INDEX oxidation states

This index is divided by element into eight parts. Each part is subdivided into sections devoted to each oxidation state, preceded by a general section. Thus if you want to fmd out about phosphine complexes of Rhodium, there is a general entry to phosphine complexes as well as separate references to phosphine complexes trader the headings of Rhodium(0), (I), (II) and (III). 

Entries where the oxidation state of a metal has been specified occur after all the entries for the unspecified oxidation state, and the same or similar entries may occur under both types of heading. Thus cyanide appears under Chromium complexes, Chromium(O) complexes, Chromium(I) complexes, etc. More specific entries, such as Chromium, hexacyano-, may also occur. Similar ligands may also occur in different entries. Thus a carboxylic acid-metal complex may occur under Carboxylic acid complexes, under entries for specific carboxylic acids, and under the specific metal. Coordination complexes may also be listed in the Cumulative Formula Index. 

The oxides of nitrogen collectively are oxidants with power increasing with oxygen content. Dinitrogen oxide will often support violent combustion, since its oxygen content (36.5%) approaches double that of atmospheric air. Nitrogen oxide and dinitrogen oxide are both endothermic and capable of detonation in the liquid state. Individually indexed oxides are ... 

These oxidations suffer from the fact that the high selectivities are only observed at low conversions (<7%). At higher conversions, the carboxylic acid products leach the transition metals out of the zeolite framework into solution where the selectivity index is much lower [63]. As these reactions proceed, the 3 -I- oxidation states of the metal ions return to their 2 -I- states, accompanied by their characteristic color change. In the case of MnAlPO-18, the spent catalyst (Mn ) was washed with methanol and reactivated in dry air at 550°C and successfully recycled (Mn Mn ) twice without appreciable loss of activity [64]. 

First things first, you need to understand the nature of elements, and their oxidation states (number of bonds). Every single element is capable of forming chemical bonds with other elements (with the exception of a few noble gases ). The oxidation states are what determines how many bonds a particular element can form, and to what other elements. When elements combine, they form chemical compounds. All of the atoms within a chemical compound show specific oxidation states. Oxidation states are not really states, but definitions of bonding, which are dictated by each individual element. Each element can form any where from either 0 to 7 bonds. These numbers represent the number of bonds the element can form (look at a modem periodic table, such that included in the Merck Index —the oxidations states are written in the upper left comer of each element). These numbers clearly indicate the number of bonds each element is capable of forming. 

Smith, D. W. Stability Index Diagrams Pictorial Representations of the Relative Stabilities of Oxidation States for Metallic Elements, J. Chem. Educ. 1996, 73, 1099-1102. 

Peroxide value, expressed as milliequivalents of peroxide per kilogram of oil, measures the primary oxidation products of oils— the hydroperoxides. The peroxide value has shown a particularly good correlation with sensory flavor scores of soybean oU, and its use during storage is quite common. The peroxide value is an index to the oxidative state of an oU. Soybean oU is considered fresh with a peroxide value <1.0 mEq/kg, to have low oxidation with 1.0-5.0 mEq/kg, to have moderate oxidation at 5.0-10.0 mEq/kg, to have high oxidation at > 10.0 mEq/kg, and to have poor flavor quality at >20 mEq/kg (6). Several methods (300-303) can be used to measure the peroxide value of an oil depending on the specific circumstance. 

Finally, in the case of a new material, the correctness of the ab initio indexing is only ensured by solving and refining the crystal structure, which makes both chemical and physical sense, i.e. has correct bond distances and angles, reasonable coordination polyhedra, oxidation states, etc. 

Polymerization mechanisms for polyaniline have been proposed in the literature [45, 46], Figure 2 illustrates some of the basic steps occurring during polymerization of aniline. The oxidation states of PANI, and of polyanilines in general, are indicated by an index for the degree of oxidation (Y). It is in its completely reduced form (leucoemeraldine) when Y = 1, and its completely oxidised form (pemigraniline) is dominant when Y = 0. At Y = 0.5, the 50% intrinsically oxidized polymer (emeraldine) is ambient [49, 50], The molecular structures of the different forms (oxidation states) of PANI are illustrated in Figure 1. 

The right lower position of an atomic symbol is reserved for an index (subscript) indicating the number of such atoms in a formula. For example, Sg is the formula of a molecule containing eight sulfur atoms (see Section IR-3.4). For formalisms when oxidation states or charges are also shown, see Section IR-4.6.1. 

When the overall oxidation state of a system is desired, unless a water is obviously anaerobic (e.g., it has an H2S odor) one should first attempt to measure dissolved oxygen as an index of system redox state. Eh measurements are unlikely to be stable and thermodynamically meaningful in surface-waters, except in acid waters (where ferrous and ferric species are usually present). Eh measurements may be stable and meaningful in anaerobic sediments or groundwaters, when species of iron, sulfur, and manganese dominate the redox chemistry, but otherwise are of qualitative value only. 

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