdered, or it may have a continuous surface in the form of a sheet, film, tape, foil, wire, fiber, fabric or foam. It may be a highly surface-porous mass which is to be impregnated and coated at the same time such as a porous catalyst support.

As is well known in the plating art, for best results the substrate to be plated should be clean especially with respect to grease and loose scale. Any of the known techniques may be l n I n I 1 Anna used to prepare the surface to be plated. For example, metal surfaces can be treated as described by Burns and Bradley in Protective Coatings for Metals, 2nd Edition, Chapter 2, Reinhold Publishing Corporation. Plastic surfaces can also be preconditioned according to known techniques. For example, the surface can be mechanically satinized" as described by Bruner and Baranano in Modern Plastics, Dec., l96l, and in Chemical and Engineering News, Mar. 25, 1963, pages 48 and 49. Or the surfaces may be chemically etched, as in the case of polyfluoroethylene being treated with an alkali metal-amine solution as described in Canadian Pat. No. 653,304, or with an alkali metal-aromatic ether solution as described in U.S. Pat. No. 2,809,130.

It is often beneficial to condition the surfaces to be plated, especially metal surfaces, with conditioners such as the commonly employed hydrohalic acids including hydrochloric, hydrobromic, hydrofluoric and hydroiodic acids or sulfuric acid, or by treating with a small amount of an inorganic reducing salt such as stannous chloride. Such promoters may be incorporated directly into the metal salt/phosphine plating composition of this invention, if desired. Conveniently this may be done in a carrier solvent, especially alcohols such as methyl, ethyl and propyl alcohols.

As an improvement within the scope of this invention, it has been discovered by other inventors that for many of the metal salt/phosphine complexes, especially those derived from the noble metals, the temperature or time required for metallization in accordance with this invention can be further reduced by sensitizing the metal salt/phosphine complex to subsequent thermal treatment. Sensitization may be accomplished by incorporating into the metal salt/phosphine complex plating composition a thermally dissociable free radical generator such as carbon tetrabromide or an organic perioxide, or by irradiating the complex with ultraviolet light, or exposing it to an electron beam or contacting it with a spark discharge. By these techniques the temperature requirement can be reduced by as much as 100 C. for plating on nonmetallic substrates. The sensitizing step is particularly advantageous in the case of heat sensitive substrates such as certain plastics. This improvement allows the use of a wider variety of complexes with these substrates.

The following examples, illustrating the novel method disclosed herein for metallizing a wide variety of substrates, are given without any intention that the invention be limited thereto. In these examples, all parts and percentages are by weight unless otherwise specified; solutions of metal salt/phosphine complexes, where employed, were prepared and used in nonmetallic (usually glass) containers; and metals to be plated were in the form of 1X1X% in. coupons unless other wise noted. Prefomied metal salt/phosphine complexes, where used, were prepared by known methods. Adherence of the metal coatings to the substrate was measured by the Scotch tape croshatch test.

A. GROUP I B PLATING Examples 1 to IS A gold-plating stock solution was prepared by dissolving 1 part of (CH P-AuCl in 80 parts of 95 percent ethanol containing 5 parts of added concentrated hydrochloric acid. Aliquots were used to plate immersed test coupons of various metals by heating at 80 C. for the time indicated in the table below.

