Complexes nickel chloride triphenylphosphine

The catalyst system for the modem methyl acetate carbonylation process involves rhodium chloride trihydrate [13569-65-8]y methyl iodide [74-88-4], chromium metal powder, and an alumina support or a nickel carbonyl complex with triphenylphosphine, methyl iodide, and chromium hexacarbonyl (34). The use of nitrogen-heterocyclic complexes and rhodium chloride is disclosed in one European patent (35). In another, the alumina catalyst support is treated with an organosilicon compound having either a terminal organophosphine or similar ligands and rhodium or a similar noble metal (36). Such a catalyst enabled methyl acetate carbonylation at 200°C under about 20 MPa (2900 psi) carbon monoxide, with a space-time yield of 140 g anhydride per g rhodium per hour. Conversion was 42.8% with 97.5% selectivity. A homogeneous catalyst system for methyl acetate carbonylation has also been disclosed (37). A description of another synthesis is given where anhydride conversion is about 30%, with 95% selectivity. The reaction occurs at 445 K under 11 MPa partial pressure of carbon monoxide (37). A process based on a montmorillonite support with nickel chloride coordinated with imidazole has been developed (38). Other related processes for carbonylation to yield anhydride are also available (39,40). 

It has recently been suggested (19) that 7r-allylnickel complexes are intermediates in reactions involving allylic halides. Although ir-allylnickel chloride-triphenylphosphine (IX) is formed from allyl chloride and Ni(CO)3P(C6H5)3 without jrielding a carbonylation product (20), the dimeric 7r-allylnickel chloride (X) [prepared (13) by heating allyl chloride with nickel carbonyl in benzene solution] reacts rapidly with carbon monoxide to form butenoylnickel dicarbonyl chloride (XI) (Eq. 13). Moreover, this complex is converted by additional carbon monoxide into butenoyl chloride and nickel carbonyl (13), Eq. (14)... 

As mentioned in the chapter on the reaction mechanism, the anion, especially of Ni-salts, is important in affecting the reaction course. The catalytic efficiency of the nickel halides strongly increases in the series fluoride, chloride, bromide, iodide [374—376]. The molar ratio of cobalt or nickel to iodine is also very important [414]. As in the hydroformylation reaction, metal carbonyls substituted by phosphine ligands are very reactive [377, 1009], and especially modified rhodium and palladium catalysts [1021, 1045] allow reactions under mild conditions. Thus, the nickel bromide triphenylphosphine allyl bromide complex shows an increased reactivity in the carbonylation of acetylenes. On the other hand, carbonyls substituted by phosphine ligands are also readily soluble in the reaction mixture [345, 377]. 

The relatively weak Ar-Br and especially Ar-I bonds would readily dissociate, giving rise to the Ni(I) paramagnetic complex and free aryl radical. This decomposition path is normally disfavored for aryl chlorides with considerably stronger Ar-Cl bonds. As a result, no Ni(I) species formed in the reactions of all chlo-roarenes studied, the only exception being [p-Me3NC6H4Cl]+. The p value of 5.4 obtained by Tsou and Kochi [33] is close to that (8.8 see above) previously reported by Foa and Cassar [32], suggesting that SET (Scheme 1) may play a certain role in some of the reactions of triphenylphosphine nickel(O) complexes with chloroarenes. It is still unclear if every reaction between any chloroarene and Ni(0) always involves the SET step. However, the excellent selectivity of the o-aryl Ni(II) complex formation from ArCl and highly reactive Ni(0) makes chloroarenes especially attractive substrates for various arylation reactions catalyzed by Ni complexes. 

Tetrachloropalladate(II) ion catalyzes the interconversion of 1- and 2-butenes in aqueous solutions containing chloride and hydronium ions. Sodium tetrachloropalladate(II) catalyzes the conversion of allylbenzene to propenyl-benzene in acetic acid solutions. Tetrakis(ethylene))Lt,/x -dichlororhodium(l) catalyzes butene isomerization in methanolic hydrogen chloride solutions . Cyclooctadienes isomerize in benzene-methanol solutions of dichlorobis-(triphenylphosphine)platinum(11) and stannous chloride. Chloroplatinic acid-stannous chloride catalyzes the isomerization of pentenes. Coordination complexes of zero-valent nickel with tris(2-biphenylyl)phosphite or triphenyl-phosphine catalyze the isomerization of cis-1,2-divinylcyclobutane to a mixture of c/5,m-l, 5-cyclooctadiene and 4-vinylcyclohexene . Detailed discussions of reaction kinetics and mechanisms appear in the papers cited. 

