US3086036A - Preparation of cyclomatic nickel nitrosyls - Google Patents

Description

United States Patent 3,056,036 PREPARATION OF CYCLOMATIC NICKEL NITROSYLS Thomas H. Cofiield, Heidelberg, Germany, and Kryn G.

Ihrman, Farmington, Mich., assignors to Ethyl Corporation, New York, N.Y., a corporation of Delaware N0 Drawing. Filed Aug. 5, 1959, Ser. No. 831,706 3 Claims. (Cl. 260439) This invention relates to new and improved chemical process. More specifically, this invention relates to a novel process for forming cyclomatic nickel nitrosyl compounds which have great utility as antiknock additives in gasoline.

An object of this invention is to provide a new and useful process for forming organometallic coordination compounds. A further object of this invention is to provide a process for forming cyclomatic nickel nitrosyl compounds. F-urther objects will become apparent from a reading of the specification and claims which follow.

The above objects are accomplished by providing a novel process for the formation of cyclomatic nickel nitrosyl compounds. This process involves the reaction of a cy-clomatic nickel carbonyl dimer with nitric oxide. Although we are not bound by any theory as to the reaction mechanism, it is believed that our process can be represented by the following reaction:

atoms. In general, such cyclomatic hydrocarbon groups can be represented by the formulae:

s 134 1 5 3 RF 6 7 1 2 Where the R groups are selected from the group consisting of hydrogen and univalent hydrocarbon radicals. The cyclomatic groups are represented by Cy in the above reaction. Typical of the cylomatic groups which may be contained in the cyclomatic nickel carbonyl dimer reactant are cyclopentadienyl, indenyl, methylcyclopentadienyl, propylcyclopentadienyl, diethylcyclopentadienyl, phenylcyclopentadienyl, tert-butyl cyclopentadienyl, p-ethylphenyl cyclopentadienyl, 4-tert-butyl indenyl and the like. These radicals are contained in the reactants cyclopentadienyl nickel carbonyl dimer, indenyl nickel carbonyl dimer, methylcyclopentadienyl nickel carbonyl dimer, propylcyclopentadienyl nickel carbonyl dimer, diethyla cyclopentadienyl nickel carbonyl dimer, phenylcyclopentadienyl nickel carbonyl dimer, tort-butyl cyclopentadienyl nickel carbonyl dimer, p-ethylphenyl cyclopentadienyl nickel carbonyl dimer and 4-tert-buty1 indenyl nickel carbonyl dimer. These reactants, when employed in our process, yield respectively cyclopentadienyl nickel nitrosyl, indenyl nickel nitrosyl, methylcyclopentadienyl nickel nitrosyl, propylcyclopentadienyl nickel nitrosyl, diethylcyclopentadienyl nickel nitrosyl, phenylcyclopentadienyl nickel nitrosyl, cert-butyl cyclopentadienyl nickel nitrosyl, p-ethylphenyl cyclopentadienyl nickel nitrosyl and 4-te-rtbutyl indenyl nickel nitrosyl.

3,086,035 Patented Apr. 16, 1963 A preferred cyclomatic nickel carbonyl dimer reactant is cyclopentadienyl nickel carbonyl dimer. This reactant is preferred since the cyclopentadienyl moiety present in the reactant is derived from cyclopentadiene, a readily available chemical of commerce. Further, the product, cyclopentadienyl nickel nitrosyl, formed when using cyclopentadienyl nickel carbonyl dimer as the reactant, is an extremely potent antiknock having great utility as a gasoline additive.

Our process may be carried out as a .gas or liquid phase reaction. When carried out essentially as a liquid phase reaction it is preferably conducted in an autoclave. The autoclave is equipped with inlet and outlet ports, pressure controls connected with said ports so that the pressure can be regulated in the autoclave, temperature controls, and agitation means which disperse the reactants so that they intimately contact each other. A solvent is preferably used as a dispersant for the reactants in our process. The solvent is preferably free of air or oxygen, and one means by which this may be conveniently accomplished is by bubbling carbon monoxide through it or by heating it so as to expel any absorbed gases. The reaction temperature in our process is maintained between about zero to about 100 C. A preferred temperature range is from about 20 to about 40 C. since within this range the reaction goes readily with a minimum of undesirable side reactions. In general, the pressure employed in the reaction vessel is not critical, and pressures ranging from one to about 50 atmospheres may be used. Normally, however, the process is conducted at pressures ranging from about one to about five atmosphere's." When conducted at one atmosphere, the reaction can be run in an open system.

