Nickel, hexafluoro

Nickel, diiodotris(trimethyl phosphite)-strpeture, 1,45 Nickel, hcxaamminc-rcactions, 1,27 Nickel, hexaaqua-reactions, 1, 204 Nickel, hexafluoro-, 5,186 Nickel, hexakis(A, Ar -dimethylurea)-tetrachloronickelate isomerization, 1,470... 

The selective, Ni-catalyzed, biphasic dimerization of 1-butene to linear octenes has been studied in the author s group. A catalytic system well loiown for its ability to form linear dimers from 1-butene in conventional organic solvents - namely the square-planar Ni-complex (q-4-cycloocten-l-yl](l,l,l,5,5,5,-hexafluoro-2,4-pen-tanedionato-0,0 )nickel [(H-COD)Ni(hfacac)] [103] - was therefore used in chloroaluminate ionic liquids. 

A similar catalytic dimerization system has been investigated [40] in a continuous flow loop reactor in order to study the stability of the ionic liquid solution. The catalyst used is the organometallic nickel(II) complex (Hcod)Ni(hfacac) (Hcod = cyclooct-4-ene-l-yl and hfacac = l,l,l,5,5,5-hexafluoro-2,4-pentanedionato-0,0 ), and the ionic liquid is an acidic chloroaluminate based on the acidic mixture of 1-butyl-4-methylpyridinium chloride and aluminium chloride. No alkylaluminium is added, but an organic Lewis base is added to buffer the acidity of the medium. The ionic catalyst solution is introduced into the reactor loop at the beginning of the reaction and the loop is filled with the reactants (total volume 160 mL). The feed enters continuously into the loop and the products are continuously separated in a settler. The overall activity is 18,000 (TON). The selectivity to dimers is in the 98 % range and the selectivity to linear octenes is 52 %. 

A more complex reaction is involved in the cooligomerization of acetylenes and tert-butyl isocyanide using nickel acetate as the catalyst (Scheme 20)43 the nature of intermediate complexes leading to the formation of 2-cyano-5-terf-butylaminopyrroles has not been established. Cocyclization of tert-butyl isocyanide with coordinated hexafluoro-2-butyne gives rise to coordinated cyclopentadienone anils for molybdenum systems,44 hence the nature of acetylene substitutents and of the organometallic catalyst play crucial roles in these processes. The pyrrole products from the former reaction can be decomposed by sulfuric acid and the overall sequence provides a simple synthesis of 5-amino-2-cyanopyrroles (Scheme 20). 

Attempts were made not only to find an alternative way to replace dimer and to deposit high-quality poly(tetrafluoro-p-xylylene) film, but also to eliminate the dibromide as the precursor because of the difficulty of synthesis. Therefore, the deposition of poly(tetrafluoro-p-xylylene) film by using hexafluoro-p-xylene as the precursor instead of dibromotetrafluoro-p-xylene was tried. However, no polymer film was deposited on the wafer. Effort was expanded and other metal reagents such as nickel or copper were used to react with l,4-bis(trifluoromethyl)-benzene to generate a,a,a, a -tetrafluoro-p-xylylene to deposit poly(tetrafluoro-p-xylylene) film. However, the result showed that no film was deposited, which was not unexpected, because a C—X bond that is weaker than C—F bonding might be necessary to initiate the formation of the desired intermediate. 

Poly[(4,4 -(Hexafluoroisopropylidene)-(4,4 -(Hexafluoro-Isopropylidene)-Phthalimide] Film Blend Containing bis[(l,2-Trifluoromethyl)Ethylene-1,2-Dithiolato] Nickel(II)... 

HEXAFLUOROSILICATE (2-), NICKEL see NDDOOO HEXAFLUORO VANADATE (3-) TRIAMMONIUM SALT see ANI500... 

Bis-3,4-(trifluoromethyl)-l,2-diselenete 651 is prepared by refluxing selenium with hexafluoro-2-butyne. It reacts with triphenylphosphine and triphenyl-arsine. Triphenylphosphine selenide was isolated, but no other compounds were identified.Ring-opened complexes with nickel, copper, vanadium, molybdenum (652), tungsten, iron, and cobalt are analogous to complexes of the 1,2-dithiete (527) (Section XXXV.2.C.). 

