Tetraselenafulvalene cation-radicals

Cyclic voltammetry on the cation 192 was not reversible attempted reoxidation of the reduction product of 192 produced the cation-radical of the tetraselenafulvalene 193. Apparently, the initially formed radicals dimerize rapidly with elimination of the SeEt groups at ambient temperatures. The cation-radical of 193 and various substituted derivatives have been reported,As with the sulfur analogs (see Section III,B,7,b), no comprehensive survey of the solid-state properties of these materials is attempted. In general, it is found that 193 and its derivatives, although rather more difficult to oxidize than tetrathiafulvalene counterparts, nevertheless do form electrically conducting salts and complexes. 

The only radicals to have been reported in this category are mentioned in work previously cited the transient existence of 197 (X = S, Se) has been inferred from electrochemical measurementsthe cis and trans isomers of dithiadiselenafulvalene have been oxidized anodically to cation-radicals in acetonitrile and the electrochemical characteristics compared with those of tetrathia- and tetraselenafulvalene. ... 

The structure of the 1,3-diselenolylium ion has been investigated for radical-cation salts of tetraselenafulvalenes, materials useful as organic conductors and semiconductors. These compounds are discussed in Chapter 1.13. 

Scheme 4 Rearrangement pathway from tetraselenafulvalene radical cation to l,3-diselenole-2-selenone radical...

Tetraselenafulvalene and tetrathiafulvalene derivatives in conducting organic radical cation salts with organic and organometallic anions 04CRV5203. 

Like their sulfur analogues, tetraselenafulvalenes and the mixed sulfur/selenium systems are excellent electron donors which are able to form radical cation salts and charge transfer complexes with appropriate electron acceptors. 

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