The nature of the solvent which may be used in our process is not critical. In general, any solvent can be utilized which does not react with the reactants employed in our process. Typical of applicable solvents are hydrocarbon "and ether solvents. The hydrocarbon solvents may be aliphatic hydrocarbons such as n hexane, n-octane, isooctane, n-heptane, various positional isomers of hexane, octane and heptane, or mixtures of the above. The sol-. vent may also be a cycloaliphatic hydrocarbon such as cyclohexane or methylcyclohexane. Further applicable solvents are cyclic olefins such as cyclohexene and methylcyclohexene. Straight and branched-chain olefins such as isoheptene, n-hexene, is-octene, and the like are also applicable. Aromatic solvents such as benzene, toluene, ethylbenzene and xylenes, either mixed or separated, may also be used. Typical of the ether solvents are the cyclic ethers such as tetrahydrofuran, 1,4-dioxane and 1,3-dioxane. Noncyclic monoethers such. as diethylether, diisopropylether and diphenylether are good solvents for use in our process. Nonscyclic polyethers such as the dimethylether of ethyleneglycol, the ,diethylether of ethyleneglycol, the dibutylether of ,ethyleneglycol, the dimethylether of diethyleneglycol, the diethyletber of diethyleneglycol and the dib-utylether of diethyleneglycol are also excellent solvents for use in our process.

A preferred group of solvents for use in our process are the .highly 'polar'ethers such as tetrahydrofuran, ethyleneglycol dimethylether, ethyleneglycol diethylether, ethyleneglycol dibutylether, diethyleneglycol dimethylether, diethyleneglycol diethylether, diethyleneglycol dibutylether and the like.

Solvents used in our process should preferably have a normal boiling point which varies by at least 25 C. from the normal boiling point of the product. A variation of at least 25 C. between the normal boiling points of the product and solvent aids greatly in separation of the product from the solvent by means of distillation.

Ordinarily, excess nitric oxide is employed in our process. This excess is preferably on the order of 50 to 100 percent so that for each mole of cyclomatic nickel carbonyl dimer reactant there are about three or four moles of nitric oxide. Greater or lesser quantities of nitric oxide can be used, although in general such use does not materially benefit our process and in some cases may reduce the processes efiiciency. The use of at least 50 percent excess nitric oxide insures that most of the cyclomatic nickel carbonyl dimer is consumed in the reaction. This is desirable since it is the more expensive reactant.

In conducting our process, it is desirable that air be excluded from the reaction mixture. This is best accomplished by using in the system a blanketing gas of nitric oxide. Since carbon monoxide is a product of the reaction, the blanketing gas will also contain some carbon monoxide. The out gases containing nitric oxide and carbon monoxide may be recycled to the autoclave.

The reaction mixture is preferably agitated so as to insure homogeneity of the reaction mass. In the autoclave, there are generally present both gases and liquids, and agitation insures that these phases are well dispersed. When the phases are well dispersed, an even reaction rate is obtained.

Cyclomatic nickel carbonyl dimer compounds are known and may be made by the reaction of nickel tetracarbonyl with a dicyclomatic nickel compound. Typical of such preparation is that of cyclopentadienyl nickel carbonyl dimer and methylcyclopentadienyl nickel carbonyl dimer which are illustrated by the following examples in which all parts and percentages are by weight unless otherwise indicated.

Example I Ten parts of dicyclopentadienyl nickel dissolved in 88 parts of benzene under nitrogen and 25.3 parts of nickel tetracarbonyl were charged to a reaction vessel. The mixture was heated to 70 C. for approximately 12 hours during which time the solution turned from green to blood red. The solvent and unreacted nickel tetracarbonyl were removed by distilling the mixture into two cold traps maintained at about 70 C. Sublimation of the residues at 70 C. gave 1.3 parts of crude cyclopentadienyl nickel carbonyl dimer contaminated with nickelocene. Further sublimation at 95 C. gave 9.5 parts of cyclopentadienyl nickel carbonyl dimer having a melting point of 143 C. (literature value-439 C.) under nitrogen. The product contained on analysis 47.2 percent carbon, 3.25 percent hydrogen and 38.6 percent nickel. Calculated for C H NiO C, 47.47; H, 3.32 and Ni, 38.66.