TABLE I Example Substrate Time, hours aluminum antimony bismuth cadmium cobah 6 copper lead 8 nickel 9 platinum l0 SILVER 1 l stainless steel 12 thallium l3 tin tungsten broke -neon or TABLE I1 Example Substrate Time, hours No. 2 carbon steel Hastelloy B lead 400 Monel nickel Ni-O'Nel 309 stainless steel 405 stainless steel 4l0 stainless steel 430 stainless steel A-bMMNNnu-w Example 26 Using the procedure described in examples I to 15, a solution containing 1 part of (Cl-l P'AuCl, parts of percent ethanol and 1 part of concentrated hydrochloric acid was used to plate 2 parts of 200-mesh powdered copper, by heating at 80 C. for 2 hours. The powdered copper was uniformly gold plated as evidenced by examination under a microscope. Example 27 The procedure of example 26 was repeated using 200-mesh powdered nickel as the substrate with the same result. Example 28 The procedure of example 26 was repeated using 200-mesh powdered stainless steel as the substrate with the same result. Example 29 A plating solution containing 1 part of (CH P-AuCl, 200 parts of ethanol and 3 parts of concentrated hydrochloric acid was prepared. A 316 stainless steel coupon was placed in the solution of 2 hours at boiling. An adherent gold coating was produced on the 316 stainless steel. Example 30 The procedure of example 29 was repeated except that 200 parts of 2-propanol were substituted for the ethanol with the same result. Example 31 were The procedure of example 29 was repeated except that 200 parts of 2-methyl-l-propanol was substituted for the ethanol with the same result. Example 32 The procedure of example 29 was repeated except that 200 parts of acetone were substituted for the ethanol with the same result. Example 33 The procedure of example 29 was repeated except that 200 parts of chloroform were substituted for the ethanol with the same result. Examples 34 to 41 Using the procedure of examples 1 to 15 various gold-plating compositions were used to adherently plate various metallic substrates under the conditions indicated in the table below.

sis III Temp., Time, Ex. Plating solution, parts G. hrs. Substrate 1 pt. (CH3); P-AuCl- 84 80 pts. 95% ethanoL 80 1 Bronze.

i3 pts.(gorI11c.)fBi .61 p 4 9 s l1 35 '{250 pts. acetonltrile U} 80 6 Copper 1 pt. (CuHs)a-PAI1C1 36 100 pts. dimethyliormamlde. 100 0. 1 Mild steel.

20 pts. acetic acid. 1 pt. (CHmP-AuL 37 160 pts. methanol 60 0. 5 Niobium.

1 pt. cone. HF 1 pt. (CHa)aP-A11I 38 o1 60 1 Aluminum.

39 60 1. 5 Uranium.

1 pt. (CH3)3PA11I 40 160 pts. acetone. 50 1. 5 Aluminum.

pt. cone. HI- 41 {1 pt. (CsHs)aP-Au 80 1 Stainless 250 pts. 95% ethanol steel.

Example 42 Silver-plating compositions, prepared by dissolving 1 part of (Cl-1 );,PAgl in 250 parts of 2-propanol, and adding 0.5 part of concentrated hydrochloride acid, produced lustrous, adherent silver plates on brass coupons immersed in the boiling solution for 0.5 hour.

Example 43 The procedure of example 42 was repeated using 250 parts of triethylamine in place of the 2propanol with the .same result.

Example 44 The procedure of example 42 was repeated using 250 parts of acetone in place of the 2-propanol with the same result. Example 45 The procedure of example 42 was repeated using 250 parts of acetonitrile in place of the 2-propanol with the same result. Examples 46 to 51 Various silver-plating compositions were used in the procedure of examples 1 to 15 to produce lustrous adherent silver plates on various substrates under the conditions indicated in the table below.

'riiia'iia n if Temp., Time, Ex. Plating composition, parts 0. hrs. Substrate 46 {1 pt. (CHmP-AgI 50 2.5 Phosphor 20 pts. acetone bronze.

1 pt. (CHmP-AgI 50 3 Copper (200 47- 16 pts. acetone mesh) powder. 1 pt. [(CsHQgPlrAgNOa 80 1 Everdur" 48.-. 16 pts. 95% methanoL Cfil-Sl-Mn a y. 1 pt. [(CaHt)2CH:P] -AgN0a 49"- 40 i ggg i g d so 0. 2 Copper.

1 pt. 3 3 gN 50 wh (C 1:1, 6 so 0.2 Do.

1 p 0 n a Z 8N "{125 pts. acetonitrile 80 2 Examples 52 to 55 Various copper salt/phosphine complexes were used in the procedure of examples 1 to 15 to produce lustrous, adherent copper plates on various substrates under the conditions indicated in th tabls slswt, V ,7 V ,7 .7

TABLE v Time,

Temp.,

C hrs.

