Tetracarbonyl nickel

The active nickel is prepared from nickel formate in an 

After the tubes from both gas soiu ces are swept out by the respective gases, a slow current of hydrogen is passed steadily and the temperature of the furnace is raised to between 190 and 200°. The more slowly the nickel is 

When the tube has cooled to room temperature, it is placed under a hood in a vertical position, with the gas entering at the top. The receiver E is immersed in a cooling mixture of solid carbon dioxide and alcohol in a Dewar tube, and the carbon monoxide is allowed to flow freely. The check valve is very necessary to prevent air from sucking back through the exit tube. After the hydrogen has been swept out, the exit tube should be nearly or even completely closed, and the carbon monoxide should be allowed to enter as fast as it will react. Liquid nickel tetracarbonyl, as well as the vapor, will pass into the receiver and freeze to a white solid. 

After the nickel tetracarbonyl is collected, the exit may be closed, the solid material in the receiver may be allowed to melt, and the liqmd may be allowed to remain in the atmosphere of carbon monoxide imtil it is convenient to transfer it to permanent containers. 

Caution. Nickel tetracarbonyl should never he poured in the open air. Since its vapor pressure at room temperature is approximately one-third atmosphere, its deadly fumes spread readily. It is somewhat liable to spontaneous combustion and ooddizes so rapidly that even a moment s exposure to the air causes a visible formation of a flocculent precipitate in the liquid. 

All carbonyls are highly toxic by all routes of exposure the volatile liquid compounds present additional inhalation risk. Toxicity may be attributed to their decomposition products, the metals and carbon monoxide, essentially the toxic metabolites of all metal carbonyls. Therefore, the unstable carbonyls, especially the mononuclear complexes, which are readily susceptible to breakdown, should be treated as dangerous poisons. The polynuclear carbonyls of heavy metals may bioactivate and exhibit severe delayed effects. Oral intake of such substances can be fatal. The health hazards associated with individual compounds are discussed in the following sections. Toxicity data for most compounds of this class are not available. 

The mononuclear carbonyls of nickel and iron that are liquid at the ambient temperatures are extremely flammable. Their vapors present flashback fire hazard. They also form explosive mixtures with air. Also, most mononuclear carbonyls that are solids at ambient conditions are pyrophoric. These include the carbonyls of vanadium and tungsten. All carbonyl complexes are air sensitive. Some of them ignite on prolonged exposure to air or may catch fire when opened to air after long storage. The dimeric and trimeric derivatives, however, are less pyrophoric than the mononuclear complexes. All carbonyl metal complexes are susceptible to explode on heating. They react violently with strong oxidants. 

Metal carbonyls may be analyzed by various instrumental techniques, including GC/MS, 

and IR spectroscopy. Metal analysis may be performed by atomic absorption or emission spectroscopy and their stoichiometric amounts in the carbonyl complexes may be determined. Samples may be digested carefully and cautiously with nitric acid in a fume hood before the determination of metal contents. For mass spectrometric determination the carbonyl complex should be dissolved in an organic solvent, injected onto a GC column and identified from the characteristic mass ions. The carbonyl ligands in the complex may be determined by thermal decomposition of the metal carbonyl followed by analysis of carbon monoxide on a GC-TCD. 

The hazardous properties of some selected metal carbonyls are presented in the following sections. 

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The carbon dioxide is removed by passage of the gas through a mixture of sodium and calcium hydroxides. Very pure carbon monoxide is produced by heating nickel tetracarbonyl (see p. 179) ... 

It also forms compounds known as carbonyls with many metals. The best known is nickel tetracarbonyl, Ni(CO)4, a volatile liquid, clearly covalent. Here, donation of two electrons by each carbon atom brings the nickel valency shell up to that of krypton (28 -E 4 x 2) the structure may be written Ni( <- 0=0)4. (The actual structure is more accurately represented as a resonance hybrid of Ni( <- 0=0)4 and Ni(=C=0)4 with the valency shell of nickel further expanded.) Nickel tetracarbonyl has a tetrahedral configuration,... 

Nickel tetracarbonyl Ni(CO)4 was the first metal carbonyl to be discovered, by Mond in 1890 it is obtained by passage of carbon monoxide over nickel metal heated to 320 K. It is a volatile, toxic liquid (b.p. 315 K), and has a tetrahedral structure. It has considerable stability, but inflames in air it is believed that in the structure... 

This is the point group to which all regular tetrahedral molecules, such as methane (Figure 4.12a), silane (SiFl4) and nickel tetracarbonyl (Ni(CO)4), belong. 

Transition metals readily form complexes, such as [Fe(CN)6], the ferrocyanide ion, Ni(CO)4, nickel tetracarbonyl, and [CuC ], the copper tetrachloride ion. MO theory applied to such species has tended to be developed independently. It is for this reason that the terms crystal field theory and ligand field theory have arisen which tend to disguise the fact that they are both aspects of MO theory. 