Example II To a stirred solution under nitrogen containing 176 parts of methylcyclopentadienyl sodium in 799 parts of tetrahydrofuran were added 446 parts of tetrapyridine nickel dichloride. The green mixture was stirred for eight hours and then filtered under nitrogen through celite into a nitrogen-flushed flask. The compound was observed to be quite air sensitive, and consequently all operations were carried out under nitrogen. The solvents were removed from the clear green filtrate by heating under vacuum. A green liquid was obtained which was transferred to a distillation column. There was obtained on distillation 60 parts of bis-methylcyclopentadieny1 nickel which melted at approximately 35 C. The analysis for this compound was 66.5 percent carbon and 6.75 percent hydrogen. Calculated: 66.4 percent carbon and 6.5 percent hydrogen.

19.9 parts of bis-methylcyclopentadienyl nickel, 25.6 parts of nickel tetracarbonyl and 88 parts of benzene were charged to a reaction vessel under nitrogen. The reaction mixture was heated with stirring to a temperature of 55 C. for two hours at which time the color of the solution turned to a deep purple. After heating the mixture for an additional 16 hours at 60 C., the solution darkened progressively. No further color change took place after heating for six more hours at 70 C. After heating for two more hours, the temperature rose to 75 C. and the formation of a nickel plate was observed on the sides of the reaction vessel. The reaction vessel was then cooled, and the contents were discharged. The benzene and unreacted nickel tetracarbonyl were removed from the reaction mixture by distillation under nitrogen into two cold traps cooled by a Dry Ice-acetone mixture. A red material having a melting point of 85 C. was obtained and purified by recrystallization from low boiling petroleum ether. The first crop of crystals, 13.5 parts, melted with decomposition at 87 C. The second crop, 7.5 parts, melted with decomposition at 85- 88 C. The total yield amounted to 21 parts of methylcyclopentadienyl nickel carbonyl dimer or 70 percent of theory. The analysis for this compound was 50.7 percent carbon, 4.44 percent hydrogen and 35.1 percent nickel. Calculated for methylcyclopentadienyl nickel carbonyl dimer: 50.9 percent carbon, 4.23 percent hydrogen and 35.2 percent nickel.

To further illustrate our process involving essentially a liquid phase reaction in an autoclave, there are presented the following examples. In these examples, all parts and percentages are by weight unless otherwise indicated.

Example 111 To a reaction vessel equipped with stirring means, a gas inlet, temperature control means and a condenser with a nitrogen T were added 266 parts of tetrahydrofuran. With the system under nitrogen, 2.6 parts of cyclopentadienyl nickel carbonyl dimer were added. As soon as the dimer had dissolved in the solvent, giving a light red solution, nitric oxide was bubbled through the system for 70 minutes. The dark reaction mixture was filtered under nitrogen to give 0.1 part of a muddy green amorphous solid which was discarded. The filtrate was concentrated by heating under vacuum, and the concentrate liquid was distilled at reduced pressure to give 1.91 parts of cyclopentadienyl nickel nitrosyl. The product had a boiling point of 57-62 C. at 27 millimeters, and its infrared spectrum and vapor phase chromatogram corresponded closely to that of an authentic sample of cyclopentadienyl nickel nitrosyl.

Example IV To an evacuated autoclave equipped as in Example III are charged 30.3 parts of cyclopentadienyl nickel carbonyl dimer, 12 parts of nitric oxide and 600 parts of diethyleneglycol dibutylether. The autoclave is maintained at a temperature of 30 C. and a pressure of one atmosphere. The reaction mixture is agitated for three hours whereupon the autoclave is cooled and discharged. The reaction mixture is then distilled in a column to give a good yield of crude cyclopentadienyl nickel nitrosyl which is purified by distillation. The residual solvent is filtered and recycled to the autoclave.

Example V Thirty and three-tenths parts of cyclopentadienyl nickel carbonyl dimer, nine parts of nitric oxide and 1400 parts of benzene are charged to an evacuated autoclave maintained at 40 C. at one atmosphere of pressure. The reac tion mixture is agitated for about four hours whereupon the autoclave is cooled and discharged. The reaction mixture is then filtered, and the filtrate is distilled. The benzene distillate is recycled to the autoclave, and the residue contains a good yield of crude cyclopentadienyl nickel nitrosyl which is purified by distillation.

Example VI To an evacuated autoclave are charged 15 parts of nitric oxide, 30.34 parts of cyclopentadienyl nickel carbonyl dimer and 1000 parts of ethyleneglycol diethylether. The autoclave is maintined at a temperature of 20 C.

and a pressure of five atmospheres. The reaction mixture is then agitated for hour, and the autoclave is discharged. The reaction mixture is filtered and distilled. The ethyleneglycol diethylether distillate is recycled to the autoclave. The residues are flash-distilled to give a good yield of essentially pure cyclopentadienyl nickel nitrosyl.

