Maleic anhydride complexes with nickel

Maize, [2Fe—2S] ferredoxins, 38 230-231 Maleic anhydride complexes with nickel, 12 311... 

Similarly, the complex 3 was formed from 3,3-dimethylcyclopropene and 2,2 -bipyridyl( 4-cy-cloocta-l,5-diene)nickel, which on treatment with maleic anhydride at 25 °C gave anti-3,3,6,6-tetramethyltricyclo[3.1.0.02,4]hexane (4) in >90% yield. Displacement of the hydrocarbon ligand from 3 with 3,3-dimethylcyclopropene proceeds at > 90"C. Since the complex 3 is regenerated in this step, 3 is the catalyst in the cyclodimerization of the cyclopropene.120... 

The stability of the olefin complexes seems to be determined by the steric and electronic characters of both the phosphorus ligand and the olefin (22). For example, ethylene complexes have only been isolated for the cases with sterically large ligands such as P(0-o-tolyl)3 and PPh3 however, maleic anhydride forms a stable isolable complex with the smaller P(0-p-tolyl)3 ligand. The nickel-ethylene bond strength is estimated to be 39 kcal/mol based on values of 36 kcal/mol for 1-hexene and 42 kcal/mol for acrylonitrile [when L = P(0-o-tolyl)3] (22). 

Although methylenecyclopropanes are highly strained molecules, they are stable at ambient temperature. At elevated temperature they undergo [2 + 2]-type reaction with alkenes such as butadiene and maleic anhydride and [3 + 2] reaction with tetracyanoethylene. The latter reaction involves a trimethyl-enemethane diradical intermediate. For catalytic transformations of methylenecyclopropanes, nickel(O) and palladium(O) complexes have been used successfully. 

Bis(maleic anhydride)nickel(O), an orange air-sensitive compound, soluble in acetone but not in benzene, is obtained by reaction of maleic anhydride with Ni(CO)4 (600). With Ni(CO)4, diphenylcyclopropenone yields, in addition to diphenylacetylene and tetraphenylcyclopenta-dienone, a pale green diamagnetic complex [(CaH5)2C2CO]gNi(CO), melting at 188°C, which is presumably tris(Tr-diphenylcyclopropenone)-carbonylnickel (66). The infrared spectrum of the complex indicates coordination at the double bond. 

In the case of tetramethylbutatriene, Ni(0) catalyzes not only the cyclodimerization (formation of [4]radialene 94), but also the cyclotrimerization, leading to [6]radialene 95 and its isomer 96 (see also Section ILD). The product pattern depends to some extent on the nature of the catalyst, but the choice of solvent seems to be more crucial. This is illustrated impressively by the Ni(cod)2-catalyzed reaction of 93, which leads exclusively to the [4]radialene in toluene solution, but to the [6]radialene in DMF. Interestingly, the stoichiometric reaction between 93 and (2,2Tbipyridyl)-(l,5-cyclooctadiene)nickel yields the nickel complex 97, which has been isolated and characterized by X-ray diffraction. On treatment of 97 with two equivalents of maleic anhydride, reductive elimination of nickel takes place and octamethyl[4]radialene (94) is formed in good yield. This reaction sequence sheds light on the mechanism of the Ni-catalyzed reactions mentioned above further ideas on the mechanism of the cyclodimerization and cyclotrimerization reactions have been developed by lyoda and coworkers. ... 

When (2,2 -bipyridine)(cycloocta-l,5-diene)nickel was used as the catalyst various isomeric (2,2 -bipyridyl)nickelaspirocycloalkanes 4 and 5a-c were isolated.As expected, treatment of the dispiro complex 4 with methyl acrylate or maleic anhydride released dispiro[2.1.2.1]oc-tane (1) whereas the complexes 5 with one cyclopropane ring opened gave mainly 5-methyl-enespiroheptane 2. The formation of the 4-methylene isomer (from 5c) has not been observed in the dimerization reaction with other nickel(O) complexes. A few more nickel(O) complexes with an ability to catalyze the oligomerization of methylenecyclopropane have been de-scribed. ... 

Most remarkably, no codimerization involving the unsaturated ester molecule is observed, even though nickel compounds such as the acrylonitrile complex are efficient catalysts for such codimerization reactions vide infra). An additional homodimer, l,3-bis(methylene)cy-clohexane (6), is formed as a minor product with phosphane-modified nickel catalysts. Only trace amounts of product 6 are obtained with maleic anhydride as cocatalyst. 

Also other routes were prosecuted to synthesize carboxylic acids by nickel induced coupling of dienes and CO2. If piperylene is reacted with carbon dioxide and the resulting nickel complex is worked up with maleic anhydride (MSA), sorbic acid is formed in yields up to 40 % [46,47] (Equation 5). 

The 1 1 complex derived from phenyltungsten trichloride and aluminium trichloride is an effective catalyst for diene-cyclobutane metathetical interconversions. Thus, the tetracyclic compounds (291) and (292) were respectively isomerized to the dienes (293) and (294). Rather more surprising was the virtually quantitative formation of the cyclobutanoid compound (296) from (295). Reaction of norbomadiene with 2,2 -bipyridyl(cyclo-octa-l,5-diene)nickel at 25°C yielded the exo-trans,endo-metal o-carbocyclic (297) which, on treatment with an activated olefin (e.g. maleic anhydride), afforded the cyclo-dimer (298 predominantly exo-trans,endo) in good yield by displacement of the hydrocarbon moiety. Catalytic conversions can also be achieved. 

Maleic anhydride acts as a r) -ligand with nickel(O) complexes and does not yield any nickelacycle. On the other hand, itaconic anhydride furnishes nickelacycle 8 in low yield, along with the Ti -complex 9, isolated as the major product. Complex 8 is also prepared by an alternative route based on the oxidative cycloaddition of carbon dioxide and allene. ... 

The nickel compounds NiRa(bipy) react with a variety of alkenes, including ethylene, norbomadiene, maleic anhydride, and tetracyanoethylene, to produce Ni(bipy)(alkene) or Ni(bipy)(alkene)2. A kinetic study, supported by characterization of intermediates from the reactions with aorolein and with acrylonitrile, indicates that the reaction mechanism involves the intermediacy of transient complexes NiR2(bipyXalkene), containing the alkene TT-bonded to the nickel as in the products. There is a correlation between the rates of these reactions and the stabilities of the respective complexes Ni(bipy)(alkene). The unstable species CoH(LL)2, where LL = bipy or phen, undergo substitution reactions with, for example, carbon monoxide, in which one LL ligand is replaced. One LL can also be replaced by alkyl halides here the reaction is oxidative elimination rather than simple substitution. ... 

---