Tetrathiabenzo[l,3-cfirst time by dimerization of thieno[2,3- >]thiophene (142) (92PS73). More recently, it was found that catalytic reduction of 3,4-dibromothieno[2,3-i]thiophene (227) with an excess of activated zinc in the presence of bis(triphenyl-phosphine)nickel(II) chloride and tetraethylammonium iodide afforded only 4,4 -dibromo-3,3-bis(thieno[2,3- )]thiophene) (228) (in a maximum yield of 28%) (89AG1254). However, the reaction in the presence of a larger amount of the nickel catalyst afforded also dipenatlene 225. Optimization of the reaction conditions made it possible to increase the yield of the latter to only 14%. An alternative procedure was employed to transform thienothiophene 227 into trimethylstannyl derivative 229. The reaction of thienothiophene 227 with organotin intermediate 229 in the presence of the palladium triphenylphosphine complex afforded dipentalene 225 (13% yield). Derivatives 226 were prepared by lithiation of... 

Alkenyl-alkenyl cross-coupling. Baba and Negishi have prepared a catalyst from this Pd(II) complex and 2 equiv. of diisobutylaluminum hydride that promotes this coupling reaction. Tetrakis(triphenylphosphine)palladium(0) is inactive, as is material prepared in situ from palladium chloride, triphenylphos-phine and HAKr-CtHg) . A nickel catalyst prepared from Ni(acac)2, PfCnHsja, and diisobutylaluminum hydride is somewhat less efficient. The coupling Involves (E)-alkenylalanes (4, 158, 159) and alkenyl halides. The products are (E,E)- and (E,Z)-dienes. 

Method E, developed by Colon and Kelsey [14], is efficient for coupling reactions of much less reactive aryl chlorides under the similar reaction conditions. The role of triphenylphosphine in all these methods is only to stabilize catalytically active nickel(O) complexes, arylnickel(II) and diaiylnickel intermediates, providing high selectivity and turnover number. 

Nickel(O) complexes tend to undergo oxidative addition of aryl halides faster than palladium(O) complexes. There are some drawbacks to the use of the nickel complexes, described above, that can outweigh the lower cost of nickel. Nevertheless, the ruckel complexes containing triarylphosphines do undergo oxidative addition of aryl chlorides (Equation 19.39) and tosylates (Equation 19.40), and some mild conditions have been developed for nickel-catalyzed cross couplings of aryl chlorides and aryl tosylates with ligands such as triphenylphosphine or tricyclohexylphosphine. ... 

It is well known that thermal decomposition of arylnickel(II) halide complexes such as bis(triphenylphosphine)phenylnickel(II) bromide [130] or bis(triethylphosphine)(4-fluorophenyl)nickel(II) chloride [131] gave the corresponding biphenyls by successive disproportionation and reductive elimination reactions [132]. Scheme 7.6 is also consistent with these facts. 

The reaction of benzyl chloride with metallic nickel in the presence of methyl acrylate was carried out at 85°C, and the expected addition product methyl 4-phenylbutanoate was formed in 17% yield (Equation 7.12). The reaction with acrylonitrile gave 4-phenylbutanenitrile in 14% yield together with cis- and tra 5-4-phenyl-2-butenenitriles, 4-cyano-6-phenylhexanenitrile, and 2-ben-zyl-4-phenylbutanenitrile (Equation 7.13). The results suggest the presence of a benzylnickel(II) chloride complex (1), which could have been formed by the oxidative addition of benzyl chloride to the metallic nickel (Scheme 7.7). The complex (I) would then be expected to add to the electron-deficient olefins, affording the addition product (111) via intermediate complex (IV). The formation of cis- and tra s-4-phenyl-2-butenenitrile (V) is reasonably explained by the reductive elimination of nickel hydride from intermediate (IV), which is analogous to the substitution reaction of olefins with alkylpalladium compound [158] and to the addition-elimination reaction of bis(triphenylphosphine) phenylnickel(II) bromide with methyl acrylate to yield methyl cinnamate [130]. Furthermore, intermediate (IV) seems to add another molecule of acrylonitrile to give the 1 2 adduct 4-cyano-6-phenylhexanenitrile (VI). 2-Benzyl-4-phenylbutanenitrile (VIII) would be formed by the metathesis of complex IV and the benzylnickel chloride (I). 

Y-Ray analysis has revealed the structure of an intermediate (366) in the oligomerization of allene by nickel complexes which contains three allene units and is assumed to be formed by the series of steps in Scheme Using rhodium dicarbonyl chloride dimer and triphenylphosphine in ethanol, an allene hexamer has been isolated for which structure (367) is proposed. 2... 

Substituted di-2-propynl ethers react with acetylenes in the presence of tris(triphenylphosphine)rhodium(i) chloride or dicarbonylbis(triphenylphosphine) nickel(o) to give 1,3-dihydroisobenzofurans. The intermediate rhodium complex (130) could be isolated and used in heterocyclic synthesis. The oligomeric Pd (DMAD>2 (DMAD=dimethylacetylene dicarboxylate) complex is an efficient... 

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