Oxidation states stabilities

Antimony(V) oxide can be prepared by treating antimony with concentrated nitric acid. It is an oxidising agent and when gently heated loses oxygen to form the trioxide. (The change in oxidation state stability shown by antimony should be noted since it corresponds to increasing metallic character.)... 

In the promotion of less-common oxidation states, much attention has been focused on the redox behaviour of transition metal ions such as nickel and copper although many other metal types have also had unusual oxidation states stabilized by macrocyclic ligands. However, within the limitations of a single chapter it is not possible to attempt a wide ranging... 

The [X"+M6024](12 ") ion, its protonated form [X, +M6024H6](6 ") , and the [Xn+M9O32](10 ", ion are among those in which the heteroatom finds itself in an octahedron of oxygen atoms. The latter is known for only two cases, namely, those in which Xn+ = Mn4+ or Ni4+ and M = Mo, but these are of interest because the hetero ions are examples of unusual oxidation states stabilized by the unusual ligand. ... 

Redox propcTties of some oxo-bridged di- and tri-nuclear complexes of the second and third transition elements. Re, Ru, Os, and Mo, are discussed with special attention to stability of the mixed-valence states. These complexes display multi-step one-election transfer processes and give fairly stable mixed-valence oxidation state. Stability of the mixed-valence states is discussed in terms of qualitative molecular orbital schemes based on dJt (metal) - prt (bridged oxygen) interactions. 

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],... 

Our attempts to prepare metal complexes in high oxidation states stabilized by other ligands capable of distributing the metal charge effectively have not yet been very successful. Complexes with cyanodithio-formate (Reaction 8) are rather insoluble (38). Complexes of p-hydroxy-... 

In this Section our attention is directed primarily towards the d—d transitions which occur in the electronic spectra of these ions, the Laporte-allowed charge-transfer bands being discussed in more detail in Section 5, although some correlations between molecular orbital calculations, oxidation state stabilities etc., and the positions of the charge-transfer excitations are indicated. 

The first equation describes the reproduction of the kink site position in the process of separation of an atom from the kink site position and formation of an ad-atom. The second step represents desorption of the ad-atom. The charge transfer is split. Following the description of partial charge transfer in Section 4.3 with the introduction of a partial charge transfer coefficient A the charge transfer in the first step is = Xz, and the charge transfer in the second step Az j = (1 — A )z. The intermediate ad-atom can be a lower valent oxidation state stabilized as an anion complex. 

Some recent additions to the series of doubly bonded Group 14 species also include the unusual compounds [L - E = E <- L] [E = Si, Ge L = C(NDippCH)2] (53) which contain the dimeric Ej unit with both tetrel atoms in the zero oxidation state, stabilized by Af-heterocydic carbene donor groups. The small L-Si=Si angles in the silicon derivative (93.4°) imply a high degree of p-orbital involvement in bonding, with minimal contributions from s electrons, which remain localized at the E centers [71, 79]. 

I in. 2-.. Pourbaix (Eh vs pH) diagram for Np (top) and Pu (bottom) in water that contains hydroxide, carbonate, fluoride ions as the main coordinating ligands. The shaded areas represent stability regions of solid phases that precipitate from a 10 mol L Np or Pu. solution. Solid lines represent the stability (lelds for solution. sivcics. The oxidation state stabilities are cnclo.sed by the area of water. stability above the top line, water is oxidized to oxygen and below the bottom line, water is reduced to hytlrogen. 

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