Oxides, Sulphides, and Related Species

Oxides, Sulphides, and Related Species.— The kinetics of the formation of MgO in the diffusion zone of a flame [reaction (2)] have been studied at pressures up to 10 mmHg in the temperature range 773—1023 The reaction takes place in 

A simple M.O. model for bonding in MgO has been developed, using Mg404 (a cube with Mg and O atoms at alternate corners) as a basis. Extension to Mg320a2 

Surface states on MgO ° and CaO ° have been studied by u,v.— vis. and i.r. diffuse reflectance spectroscopy. The effect of outgassing (773—1073 K) is to develop u.v. absorption bands in the range 30 000—50 000cm . ° These bands have been attributed to absorptions at surface oxide sites in different states of co-ordinative unsaturation, the lower energy band corresponding to lower coordination. A theory has been developed for the surface centre in MgO the defect consists of an electron trapped at an anion vacancy on a (001) surface.  

The formation of Yb and of Eu in CaO has been established in diffuse reflectance spectroscopy experiments. Interest in these materials, which were produced by the reduction of M2O3 with Ca vapour, arises from their application as laser or photochromic materials.  

Single crystals of BaS2 have been obtained by heating 1 1 BaS S mixtures up to 1073 K in a graphite tube they are monoclinic, of space group C2/c, with unit-cell parameters a = 0.9299, h = 0.4736, c = 0.8993 nm, /3 = 118.37°. The 

The reactions of a number of atoms (H, F, O, S), radicals (OH), diatomic molecules (N2,02), and ions (He+,Ne+,H+,0 ) with these molecular species have been studied the systems examined are summarized in Table 11. Several reactions of CO with O, OH, 02, and O are included in Table 11  

Letters, 1974, 24, 516. 

A mass-spectrometric investigation of the ionic species present during both the oxidation of CO and the decomposition of C02 in an r.f. discharge has been undertaken.195 A particularly interesting feature is that C+ is one of the predominant ions an analysis of the reaction mechanism suggests that it is formed in reaction (37). Cross-sections for the production of 02 and C  

Photoionization of C02201 and C02-C0-02 mixtures202 has been studied by two groups of workers. In C02-C0 mixtures, interaction of C02 ions leads to the production of (CO)2 and [(C0)2C02]+ cluster ions photoionization of C02-C0-02 mixtures, however, yields mainly oxygen-containing 

Elements of Group IV clusters. Investigation of C0-02 mixtures also revealed reactions between Ol and CO. The role of impurity reactions involving H20 is considered in detail and the implications of all data to the vapour-phase radiolysis of C02 are discussed.202 A wide range of heteromolecular clusters containing CO and/or C02 together with S02, NO, or H20 has been found in isentropically expanding jets 203 the observed clusters and their formation conditions are summarized in Table 12. These clusters, particularly the hydrates, are of importance in atmospheric chemistry since favourable conditions for their formation are known to be present in jet-aircraft exhausts.203 

Derivatives of Group VI Elements.—Oxides Sulphides and Related Species. Following the pattern adopted in the previous Report, these simple species will be considered in order of increasing formal oxidation state. Carbon suboxide, C3O2, has been prepared by the reaction of chemically generated carbon atoms with carbon monoxide  

absorption spectra of matrix-isolated CO (in argon at liquid-helium temperatures) have been recorded as a function of deposition conditions and recording temperatures. Double-doping experiments have also been carried out with HgOjNHg, and Ng. The spectra were found to be extremely sensitive to experimental conditions, particularly to the presence of impurities it was concluded that, in generd, spectroscopic data associated with matrix-isolated species must be carefully examined to avoid confusion between absorption frequencies due to isolated solute molecules and those due to solute molecules interacting with small impurities such as water,  

A detailed high-resolution i.r. study of specific vibrations of the borine carbonyl species BH3—CO has been undertaken in an attempt to further an understanding of the bonding in the molecule. 

Dubost and L. Abouaf-Marguin, Chem. Phys. Letters, 1972, 17, 269. 

Finally, a study has been made of the i.r. chemiluminescence emitted from vibrationally excited CO, formed in the flash photolysis of N02-CSa and NOa-CSea mixtures according to the reaction sequence  

Matousek, A. Fojtik, and R. Zahradnik, Coll. Czech. Chem. Comm., 1975, 40, 1679. 

Although many spectroscopic studies of these molecules have been undertaken (Table 10), very few are of more than peripheral interest to the inorganic chemist. The most interesting is a C n.m.r. study of C3O2 in CDCI3 at -40 The data obtained are consistent with considerable oxonium ion character at C-1 and a high electron density at C-2, as represented by resonance structure (27).  

A major part of the research effort in this field is associated with the oxidation of The catalytic activity of Pd—Sn02, Fe203, and ZnO  

Jonsson, G. Karlstrom, and H. Wennerstrom, Chenu Phys. Letters, 1975, 30, 58. 

---

The kinetics of decomposition of certain inorganic oxides and sulphides and a few related compounds are reviewed in this chapter. Discussion is limited to the gas and liquid phase and to the reactions of neutral species. Accordingly, reactions in ionizing solvents have been excluded. The decompositions of the following compounds are considered C302, CO, C02, CS2, COS, CSe2, COSe, N20,... 

---