Tetrakis nickel

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... 

BIPHENYLS Bis(l,5-cyclooctadiene)nickel. Tetrakis(triphenylphosphine)palladium. Thallium(III) trifluoroacetate-Palladium(Il) acetate. Titanium(IV) chloride. 

The nickel-catalyzed hydrocyanation of butadiene is a two-step process (Figure 3.32). In the first step, HCN is added to butadiene in the presence of a nickel-tetrakis(phosphite) complex. This gives the desired linear product, 3-pente-nenitrile (3PN), and an unwanted branched by-product, 2-methyl-3-butenenitrile (2M3BN). The products are separated by distillation, and the 2M3BN is then isomerized to 3PN. In the second step, 3PN is isomerized to 4PN (using the same nickel catalyst), followed by anti-Markovnikov HCN addition to the terminal double bond. The second step is further complicated by the fact that there is another isomerization product, CH3CH2CH=CHCN or 2PN, which is thermodynamically more stable than 4PN. In fact, the equilibrium ratio of 3PN/2PN/4PN is only 20 78 1.6. Fortunately, the reaction kinetics favor the formation of 4PN [95],... 

Nickel, tetrakis(tris(methyl phenyl) phosphite-P)-. 

EINECS 252-777-2 Nickel, tetrakis(tris(methylphenyl) phosphite-P)- Nickel, tetrakis(tritolyl phosphite)- Tetrakis(tritolyl phosphite )nickel. 

Nickel, tetrakis(tritolyl phosphite)- 2665 ionic acid thioglycolate 1987... 

Nickel, methyltetrakis(trimethylphosphine)-tetraphenylborate stereochemistry, 44 Nickel, tetracarbonyl-exchange reactions, 288 Nickel, tetrakis(dinitrogen)-synthesis... 

EDA and other alkylene amines react readily with acrylonitrile or acrylate esters. EDA reacts with acrylonitrile to give tetrakis(2-cyanoeth5i)-ethylenediamine which is reduced over Raney nickel to give tetralds(3-anainoprop5i)-ethyl-enediainine (52). With methyl acrylate and EDA under controlled conditions, a new class of starburst dendritic macromolecules forms (53,54). 

In Gegenwart von Tetrakis-[pyridin]-nickel-diperchlorat oder Nickel(II)-chlorid in Athanol mit Tetrabutylammonium-perchlorat als Leitsalz erhalt man unter partieller Hy-drierung und Oligomerisation aus Butadien-(1,3) all-trans-Hexadecatetraen-(1,6,10, J4) in Gegenwart von Bis-[triphenylphosphin]-nickel(II)-chlorid wird Octatrien-(l,3,7) er-halten4. 

L = PPhj, AsPhj) were reported from direct reaction of the phosphine or arsine and NiL4 (104). Phosphite (98) and PF3 (68) derivatives were also reported, formed from the tetrakis(phosphite) or tetrakis(PF3)-nickel(0) species and an isocyanide [Eqs. (25, 26)]. 

The orange, air-stable, homoleptic tetrakis( 71-phosphabenzene)nickel (1046) is tetrahedral (point symmetry 54) and can be obtained from phosphabenzene and [Ni(cod)2].2 25 It features a short Ni—P bond length of 2.1274(5) A with considerable N i P 7r-backbonding and a i/(Ni—P) stretch at 168 cm-1. In solution, partial dissociation of one phosphabenzene ligand is observed. 2-Diphenylphosphino-3-methylphosphinine forms with [Ni(cod)2] in the presence of the CO the dinuclear complex (1047) with a W-frame structure.2526... 

Although the copper mediated Ullmann reaction is a well known method for biaryl synthesis, drastic conditions in the range of 150-280 °C are required. Zerovalent nickel complexes such as bis(l,5-cyclooctadiene)nickel or tetrakis(triphenylphosphine)nickel have been shown to be acceptable coupling reagents under mild conditions however, the complexes are unstable and not easy to prepare. The method using activated metallic nickel eliminates most of these problems and provides an attractive alternative for carrying out aryl coupling reactions(36,38). 

