Tricarbonyl nickel

Recent developments are ring-cleavage reactions of the heterocycles [R2M-SbR2]w with 4-(dimethylamino)pyridine leading to base-stabilized monomers, [L — R M-SbR, (R = Me, SiMe3 R = Me, Et, i-Bu M = A1, Ga).83,84 Reaction of [L-Al(Me2)-Sb(SiMe3)2] [L = 4-(dimethylamino)pyr-idine] with [Ni(CO)4] leads to the corresponding tricarbonyl nickel complex (Equation 4).85... 

The formation of the active catalyst can be retarded with high carbon monoxide partial pressure. High CO partial pressure leads to more CO in solution which competes with the ligand over the tricarbonyl species, Ni(C0)3, and forms the inactive nickel tetracarbonyl. The active complex stability was retained by increasing the promoter concentration. The complex formed between nickel and promoters is more stable than Ni(C0)4. In addition, promoters may impart higher electron density to the central atom and increase its nucleophilic character towards methyl iodide. 

In the case of phosphine, the active catalyst is presumably either bisphosphine dicarbonyl or the phosphine tricarbonyl complex. Kinet-ically the bis-phosphine nickel complex cannot be the predominant species. However, in the presence of very high phosphine concentration it may have an important role in the catalyst cycle. After ligand loss and methyl iodide oxidative addition, both complexes presumably give the same 5 coordinate alkyl species. 

Strengthening of the Ni-C bond by electron charge donation of a trans phosphine ligand in the bisphosphine complex (equation 18) retards the elimination of CO prior to the oxidative step (30, 31). This is not the case for the phosphine nickel tricarbonyl (equation 19) where carbon monoxide is easier to eliminate (32). 

The generality of the carbon monoxide insertion reaction is clear from reports that methylcyclopentadienyliron dicarbonyl (16), ethylcyclopentadienylmolylbde-num tricarbonyl (66), alkylrhenium pentacarbonyls (50), alkylrhodium dihalo carbonyl bisphosphines (34), allylnickel dicarbonyl halides (35), and mono-and di-alkyl derivatives of the nickel, palladium, and platinum bisphosphine halides (P), also undergo the reaction. The reaction of Grignard reagents (24), and of boron alkyls (51) with carbon monoxide probably takes place by the same mechanism. 

The tris(chloromethyldifluorophosphine)molybdenum tricarbonyl exhibited strong CO absorptions typical for terminal CO groups at 2038 and 1970 cm.-1. Strong P-F absorptions were found at 866 and 842 cm.-1, which in view of the above-mentioned observation in the case of tetrakis(trifluorophosphine)nickel-(0) may also be representative ef the uncoordinated fluorophosphine. Compared with molybdenum tricarbonyl derivatives with nitrogen compounds as donor mole-... 

Ethanediylbis(diphenylphosphine-K P)] -[3-(methylamino-KAT)propanalato(2-)-KCl]nickel Amminedichloro(ti2-ethene)plalinum(II) Tricarbonyl(2,5-dihydro-Ti2-thiophene-l-oxide-KO)-iron... 

Arene(tricarbonyl)chromium complexes, 19 Nickel boride, 197 to trans-alkenes Chromium(II) sulfate, 84 of anhydrides to lactones Tetrachlorotris[bis(l,4-diphenyl-phosphine)butane]diruthenium, 288 of aromatic rings Palladium catalysts, 230 Raney nickel, 265 Sodium borohydride-1,3-Dicyano-benzene, 279 of aryl halides to arenes Palladium on carbon, 230 of benzyl ethers to alcohols Palladium catalysts, 230 of carboxylic acids to aldehydes Vilsmeier reagent, 341 of epoxides to alcohols Samarium(II) iodide, 270 Sodium hydride-Sodium /-amyloxide-Nickel(II) chloride, 281 Sodium hydride-Sodium /-amyloxide-Zinc chloride, 281 of esters to alcohols Sodium borohydride, 278 of imines and related compounds Arene(tricarbonyl)chromium complexes, 19... 

Nickel tetracarbonyl is known to dissociate into the more reactive tricarbonyl readily [step (1)] and this species is known to react readily with a variety of halides by oxidative addition presumably as shown in steps (2) and (3). Subsequent loss of CO would give an equilibrium mixture of the four complexes shown in (3). Step (4) is the well-known carbon monoxide insertion reaction. The acylnickel complex formed in this step then may re-ductively eliminate acid halide [step (5)], which then alcoholizes [step (6)] or it may react directly with alcohol to form ester and a hydridonickel complex (7), which then reacts with CO and decomposes to nickel tricarbonyl and HC1 (8) ... 

Density functional theory studies arene chromium tricarbonyls, 5, 255 beryllium monocyclopentadienyls, 2, 75 chromium carbonyls, 5, 228 in computational chemistry, 1, 663 Cp-amido titanium complexes, 4, 464—465 diiron carbonyl complexes, 6, 222 manganese carbonyls, 5, 763 molybdenum hexacarbonyl, 5, 392 and multiconfiguration techniques, 1, 649 neutral, cationic, anionic chromium carbonyls, 5, 203-204 nickel rj2-alkene complexes, 8, 134—135 palladium NHC complexes, 8, 234 Deoxygenative coupling, carbonyls to olefins, 11, 40 (+)-4,5-Deoxyneodolabelline, via ring-closing diene metathesis, 11, 219... 

IR results show that the tricarbonyl complex is not formed. To check this result modelling was performed. It was not possible to reach a minimum in the potential energy surface for the tricarbonyl Nin complex with a nickel dicoordinated to the cluster the structure evolves toward a dicarbonyl complex. Even if a ligand displacement of the silica surface is assumed by adding a third CO molecule as shown by the reaction ... 

Tricarbonyl(triphenylphosphine)nickel, (CO)3Ni[P(C6H5)3] (1). Preparation.1 This metal carbonyl is stable and less toxic than Ni(CO)4. 

The intermediate cyclized allylnickel species can be trapped by methoxycarbonylation when CO and CH3OH are present and tricarbonyl(triphenyl-phosphine)nickel is the catalyst. 

Coupling of an intramolecular nickel-ene process with a methoxycarbonylation shows a striking preference for products with ci5-ielated metal donor (C-1) and acceptor (C-8) sites. ° Thus tricarbonyl(tri-phenylphosphine)nickel (25 mol %), a stable, easy-to-handle solid [compared with the highly volatile and toxic Ni(CO)4], readily catalyzed the conversion of dienyl iodide (278) (THF/MeOH 4 1, 1 atm CO, r.t.) into monocyclic cu-substituted pyrrolidine (280 29%) and the bicyclic cyclopentanone (281 47%, 4 1 isomer mixture) (Scheme 58). ... 

The bis(77-allyl)nickel, -palladium, and -platinum complexes also react with iron enneacarbonyl under analogous conditions. In the presence of iodine, 77-allyliron tricarbonyl iodide has been isolated (158). 

Other metal compounds that are capable of decomposing at end gas temperatures to produce oxide smokes also can act as anti-knocks. These include iron and nickel carbonyls, trimethyl bismuth and methyl cyclopen-tadienyl manganese tricarbonyl [6]. The last has been used commercially for some years in Canada. Its anti-knock properties also can be amplified by organic co-anti-knocks (diketones in this case) [47]. Concerns over the possible toxicity of fine aerosols which are emitted in the exhaust will limit the acceptability of these metal containing materials in the future. 

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