Diselenols

In an analogous fashion the oxidative coupling of 1,3-diselenols is used for the preparation of 1,2-diselenolanes, the precursors being obtained by a variety of methods (see Chapter 4.35). Similar reaction s have been used for the preparation of 1,2-thiaselenolanes. Substituted propane-1,3-diselenones (287) are oxidized by halogen to the corresponding 3,5-diamino-l,2-diselenolylium chloride (288) (67AJC1991). 

Condensation of dicesium 2-thioxo-l,3-dithiole-4,5-diselenolate with fo/s-alkylating polythioethers under high dilution conditions afforded the TTF-containing macrocycles possessing soft donor sites and 12-, 15-, and 18-membered rings <%JCS(P1)1995>. 

The synthesis of halogenated TTF is most often based on the lithia-tion/electrophilic halogenation of either the TTF core itself [50] or the five-membered l,3-dithiole-2-thione [36,51]. This procedure has been recently expanded to the analogous l,3-diselenole-2-thione [52,53], allowing for the formation of a wide variety of iodo- and bromotetraselenafulvalenes or dithiadiselenafulvalenes shown in Schemes 6 and 7. 

Insertion of a C=0 or C=S group between two thiol or two selenol functions of a 1,2- or 1,3-dithiol or diselenol results in formation of the corresponding five- or six-membered heterocycles. 

Several substituted title salts, intermediates in the preparation of 1,3-diselenole-2-selenones, exploded on heating, ignition or shock. The tetrafluoroborate salts were stable, safe intermediates for large-scale application. Individually indexed compounds are ... 

One of the rare examples in which selenium is involved as a donor atom results from the reaction of Tc-gluconate with 2 equivalents of l,l-dicyanoethene-2,2-diselenolate (dcds), which gives the selenium analogue of (87), [TcO(dcds)2], in 50% yield. The complex was structurally characterized and shown to be square pyramidal, with Tc— Se averaging 2.474 A and the Tc 0.88 A above the basal plane. ... 

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