Sulphur dioxide complexes

Structure and bonding of transition metal-sulphur dioxide complexes. R. R. Ryan, G. J. Kubas, D. C. Moody and P. G. Eller, Struct. Bonding (Berlin), 1981, 46, 48-100 (210). 

A new type of sulphur dioxide complex of the type [Ir(S02)(C0)(PPh3)2-(I—SO2)] has been reported from the treatment of [Ir(CO)(PPh3)2l] with SO2. Co-ordination of the SO2 to I is confirmed from the i.r. spectrum, and by analogy with the similar [Pt(PPh3)2 Mel —SO2] for which an X-ray analysis has been performed (see Table 8). This report provides a warning that SO2 may attach to sites other than the metal in metal complexes. ... 

P. Reich-Rohrwig, A. C. Clark, R. L. Downs, and A. Wojcicki, /. OrganometalHc Chem., 1978, 145, 57. Reaction of Na[Fe(CO)2(ij-C5Hs)] with sulphur dioxide. Synthesis of iron-sulphur dioxide complexes. 

Selenium dioxide,a triethylamine-sulphur dioxide complex, diphosphorus tetraiodide, and various phosphonyl halides and imidazoles have been recommended for dehydrating aldoximes to form nitriles. 

Elimination of sulphur dioxide from an S-bonded sulphinate complex is a process related to sulphur dioxide insertion. Kinetic studies on the rearrangement of the five-co-ordinate sulphinato-complexes (20) to the sulphur dioxide complexes (21) show that if the organic group R contains electron-withdrawing... 

Concentrated sulphuric acid is an oxidising agent, particularly when hot, but the oxidising power of sulphuric acid decreases rapidly with dilution. The hot concentrated acid will oxidise non-metals, for example carbon, sulphur and phosphorous to give, respectively, carbon dioxide, sulphur dioxide and phosphoric(V) acid. It also oxidises many metals to give their sulphates cast iron, however, is not affected. The mechanisms of these reactions are complex and the acid gives a number of reduction products. 

It is extensively used industrially as a catalyst, notably in the oxidation of sulphur dioxide to the trioxide in sulphuric acid manufacture. It is an essentially acidic oxide, dissolving in alkalis to give vanadates however, addition of acid converts the anionic vanadate species to cationic species, by processes which are very complex, but which overall amount to the following ... 

Atmospheric emissions of sulphur dioxide are either measured or estimated at their source and are thus calculated on a provincial or state basis for both Canada and the United States (Figure 2). While much research and debate continues, computer-based simulation models can use this emission information to provide reasonable estimates of how sulphur dioxide and sulphate (the final oxidized form of sulphur dioxide) are transported, transformed, and deposited via atmospheric air masses to selected regions. Such "source-receptor" models are of varying complexity but all are evaluated on their ability to reproduce the measured pattern of sulphate deposition over a network of acid rain monitoring stations across United States and Canada. In a joint effort of the U.S. Environmental Protection Agency and the Canadian Atmospheric Environment Service, eleven linear-chemistry atmospheric models of sulphur deposition were evaluated using data from 1980. It was found that on an annual basis, all but three models were able to simulate the observed deposition patterns within the uncertainty limits of the observations (22). 

Reactions of carbon subsulphide and of elementary phosphorus, sulphur and selenium with complexes of the platinum metals Sulphur dioxide insertion reactions of transition metal alkyls and related complexes... 

Wiberg has reviewed this oxidation and suggests that the complex of Mason and Kowalak is a mixed anhydride, cf. the oxidations of sulphur dioxide (p. 285) and formic acid (p. 316). The anhydride cannot be of neutral charge, however, as no acidity dependence is observed and a possibility is... 

Verhoef and co-workers suggested omitting the foul smelling pyridine completely and proposed a modified reagent, consisting of a methanolic solution of sulphur dioxide (0.5 M) and sodium acetate (1M) as the solvent for the analyte, and a solution of iodine (0.1 M) in methanol as the titrant the titration proceeds much faster and the end-point can be detected preferably bipoten-tiometrically (constant current of 2 pA), but also biamperometrically (AE about 100 mV) and even visually as only a little of the yellow sulphur dioxide-iodide complex S02r is formed (for the coulometric method see Section 3.5). 

There is another substitution reaction, not involving transition-metal complexes, namely, reaction of trifluoromethyl bromide with sulphur dioxide anion radicals (165) (Andrieux et al., 1990a) (this is an interesting route... 

According to G. Calcagni, 100 c.c. of a cold 66 per cent, of sodium hydroxide dissolves 24 55 grms. of sulphur or 57 parts of sulphur per 23 parts of sodium while 100 c.c. of a similar soln. of potassium hydroxide dissolves 17 70 grms. of sulphur, or 59 35 parts of sulphur per 39 15 parts of potassium. The soln. reacts for sulphides, polysulphides, thiosulphates, and sulphites. The reaction between alkali hydroxides and sulphur is complex probably sulphides are first formed from which thiosulphates are produced, and by the dissolution of more sulphur, polysulphides the thiosulphates Ipse part of their sulphur forming sulphites. In the more cone. soln. of sulphur part of the latter appears to be uncombined because these soln. yield sulphur to hot benzene. All the soln. are decomposed by carbon dioxide yielding sulphur and hydrogen sulphide. 

In the case of tin salts the action of sulphur dioxide is complex. In warm acid solution stannous sulphide is first precipitated and then yellow stannic sulphide mixed with sulphur. In highly concentrated acid solution, however, the sulphides are not precipitated, but hydrogen sulphide is evolved ... 

Another indication of tire unsaturated nature of sulphur dioxide is given by its action on the alkali iodides and thiocyanates. Complexes of the type MI.rS02 are obtained, where M is an alkali metal.4... 

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