Cations nickel

Senegas and Galy obtained the same type of structure for Ni2Nb03F3, while investigating solid solutions in a NiF2 - NiNb2C>6 system [263]. Niobium and nickel cations are randomly located in the oxyfluoride octahedrons, which are linked via their sides. 

Foreign cations can increasingly lower the yield in the order Fe, Co " < Ca " < Mn < Pb " [22]. This is possibly due to the formation of oxide layers at the anode [42], Alkali and alkaline earth metal ions, alkylammonium ions and also zinc or nickel cations do not effect the Kolbe reaction [40] and are therefore the counterions of choice in preparative applications. Methanol is the best suited solvent for Kolbe electrolysis [7, 43]. Its oxidation is extensively inhibited by the formation of the carboxylate layer. The following electrolytes with methanol as solvent have been used MeOH-sodium carboxylate [44], MeOH—MeONa [45, 46], MeOH—NaOH [47], MeOH—EtsN-pyridine [48]. The yield of the Kolbe dimer decreases in media that contain more than 4% water. 

Nickel cations (hRf 35-40) appeared as red and cobalt cations (h/ij 40-45) as yellow chromatogram zones on a colorless background. 

NBP reagent la 90, 359 Neatan perservation la 134 Neoamygdalline lb 121 Neo-kestose lb 423 Neomycin la 287,423 Neostigmine lb 290 Nephopam la 45 Nerol la 76,327 -, glucoside la 327 Netilmicin la 105,286,287 Nettle leaf extract lb 217 Neuroleptics lb 352 Nickel-DMSO complex lb 259 Nickel cations la 144,145,311 lb 259-260... 

The pillaring process also affected the concentration and the strength of acid sites, as confirmed by NH3-TPD (Table 1). Also, the ion exchange with Ni2+ cations modified the acid properties of surfaces new Lewis (nickel cations) and Bronsted (H+) acid sites have been created during the ion exchange and thermal activation (eq. 1), respectively. 

When the temperature is increased at 550 °C, the water removed from the solid reduces Ni2+ to Ni+. The formation of the monovalent nickel cations by thermal reduction of Ni2+-exchanged Y zeolite has been detected using the IR spectroscopy of CO adsorption [9]. The NH3-TPD measurements have evidenced that the acid sites strength strongly... 

High acid ionomers are neutralized to various extents by several different types of metal cations, such as by manganese, lithium, potassium, calcium and nickel cations. Several types can be blended. It has been found that these by additional cations neutralized high acid ionomer blends produce compositions exhibiting enhanced hardness and resilience due to synergies, which occur during processing (12). 

The zinc cation gives by far the most active catalyst. Iron, cobalt, and nickel cations also gave salts with considerable catalytic activity. Cadmium, because of its chemical similarity to zinc, and aluminum, because of its use in other epoxide polymerization catalysts, were considered as likely candidates to give active catalysts. However, complexes of the salts of these cations were only slightly catalytic. The salts used as cation sources in catalyst preparations also affected catalytic activity. Zinc salts, especially zinc chloride and zinc bromide, were retained in considerable amounts in the finished complexes, and the use of these salts gave the most active catalysts. 

In the most important series of polymers of this type, the metallotetraphenylporphyrins, a metalloporphyrin ring bears four substituted phenylene groups X, as is shown in 7.19. The metals M in the structure are typically iron, cobalt, or nickel cations, and the substituents on the phenylene groups include -NH2, -NR2, and -OH. These polymers are generally insoluble. Some have been prepared by electro-oxidative polymerizations in the form of electroactive films on electrode surfaces.79 The cobalt-metallated polymer is of particular interest since it is an electrocatalyst for the reduction of dioxygen. Films of poly(trisbipyridine)-metal complexes also have interesting electrochemical properties, in particular electrochromism and electrical conductivity.78 The closely related polymer, poly(2-vinylpyridine), also forms metal complexes, for example with copper(II) chloride.80... 

It is also clear that double-bond-shift is relatively facile on the nickel-silica-alumina catalysts. Double-bond shift may occur on the nickel cation centers or on the silica-alumina support or on both14. The hexene products formed from ethene are as expected for a reaction sequence involving (1) dimerization of ethene to but-l-ene etc, (2) double-bond-shift of but-l-ene to a but-2-ene mixture, and (3) reaction of but-2-ene with a further ethene... 

The nickel ) complex of 92 cannot be prepared directly via the template method, but can be prepared by a transmetallation procedure. Synthesis of the macrocycle in the presence of one of the metal ions known to be effective as a template is followed by a metal exchange process in solution to insert the nickel ) ion. This cation exhibits a strong preference for the square planar, square pyramidal, and octahedral geometries 79). Thus the failure of the nickel ) cation to behave as a template ion in the synthesis of 92 is probably due to the disinclination of the metal to accommodate the pentagonal array of donor nitrogen atoms necessary for reaction to occur. 

