Ozone reaction + metal atoms

Electronically excited metal oxides have been produced in the reactions of ozone with molecular beams of metal atoms, A,... 

Emissions from B02 [103], AsO, and SbO [103, 104] in an FPD flame have been used to detect organics or highly reduced species containing B, As, and Sb, respectively. These metal atoms react to form the same excited-state metal oxides discussed in their reactions with ozone above. These analytes have limits of detection measured to be approximately 50 ppbv, 10 ppbv, and 20 ppbv, respectively [93],... 

Matrix reactions of the alkali-metal atoms with ozone have been followed by i.r. spectroscopy. At 15 K, deposition of alkali-metal atoms and ozone at high dilution in argon produced very intense bands at 800 cm1 and weak bands at ca. 600 cm"1, which showed appropriate isotopic shifts for assignment to v3 and v2 of the 03 ion. There was evidence for a symmetrically bound cation to 03, with C2v symmetry. The symmetric interionic stretching mode was observed at 281 cm"1 for Cs+03. The reaction between these constituents produced the CsO fundamental at 322 cm"1 and CszO at 457 cm-1. Simultaneous photolysis using a mercury arc was required to yield the LiO absorption at 752 cm 1 from the Li-03-argon-matrix reaction.158... 

Sequence 16 clearly demonstrates electrophilic attack by ozone in these reactions. As noted by Jensen and Rickborn (2), the rate of electrophilic cleavage of a carbon-metal bond increases as the polarization of that bond increases. This, in turn, is a direct consequence of the electronegativity of the second atom attached to mercury. The following representations, based on Pauling electronegativity values, illustrate this relationship. 

Only fluorine, atomic oxygen and FgO have higher redox potentials. The gas oxidises moist sulphur to jH2S04, raises silver(I) compounds to the 2 state and converts olefinic compounds to ozonides. The reaction 2O3 -> SOg, which is catalysed by many metals and metal oxides, is exothermic and rapid above 200°. Gaseous ozone is deeper blue than oxygen it condenses at — 112° to a dark blue liquid which freezes at —193° to a dark purple solid. Surprisingly, the liquid is not completely miscible with liquid oxygen. 

An interesting way to bypass the electronic noncomplementarity of typical reactions between transition metal ions or complexes and dioxygen is based on an oxygen atom transfer from an oxygen allotrope, ozone. This approach was very successful in generating aqueous ferryl, an otherwise hardly accessible species71 ... 

Ozone is best prepared by flowing O2 at 1 atm and 25° through concentric metallized glass tubes to which low-frequency power at 50-500 Hz and 10-20kV is applied to maintain a silent electric discharge (see also p. 611). The ozonizer tube, which becomes heated by dielectric loss, should be kept cooled to room temperature and the effluent gas, which contains up to 10% O3 at moderate flow rates, can be used directly or fractionated if higher concentrations are required. Reaction proceeds via O atoms at the surface M, via excited O2 molecules, and by dissociative ion recombination ... 

A series of examples has become known recently, and more are reported in this volume, of catalytic reactions on oxide surfaces, involving electron transfer from reactant molecules to the catalyst, or vice versa. The general electronic concept of catalytic activation, first established for metals and alloys, has thus been extended to semiconductors. It appears certain that mobile quasi-free electrons or positive holes can migrate to the surface and can there bind reactant molecules in a charged or polarized state. This presupposes the presence of electrons in the conduction band (or of holes in the valence band), which in normal oxide semiconductors contains appreciable concentration of electrons only at elevated temperatures. Hence, the examples mentioned refer to high-temperature catalysis (N2O decomposition, CO oxidation). At ordinary temperatures, only those substances capable of releasing electrons from surface atoms or surface bonds, i.e., solid Lewis bases, are suitable as catalysts. This has been shown (I) to be true for the decomposition of ozone by various metal oxides. 

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