Example VI is repeated at 0 C. and one atmosphere of pressure for six hours, and good yields of cyclopentadienyl nickel nitrosyl are obtained. Likewise, when Example VI is repeated using a temperature of 100 C. and a pressure of 50 atmospheres, cyclopentadienyl nickel nitrosyl is obtained.

Example VII Thirty-three and one-tenth parts of methylcyclopentadienyl nickel carbonyl dimer, nine parts of nitric oxide and 400 parts of tetrahydrofuran are charged to an evacuated autoclave maintained at 30 C. and two atmos pheres of pressure. The reaction mixture is agitated for one and one-half hours whereupon the autoclave is cooled and discharged. The reaction mixture is filtered and distilled. The tetrahydrofuran distillate is recycled to the autoclave and a good yield of crude methylcyclopentadienyl nickel nitrosyl is obtained from the residue.

When using hexylcyclopentadienyl nickel carbonyl dimer in place of the rnethylcyclopentadienyl nickel carbonyl dimer in Example VII, good yields of hexylcyclopentadienyl nickel nitrosyl are obtained. Likewise, the use of di-tert-butylcyclopentadienyl nickel carbonyl dimer and tetramethylcyclopentadienyl nickel carbonyl dimer in this reaction gives good yields of di-tert-butylcyclopentadienyl nickel nitrosyl and tetnamethylcyclopentadienyl nickel nitrosyl.

Example VIII Forty and three-tenths parts of indenyl nickel carbonyl dimer, 24 parts of nitric oxide and 2000' parts of n-octane are charged to an evacuated autoclave maintained at 50 C. and atmospheres of pressure. The reaction mixture is agitated for about six hours, and the autoclave is cooled and discharged. The solvent is removed from the reaction mixture by means of distillation to give a good yield of crude indenyl nickel nitrosyl in the residues.

Our process may be carried out essentially in the gas phase. In one such modification, a gaseous cyclomatic nickel carbonyl dimer and gaseous nitric oxide are fed through an externally heated tube reactor which may be packed with particulate materials such as Raschig rings, Berl saddles or the like to insure intimate mixing of the reactant gases. The throughput of reactants is controlled so that their temperature in the tube reactor is within about 60 to about 125 C.

The cyclomatic nickel carbonyl dimer utilized in this process may, as stated previously, contain cyclopentadienyl and indenyl moieties which are substituted with alkyl, aryl or cycloalkyl substituents. Further, the cyclopentadienyl or indenyl moiety may contain from about five to about 13 carbon atoms.

The cyclom atic nickel carbonyl dimer is generally sublimed in a gasifier unit which is located adjacent the tube reactor. Gasification is accomplished by heating the dimer at temperatures between about 60 and about 125 C. under pressures ranging from about 0.5 mm. to about 10 mm. During heating, an inert gas such as nitrogen, krypton or argon is passed over or through the cyclornatic nickel carbonyl dimer in a particulate state. The dimer is then either sublimed or carried along with the stream of neutral gas through a pipe into the tube reactor where it contacts the nitric oxide.

The overall pressure in both the gasifier unit and the tube reactor is maintained fairly constant by means of a vacuum pump or similar device which is connected to the opposite end of the tube reactor with respect to the pipes leading into the reactor from the gasifier unit and nitric oxide source.

Thus, the gasifier unit and tube reactor are in series with the vacuum pump so that the pressure is maintained fairly constant throughout the entire system.

The quantity of nitric oxide employed is preferably in the order of about one to about two equivalents based on the amount of the cyclomatic nickel carbonyl dimer used. For each mole of the cyclomatic nickel carbonyl dimer there are used, therefore, from about two to about four moles of nitric oxide. The temperature of the nitric oxide gas entering the tube reactor is maintained at a temperature closely approximating that of the entering cyclomatic nickel carbonyl dimer. This temperature control is desirable since contact of a cold nitric oxide stream with the warm cyclornatic nickel carbonyl dimer stream could result in solidification and settling out of solid cyclomatic nickel carbonyl dimer in the reactor.

