Nickel comparison with cobalt

M. PeUarin, B. Baguenard, J. L. Vialle, J. Lerme, M. Broyer, J. Miller and A. Perez, Evidence for icosahedral atomic shell structure in nickel and cobalt clusters. Comparison with iron clusters , Chem. Phys. Lett. 217 349 (1994). 

Another important consideration pertains to the metal content of the deposit. A deposit with a content of iron of about 20% can have little value as an iron ore since there are several deposits with 30-50% iron. Earlier, a copper ore with a minimum of 5% copper was regarded or accepted as a copper ore. However, today, thanks to advancements in technology, rocks with as little as 0.5% copper are mined and processed economically despite the fact that the price of copper, in comparison with those of some other metals, might be showing a downward trend. It is possible that in the future, other resources, which are not considered to be worth exploiting today (such as the manganese nodules or the clays), would become acceptable ores for manganese, copper, nickel, cobalt, and aluminum. 

Three syntheses of 1,2-dicyanocyclobutene (2) have been previously described. The first, involving dehydration of cyclobutene-1,2-dicarboxamide does not specify the yield.9 The second procedure involves a concomitant chlorination and catalytic dehydrochlorination of 1,2-dicyanocyclobutane in the gas phase, yielding 1,2-dicyanocyclobutene (2) in a mixture of several other products.10 The third method consists of dechlorination of 1,2-dichloro-1,2-dicyanocyclobutane using metals, such as zinc copper couple,11 Raney nickel,11 and, especially, Raney cobalt.2 In comparison with this last-mentioned synthesis, the overall yield of the present procedure is 5-10% higher. Furthermore, the reaction is performed in less time and utilizes considerably cheaper reagents. 

Fig. 7. Current voltage curves of the anodic oxygen evolution at different temperatures in 30 wt% KOH at nickel anodes with coatings containing cobalt oxides (a) La0 5Co -.EaC), (b) Nin2, CouxLaO , (c) Co,04, and, for comparison, (d) RuO..

That this interpretation is reasonable is indicated by a comparison with the octahedral radii of iron, cobalt, and nickel, indicated in Figure 11-9 by squares, with the oxidation numbers also shown. The smaller octahedral radii correspond to d2sp8 orbitals, with 33 percent d character, and the radii that are about 0.10 greater correspond to dsp orbitals, with 20 percent d character. It is evident that there is a rapid decrease in single-bond radius with increase in the amount of d character... 

The reappearance of Brdnsted acid sites has been observed for the high calcined nickel-molybdenum-alumina catalysts. The presence of a nickel aluminate phase has been concluded from the reflectance spectra. The second Lewis band (1612 cm l) has a very low intensity, in comparison with the cobalt containing catalysts of a same composition and after the same calcination conditions. 

The quasi-reversible character of these redox reactions indicates that some geometrical changes are taking place without changing the clathrochelate framework. As in the case of trinuclear cobalt complexes, macrobicyclic nickel dioximates are characterized by a high oxidation state stabilization in comparison with other nickel complexes. For example, for Ni(HDm)2 bis-dioximate, two processes (oxidation and reduction) were observed for nickel(II) ion [80],... 

Camner P, Curstedt T, Jarstrand C, et al. 1985. Rabbit lung after inhalation of manganese chloride A comparison with the effects of chlorides of nickel, cadmium, cobalt, and copper. Environ Res 38 301-309. 

Martin, C.J. and Evans, W.j. (1 987) Phytic acid divalent cation interactions. V.Titrimetric, calorimetric, and binding studies with cobalt (II) and nickel (II) and their comparison with other metal ions. Journal of Inorganic Biochemistry 30, 101-119. 

Stability constants for palladium complexes, [Pd(S2CNR2)2] (R = Me, Et, Pr, /-Pr), have been measured in ethanol using UV-vis spectroscopy (393). Their stability varies in the order i-Pr > Pr > Et > Me being the same as that found for the analogous nickel complexes. Further, a comparison with related nickel and cobalt complexes showed the palladium complexes to be the most stable Pd > Ni > Co (393). 

In comparison with nickel and cobalt, copper shows a considerably lower catalytic activity in the hydrogenation of nitriles and the differences are much more important than with conventional catalysts (Nl/Co/Cu 20/ 10/1 (4-,5). Moreover, even with copper catalysts, the tertiary amine is... 

One-electron oxidation of the vinylidene complex transforms it from an Fe=C axially symmetric Fe(ll) carbene to an Fe(lll) complex where the vinylidene carbon bridges between iron and a pyrrole nitrogen. Cobalt and nickel porphyrin carbene complexes adopt this latter structure, with the carbene fragment formally inserted into the metal-nitrogen bond. The difference between the two types of metalloporphyrin carbene, and the conversion of one type to the other by oxidation in the case of iron, has been considered in a theoretical study. The comparison is especially interesting for the iron(ll) and cobalt(lll) carbene complexes Fe(Por)CR2 and Co(Por)(CR2) which both contain metal centers yet adopt... 

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