Ex. Plating solution, parts Substrate {1 pt. [(CtHQaPCllClZ n} 52- 100 pts, dimethyltormamide O. 3 Mild steel,

00 pts. 95% ethanol... 80 2 Brass.

pts. conc. HCl. {1 pt. on-mar uOC(O)CH 100 pts. acetonitrile 3 Gold Example 56 The liquid complex, (C,H,,);,P-AuCl, was spread on a silicon wafer which was then-heated on a 180C. hot plate. Within 5 minutes, the wafer had become coated with an adherent, electrically conductive gold layer. When cooled, the resistance of the wafer was less than 0.5 ohm/cm or less than 1/ 1,000 of the original resistance.

It will be apparent to those skilled in the solid-state electronics art that this process and the gold-coated silicon produced thereby are useful for preparing integrated microcircuits.

Example 57 A 0.1 percent solution of (Cl-l hP-AgNo in acetone was spread over a 1X1 in. film of polytetrafluoroethylene whose surface previously had been treated with a sodiumnaphthaJene-tetrahydrofuran solution essentially as disclosed in US. Pat. No. 2,809,120. After the acetone had evaporated, the film was placed with the coated side up on a C. hot plate while the coated side was simultaneously heated with a hot air stream from a commercial hair dryer at a somewhat lower temperature. A bright silver coating appeared almost immediately. The silver coating was flexible, adherent, had a resistance of about 10 ohm/cm, and could be wiped with a paper towel to a mirror-bright finish. Rubbing and cornpressing the coating with a spatula further improved its luster and conductivity.

Example 58 Example 57 was repeated on a film of Delrin polyacetal resin that had previously been satinized as described by Bruner and Baranano in Modern Plastics, Dec. 1961. Simply heating on a hot plate at C. for 15 minutes produced a lustrous, flexible, adherent and electrically conductive silver coating on the film.

Example 59 The procedure of example 58 was repeated except that an untreated Zytel polyamide resin film was used as the substrate with essentially the same result.

Example 60 The procedure of example 58 was repeated except that an untreated Mylar polyester film was used as the substrate with essentially the same result.

Example 61 The procedure of example 58 was repeated except that an untreated Kapton type H polyimide film was used as the substrate with essentially the same result.

Example 62 A solution containing 1 part of (Ce,,ll,),CH,P-AgNO,, 1 part of a filmfonning vinylidene fluoride/tetrafluoroethylene copolymer and 4 parts of acetone was cast as a film on aluminum foil. The acetone was evaporated and the coated piece heated at C. for 5 minutes to develop a flexible, silvery coating which was adherent to the aluminum foil.

Example 63 The procedure of example 62 was repeated except that a glass plate was used in place of the aluminum foil with the same result. The metal-impregnated coating adhered to the glass.

Example 64 A piece of Torvex ceramic honeycomb (4 in. in diameter, 1 in. thick and having a three-sixteenths in. pore size) was dipped into one liter of a 1 percent solution of (CH P- AgNO, in acetonitrile, air-dried to evaporate the acetonitrile, and subjected a stream of hot air from a hot-air gun at approximately 200 C. to develop a silvery coating. The procedure was repeated eight times to build up a continuous silver coating throughout the porous structure.

Such product, presenting a large silver surface, but with its open honeycomb structure substantially unchanged so that gas flowing through it remains substantially unimpeded, is useful as a silver catalyst in vapor-phase reactions.

.13.: ELA QW THQRQU 1 B METALS Examples 65 to 71 Metal coupons to be plated, 1X1 .5 in., were immersed in liquid plating compositions, consisting of 1 part of a bis(trialkylphosphine) metal halide diluted with about 2.5 parts of an inert solvent as specified in the table below. The coupons were held in the baths for the times and at the temperatures noted in the table below, removed, rinsed with water and acetone, and inspected. I

Examples 82 to 88 Metal plates were produced on copper test coupons with Yellow metal substrates were chosen for these tests so that 5 the plating compositions specified in the table below which the formation of silvery-white metal coatings would be readily apparent on visual inspection. All coatings were adherent.