FuNjOaPdCjiiHid, Palladium(II), (2,2 -bipyr-idine)(l,l,l,5,5,5-hexafluoro-2,4-pen-tanedionato)-, l,l,l,5,5,5-hexafluoro-2,4-dioxo-3-pemanide, 27 319 FijNaNiOjPjCjiH, , Nickel(II), [2,12-di-methyl-3,1 l-bis( 1-methoxyethylidene)-... 

The solvent properties of alcohols with short carbon chains are similar to those of water and such alcohols could be used as the nonaqueous catalyst phase when the products are apolar in nature. The first commercial biphasic process, the Shell Higher Olefin Process (SHOP) developed by Keim et al. [4], is nonaqueous and uses butanediol as the catalyst phase and a nickel catalyst modified with a diol-soluble phosphine, R2PCH2COOH. While ethylene is highly soluble in butanediol, the higher olefins phase-separate from the catalyst phase (cf. Section 2.3.1.3). The dimerization of butadiene to 1,3,7-octatriene was studied using triphenylphosphine-modified palladium catalyst in acetonitrile/hexafluoro-2-phe-nyl-2-propanol solvent mixtures [5]. The reaction of butadiene with phthalic acid to give octyl phthalate can be catalyzed by a nonaqueous catalyst formed in-situ from Pd(acac)2 (acac, acetylacetonate) and P(0CeH40CH3)3 in dimethyl sulfoxide (DMSO). In both systems the products are extracted from the catalyst phase by isooctane, which is separated from the final products by distillation [5]. 

Two convenient methods of synthesis of the nickel(II) and cobalt-(II) complexes are described here. Method A, based on reaction of the sodium enolate salt of l,l,l,5,5,5-hexafluoro-2,4-pentanedione with the transition-metal chlorides in dimethylformamide (dmf), gives almost quantitative yields of Ni(hfa)2(dmf)2 and Co(hfa)2(dmf)2. Method B gives lower yields (50-75%) of the same products but can be carried out rapidly in common laboratory equipment (Method A is best carried out by vacuum-line techniques7). 

The l,l,l,5,5,5-hexafluoro-2,4-pentanedionato complexes ofnickel-(II) and cobalt(II), when isolated as dimethylformamide adducts, are crystalline solids, stable to at least 135° in vacuo. The crystalline nickel complex is unaffected by immersion in water at room temperature for 3 days. 

Niccolates(II), hexafluoro-, 186 Niccolates(II), tetracyano-, 67 Niccolates(II), tetrahalogeno-, 186 Niccolates(II), trihalogeno-, 186 Nickel... 

Phenols have been condensed with alkenoylesters to give chromans by an oxa-Michael addition/electrophilic aromatic addition sequence with magnesium(II)- or copper(II)-bis-oxazoline complexes as chiral Lewis acid catalysts (Scheme 17b) [97]. This reaction may be initiated by an oxa-Michael reaction, followed by a hydroarylation of a carbonyl group. The authors suggest that the initial stereodetermining oxa-Michael addition is followed by a fast diastereoselective aromatic substimtion [97]. A nickel Lewis acid, derived from Ni(hfacac)2 (hfacac = 1,LL5,5,5-hexafluoro-3,5-dioxopentane enolate) and chiral Al-oxide ligands, catalyzes the enantioselective oxa-Michael cyclization of 2-tert-butyloxycarbonyl-2 -hydroxy-chalcones to 3-ferf-butoxycarbonyl flavanones, which can be decarboxylated to flavanons in a separate step (Scheme 17c) [98]. A Lewis acid activation of the unsaturated p-ketoester unit can be assumed. 

Aryne-nickel complexes, which were carefully studied by Bennett [6, 7], show a different reactivity, since following the insertion of a first unsaturated species, the metallacycles so formed usually undergo a second insertion and subsequent reductive elimination (Scheme 9). Thus, complex 44 undergoes the insertion of two molecules of 3-hexyne to afford 43 in good yield, and double insertion of the asymmetric alkyne t-butylacetylene into complex 44 yields naphthalene 45 with a high regioselectivity attributed to steric factors. Interestingly, the reaction of 44 with the more electron-deficient alkyne hexafluoro-... 

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