Nickel complexes chloride

Pipette 25 mL nickel solution (0.01 M) into a conical flask and dilute to 100mL with de-ionised water. Add the solid indicator mixture (50mg) and 10 mL of the 1M ammonium chloride solution, and then add concentrated ammonia solution dropwise until the pH is about 7 as shown by the yellow colour of the solution. Titrate with standard (0.01 M) EDTA solution until the end point is approached, then render the solution strongly alkaline by the addition of 10 mL of concentrated ammonia solution, and continue the titration until the colour changes from yellow to violet. The pH of the final solution must be 10 at lower pH values an orange-yellow colour develops and more ammonia solution must be added until the colour is clear yellow. Nickel complexes rather slowly with EDTA, and consequently the EDTA solution must be added dropwise near the end point. 

In the reaction of Ni(CNBu )4 and methyl iodide oligomerization of the isocyanide was observed the only isolable nickel complex was (I), shown below. This product is believed to arise through sequential insertions of three isocyanides into a nickel-carbon bond. Upon further treatment with additional isocyanide at a temperature greater than 60° C one obtains a polymer (RNC) presumably through multiple isocyanide insertion reactions. The addition of benzoyl chloride to Ni(CNBu )4 gave two isolable compounds Ni(CNBu )3(COPh)Cl (74%) and (II) (8.2%). This latter reaction, and the isolation of (II) in particular, suggests that the proposed mechanism for polymerization of isocyanides is reasonable. 

In contrast to 4, 2-acetylpyridine iV-methylthiosemicarbazone, 3a, formed yellow-green, paramagnetic, octahedral [Ni(3a)2A2] complexes with nickel(II) chloride and bromide. The neutral form of the ligand was proposed to be NN eoordinated [180]. Brown, paramagnetic [Ni(3a-H)2] was prepared from nickel(II) acetate with NNS coordination, and its d-d spectrum and ligand field... 

Lutidylphenylketone thiosemicarbazone, 38, and nickel(II) chloride, bromide, or iodide yield [Ni(38-H)2]A2 with NNS coordination based on infrared spectra [187]. All three complexes are electrolytes and the cations are dimeric with sulfur atoms acting as bridges interdimer interactions via sulfur are present. The electronic spectra suggest a nickel(Il) stereochemistry other than tetrahedral or octahedral for these paramagnetic complexes. 

Solution studies of nickel(II) complexes of 2,6-diacetylpyridine bis(thiosemi-carbazone), 28, have been carried out [147]. From a refluxed methanolic solution containing 28 and nickel(II) chloride, [Ni(28)Cl2] was isolated which behaved as a 1 1 electrolyte in methanol [152], Based on spectral information it is proposed that the complex is a distorted octahedron with a SNNNS pentadentate ligand. 

Activated aryl chlorides, which are close in reactivity to unactivated aryl bromides, underwent reaction with the original P(o-tol)3-ligated catalyst.58 Nickel complexes, which catalyze classic C—C bond-forming cross-couplings of aryl chlorides, 9-64 also catalyzed aminations of aryl chlorides under mild conditions.65,66 However, the nickel-catalyzed chemistry generally occurred with lower turnover numbers and with a narrower substrate scope than the most efficient palladium-catalyzed reactions. 

The electrochemistry of cobalt-salen complexes in the presence of alkyl halides has been studied thoroughly.252,263-266 The reaction mechanism is similar to that for the nickel complexes, with the intermediate formation of an alkylcobalt(III) complex. Co -salen reacts with 1,8-diiodo-octane to afford an alkyl-bridged bis[Co" (salen)] complex.267 Electrosynthetic applications of the cobalt-salen catalyst are homo- and heterocoupling reactions with mixtures of alkylchlorides and bromides,268 conversion of benzal chloride to stilbene with the intermediate formation of l,2-dichloro-l,2-diphenylethane,269 reductive coupling of bromoalkanes with an activated alkenes,270 or carboxylation of benzylic and allylic chlorides by C02.271,272 Efficient electroreduc-tive dimerization of benzyl bromide to bibenzyl is catalyzed by the dicobalt complex (15).273 The proposed mechanism involves an intermediate bis[alkylcobalt(III)] complex. 