were prepared as in examples 75 to 81. Heating was l6 hours at 100 C. except in the case of example 88 which was for 12 v Temp, Time, Example Plating composition 0. hrs. Substrate Result 65 (CHi)3P]:-ZnBrz+dlrnethyli'ormamide 100 0.5 Copper. Zn coating; 66. (C4Ho)iPlr-Zn(OC(0)0H,),+dlmethylformamide. 25 24 Brass. Do. 67. ((CH;)|N) P]|-ZnCli+hexamethylphosphoramlde. 100 24 Cop er. Heavy Zn coating. 68. [((CHs)2N)3P]:ZnI +hexamethylphosphoramide. 100 24 m Do. 69. [(C4HmPh-Cd0h+tetradecane 150 0.5 .do....... Lustrous Cd plating. V

C. PLATlNG WITH GROUP lll METALS hours. Plating in examples 82 to 84 was confirmed by X-ray p 7 emission and fluorescentm spectra of the coatings.

Aluminum was plated on copper by heating a copper test 25 TABLE V III coupon at 35 C(for 6 hours in a plating solution prepared by P1 n t adding 20 g. of triphenylphosphine (0.076 mole) in 100 ml. of a g ether to a filtered solution containing 5 g. of anhydrous AlCl Example salt {gigg solvent (0.038 mole) lll l00 ml. of ether and removing the small amount of oil that separated. 82 figf Example7l B t l T Do.

Thallium was plated on copper by heating a copper test cou- T 01 f y pon in a solution containing 2.6 g. of TlOC(O)CH (0.01 '87 Niels 3l o.K.?T -?III l io. mole) and 4.1 g. of tributylphosphine (0.02 mole) in 50 ml. of Ebola 'f Hexamemyphmphommme' toluene for 16 hours at 100 C. Example 72 F. PLATING WITH GROUP VI METALS lndium was heavily deposited on a gold coupon by heating ,Examples 89 to 92 the gold coupon in a solution containing 2.2 g. of lnCl, (0.01

mole) and 8.l g. of tributylphosphine (0.04 mole) in 50 ml. of 4 acetonitrile for 3 hours at 80 C.

D. PLATING WITH GROUP IV METALS The procedure of example 73 was repeated except that a silver test coupon was used in place of copper with the same result. Examples 75 to 8l Metal plates were obtained by immersing a substrate in a plating composition and heating for 16 hours under the conditions summarized in the table below. The plating compositions were prepared by mixing approximately 2.2 molar proportions of a phosphine, a molar proportion of a Group W B metal salt and optionally about 10 parts of a diluent per part of metal salt. Visual inspection and, where taken", the X-ray fluorescence or emission spectrum of each resulting test piece shown a Group IV B metallic coating on its surface.

Metal plates were produced on copper test coupons with 0 the plating compositions specified in the table below which were prepared as in examples to 81. Heating was 16 hours at l00 C. X-ray emission spectroscopy confirmed that the example 91 plate was chromium.

Following the procedure of examples 75 to 81, amanganese coating, confirmed by X-ray emission spectroscopy, was plated on copper by heating a test coupon in a (CH;)',N] ,P- MnCl, hexamethylphosphoramide solution for l2 hours at [50 C.

u. PLATING WITH 0110p Vlll METALS Examples 94 to 103 The procedure followed was e ssentially that described for examples 75 to 81, except that the plating compositions and MX -R P was added directly to the plating solvent. In all cases the coatings were adherent.

piece of wood was used in place of the glass slide with substantially the same result. Example 1 The procedure of example 107 was repeated except that a carbon sheet was used in place of the glass slide with substanie!!! lh'PFPE-EQUH V.