The vapometahurgical refining of nickel is based on the reaction of the metal with carbon monoxide to form gaseous nickel tetracarbonyl... 

Chloro-a,/3-unsaturated aldehydes condense with ammonium thiocyanate to give isothiazoles (76EGP122249). 2,3-Diphenylcyclopropenone reacts with iV-sulfinyl-cyclohexylamine in the presence of nickel tetracarbonyl to give the isothiazolin-3-one 1-oxide (197) (79SST(5)345). Cholesteryl acetate reacts with trithiazyl trichloride in pyridine to give the isothiazolo steroid (198) (77JCS(P1)916). 

Nickel, methyltetrakis(trimethylphosphine)-tetraphenylborate stereochemistry, 1,44 Nickel, pentacyano-isomerism, 1, 206 structure, 1, 40 Nickel, tetracarbonyl-cxchangc reactions, 1,288 Nickel, tetracyano-, 5,67 Nickel, tetrahalo-, 5, 186 Nickel, tetrakis(dinitrogen)-syn thesis... 

The impure nickel is then refined by first exposing it to carbon monoxide, with which it forms nickel tetracarbonyl, Ni(CO)4 ... 

Nickel tetracarbonyl is a volatile, poisonous liquid that boils at 43°C and can therefore be removed from impurities. Nickel metal is then obtained by heating the pure nickel tetracarbonyl to about 200°C, when it decomposes. 

Newton s second law, L0 nickel, 49, 665 nickel arsenide structure, 201 nickel surface, 189 nickel tetracarbonyl, 665 nickel-metal hydride cell, 520 NiMH cell, 520 nitrate ion, 69, 99 nitration, 745 nitric acid, 629 nitric oxide, 73, 629 oxidation, 549 nitride, 627 nitriding, 208 nitrite ion, 102 nitrogen, 120, 624 bonding in, 108 configuration, 35 photoelectron spectrum, 120... 

Methyl isocyanate Nickel tetracarbonyl Nitrogen oxides Oxygen difluoride Pentaborane Phosgene... 

Methyl bromide 5/b Methylene chloride 100/a Monostyrene 10/a Monostyrene 10/b Monostyrene 50/a Natural gas test Nickel tetracarbonyl 0,1 /a Nitric acid 1 /a... 

It has been pointed out that the types of solvents which are used here, are not generally such as would enter into strong association with the substrate. The molecularity of the substitution reaction may then stand more chance of being an operational concept. Amongst the binary carbonyls, the only systems which have been extensively studied have been nickel tetracarbonyl and the hexacarbonyls of group VI. For the former, the observation of a first-order rate is at least consistent with a rate-determining dissociation of one carbonyl ligand followed by reaction of the intermediate with whichever nucleophile should be available. 

In the case of the hexacarbonyls, the rate-expression contains not only the same type of first-order term but in addition one second-order overall. For good entering groups (but not CO, for example) the rate expression contains a term strictly first-order in both the complex and the entering nucleophile. The first-order rates of CO exchange are practically identical with the rates of substitution in hydrocarbon solvents, but there is nevertheless some acceleration in ether (THF, dioxan) solutions. This solvent-dependence is not so well-marked ° as in the case of nickel tetracarbonyl. The second-order rate of substitution very strongly depends upon the basicity of the entering nucleophile... 

According to the free energy change associated with the pertinent reaction, nickel will form nickel tetracarbonyl at low temperatures, and this carbonyl will become unstable and revert back to nickel and carbon monoxide at moderate temperatures. The Mond process for refining nickel is based on these features. In this process, impure nickel is exposed to carbon monoxide gas at 50 °C, whereby volatile nickel tetracarbonyl (Ni(CO)4) forms. No impurity present in the crude nickel reacts with carbon monoxide. Since formation of the... 

Carlton and Oxley A.I.Ch.E. J., 13 (86), 1967] have studied the heterogeneous catalytic decomposition of nickel tetracarbonyl over the temperature range from 100 to 225° C. 

The equilibrium conversion for this reaction is shown as a function of temperature and pressure in Figure 6P.8. The conversion is expressed in terms of the percent nickel tetracarbonyl decomposed at equilibrium. 

It is supposed that the nickel enolate intermediate 157 reacts with electrophiles rather than with protons. The successful use of trimethylsilyl-sub-stituted amines (Scheme 57) permits a new carbon-carbon bond to be formed between 157 and electrophiles such as benzaldehyde and ethyl acrylate. The adduct 158 is obtained stereoselectively only by mixing nickel tetracarbonyl, the gem-dibromocyclopropane 150, dimethyl (trimethylsilyl) amine, and an electrophile [82]. gem-Functionalization on a cyclopropane ring carbon atom is attained in this four-component coupling reaction. Phenyl trimethyl silylsulfide serves as an excellent nucleophile to yield the thiol ester, which is in sharp contrast to the formation of a complicated product mixture starting from thiols instead of the silylsulfide [81]. (Scheme 58)... 

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