Nickel organometallic compounds, 898

In the second paper [118] tin, iron and nickel organometallic compounds were separated using aluminium-clad high temperature columns coated with 0.1 xm films of HT-5. Various column lengths and temperature gradients were used to separate the species. Helium was used as the carrier gas. The same GC-ICP-MS set up was used as in the previous paper with slight modification of the transfer line for the analysis of nickel diethyldithiocar-... 

A large number of organometallic compounds are based on transition metals Examples include organic derivatives of iron nickel chromium platinum and rhodium Many important industrial processes are catalyzed by transition metals or their complexes Before we look at these processes a few words about the structures of transition metal complexes are m order... 

Besides [Ni(CO)4] and organometallic compounds discussed in the next section, nickel is found in the formally zero oxidation state with ligands such as CN and phosphines. Reduction of K2[Ni (CN)4] with potassium in liquid ammonia precipitates yellow K4[Ni (CN)4], which is sensitive to aerial oxidation. Being... 

Many metals occur in crude oils. Some of the more abundant are sodium, calcium, magnesium, aluminium, iron, vanadium, and nickel. They are present either as inorganic salts, such as sodium and magnesium chlorides, or in the form of organometallic compounds, such as those of nickel and vanadium (as in porphyrins). Calcium and magnesium can form salts or soaps with carboxylic acids. These compounds act as emulsifiers, and their presence is undesirable. 

Some data have been obtained on the activity of the catalyst in a reduced state [for nickel (141,143,144), palladium (144°), and molybdenum (145, 145a). In the case of nickel catalysts the formation of nickel in the zero oxidation state takes place during the reduction of the surface organometallic compound by H2. The infrared spectrum shows the total restoration of the concentration of Si—OH groups (139), so the reduction proceeds according to the scheme ... 

Development of new methodologies for formation of carbon-carbon bonds has been one of the major tasks in organic chemistry. Obviously, organometallic compounds, particularly zinc derivatives, have found great use in such reactions. During the past several years, there have been several significant reports of nickel- and palladium-catalyzed reactions of dialkylzincs and alkylzinc halides with alkyl halides of diverse structure. A detailed account of most of these studies can be found in a recent review by Knochel et al,246... 

A) Ziegler method Catalyst systems can be prepared by reacting a nickel(II) salt with an organometallic compound of the main group metals but aluminum is preferred. 

B,) Treatment of an organo- or a hydrido-nickel(II) compound with a Lewis acid. Organometallic compounds, such as alkylaluminum halides, which have Lewis acid properties, can also be used. 

Table 26. Selected bond enthalpy contributions, D (M-L) and (M-L) kJ mol-1, in organometallic compounds of chromium, manganese, iron cobalt and nickel and related compounds (An asterisk ( ) denotes the average value in a series)...

Mass spectroscopic studies of organometallic compounds are almost as old as the field of mass spectrometry nickel tetracarbonyl was studied by J. J. Thomson (/) and Aston (2,3) in their work on the isotope ratios of nickel. Following this early flurry of specialized interest, however, inorganic and organometallic mass spectral studies were... 

The electrochemical reduction of bromotrifluoromethane (CF3Br) in DMF in a cell fitted with a sacrificial zinc anode and a stainless steel or nickel cathode is a typical case where the organometallic compound formation can be realized according to two different processes, and where a transient species having a different reactivity compared to usual organometallics can be produced. 

The most systematic study of reactions of transition metal atoms with halogen compounds has been the work of Klabunde on oxidation of nickel and palladium atoms. Some work has been done with copper, silver, gold, and platinum, but only scattered results have been reported for other metals. Klabunde s research has shown that perfluoroorgano-halides form isolable organometallic compounds on reaction with metal atoms much more commonly than nonfluorinated halides. The types of reactions observed with different classes of organic halides are considered next. 

Physical methods of fractionation of tar sand bitumen usually indicate high proportions of nonvolatile asphaltenes and resins, even in amounts up to 50% wt/wt (or higher) of the bitumen. In addition, the presence of ash-forming metallic constituents, including such organometallic compounds as those of vanadium and nickel, is also a distinguishing feature of bitumen. 

Vanadium and nickel are present in parts-per-million quantities in most crude oils, usually in large, oil-soluble organometallic compounds termed porphyrins. The chemical structure of porphyrins is closely akin to the coloring matter in blood and to chlorophyll in plants. 

A few representative examples of simple organometallic compounds of nickel(II) including carbonyl and hydrido compounds are reported here. A more complete listing of such types of compound is given in Comprehensive Organometallic Chemistry (vol. 6, p. 37) and references therein. Selected structural data for organometallic nickel(II) complexes with monodentate phosphines are reported in Table 61. 

CO reacts imder normal conditions of pressure and temperature with some nickel(II) organometallic compounds and an insertion reaction into the original Ni—C a bond results (equations 156-158).1201,1236,1247-1249 A different example of an insertion reaction of CO is reported in equation (159).1250... 

The reaction of CO with some of the preceding organometallic compounds is rapid at room temperature and pressure and insertion of CO into the Ni—C bond results (equation 175).1445 In the case of the np3 ligand the first product isolated is a solid solution of the acyl derivative of nickel(II), [Ni(COR)(np3)]+, and a carbonyl complex of nickel(I), [Ni(CO)(np3)]+, in a 1 1 ratio. When this solid solution is dissolved in THF and EtOH, the pure acyl derivative (190) resulted. The acetyl derivative spontaneously loses CO on exposure to air restoring the original methyl derivative. 

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