Not only do palladium complexes catalyze reactions of Eq. (58), but nickel complexes were also effective (51) and formed the same products. Complexes such as Fe(CO)5 and Fe2(CO)8 were ineffective. Cobalt carbonyl, and tris-triphenylphosphinerhodium chloride were effective even at room temperature, but no 2 1 adducts were made. With both palladium and nickel, the activity of the catalyst and the distribution of products between 1 1 and 2 1 adducts is greatly dependent on the nature of the donor ligands on the metal. 

The regioselectivity is maintained with mono- and even disubstituted propargylic chlorides (Table 9.33) [56], The copper complex affords allenylcarbinols (A) and the nickel complex favors homopropargylic alcohols (B). In the latter case, the syn adducts are predominant, suggestive of an acylic transition state. 

Schrauzer, Mayweg and Heinrich have reported the preparation of the complex 5 from the reaction of aqueous nickel(ll) chloride with a reaction mixture of benzoin in dioxane and phosphorus(V) sulfide. The parent acid and its salts have not been characterized. The only other closed ring complex, 6, was isolated in low yield (3%) subsequent to the reaction of nickel (II) acetate with the mixture resulting from the reaction of 1,3-propanediol with phosphorus(V) sulfide. As for 5, the parent acid and its salts were not... 

Bromostyrenes 162 react with 1-ethylphenylmagnesium chloride under Ni catalysis providing 1,3-diaryl-l-butenes 163. When chiral nickel complexes are used, the products... 

The addition of olefins to olefins426 can also be accomplished by bases427 as well as by the use of catalyst systems428 consisting of nickel complexes and alkylaluminum compounds (known as Ziegler catalysts), 29 catalysts derived from rhodium chloride,430 and other transition metal catalysts. These and similar catalysts also catalyze the 1,4-addition of olefins to conjugated dienes,431 e.g.,... 

It was shown that room-temperature molten salts derived from the combination of 1,3-dialkylimidazolium chloride and A1C13 can be used as solvents in two-phase catalytic dimerization of propene to give hexenes catalyzed by Ni(II) compounds (125). The effects of phosphane ligands coordinated to nickel and operating variables were also investigated (126). The dimerization products separate as an organic layer above the molten salt. This reaction has been carried out with n-butenes as the reactant and cationic nickel complex catalysts dissolved in organochloroaluminate liquids (127). 

The neutral complexes Ni(C3H3N2)2 are obtained by the reaction of hydrated nickel(II) chloride and pyrazole, or imidazole, in an aqueous ammonia solution. These insoluble complexes contain uninegative exobidentate pyrazolates or imidazolates which act as bridges between two metals (104).899,904,905 Two additional ligands such as NH3, H20 or py may be... 

In 1959, the coordinated mercaptide ion in the gold(III) complex (4) was found to undergo rapid alkylation with methyl iodide and ethyl bromide (e.g. equation 3).9 The reaction has since been used to great effect particularly in nickel(II) (3-mercaptoamine complexes.10,11 It has been demonstrated by kinetic studies that alkylation occurs without dissociation of the sulfur atom from nickel. The binuclear nickel complex (5) underwent stepwise alkylation with methyl iodide, benzyl bromide and substituted benzyl chlorides in second order reactions (equation 4). Bridging sulfur atoms were unreactive, as would be expected. Relative rate data were consistent with SN2 attack of sulfur at the saturated carbon atoms of the alkyl halide. The mononuclear complex (6) yielded octahedral complexes on alkylation (equation 5), but the reaction was complicated by the independent reversible formation of the trinuclear complex (7). Further reactions of this type have been used to form new chelate rings (see Section 7.4.3.1). 

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