United States Patent Office E. 2 atively large amounts and only small amounts of the com 3,032,572 pounds RNia(CO)a are obtained. All these products CYCLOPENTADENY, NCKEL CARBONY, COM are readily soluble in numerous organic solvents and in POUNDS AND PROCESS THEREFOR crystalline form are stable for a long time in the air. The Ernst Otto Fischer, Munich-Soln, and Christof Palm, preparation of the compounds of this invention is illus Ludwigshafen (Rhine), Germany, assignors to Union Carbide Corporation, a corporation of New York trated by the following examples. No Drawing. Filed July 15, 1958, Ser. No. 748,584 Example Claims priority, application Germany July 16, 1957 Ten milliliters of technical nickel-tetracarbonyl and 5.0 9 Claims. (C. 260-439) Io grams of dicyclopentadienyl nickel were dissolved in 60 This invention relates to organometallic compounds of milliliters of pure nitrogen-saturated benzene under nitro nickel and a method for producing them. More partic gen in a 250 milliliter three-neck flask provided with a ularly, the invention relates to cyclopentadienyl nickel reflux condenser, agitator, dropping funnel and excess carbonyls and their preparation by the reaction of a di pressure valve. Thereupon the solution was slowly heated cyclopentadienyl nickel with nickel tetracarbony. 15 on a water bath to between 70 and 80° C. After 3 Organometallic compounds of transition metals which hours, the solution had become red. The temperature contain a cyclopentadienyl radical in addition to carbon was then raised, with continued stirring, to between 80 monoxide have been known for a long time. They are and 85 C. and kept at this temperature for several hours prepared for instance by reacting cyclopentadienyl com until the main portion of the nickel carbonyl had de pounds of the metal in question with carbon monoxide 20 composed. under pressure, or by reacting the metal carbonyl with Thereupon the benzene was distilled off in vacuum, the cyclopentadiene vapor. However, it has heretofore not unreacted nickel carbonyl passing over with it. The been possible to produce corresponding compounds of residue was subjected to sublimation in a high vacuum. nickel since when treating dicyclopentadienyl nickel with In the sublimation step, the main portion of the unre carbon monoxide under pressure, nickel tetracarbonyl is 25 acted dicyclopentadienyl nickel was first of all vaporized immediately produced and, conversely, when treating nick at 80 to 90° C. At 90 to 110° C., crystals of a dark el tetracarbonyl with cyclopentadienyl vapor, dicyclo green shimmer which appeared red in transmitted light pentadienyl nickel is formed. It therefore had to be as and which were of substantially less volatility were ob sumed that nickel compounds which contain both a cyclo tained. These crystals were identified as dimeric cyclo pentadienyl radical and carbon monoxide in the same 30 pentadienyl nickel carbonyl (C5H5)2Nia(CO). molecule were not stable. The yield of the crystals of red color in transmitted It has surprisingly now been found that compounds light was 4.0 grams. of nickel which contain both a cyclopentadienyl radical At a temperature above 140 C., there sublimed from and carbon monoxide in the same molecule can be pre the residue, crystals of a dark green shimmer having a pared. The compounds of this invention may be repre 3 5 deep brown color when seen in transmitted light, which sented by the formula RNi(CO), wherein R is a crystals also contained nickel, carbon monoxide and cy group selected from the class consisting of cyclopentadi clopentadienyl radicals in the molecule and which were enyl and alkyl-substituted cyclopentadienyl and the sub identified as (C5H5)3Nia(CO)2. scripts in and n are the same and may have the integral Example II values 2 or 3. Examples of the compounds represented by 40 this formula are dicyclopentadienyl dinickel dicarbonyl, Three grams of finely pulverized dicyclopentadienyl (CH)Ni(CO); di(ethylcyclopentadienyl) dinickel di nickel and 15 mililiters of pure benzene were introduced carbonyl, (CH3C5H4)2Ni(CO); and tri(methylcyclo into a 30 milliliter sealed tube of Jena glass. There pentadienyl) trinickel dicarbonyl, (CH3C5H4)Nia(CO)2. upon the tube was cooled by placing it in a mixture of ice The compounds of this invention may be prepared in a and sodium chloride. Seven milliliters of technical nickel simple manner and in good yield by the reaction of nickel 45 tetracarbonyl were then introduced and the tube frozen. tetracarbonyl with a dicyclopentadienyl nickel. The dicy The tube was then evacuated and sealed closed. clopentadienyl nickels may be represented by the formula Thereupon the tube was heated to room temperature, RNi wherein R is a group selected from the class con shaken well and heated at 105 C. for 60 hours. After sisting of cyclopentadienyl and alkyl-substituted cyclo opening the tube, brownish-red reaction mixture was pentadienyl. 