Carbonyl complexes of nickel

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. 

Carbonyl complexes of nickel and perfluoroketonesin donor solvents are thermally stable against fluorine elimination. However, in the presence of iodobenzene loss of fluorine has been observed with a concomitant benzoylation at the carbonyl oxygen.213... 

There are many carbonyl complexes of nickel, palladium, and platinum containing phosphines (L). Nickel compounds of the type [Ni(CO)4 j,Lj,] are readily formed in substitution reactions of [Ni(CO)4]. Palladium and platinum phosphine carbonyls are prepared by reactions of compounds of these metals with carbon monoxide in the presence of phosphines. The following complexes are known [M(CO)L3], [M3(C0)3L3], [M3(C0)3L4], [Pt(CO)2L2] and [M4(CO)5L4] (M = Pd, Pt). Trinuclear platinum compounds resist oxidation. 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

As a further illustration of the dependence of n i 7t pi-backbonding interactions on metal and ligand character, we may compare simple NiL complexes of nickel with carbonyl (CO), cyanide (CN-), and isocyanide (NC-) ligands, as shown in Fig. 4.41. This figure shows that the nNi 7rL pi-backbonding interaction decreases appreciably (from 28.5 kcal mol-1 in NiCO to 6.3 kcalmol-1 in NiNC-, estimated by second-order perturbation theory) as the polarity of the 7Tl acceptor shifts unfavorably away from the metal donor orbital. The interaction in NiCO is stronger than that in NiCN- partially due to the shorter Ni—C distance in the... 

Ni(CO)4 is the sole binary carbonyl complex of the elements of group 10 that is stable (Table 8.1). However, very few studies in which Ni(CO)4 is used in the preparation of catalysts have been reported [43]. This is probably due to the difficulty of manipulation of Ni(CO)4 and its very high toxicity. However, surface Ni(CO)4 species have been identified after the interaction of CO with highly dispersed supported nickel catalysts prepared by other routes [44]. Recent interest in the use of Ni(CO)4 has focused on the controlled production of nickel nanoparticles for specific purposes, such as in automotive converters [45]. The use of nickel tetracarbonyl as an agent for the nucleation process in the growth of single-wall carbon nanotubes has also been reported [46]. 

Carbonylation of methanol to form acetic acid has been performed industrially using carbonyl complexes of cobalt ( ) or rhodium (2 ) and iodide promoter in the liquid phase. Recently, it has been claimed that nickel carbonyl or other nickel compounds are effective catalysts for the reaction at pressure as low as 30 atm (2/4), For the rhodium catalyst, the conditions are fairly mild (175 C and 28 atm) and the product selectivity is excellent (99% based on methanol). However, the process has the disadvantages that the proven reserves of rhodium are quite limited in both location and quantity and that the reaction medium is highly corrosive. It is highly desirable, therefore, to develop a vapor phase process, which is free from the corrosion problem, utilizing a base metal catalyst. The authors have already reported that nickel on activated carbon exhibits excellent catalytic activity for the carbonylation of... 

It has been claimed that attempts to prepare iron and nickel carbonyl complexes of 1,2-and 1,4-dihydropyridines resulted in reduction of the metal (67AG(E)988). This problem has been avoided by using dihydropyridines with electron withdrawing groups on the nitrogen... 

Carbonyl Vibrational Frequencies and Carbon Monoxide Binding Constants for Nickel(I) Carbonyl Complexes of Macrocycuc Ligands... 

Only a limited number of cyano and isocyano complexes and mixed carbonyl, nitrosyl and phosphine cyano complexes of nickel(O) have been described so far.16... 

Tetrakis(alkyl isocyanide) complexes of nickel(O), Ni(CNR)4, and the mixed isocyanide complexes with phosphines and unsaturated molecules are strictly analogous to the corresponding carbonyl complexes.23,24 They are generally more stable than [Ni(CN)4]4-. Mixed isocyanide complexes have been prepared by the reaction of Ni(cod)2 and CNBu followed by reaction with the appropriate phosphine or unsaturated molecules (alkenes, arylnitroso compounds, azo compounds, etc.) as outlined in equations (7) and (S).25... 

The [Ni2(CN)6]4 anion absorbs both CO and NO. In the latter case a nitrosyl complex of nickel(0) results, namely K N CN NO].307 The formulation of the carbonyl compound is dubious.308... 

In contrast to the chalcogen-bridged complexes, no similar oxygen-bridged compounds of iron, cobalt, or nickel exist. However, we obtained such oxo or i-ol-carbonyl complexes of chromium and its homologs, as well as of rhenium. The compounds are the products of the reactions of the respective metal carbonyls with bases (VII). 

To obtain the HMC as an active component zero-valent nickel complexes of the general formula - Ni[PRj] (n=2-4), where R was Ph or EtjN, characterized by high activity in oligomerization of lower olefins in homogeneous conditions were taken. Heterogenization of these complexes was conducted by method of ligand exchange. In the Literature there are examples of carbonyl complexes of palladium prepared by this method, which show activity in propylene dimerization [8], However, we have failed to find data on such nickel catalysts in the literature. 

The metal carbonyls, complexes of metals with carbon moijoxide, are interesting substances of some practical importance. In the Mond process of obtaining pure nickel from iron-nickel ores the ore is re duced with hydrogen to metallic nickel under conditions such that the... 

Table 4. Selected IR properties of some carbonyl and cyanide complexes of nickel and iron with the PS3 and PS3 ligands [70, 71).

Until about 1957, only metals toward the end of the transition series, such as Pd, Pt, Cu, Ag, and Hg, were known to form mono-olefin complexes. In 1959 Schrauzer 219, 220) prepared the first olefin complex of nickel, starting with nickel carbonyl and acrylonitrile ... 

Vanhoye and coworkers [402] synthesized aldehydes by using the electrogenerated radical anion of iron pentacarbonyl to reduce iodoethane and benzyl bromide in the presence of carbon monoxide. Esters can be prepared catalytically from alkyl halides and alcohols in the presence of iron pentacarbonyl [403]. Yoshida and coworkers reduced mixtures of organic halides and iron pentacarbonyl and then introduced an electrophile to obtain carbonyl compounds [404] and converted alkyl halides into aldehydes by using iron pentacarbonyl as a catalyst [405,406]. Finally, a review by Torii [407] provides references to additional papers that deal with catalytic processes involving complexes of nickel, cobalt, iron, palladium, rhodium, platinum, chromium, molybdenum, tungsten, manganese, rhenium, tin, lead, zinc, mercury, and titanium. 

Fig. 15.2 Structures of the simple carbonyl complexes of chromium, iron, and nickel.

Upon heating to — 30 "C, metal insertion occurred yielding metallacyclobutenone 5. Similar reactions had earlier been observed with carbonyl complexes of cobalt, iron, and nickel. 

Some related carbonylation reactions of nickel complexes have been postulated to proceed via Ni—H species (128), and reactions of acetylenes with iron carbonyls in alkaline solution (233, 234) maY proceed via Fe—H intermediates (249). 

Nickel carbonyl complexes of (332) and (334) [NiL(CO)3 NiL2(CO)2] have been prepared (73MI 626-03 >. 

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