Tetraselenafulvalene derivatives

A series of papers describing detailed studies on dibromo- and diiodo-dithiadiselenafulvalene and tetraselenafulvalene derivatives has appeared including examples such as 54 <06JMAC4110>, 55 <06JMAC3381>, 56 and 57 <06JMAC162> and 58... 

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. 

New trends in the synthesis of tetraselenafulvalene and tetrathiafulvalene derivatives as 7i-electron donors for molecular conductors and superconductors 04CRV5057. 

Tetraselenafulvalene and tetrathiafulvalene derivatives as organic conductors with unusual band fillings 04CRV4947. 

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

Usually, coupling of a selone gives better yield than use of the corresponding thione transformation of a thione into the selone can be done (as shown in Scheme 21) from a 2-alkylthio-l,3-diselenolylium cation (100) as the example demonstrates <83JOC47i3>. Although coupling of the 1,3-dithiole-2-selone did give the expected TTF derivative, the tetraselenafulvalene (102) was only formed in trace amounts. 

Organic Conductors Derived from Substituted Tetraselenafulvalenes (Abstract only) 315... 

ORGANIC CONDUCTORS DERIVED FROM SUBSTITUTED TETRASELENAFULVALENES... 

Tetrathiafulvalenes.—Preparations of ever more elaborate compounds of this class have been announced. Coupling of the dithiolethiones (293 n = 2 or 3) by means of triethyl phosphite affords the tetracyclic derivatives (294) °° mixtures of the dithioleselones (295) and (296) give good yields of the crossed product (297) in this reaction.The tetraselenafulvalene (299) is obtained by photolysis of 3,4-diphenyl-l,3-diselenole-2-thione (298). Even cyclophanes containing the tetrathiafulvalene structure have been reported thus compound (300), on sequential treatment with methyl iodide, sodium borohydride, and fluoroboric acid-acetic anhydride, affords a mixture of the tetrathiafulvalenophanes (301) and (302), ° and the paracyclophanes (304) and (305) result from the para-substituted benzene (303). 

Replacement of the four sulphur atoms of TTF by four selenium atoms leads, in the TCNQ complex, to enhanced metallic behaviour. The required tetraselenafulvalene (56 R = H, X = Se) was prepared by deselenization of l,3-diselenole-2-selone a convenient alternative route has been described. Similar methods have been used to prepare tetramethyltetraselenafulvalene (56 R = Me, X = Se) (which forms two salts with TCNQ, one a red insulator and the other a black conductor), a series of similar derivatives, and a tetrakis-methylselenotetraselenafulvalene (56 R = MeSe, X = Se). ... 

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