Oxides of transition metals

Trimethylchlorosilane TCS 14 readily transforms metal oxides such as ZnO, MgO, MnO, BeO, AI2O3, or Ti02 and oxides of transition metals such as SmO or Iu203 into the corresponding reactive anhydrous chlorides and volatile HMDSO 7 (b.p. 100°C) (Scheme 13.6). 

Photoseni bilization - induced formation of singlet oxygen on the surface of deposited oxides of transition metals... 

The formation of singlet oxygen through the Kautsky mechanism [78] was observed not only when sensibilization was induced by adsorbed dye molecules but also in case when sensibilization was provided by deposited oxides of transition metals [92, 93]. This is very important for understanding numerous heterogeneous and photocatalytic processes. 

M.V. Yakunichev, Photostimulated Emission of Singlet Oxygen from the Surface of Deposited Oxides of Transit Metals (Photocatalysts), PhD Thesis, Moscow, 1986 (in Russian)... 

The kinetic parameters characterizing the oxidation of transition metal ions by dioxygen are collected in Table 10.8. 

Rate Constants of Oxidation of Transition Metal Ions by Dioxygen... 

The most important phosphors are sulphides and oxides of transition metals. The sulphides of zinc and of cadmium are the most important materials of the sulphide type. An important condition of achieving a highly efficient phosphor is to prepare a salt of the highest possible chemical purity. The emission of zinc sulphide can be shifted to longer wavelengths by increasingly replacing the zinc ions with cadmium. 

Oxides of transition metals can act as acid-base or redox catalysts. Oxides of non-transition metals (AI2O3, SiOj) are, however, good acid-base catalysts. There is a large family of aluminosilicate zeolitic acids (e.g. H -ZSM-5, H-mordenite). Micropor-ous aluminium phosphates (ALPOs) can be modified to yield acidic SAPOs (Si replaces... 

As before, however, this oxidation process need not stop at this surface stage. Indeed, nickel oxide, as can many other oxides of transition metals, can accommodate a stoichiometric excess of oxygen in the bulk crystal (33). While the amount of this excess is not particularly large as compared... 

At the beginning of 1950, Professor A. Magneli s group in Sweden started a systematic study of the crystal structures of the oxides of transition metal elements such as Ti, V, Mo, and W, mainly by X-ray diffraction techniques. 

The performance of a number of single oxides of transition metals was studied by Skorbilina et al. [295] using a differential reactor. As usual, o-tolualdehyde, phthalic anhydride and carbon oxides are the main reaction products. The initial selectivity with respect to partial oxidation products decreases in the order Co > Ti > V > Mo > Ni > Mn > Fe > Cu from 71% to 33%. The relatively high initial selectivities demonstrated by the deep oxidation catalysts (e.g. Co, Ni, Mn) indicates that the primary activation is probably the same for all these catalysts, while the differences that actually determine the character of the catalyst are connected with the stability of intermediates and products. 

Mixed Metal Oxide Pigments. The starting material is a Ti02 hydrolysate, which is calcined with oxides of transition metals to form chromium rutile or nickel rutile pigments (see Section 3.1.3.1). 

Oxides of transition metals exhibit more complex add-base properties that may depend on the oxidation number of the metal. 

Again, in the oxidation of transition-metal ions, adducts have been established as intermediates [e.g., reaction (35) O Neill and Schulte-Frohlinde 1975 Asmus et al. 1978 for the equilibrium of Tl2+ and OH, see Schwarz and Dodson 1984],... 

The autoxidation of aqueous solutions of sulfur dioxide (sulfite, bisulfite) is a classic problem in chemistry. Basic features of this reaction have been known since early in this century, when it was established that the reaction is trace metal ion catalyzed (1 ) and most likely involves free radicals (2). Certain chemical effects associated with sulfite autoxidation were noted also. Before the turn of the century, it was noted that sulfite would induce the oxidation of transition metal ions (3) and it was reported later that the oxidation of organic compounds was brought about during sulfite autoxidation ( 0. Conversly, organic compounds were also shown to serve as inhibitors of sulfite autoxidation (5). 

Oxides of transition metal compounds need special consideration for CFSE since d-electrons are involved in chemical bonding. Then Eq. 25 may be written ... 

Oxidation of transition metal ions in sedimentary processes Under the relatively oxidizing environments existing near the Earth s surface provided by aerated aqueous solutions in contact with the atmosphere, several... 

The electrical behaviour of some oxides of transition metals (belonging to fourth period) is given in following table. It may be noted that these oxides show wide variation in their electrical behaviour. 

Magnetic behaviour of some oxides of transition metals are given in table below. 

Supported oxides of transition metals, particularly of groups Vb (V), VIb (Cr, Mo, W) and Vllb (Re) are widely used as catalysts or catalyst precursors for vari-... 

J. B. Torrance, P. Lacorre, C. Asavaroengchai, and R. M. Metzger, Simple and perovskite oxides of transition metals Why some are metallic, while most are insulating, J. Solid State Chem. 90 168-172 (1991). 

One-electron oxidations of transition metals by organic halides can take two forms, which result in either metal-carbon bond formation ... 

A different group consisting generally of supported oxides of transition metal elements from Groups V-VII of the periodic table are used to produce linear polyethylene. 

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