Oxygen, Sulphur, and Selenium

Photolysis of the 03/Brp complex leads to a new species which may be BrOBr.  

Photolysis of the sterically protected 1,2,3-selenadiazole (8) in the presence of a suitable olefin leads to the regloselective cycloadducts (9) R - CO Me, CN) via an initially formed zwitterionic intermediate.  

Rate constants for the reaction of hydrogen, methane, or ammonia with hydroxyl radicals generated by flash photolysis of water in the gas phase have been determined. 

The photoreactions of SOj in argon, nitrogen, or oxygen matrices at 12 K have been studied.Only in oxygen matrices are photoproducts (SO3) observed and it was demonstrated that the dimer (803)2, not monomeric SO2, was reactive. 

In the gas-phase photochemistry of both h (CH O and CH2(CH2)3SO the primary photoprocess appears to be rupture of a C—S bond to give a diradical that subsequently ejects SO. 

A very detailed laser-molecular beam study of the multi-i.r.-photon dissociation of SFg has been reported.The translational energy distribution and the dissociation lifetime of the excited SF have been studied as a function of the laser intensity and energy influence, and it has been demonstrated that the dissociation of the excited SFg (to SF5 and F) is in good agreement with the predictions of RRKM theory. 

The photo-induced cyclizations of the selenol esters (20) and (21) to give (22) and (23), respectively, have been described. Photolysis of benzyl phenyl selenide (24a) or of the phenyl ribosyl derivative (24b) yield the corresponding diselenides (25). The photoreduction of acetophenone by H2Se has been investigated.  

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Oxygen, sulphur and selenium are known to exist in more than one allotropic form. 

Another class of compounds, dihydrotellurophenes, exhibits antioxidant activity together with the oxygen, sulphur and selenium analogues. ... 

It ignites in fluorine and chlorine without the application of heat, and on gentle warming in the vapour of bromine, iodine, or phosphorus. It combines with oxygen, sulphur, and selenium at dull redness. 

The increasing reactivity with alkyl substitution in the acetylenes is very pronounced something in excess of a factor of 100 in relative rates at 298°K. This, it may be observed, is substantially greater than the factor of 20 between the reactivities of ethylene and 2-butene. Such large relative reactivity differences are rare in free radical reactions, and one realizes that the triplet sulphur atom must be very selective in its reaction with different olefins. A comparison of the behaviour of the triplet state atoms of oxygen, sulphur and selenium will be deferred until the end of the discussion of this whole group of atom additions. 

Our study shows that the trans form a is favoured over the other two in the case of oxygen, sulphur and selenium but not for tellurium for which the cyclic form b is the most stable one. The energy difference between the absolute and the relative minimum b decreases significantly in going from O3 to Sep, systems and becomes negative in the Te3 one. For O3H+ and S3H+ species the comparison is possible with previous ab-initio QCISD calculations [79,83]. The stability order of isomers is the same and the energy differences quite similar. 

In 1807 J.J. Berzelius (2), with Baron Hisinger as coauthor, published a paper based on the electrolysis of salt solutions. As a result of his extensive studies, he formulated an electrochemical series. He arranged 54 elements beginning with the negative elements oxygen, sulphur and selenium and concluding with the positive elements sodium and potassium. Berzelius version of the electrochemical series played an important and orientating role in the direction of the chemical research which was to follow. 

The methyleneamide II shows a remaikable chemical and elearochemical reactivity. It reacts directly with elemental oxygen, sulphur and selenium to give isocyanato-, isothiocyanato-, and isoselenocyanato- complexes, for example, irons - [Mo(NCS)Q(Ph2PCH2CH2PPh2)2] which has... 

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