Dialkylindolines and 1,3-dialkylindoles are formed in poor yield (<10%) from the reaction of ethyl- or phenymagnesium bromide with 2-chloro-N-methyl-N-allylaniline in the presence of catalytic quantities of (bistriphenylphosphine)nickel dichloride.72 In a modification of this procedure, the allyl derivatives can be converted by stoichiometric amounts of tetrakis(triphenylphosphine)nickel into 1,3-dialkylindoles in moderate yield72 (Scheme 43) an initial process of oxidative addition and ensuing cyclization of arylnickel intermediates is thought to occur. In contrast to the nickel system,72 it has proved possible to achieve the indole synthesis by means of catalytic quantities of palladium acetate.73 It is preferable to use... 

The 1,4-reduction of a,/3-unsaturated aldehydes is best carried out with diphenylsilane in the presence of zinc chloride and tetrakis(triphenylphosphine) palladium436 or a combination of triethylsilane and tris(triphenylphosphine) chlororhodium 437 Other practical approaches use phenylsilane with nickel (0) and triphenylphosphine438 and diphenylsilane with cesium fluoride.83 It is possible to isolate the initial silyl enol ether intermediate from the 1,4-hydrosilylation of o, /3-unsaturated aldehydes (Eq. 264).73,411 The silyl enol ethers are produced as a mixture of E and Z isomers. 

This complex is not the actual catalyst for the hydrovinylation, but needs to be activated in the presence of a suitable co-catalyst. The role of this additive is to abstract the chloride ion from the nickel centre to generate a cationic allyl complex that further converts to the catalytically active nickel hydride species. In conventional solvents this is typically achieved using strong Lewis acids such as Et2AlCl. Alternatively, sodium or lithium salts of non-coordinating anions such as tetrakis-[3,5-bis(trifluoromethyl)phenyl]borate (BARF) can be used to activate hydrovinylation... 

The Lewis acidity and reactivity of these alkyl aluminum cocatalysts and activators with Lewis basic polar monomers such as acrylates make them impractical components in the copolymerization of ethylene with acrylates. To address this shortcoming, Brookhart et al. developed well-defined cationic species such as that shown in Fig. 2, in which the counterion (not illustrated) was the now-ubiquitous fluorinated arylborate family [34] such as tetrakis(pentaflurophenyl)borate. At very low methyl acrylate levels the nickel catalysts gave linear copolymers but with near-zero levels of acrylate incorporation. 

Potassium bis(propynyl)platinate, 2309 Potassium diethynylpalladate(2—), 1394 Potassium diethynylplatinate(2—), 1395 Potassium hexaethynylcobaltate(4—), 3446 Potassium hexaethynylmanganate(3—), 3448 Potassium tetraethynylnickelate(2—), 2896 Potassium tetraethynylnickelate(4—), 2897 Potassium tetrakis(propynyl)nickelate(4—), 3513... 

First we will describe the hydrocyanation of ethene as a model substrate. The catalyst precursor is a nickel(O) tetrakis(phosphite) complex which is protonated to form a nickel(II) hydride. Actually, this is an oxidative addition of HCN to nickel zero. In Figure 11.1 the hydrocyanation mechanism in a simplified form is given the basic steps are the same as for butadiene, the actual substrate, but the complications due to isomer formation are lacking. 

C7H704Rh, Rhodium(I), dicarbonyl(2,4-pentanedionato)-, 34 128 C7HgN4, Bis(l-pyrazolyl)methane, bpm, complex with nickel(ll), 34 139 CgH5FeKN20, Ferrate(ll), carbonyldicyano-(cyclopentadienyl)-, potassium, 34 172 CgH23Ns, Tetraethylenepentamine, tetren, complex with nickel(ll), 34 147, 148 CgH24B2N4, Diborane(4), tetrakis(dimethyl-amino)-, 34 1... 

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