Selenides and Diselenides

Because organic selenides and diselenides are regarded as some of the most im- 

Unsymmetrical organic selenides, on the other hand, can be obtained by the 

---

Table 15 Oxidation potentials and peak potentials of selenides and diselenides...

A similar reduction of selenium with a metal naphthalenide provides an in situ synthesis of alkali metal selenides and diselenides.3... 

Reduction of elemental selenium with Sml2 leads to the selective formation of Se and Se depending on the reaction stoichiometry, similar to the reduction with NaBH4 and hydrazine (Sects. 2.2.2 and 2.2.3). These inorganic dianions react with alkyl bromides to produce dialkyl selenides and diselenides, respectively, in excellent yields (Scheme 15) [17a]. 

The data of Table 6 ), determined by internal cahbration on polycrystalline materials show the expected increase in covalency from oxide to sulphide ( 2x) and from sulphide to telluride. The sulphide, selenide and diselenide are all seen... 

In addition to the selective synthesis of selenides and diselenides, symmetrical dialkyl tellurides [5a, 47-49, 50a, 58] and ditellurides [48a, 51a, c, 59] can be prepared with high selectivity by alkylation of Na2Te and Na2Te2, respectively, with alkyl halides (Scheme 15.20). 

Selenides and diselenides. By manipulation of reaction conditions it is possible to prepare either RSeR or RSeSeR. ... 

The synthesis of hexamethyldisilathiane from sodium sulfide and chloro-trimethylsilane is described here. The present method is based on the convenient in situ syntheses of alkali metal selenides and diselenides. Commercial sodium sulfide or lithium sulfide are reported to be poor substitutes for in situ generated sulfides in this reaction. For example, in 1961 Abel reported that disodium sulfide reacts with chlorotrimethylsilane in pressure vessels at 250°C for 20 h to produce I. Our procedure is very convenient, utilizing readily available starting materials and apparatus under mild conditions. The yields are t3q)ically 80-88% at 0.3-mol scale. However, it can be improved to 90-95% on small scale ( 50-mmol) reactions. This procedure can be applied to the synthesis of various disilathianes. 

The Ramberg-B cklund reaction of a-halo-sulphones to give olefins is a versatile reaction, and the use of phase-transfer catalysis permits far more diverse functionality to be incorporated in the starting materials (Scheme 14). The related extrusion of selenium from selenides and diselenides by pyrolysis to give dibenzyl olefins and related compounds has been studied by Misumi s group. ... 

A number of halogenated methanes and 2,2,2-trifluoroethanol have been found to exert solvent effects up to 48 Hz on the Se chemical shifts of some dialkyl selenides and diselenides (R-Se-R and R-Se-Se-R R = Me, Et and Pf) these were interpreted in terms of an intermolecular polarizability concept (88Lut). 

---