Following reaction of the gases in the tube reactor to form a cyclomatic nickel nitrosyl compound, they are drawn out through the pipe leading to the vacuum pump. One or more cold traps are located in series in the line leading to the vacuum pump. On entering the cold traps, the cyclomatic nickel nitrosyl products are condensed as liquids and collected in the bottom of the traps. These traps are maintained at temperatures between about 20 to about -78 C. The collected liquid may be further purified, as for example, by distillation.

After leaving the Dry Ice traps in which the product has been condensed as a liquid, the out gases are passed through the vacuum pump. After leaving the vacuum pump, they may be recycled to the tube reactor or discarded.

Our process involving gas phase reaction of a cyclomatic nickel carbonyl dimer and nitric oxide is further illustrated in the following examples in which all parts and percentages are by weight unless otherwise indicated.

Example IX Nitrogen is bubbled slowly through powdered cyclopentadienyl nickel carbonyl dimer at a temperature of about 70 C. under a pressure of 1.5 mm. The nitrogen stream containing gaseous cyclopentadienyl nickel carbonyl dimer is drawn from the gasifying unit into a tube reactor. The feed rate is maintained at about 3.03 parts of cyclopentadienyl nickel carbonyl dimer per minute. 1.2 parts per minute of gaseous nitric oxide are fed to the tube reactor. The residence time of the cyclopentadienyl nickel carbonyl dimer and nitric oxide is controlled so that the gaseous reactants are heated to a temperature of 80 C. in the reactor. The out gases are passed through a cold trap where crude cyclopentadienyl nickel nitrosyl is obtained. The crude cyclopentadienyl nickel nitrosyl is purified by distillation, and the exit gases from the cold trap are recycled to the tube reactor.

Example X Three and three hundredths parts per minute of cyclopentadienyl nickel carbonyl dimer along with a nitrogen carrier stream and 1.2 par-ts per minute of nitric oxide are carefully fed to a tube reactor maintained at a pressure of 10 mm. The gases are heated to a temperature of C. in the reactor and are discharged into a cold trap where a good yield of cyclopentadienyl nickel nitrosyl condenses. The out gases are then recycled to the tube reactor.

Example XI A nitrogen stream containing cyclopentadienyl nickel carbonyl dimer is carefully fed to a tube reactor so that the input of cyclopentadienyl nickel carbonyl dimer is 3.03 parts per minute. Six-tenths part per minute of nitric oxide is also fed to the tube reactor. The reactor is maintained at a pressure of 0.5 mm. The gaseous reactants are maintained at a temperature of 60 C. while in the tube reactor and are discharged through a cold trap. A good yield of cyclopentadienyl nickel nitrosyl is condensed in the cold trap and is further purified by 7 means of distillation. The out gases are vented from the cold trap into the atmosphere.

Example XII Thirty-three and one tenth parts per hour of methylcyclopentadicnyl nickel carbonyl dimer contained in a stream of nitrogen are carefully fed to a tube reactor maintained at a pressure of 0.5 mm. Six parts of nitric oxide per hour are also fed to the tube reactor. The reactants are heated to a temperature of 80 C. While in the reactor. The exit gases are passed through a cold trap where a good yield of methylcyclopentadienyl nickel nitrosyl is separated from the gases. The out gases are then discharged to the atmosphere.

As shown by the preceding examples, our process Works very well to produce a cyclomatic nickel nitrosyl compound through the gas phase reaction of a cyclomatic nickel carbonyl dimer and nitric oxide. When various cyclomatic nickel carbonyl dimer reactants are employed in our gas phase process, there are obtained a wide variety of cyclomatic nickel nitrosyl products. For example, when indenyl nickel carbonyl dimer, pl1enylcyclopentadienyl nickel carbonyl dimer or 4-tert-butyl indenyl carbonyl dimer are employed as reactants in this process along with nitric oxide, there are obtained respectively the products indenyl nickel nitrosyl, phenylcyclopentadienyl nickel nitrosyl and 4-tert-butyl indenyl nickel nitrosyl.

The cyclomatic nickel nitrosyl compounds produced by our process :are excellent antiknoeks. They have been tested by the Research Method to determine their antiknock effect in a hydrocarbon fuel. The Research Method of determining octane number of the fuel is generally accepted as a test method which gives a good indication of fuel behavior in full-scale automotive engines under normal driving conditions. It is the method most used by commercial installations in determining the value of a gasoline additive.

The Research Test Method is conducted in a single cylinder engine especially designed for this purpose and referred to as the CFR engine. This engine has a variable compression ratio and during the test the tempera ture of the water jacket is maintained at 212 F., and the inlet air temperature is controlled at 125 F. The engine is operated at a speed of 600 rpm. with a spark advance of 13 before top dead center. This test method is more fully described in Test Procedure D90855 contained in the 1956 edition of ASTM Manual of Engine Test Methods for Rating Fuels.