TABLE X Plating composition Phos hine Temp Time, Example Salt RiP, Solvent hrs. Substrate Result MezN Hexamethylphosphoramlden 150 12 Fe coat. Butyl Acetonitrlle 80 3 Co coat. MezN.. Hexamethylphosphoramide 150 12 Rh t, Phenyl. 83% acetonitrlle, 17% acetic acld 80 1 Bright N1 coat. Butyl Acetic acid 100 3. 5 Lustrous N1 coat. o... -..do 100 2 Do. Methyl 95% ethanol 5% cone. H01 70 2 Ni oat, 101..."... PdCl: .d0 95% ethanol 5% cone. H01....... 70 1 Lustrou Pd coat. 102 Ptcl, do 95% ethanol trace HF 70 7 Copper Lustrous P1;

103 Pm do 95% ethanol trace HF 70 7 Pt mm Example 104 About I g. of finely powdered [(CH:,);,P],'PdCl was spread on a 2 mil. thick, 3X3 in. square of a high-temperature resistant Kapton type H polyimide film. The coated film was gradually heated on a hot plate under a nitrogen atmosphere- I. EXAMPLES ILLUSTRATING IMPROVEMENTS WITHIN THE SCOPE OF THIS INVENTION Example 105 One part of (CH P-AuCl was dissolved in 25 parts of a percent solution of Orlon polyacrylonitrile in dimethylformamide. The solution was spread on a glass microscope slide and warmed with a heat lamp to evaporate the dimethylformamide. The slide was then exposed to a Tesla coil spark discharge to sensitize the gold salt complex to thermal decomposition and placed treated-side up on a 200 C. hot plate for about 5 minutes. The resulting uniformly distributed golden coating was adherent to the glass and electrically conductive. Example 106 A (CH P-AuCl/polyacrylonitrile/dimethylfonnamide solution, substantially as described in example 105, was spread on a glass side and the dimethylformamide evaporated by warming under a heat lamp. The resulting film was then covered with a stencil, irradiated with high intensity light by contact flashing with a 200 watt-second xenon flash tube (Hico lite, Model K; 1 millisecond duration flash), then heated at 100 C. for aboutS minutes. The resulting slide showed a lustrous, electrically conductive, adherent golden image corresponding to the irradiated areas. Example 107 Example 105 was repeated with 1 part of (CH P-AuCI per 5 parts of poly[4,4' (hexafluoroispropylidene)diphenol isophthalate] polyester as the carrier substrate in 100 parts of methylene chloride. The resulting film, after having been exposed to the spark discharge and heated at 200 C. for 2 minutes, was golden, adherent and electrically conductive.

Such products are useful in printed circuitry for use at elevated temperatures. Example 108 The procedure of example 107 was repeated except that a piece of porcelain was used in place of the glass slide with substantially the same result. Example 109 The procedure of example 107 was repeated except that a The procedure of example 107 was repeated except that a piece of ceramic was used in place of the glass slide with substantially the same result.

Example 112 Repeating example 107 with 0.5 part of the gold complex produced uniformly colored purple slides, indicating colloidal gold dispersed throughout the polymeric film, which were useful as interference filters.

Example 113 A mixture of I part of (CH P-AgNO and 70 parts of filmforming polyvinylchloride, cast as a film on glass from dimethylformamide solution, was irradiated three times through a stencil with the light source described in example 106 and then heated to 180 C. for 5 minutes to develop a silvery image. The silver deposit was much less noticeable in the unirradiated area.

Example 114 The procedure of example 113 was repeated except that 1 part of (C,,l'I,,) P-AgClO was used as the silver complex with the same result.

Example 115 The procedure of example 113 was repeated except that 1 part of (C I-I P-Ag0C(O)CH was used as the silver complex with the same result.

Example 116 The procedure of example 113 was repeated except that 1 part of (C H P-AgI was used as the silver complex with the same result.

Example 117 The procedure of example 1 13 was repeated except that 1 part of (C,;H P-AgOC(O)CF was used as the silver complex with the same result.

Example 118 The procedure of example 113 was repeated except that 1 part of [(C H P] 'Ag C0,- was used as the silver complex with the same result.

Example 119 The procedure of example 113 was repeated except that 1 part of (C H,,) P'AgCN was used as the silver complex with the same result.