If the BVS rule is not satisfied (i.e. when the BVS are not very near to the formal charges for the ions) this may indicate metastability. In LaNiOa.s, for example, BVS calculations give a lanthanum valence of -1-2.63 and valences of -1-2.20 and -1-2.13 for the octahedral and square planar nickel cations, respectively. Although the Ni cation prefers square planar coordination, this oxide readily takes up oxygen upon heating in undergoing a stmctural transition to the perovskite LaNiOs, where the BVS are -1-3.05 and -1-3.01 for lanthanum and nickel, respectively (Alonso et al., 1997). The following worked example illustrates how to use Eqs. 3.20 and 3.21 with Table 3.7. 

Figure 6. Hydrogen uptake for rhodium, platinum and nickel cations as a function of duster size. H/M is the measured hydrogen to metal stoichiometry of the duster.

Studies of the above type have been extended to the preparation of other singlemetal catenanes. These include the synthesis of the nickel(I) and nickel(II) analogues of the above copper(I) catenane 4 both nickel species were characterised by X-ray diffraction. An electrochemical investigation of the nickel(II)/nickel(I) couple indicated strong stabilisation of the nickel(I) state. This has been attributed to the ready adoption of a favourable tetrahedral geometry by the monovalent nickel cation - a geometry not especially favoured by nickel(II) which is most commonly octahedral in its high spin state. 

Chemistry related to the above was also observed when the nickel cation 4.31d was subject to electrochemical reduction. In this instance, it was determined that one electron reduction afforded the neutral, stable radical species 4.34. Further... 

Catalyst Composition. Chemical compositions of typical nickel and cobalt zeolites are summarized in Table 1. Based on the total CEC derived from the initial sodium composition, 23 to 37% of the Zeolon and 8.4% of the Linde SK400 exchange sites are occupied by nickel cations. In Zeolon, 55% of the exchange sites are occupied by cobalt cations. A ratio of 1.41 1 for cobalt to nickel on the Zeolon exchange sites resulted where nickel and cobalt were exchanged under comparable conditions. 

The nickel cationic complex [Ni(Me)(np)3] reacts with CO giving the corresponding acetyl derivative ... 

Nickel sulfate keeps the hydrated form at 100° and takes the anhydrous form at 500°, both containing nickel cations. Both nickel nitrate and nickel hydroxide decompose into nickel oxide when heated at 500°. These variations of the chemical forms of nickel correspond well with the variation of observed spectra in Fig. 13. Thus it became clear that the chemical form of nickel on the surface of NiSA is surely anhydrous nickel cation which is stable even at 500° in the air. 

The nickel arsenide structure is shown in Figure 1.18. Arsenide ions in identical close-packed layers are stacked directly over each other, with nickel ions filling all the octahedral holes. The larger arsenide anions are in a trigonal prism of nickel cations. Both types of ion have a coordination number of six. 

The temperature programmed reduction (TPR) of NiST proceeds in two steps with maxima at around 700 and 815 K (Fig. 2). The observed TPR peaks are indicative for the presence of Ni with different reactivity for hydrogen toward the zero-valent state. Since the non-crystalline silica-alumina phase gave a much poorly resolved TPR profile (Fig. 2), the peaks should be related to the crystal structure of NiST. The nickel cations placed inside the octahedral sheets being coordinated with sbc framework oxygen atoms should be more stable than Ni exposed at the edges of the clay platelets. Consequently, the first reduction step can most likely be attributed to the reduction of the N cations located at those positions. Since the reduction of NiO takes place at approximately 570 K, these data show... 

Some of these helper proteins such as UreE and HybB bind the nickel cations meant for incorporation into nickel-containing enzymes (Lee et al. 1993, Park et al. 1994, Lee etal., 2002b, Song etal. 2001, Remaut etal. 2001). These proteins act as metal chaperones, which discriminate between anabolic nickel that serves as a trace element and toxic nickel. Ni(II) binds to polyphosphate, like many other divalent cations (Gonzalez and Jensen 1998), but... 

ICC1063) and di- 318 (02JCS(D)441) azine-coordinated nickel complexes can be prepared from pyridine-containing aldimines of 2,6-diformyl-4-methylphenol. A nickel cationic complex of a 2,6-bis-azomethine derivative contains two coordinated pyridine N-substituents 319 (M = Ni, R = H, R = Me, = MeOH) (96T3521). Zinc chelate 319 (M = Zn, R = R = Me, no L) has a similar structure (02IC6426). Tetranuclear manganese poly-chelate contains two coordinated pyridine... 

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