Nickel binary structures

Binary Compounds. Nickel n) oxide, a green solid, with the rock-salt structure is formed when the hydroxide, carbonate, oxalate or nitrate of nickel(n) is heated. It is insoluble in water but dissolves readily in acids. 

However, it became evident in the post-war period that, valuable as they were, these band-structure concepts could not be applied even qualitatively to key systems of industrial interest notably steels, nickel-base alloys, and other emerging materials such as titanium and uranium alloys. This led to a resurgence of interest in a more general thermodynamic approach both in Europe (Meijering 1948, Hillert 1953, Lumsden 1952, Andrews 1956, Svechnikov and Lesnik 1956, Meijering 1957) and in the USA (Kaufman and Cohen 1956, Weiss and Tauer 1956, Kaufman and Cohen 1958, Betterton 1958). Initially much of the work related only to relatively simple binary or ternary systems and calculations were performed largely by individuals, each with their own methodology, and there was no attempt to produce a co-ordinated framework. 

A special technique which has yielded highly unstable and simple dinitrogen complexes trapped in low-temperature solids (N2 or Ar) is the metal atom cocondensation technique in low-temperature matrices. By the cocondensation of nickel atoms and N2 at 4.2-10 K the binary compounds Ni(N2) (n = 1-4) result, whose structure has been inferred from IR and... 

Of the transition metals, the nickel triad has been the most studied in terms of xanthate structures, especially nickel xanthates. Thus, binary xanthate structures are known for all elements with no less than 15 binary nickel xanthate structures known and these aggregate in the solid state in six distinct supramolecular architectures. There is also a rich diversity of adducts as well as mixed-ligand complexes, in particular for nickel. 

CH2CH2 -Pr (78, 79), CH2CH2 f-Bu (80), hex (68), CH2CF3 (81, 82), CH2CH2OMe (83), CH2Ph (84), Cy (68), 4-MeCy (85), and 4-f-BuC6H4 (60). Table II summarizes the salient features of the structural chemistry of the binary nickel xanthates with data from the most precise structure determination included for cases where more than one determination is available in the... 

Structural Data for Binary Nickel Xanthates, Ni(S2COR)2... 

The important point to appreciate is that the formal valency of zinc is satisfied by two bonds to sulfur so that the additional interactions are indeed hypervalent interactions. Thus, the nature of the adopted structures arises from the ability of the central element to form hypervalent, or secondary, interactions and it is proposed that this ability is moderated by steric considerations associated with the alkyl substituents. As noted from the structural studies for the uncoordinated xanthate anions summarized earlier in Section II, there are no electronic differences among the xanthate ligands that can be correlated with the nature of the oxygen-bound substituent. This conclusion is vindicated by the homogeneity of the molecular structures of the binary nickel xanthates as... 

Duplex structures are also formed in reaction couples of the type ApBq AiBn. In the Ni-Sn binary system, such a structure is typical of the Ni3Sn2 layer occurring between the Ni3Sn and Ni3Sn4 phases. In the Ni3Sn2 lattice, nickel atoms diffuse much faster than tin atoms. Therefore, the Ni3Sn2 layer grows mainly by means of the reaction... 

With time, the Ni3Zn22 phase must be consumed in the course of the latter reaction. However, if the experiment is interrupted before its full consumption, then the layers of all the intermatallic compounds of the Ni-Zn binary system, stable at a given temperature, will be present between nickel and zinc. Moreover, metallographic examination of the cross-section surface after repeated anneals in the as-received condition may well show a greater number of distinquishable layers in the Ni-Zn transition zone than the number of those compounds because some will have duplex structures. 

The reactions described in Section II dealt with reactions of binary nickel(0)-olefin complexes with AmR, AmH, and AmPR2 and are characterized by the fact that the charge of alkali metal atoms is transferred to nickel and the respective 7r-ligands via C, H, or P atoms. That the charge from alkali metal atoms can also be directly transferred to nickel(O) -jr-lig-and systems is demonstrated in the syntheses (14, 31-33), structures (14, 34), and NMR data (18,35) of the dilithium-nickel-olefin complexes now described. 

Some solid-state metal hydrides are commercially (and in some cases potentially) very important because they are a safe and efficient way to store highly flammable hydrogen gas (for example, in nickel-metal hydride (NiMH) batteries). However, from a structural and theoretical point of view many aspects of metal-hydrogen bonding are still not well understood, and it is hoped that the accurate analysis of H positions in the various interstitial sites of the previously described covalent, molecular metal hydride cluster complexes will serve as models for H atoms in binary or more complex solid state hydride systems. For example, we can speculate that the octahedral cavities are more spacious in which H atoms can rattle around , while tetrahedral sites have less space and may even have to experience some expansion to accommodate a H atom. 

In addition to the binary catalysts from transition metal compounds and metal alkyls there 2ire an increasing number which are clearly of the same general type but which have very different structures. Several of these are crystalline in character, and have been subjected to an activation process which gives rise to lattice defects and catalytic activity. Thus, nickel and cobalt chlorides, which untreated are not catalysts, lose chlorine on irradiation and become active for the polymerization of butadiene to high cis 1,4-polymer [59]. Titanium dichloride, likewise not a catalyst, is transformed into an active catalyst (the activity of which is proportional to the Ti content) for the polymerization of ethylene [60]. In these the active sites evidently react with monomer to form organo-transition metal compounds which coordinate further monomer and initiate polymerization. 

A special type of catalyst which is typified by Raney Nickel is prepared by leaching out one component from a binary alloy leaving a skeletal structure of the desired catalyst. Raney Nickel itself is made by leaching out aluminium from an aluminium-nickel alloy with sodium hydroxide. Cobalt and iron catalysts have also been prepared in this manner. 

Binary transition metal complexes have been the subject of a wide range of studies regarding their structure and spectroscopy for many years beginning with Mond et al. [4] who first reported Ni(CO)4 whilst investigating the Action of Carbon Monoxide on Nickel in 1890. A wide range of spectroscopic methods and techniques has subsequently been utilised, including X-ray and electron diffraction, IR, and UV/Vis spectroscopy. In almost all cases the Jahn-Teller effect has been invoked to explain certain spectroscopic features. Due to a wide breadth of smd-ies reported in the literature, this review will not be comprehensive. Instead it is... 

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