Example 120 The procedure of example repeated except that l Thus, it should be apparent from the above examples that this invention has wide utility. It is useful to produce metallized objects having continuous, adherent and, where needed, flexible, electrically conductive metal coatings. For example, it is useful to produce (1) metallic coatings that protect the underlying material and that reflect light and infrared radiation; (2) electrically conductive articles such as printed circuits, resistors, capacitors, and electrodes for fuel cells and batteries; (3) various decorative pieces (e.g., automotive hardware), effects, and images based on the formation of metal surfaces; (4) new catalyst structures wherein a catalytically active heavy metal is impregnated and coated on a porous substrate carrier; and (5) metallized films showing selective light transmission which can be used as optical filters. It is also useful to obtain coatings of the normally brittle metals such as titanium, zirconium, chromium, vanadium, niobium, and manganese which are difficult to obtain by other methods. It is also useful to produce metallized plastics wherein the metal is uniformly distributed throughout the body of the plastic as well as on its surface. This is of great practical advantage when the surface of the plastic is normally subjected to abrasion.

In addition to their uses as intermediates for producing metallized products having wide utility as described above, the metal salt/phosphine/substrate compositions can also be used as temperature indicators and time-temperature integrators, recording by metal deposition the degree of exposure of the supported material when certain characteristic temperatures (threshold temperatures for metallization) have been reached and exceeded. The metal salt/phosphine/substrate compositions also have wide utility in their premetallized state, wherein the supporting substrate functions as a carrier, a reaction medium or a means for facilitating chemical reactions of the metal salt/phosphine complexes; they may afford advantages over the corresponding unsupported metal salt/phosphine complexes; such as disclosed in US. Pat. No. 3,045,775 and British Pat. No. 714,202.

The complexes represent higher oxidation states of the metal moiety with respect to lower valent, including zero valent, states of the metal and thus are useful broadly as oxidin'ng agents or electron acceptors. The transition metals are variable-valent and in some of the complexes included herein, for example [C,H P] RhCl and [[(CH ),N],PtCl P]FeCl,, are in lower valent states; thus the supported materials can function as electron-donating or reducing agents towards a proper electron acceptor. The potentials, or the ability of a particular supported complex to efiect oxidations or reductions, can be determined by standard methods and related to reference electrodes. The potentials will vary with the particular phosphines and the other ligands, and the number thereof, which are coordinated to the central metal atom.

Supported transition metal salt/phosphine complexes can further complex with ethylene and other donor-acceptor ligands and can be used to separate olefins from nonolefins and to fonn olefin complexes'for further reaction of the bound ligands. For example, supported complexes such as H );,P] RuCl,, [(C,H P],RhC1 and [(C,,l-l P] PtCl -SnC] can be used to catalyze olefin and nitrobody hydrogenations. Supported complexes of trialkyl or triaryl phosphines, for example, tributyl or triphenyl phosphine, and metal halides such as nickel, palladium or platinum chlorides or bromides can be used to decarbonylate aldehydes to hydrocarbons and carboxylic acid chlorides to chlorohydrocarbons. Supported corn:

plexes of trialkyl and triaryl phosphines, as above, and chlorides or cobalt, palladium, platinum or rhodium can be used to catalyze double bond migration in olefins, dimerization of olefins and polymerization of dienes.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A supported metal salt/phosphine complex comprising a metallic or nonmetallic substrate coated or impregnated with a metal salt/phosphine complex, said complex being derived from one mole of a nonorganometallic salt of a nonnally solid heavy metal of the Deming Periodic Table and l to 4 moles of a triorganophosphine in which each organo group is hydrocarbyl or dihydrocarbylamino.

2. The supported complex of claim 1 wherein the complex is a coating on the substrate.

3. The supported complex of claim 1 wherein the heavy metal is a transition element, the triorganophosphine is a trihydrocarbylphosphine and the substrate is a nonmetallic substrate.

4. The supported complex of claim 3 wherein the transition element is a Group [B or Group VIII element, the trihydrocarbylphosphine is a trialkylphosphine, and the nonmetallic substrate is a siliceous solid, a carbonaceous solid, a refractory material, a cellulosic material, a proteinaceous material or a polymeric material.