The fuel employed in these tests was a synthetic mixture which is representative of commercial gasolines in present production. It is used since it gives a standard antiknock response and hence gives results that are reproducible. The mixture consists of 20 volume percent diisobutylcne, 20 volume percent toluene, 20 volume percent isooctane and 40 volume percent n-heptane. This fuel, when rated without an antiknock additive, had a research octane number of 91.3. When the fuel contained one gram of nickel per gallon as cyclopentadienyl nickel nitrosyl, it had a research octane number of 93.8. Two grams of nickel per gallon as cyclopentadienyl nickel nitrosyl raised the octane number of the base fuel to 95.0.

In addition, a typical compound produced by our process, cyclopentadienyl nickel nitrosyl, was tested as a supplemental antiknock. In this test, one gram of nickel per gallon as cyclopentadienyl nickel nitrosyl was added to a base fuel which contained three milliliters of tetraethyllead per gallon. The presence of the nickel additive resulted in an increase of 3.4 octane numbers over that ohtainable with the tetraethyllead alone. This increase represents an outstanding improvement in antiknock effectiveness.

Although the process of our invention has been illustrated only with respect to the production of cyclomatic nickel nitrosyl compounds, it works equally as well in producing similar compounds of platinum and palladium.

Having fully described our novel and inventive process by the foregoing examples and discussion, we desire that our invention be limited only within the scope of the appended claims.

We claim:

1. Process for formation of a cyclomatic nickel nitrosyl compound wherein the cyclomatic group is a hydrocarbon radical containing from 5 to about 13 carbon atoms and is selected from the class consisting of the cyclopentadienyl radical, the indenyl radical, and hydrocarbon substituted cyclopentadienyl and indenyl radicals, wherein the hydrocarbon substituents are selected from the class consisting of alkyl, phenyl, and alkylphenyl radicals; said process comprising reacting the cyclomatic nickel carbonyl dimer containing the corresponding cyclomatic radical with nitric oxide.

2. Process of claim 1 wherein the reaction is carried out essentially in the liquid phase.

3. The process of claim 1 wherein the cyclomatic nickel carbonyl dimer is cyclopentadienyl nickel carbonyl dimer, and the product formed is cyclopentadienyl nickel nitrosyl.

References Cited in the file of this patent

Claims (1)

1. PROCESS FOR FORMATION OF A CYCLOMATIC NICKEL NITROSYL COMPOUND WHEREIN THE CYCLOMATIC GROUP IS A HYDROCOMPOUND WHEREIN THE CYCLOMATIC GROUP IS A HYDROCARBON RADICAL CONTAINING FROM 5 TO ABOUT 13 CARBON ATOMS AND IS CARBON RADICAL CONTAINING FROM 5 TO ABOUT 13 CARBON ATOMS AND IS SELECTED FROM THE CLASS CONSISTING OF THE SELECTED FROM THE CLASS CONSISTING OF THE CYCLOPENTADIENYL RADICAL, THE INDENYL RADICAL, AND HYDROCARBON SUBSTITUTED CYCLOPENTADIENYL RADICAL, THE INDENYL RADICAL, AND SUBSTITUTED CYCLOPENTADIENYL AND INDENYL RADICALS, WHEREIN CYCLOPENTADIENYL AND INDENYL RADICALS, WHEREIN THE HYDROCARBON SUBSTITUENTS ARE SELECTED FROM THE CLASS CONSISTING THE HYDROCARBON SUBSTITUENTS ARE SELECTED FROM THE CLASS CONSISTING OF ALKYL, PHENYL, AND ALKYPHENYL RADICALS; SAID OF ALKYL, PHENYL, AND ALKYLPHENYL RADICALS; SAID PROCESS COMPRISING REACTING THE CYCLOMATIC NICKEL CARBONYL DIMER PROCESS COMPRISING REACTING A MIXTURE OF THE TRICYCLOMATIC NICKEL DICARBONYL COMPOUND AND THE CYCLOMATIC NICKEL CONTAINING THE CORRESPONDING CYCLOMATIC RADICAL WITH NITRIC CARBONYL DIMER COMPOUND BOTH CONTAINING THE CORRESPONDOXIDE. ING CYCLOMATIC RADICAL, WITH NITRIC OXIDE.