Nickel complex characterization

Synthesis, characterization, and chemistry of core-modified porphyrins and their nickel complexes 97NJC691. 

Quite a number of silylnickel and silylenenickel compounds have been reported, and only a few can be cited here2305-2309 Bis(silyl)nickel complexes have been implicated as important intermediates in Ni-catalyzed double silylation of various organic substrates. Using an o-bis(dimethylsilyl)carborane ligand, complex (930) could be isolated and structurally characterized 2310 Its unusual thermal stability is attributed to the advantageous steric and electronic properties of the carboranyl unit. (930) undergoes... 

The Pd-PPh3 system (Scheme 3) is characterized by a two-electron reduction step of the cr-aryl-palladium intermediate [37], as also proposed previously for aryl-nickel complexes ligated to PPha [23, 38]. The formation of the biaryl proceeds by reductive elimination from the diarylpalladium and regeneration of Pd°. 

The use of six equivalents of dihydrogen peroxide leads to a clean conversion of the dithiolate complex to the disulfonate compound. Earlier studies on oxidation of nickel thiolates showed that oxidations with dioxygen stop at monosulfinates. Our observation and the characterization of the first chelating bis-sulfonato nickel complex formed from the direct oxidation of a mononuclear nickel dithiolate, may also provide new insight into the chemistry of sulfur-rich nickel-containing enzymes in the presence of oxygen. 

Reaction systems containing cobalt and nickel were characterized by the production of flocculent precipitates of compounds other than hydroxides in the presence of all thiols, except for thiophenol and tert-butanethiol. Samples of these complexes produced from the ethanethiol system were washed, dried, and subjected to microanalysis. For nickel, the precipitate could be separated into two fractions by extracting with... 

The potassium salt of monothiooxalate can be prepared.46 Two isomers of the dithiooxalic dianion (1,1 and 1,2) and the trithiooxalato anion can also be prepared.46 Transition metal complexes of these ligands are unknown until now. The tetrathiooxalato anion was synthesized and characterized in in the form of the nickel complex. The ligand coordinates as a 1,2-dithiolate.47... 

The MS fragmentation patterns of dithio-/J-diketonato complexes differ from those of both /J-diketonato and monothio-/J-diketonato complexes. The mass spectra of bivalent dithioacetyl-acetonato complexes are characterized by a molecular ion peak M and a much stronger peak for L+ due to the formation of the 3,5-dimethyl-l,2-dithiolium ion another peak at tn/e 96 is due to the loss of HS from the dithiolium cation. The mass spectra of nickel complexes of dithio-/ -diketones are dominated by fragmentation products of the uncomplexed oxidized ligand, which is consistent with the low stability of dithio-/J-diketones and the greater stability of the 1,2-dithiolium... 

The metal(O) isocyanide clusters Ni4(CNBu )7 (45)5 (60), Pt3(CNBu )6 (46) (23) and Pt7(CNXylyl),2 (47) (20) have been characterized crystallographi-cally. In the nickel complex the nickel atoms define the vertices of a highly compressed C3v tetrahedron, with each nickel having a terminal isocyanide and three basal nickel atoms joined by three four-electron donor isocyanide ligands. The unusual feature of the structure of Pt7(CNXylyl),2 is that one... 

Thus, the historical development of the chemistry of metallocorrolates until 1980 includes complexes with Cu2+, Ni2+, Pd2+, Fe3+, Co3+, Rh+, Mo5+ and Cr5+. The palladium complex has been isolated as its pyridinium salt since the neutral species was too unstable to be isolated or spectroscopically characterized [19]. The nickel complex was non-aromatic, with one of the potentially tautomeric hydrogens displaced from nitrogen to carbon in such a way as to interrupt the chromophore. In contrast the electronic spectrum of the paramagnetic copper complex is similar to those of the fully conjugated lV(21)-methyl derivatives [11],... 

The 1,19-substituted octadehydrocorrin complexes have been isolated as crystalline materials and characterized. In the case of the 1-substituted species only the nickel complex turned out to be stable, while the cobalt derivative showed a very high reactivity and all attempts of purification afforded a mixture of compounds [56, 57]. 

Di(carbene)gold(I) salts, oxidation, 2, 293—294 Dicarbido clusters, with decarutheniums, 6, 1036 Dicarbollide amides, with tantalum, 5, 184 Dicarbollide thorium complexes, synthesis and characterization, 4, 224—225 Dicarbollyl ligands, in nickel complexes, 8, 185 Dicarbonyl complexes arylation with lead triacetates diastereoselectivity, 9, 389 enantioselectivity, 9, 391 mechanisms, 9, 387 reaction examples, 9, 382 indium-mediated allylation, 9, 675 with iridium, 7, 287 reductive cyclization, 10, 529 in Ru and Os half-sandwiches, 6, 508 with Zr—Hf(II), 4, 700... 

Their advantage over other types of dendrimers is their straightforward synthesis and, most importantly, their chemical and thermal stabilities. Two distinct steps characterize their synthesis a) an alkenylation reaction of a chlorosilane compound with an alkenyl Grignard reagent, and b) a Pt-cata-lyzed hydrosilylation reaction of a peripheral alkenyl moiety with an appropriate hydrosilane species. Scheme 2 shows the synthesis of catalysts Go-1 and Gi-1 via this methodology. In this case, the carbosilane synthesis was followed by the introduction of diamino-bromo-aryl groupings as the precursor for the arylnickel catalysts at the dendrimer periphery. The nickel centers of the so-called NCN-pincer nickel complexes were introduced by multiple oxidative addition reactions with Ni(PPh3)4. 

The catalytic cycle for the formation of 3PN and 2M3BN is shown in Fig. 7.13. The following points deserve attention. First, interactions of Lewis acid with the coordinated cyano groups are not shown. The evidence for such interactions comes from full characterization of HNiL3CN-BPh3 (L = o-tolylphosphite) as well as detailed IR and multinuclear NMR studies of a number of analogous nickel complexes. Second, the intermediates NiL3 and 7.45-... 

The group 8 (VIII) metals comprise almost 80% of the structurally characterized homoleptic bis(dithiolene) units. Nickel complexes alone account for... 

To obtain the HMC as an active component zero-valent nickel complexes of the general formula - Ni[PRj] (n=2-4), where R was Ph or EtjN, characterized by high activity in oligomerization of lower olefins in homogeneous conditions were taken. Heterogenization of these complexes was conducted by method of ligand exchange. In the Literature there are examples of carbonyl complexes of palladium prepared by this method, which show activity in propylene dimerization [8], However, we have failed to find data on such nickel catalysts in the literature. 

Solubility of Exocellular Nickel Complexes in the Soil. To evaluate the effect of microbial metabolites on Ni solubility in soil, the soluble exocellular solution, separated after growth of the 20 selected bacterial isolates and all fungal isolates, was eluted through a column of soil. The concentrations and forms of Ni in the eluates were compared to the concentrations and forms of Ni in water and in the growth medium before and after microbial growth. A column (0.8 x 4 cm) was packed (1.5 g/cc) with sieved (<2 mm), air-dry Ritzville silt loam (1.0 g) and an aliquot of the filtered (<0.4 M<) exocellular medium (2 ml) was eluted through the soil. After 1 ml of eluant was collected, the Ni concentration was determined from the concentration of radio-tracer. Metal form was characterized in soil eluates by TLC and TLE as previously described. 

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