5. The supported complex of claim 4 wherein the salt is gold chloride, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a polymeric material.

6. The supported complex of claim 4 wherein the salt is silver nitrite, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a polymeric material.

7. The supported complex of claim 4 wherein the salt is palladium chloride, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a polymeric material.

8. The supported complex of claim 4 wherein the salt is silver nitrite, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a porous ceramic body.

9. The supported complex of claim 4 wherein the nonmetallic substrate is a synthetic polymer and the complex is a coating on the substrate.

10. The supported complex of claim 4 wherein the nonmetallic substrate is a synthetic polymer and the complex is impregnated within the substrate.

11. A method for preparing a supported metal salt/phosphine complex wherein the complex is coated on a substrate, which method comprises contacting a metallic or nonmetallic substrate and a volatile inert solvent solution of a complex derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table and l to 4 moles of a triorganophosphine in which each organo group is hydrocarbyl or dihydrocarbylamino, and evaporating the volatile inert solvent to produce a coated substrate.

12. A method for preparing a supported metal salt/phosphine complex wherein the complex is impregnated within a polymeric substrate, which method comprises dissolving in a volatile inert solvent a polymer and a complex derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table and 1 to 4 moles of a triorganophosphine in which each organo group is hydrocarbyl or dihydrocarbylamino, and evaporating the volatile inert solvent to product an intimate salt/phosphine/polymer mixture.

Disclaimer 3,625,755.Earle M. Potmfke, Wilmington, Del. SUPPORTED METAL SALT/PHOSPHINE COMPLEXES AND METALLIZED PRODUCTS THEREFROM. Patent dated Dec. 7 1971. Disclaimer filed Aug. 20, 1970, by the assignee, E. du Pont de Nemours and Company.

Hereby disclaims all that portion of the term of the patent subsequent to Apr. 15,1986.

[Ofiicz'al Gazette September 12,1972]

Claims

2. The supported complex of claim 1 wherein the complex is a coating on the substrate.
3. The supported complex of claim 1 wherein the heavy metal is a transition element, the triorganophosphine is a trihydrocarbylphosphine and the substrate is a nonmetallic substrate.
4. The supported complex of claim 3 wherein the transition element is a Group IB or Group VIII element, the trihydrocarbylphosphine is a trialkylphosphine, and the nonmetallic substrate is a siliceous solid, a carbonaceous solid, a refractory material, a cellulosic material, a proteinaceous material or a polymeric material.
5. The supported complex of claim 4 wherein the salt is gold chloride, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a polymeric material.
6. The supported complex of claim 4 wherein the salt is silver nitrite, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a polymeric material.
7. The supported complex of claim 4 wherein the salt is palladium chloride, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a polymeric material.
8. The supported complex of claim 4 wherein the salt is silver nitrite, the trialkylphosphine is a tri-lower alkylphosphine, and the substrate is a porous ceramic body.
9. The supported complex of claim 4 wherein the nonmetallic substrate is a synthetic polymer and the complex is a coating on the substrate.
10. The supported complex of claim 4 wherein the nonmetallic substrate is a synthetic polymer and the complex is impregnated within the substrate.
11. A method for preparing a supported metal salt/phosphine complex wherein the complex is coated on a substrate, which method comprises contacting a metallic or nonmetallic substrate and a volatile inert solvent solution of a complex derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table and 1 to 4 moles of a triorganophosphine in which each organo group is hydrocarbyl or dihydrocarbylamino, and evaporating the volatile inert solvent to produce a coated substrate.
12. A method for preparing a supported metal salt/phosphine complex wherein the complex is impregnated within a polymeric substrate, which method comprises dissolving in a volatile inert solvent a polymer and a complex derived from one mole of a nonorganometallic salt of a normally solid heavy metal of the Deming Periodic Table and 1 to 4 moles of a triorganophosphine in which each organo group is hydrocarbyl or dihydrocarbylamino, and evaporating the volatile inert solvent to product an intimate salt/phosphine/polymer mixture.