50 filtered by means of a glass frit with the exclusion of air. The reaction in accordance with the invention is ad The black crystals which remained on the filter were vantageously carried out in a suitable inert organic sol washed with cyclohexane until the cyclohexane passed vent, for instance benzene, with the exclusion of atmos through the filter with a yellow color. The crystals were pheric oxygen. In order to obtain good yields, it is ad introduced, with the exclusion of air, into an extraction visable to operate at a moderately elevated temperature, 65 thimble and extracted with cyclohexane. From the dark for instance temperatures between 50 and 115 C. In brown solution there was obtained, by filtration, after general, the starting materials are used in approximately cooling, small crystal needles of a dark green glitter which equimolar quantities. It is advantageous to use an ex are shown by analysis and molecular weight determina cess of the more easily decomposable carbonyl. Depend tion to have the formula (C5H5)Nia(CO)2. The yield ing on the reaction conditions and the method of purify 60 was 1.86 grams. A small quantity of (C5H5)Ni(CO)a ing the reaction mixture, varying proportions of two vola was isolated from the wash cyclohexane. tile reaction products of different molecular weight and The compound (C5H5)Nis (CO) may also be pre different organic group: nickel:carbon monoxide ratios pared by thermal decomposition of the (C5H5)2Nia(CO)a are obtained. When the reaction is carried out at ap prepared in accordance with Example I by carrying out proximately atmospheric pressure, the compounds the sublimation of this compound at a temperature above RNi(CO), n and n have the value 2 in the formula about 30° C. hereinabove, are produced in relatively large amounts Compounds containing alkyl-substituted cyclopentadi and the compounds RNi(CO), n and m have the value ene groups may be prepared in a similar manner. For 3 in the formula hereinabove, are produced in relatively example, the reaction of di(ethylcyclopentadienyl) nickel small amounts. When the reaction is carried out under 0 with nickel tetracarbonyl at atmospheric pressure yields pressure, the compounds RNis(CO)2 are produced in rel primarily (CHCH)Ni(CO) while the reaction of 3,032,672 3 4. di(methylcyclopentadienyl) nickel with nickel tetracar 4. Di (ethylcyclopentadienyl) dinickel dicarbonyl, bonyl under pressure produces primarily (CHCH)Nis(CO) (CH3C5H4)2Ni(CO)a The compounds of the present invention may be used 5. Tricyclopentadienyl trinickel dicarbonyl as catalysts for organic syntheses, for the preparation of nickel coatings and as fuel additives. (C5H5)Ni(CO) A nickel film may be deposited on a metal substrate such as copper by sealing the metal to be coated and a 6. Tri(methylcyclopentadienyl) trinickel dicarbonyl, cyclopentadienyl nickel carbonyl compound of this in O (CH3C5H4)3Nis (CO). vention in an evacuated glass tube. The tube is then 7. Process for producing organo-nickel compounds hav heated to a temperature above the decomposition tem ing the formula RNim (CO) wherein R is a group se perature of the nickel compound employed for about one lected from the class consisting of cyclopentadienyl and hour. The tube is then cooled before removing the con mono lower alkyl-substituted cyclopentadienyl and the tents. The nickel film provides a corrosion-resistant coat 5 subscripts in and m are the same and have integral values ing for the metal substrate. selected from the group consisting of 2 and 3, which proc The cyclopentadienyl nickel carbonyl compounds of ess comprises reacting a dicyclopentadienyl nickel com this invention may also be used to improve the anti-knock pound having the formula R2Ni, wherein R has the mean properties of hydrocarbon fuels of the types used in ing defined hereinabove, with nickel tetracarbonyl. spark iginition engines. The compounds are readily sol 8. Process in accordance with claim 7 wherein the re action is carried out in an inert organic solvent. uble in hydrocarbons and such solutions are relatively 9. Process for producing organo-nickel compounds hav stable on exposure to air. ing the formula RNi(CO) wherein R is a group se What is claimed is: lected from the class consisting of cyclopentadienyl and 1. As compositions of matter the organo-nickel com mono lower alkyl-substituted cyclopentadienyl, which pounds having the formula RNim (CO), wherein R is a 25 group selected from the class consisting of cyclopentadi process comprises heating a compound having the for enyl and mono lower alkyl-substituted cyclopentadienyl mula R2Ni(CO), wherein R has the meaning defined and the subscripts in and n are the same and have in hereinabove, under reduced pressure to a temperature tegral values selected from the group consisting of 2 and above about 130 C, 3. $0 2. Dicyclopentadienyl dinickel dicarbonyl, References Cited in the file of this patent UNITED STATES PATENTS 3. Di(methylcyclopentadienyl) dinickel dicarbonyl, 2,849,471 Thomas ------Aug. 26, 1958 (CH3CH)Nia(CO) 35