Oxo anion

The performance of many metal-ion catalysts can be enhanced by doping with cesium compounds. This is a result both of the low ionization potential of cesium and its abiUty to stabilize high oxidation states of transition-metal oxo anions (50). Catalyst doping is one of the principal commercial uses of cesium. Cesium is a more powerflil oxidant than potassium, which it can replace. The amount of replacement is often a matter of economic benefit. Cesium-doped catalysts are used for the production of styrene monomer from ethyl benzene at metal oxide contacts or from toluene and methanol as Cs-exchanged zeofltes ethylene oxide ammonoxidation, acrolein (methacrolein) acryflc acid (methacrylic acid) methyl methacrylate monomer methanol phthahc anhydride anthraquinone various olefins chlorinations in low pressure ammonia synthesis and in the conversion of SO2 to SO in sulfuric acid production. 

The oxo-anions of chlorine are weaker oxidants than the corresponding acids. Because they are also more stable, it is not too difficult to isolate certain salts of those acids that can be obtained only in aqueous solution. Hypochlorites and chlorites are hydroly2ed in aqueous solution since HOCl and HCIO2 have acid dissociation constants of 10 and 10 , respectively however, aqueous chloric and perchloric acids are hiUy iorrhed. 

SORPTION-SPECTROPHOTOMETRIC AND VISUAL TEST-DETERMINATION OF OXO-ANIONS OF IODINE AT THE SILICA GEL MODIFIED BY QUATERNARY AMMONIUM SALTS... 

There are notable differences in both structures and stabilities for binary N-O and S-N anions (Section 5.4). The most common oxo-anions of nitrogen are the nitrite [N02] and the nitrate anion [NOs] the latter has a branched chain structure 1.1. The sulfur analogue of nitrite is... 

This review deals with the chemistry and coordination complexes of isoelectronic analogues of common oxo-anions of phosphorus such as PO3, POl", RPOl" and R2POy. The article begins with a discussion of homoleptic systems in which all of the 0x0 ligands are replaced by imido (NR) groups. This is followed by an account of heteroleptic phosphorus-centered anions, including [RN(E)P(/<-NR )2P(E)NR]2-, [EP(NR)3]3-, [RP(E)(NR)2] and [R2P(E)(NR )] (E=0,S, Se, Te). The emphasis is on the wide variety of coordination modes exhibited by these poly-dentate ligands, which have both hard (NR) and soft (S, Se or Te) centers. Possible applications of their metal complexes include new catalytic systems, coordination polymers with unique properties, and novel porous materials. 

An examination of the data for oxo acids82( Table 10) shows that the factors leading to stabilization of the oxo anions and thus to a decrease of -AGq, (A-) and AG°cid (AH) can be expressed by a few simple rules stated in order of decreasing importance ... 

The number of equivalent oxygens over which the negative charge in the oxo anion is delocalized. 

These rules will be illustrated by a few examples. The oxo anions of phosphorous show the following hydration energies (kcal/mol) ... 

Suzuki, T. M., Tanaka, D. A. P., Tanco, M. A. L., Kanesato, M., H., Yokoyama, T., Adsorption and removal of oxo-anions of arsenic and selenium on zirconium(IV) loaded polymer resin functionalized with diethylenetriamine-N, N,N ,N -polyacetic acid, J. Environ. Monit., 2, 2000, 550-555. 

There are many simple examples of common covalently bonded oxo-anions, some being CO NO3. SOj and PO4 The carbonate... 

ArmentroutPB (1999) Gas-Phase Organometallic Chemistry. 4 1-45 Astruc D, Daniel M-C, Ruiz J (2006) Metallodendritic Exo-Receptors for the Redox Recognition of Oxo-Anions and Halides. 20 121-148 Aubert C, Fensterbank L, Gandon V, MalacriaM (2006) Complex Polycyclic Molecules from Acyclic Precursors via Transition Metal-Catalyzed Cascade Reactions. 19 259-294... 

Finally we should mention that the cationic influences are greater on oxo-anion than on pure or mixed thio- or selenoanions. 

EdsalP has presented a cogent analysis of the various rates of hydration and dehydration, including the ability of oxygen acids to catalyze these reactions. See Oxygen, Oxides Oxo Anions... 

The properties of this odorless and extremely poisonous diatomic gas are described under Oxygen, Oxides Oxo Anions. 

The vanadium oxide V04 [conjugate base of the acid V03(0H) ] that adopts trigonal bipyramidal geometry and acts as a transition-state mimic for in-hne phosphoryl transfer enzymes. See Oxygen, Oxides, Oxo Anions... 

The strong hydration of halide ions in water is partly due to outer-sphere effects. Oxo anions in aqueous solution may complex with outer-sphere water molecules as in the hydrated chromate and permanganate ions ... 

Praesodymium salts containing oxo anions such as sulfate, hydroxide, carbonate, silicates, oxalate, thiosulfate, chromate, molybdate, and borate are known. 

Ochs, M., Lothenbach, B. Giffaut, E. 2002. Uptake of oxo-anions by cements through solid-solution formation experimental evidence and modelling. Radiochimica Acta, 90, 639-646. 

The more exact forms of the aqueous cations, with their primary hydration shells, are normally omitted from the diagrams. As is the case with Crvl, which in acid solution exists as the dichromate ion, Cr2072-, the forms of any oxo anions are indicated by their formulae in the diagrams. The diagram for chromium summarizes the following important properties ... 

The largest known discrete lithium amide stracture, the tetradecameric [Lii4(O)(N(H)-(C5H9))i2] cage was synthesized in the presence of water it has a central oxo-anion. Fig. 2.2 highlights the Li 14N12O metal-heteroatom core. 

The Structural principles of the elements can also be found in a number of ternary Zintl phases. For example, KSnSb contains (SnSb ) layers as in a-arsenic. In other ternary ZiNTL phases the anionic part of the structures resembles halo or oxo anions or molecular halides. For example, in Ba4SiAs4 there are tetrahedral SiAs particles that are isostructural to SiBr4 molecules. In Ba3AlSb3 dimeric groups Al2Sbg2 are present, with a structure as in A Clg molecules (Fig. 13.4). Ca3AlAs3 contains poly-... 

Table 11 Borates with Oxo-anion Ligands and their Preparation...

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