Tetrathiafulvalenes and Related Compounds

Tetrathiafulvalenes and Related Compounds. - Thermolysis of the l,l, 2,2 -tetrathiafulvalenes (227 = H, Me, or Ph) furnishes thienothiophens 

The bis-dithiolan (231), obtained from ethane-l,2-dithiol and 2,5-dihydro- 

5-dimethoxyfuran, forms a 1 1 ion-radical salt with tetracyanotetrafluoro- 

Voronkov, Khim. Geterotsikl Soedin., 1981, 329 (Chem. Abstr., 1981, 95, 42 963). 

Deselenation of compound (239) with triethyl phosphite yields the syn-tetraselenafulvalene (240), together with the znrz-isomer. A five-step synthesis of the tetratellurafulvalene (241) has been described. 

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TTF (tetrathiafulvalene) and related compounds have been the subject of intense interest in the materials chemistry community because of their semi-conduction and superconduction properties. Recently, TTF has emerged as a unique radical initiator because its radical cation can be easily formed. The ease of formation is presumably derived from the favorable structure of the radical cation that incorporates an aromatic disulfonium salt and a very delocalized radical [49a]. Murphy et al. demonstrated a novel one-pot reaction cascade... 

Table 5 Half-Wave Potentials for the Oxidation of Some Tetrathiafulvalenes and Related Compounds to the Corresponding Cation Radicals and Dications ... 

Dithioles, Diselenoles, and Ditelluroles 245 Tetrathiafulvalenes and Related Compounds 248 Pyrazoles 250... 

Dithiolo-l,2-dithioles, thermolysis and photolysis of 91PS(58)179. Structure of trithispentalenes and related compounds 91PS(58)17. Synthesis and properties of new functionalized tetrathiafulvalene jr-... 

Work on tetrathiafulvalenes (TTFs) and related compounds has continued at a high level. TTF itself has been used for reduction of silver nitrate to produce silver dendritic nanostructures... 

Dithiocarboxylic acids and related compounds yield both acyclic and cyclic adducts. A number of reactions of the type given in equation (153) , which may continue on to tetrathiafulvalenes , have been regarded as cycloadditions. Nevertheless equation (153) may be initiated, as equations (154)-(156) seem to be, by nucleophilic attacks. 

Similarly to tetrathioethylenes and tetrathiafulvalenes, 1,4-dithiin (LV) and its benzoder-ivatives (LVI and LVII) are electron-rich compounds that can be easily oxidized to their corresponding cation radicals and dications. There are several reviews [2, 3, 186, 187] on the chemistry of the radical cations of dibenzo-1,4-dithiin (LVH) and related compounds. 

Synthesis and applications of tetrathiafulvalenes and ferrocene-tetrathia-fulvalenes and related compounds as electroactive organic materials 05T3889. 

Tetracyanoquinodimethane (TCNQ) and related compounds [10], have been extensively investigated in the last decades. When combined with tetrathiafulvalene (TTF) and some metals such as Ag and Cu, it may show very useful properties such as electrical and optical bistability. However, to apply these organic thin films in electronic or photoelectric devices, it is of great importance that the films should exhibit few impurities and defects and it is also desired that the films crystallinity can be controlled. For these reasons, we explore an ionized cluster beam deposition method to fabricate organic crystalline thin films. 

Whereas the fulvalenes 1-6 are relatively unstable hydrocarbons and therefore largely of theoretical interest, their heteroatom analogs demand considerable attention in synthetic chemistry and material sciences. Tlie general principle of heterocyclic chemistry to relate heterocyclic compounds to carbocyclic ones was the driving force for the synthesis and their application to heteroful-valenes. Numerous heterocyclic derivatives iso-rr-electronic with, for example, heptafulvalene 3 were accessible in which pairs of carbon atoms linked by double bonds were replaced by heteroatoms capable of contributing two tt-electrons. By this principle, the well-known tetrathiafulvalene and its derivatives have been synthesized successfully (Scheme 2). 

Tetrathiafulvalene Derivatives and Related Organic Materials. - Wittig-type reactions and reagents continue to play an important role in this burgeoning field of research. Some examples of the types of compounds being prepared using these routes are illustrated here. 

MNDO calculations have been reported for the heterocycle (7) in order to predict its HOMO energy and ionization potential <89SM179>. Compound (7) is a derivative of tetrathiafulvalene (8) and sulfur-containing compounds related to heterocycle (8) are of intense current interest as organic metals. CNDO calculations on 3,6-dithioxo-l,2,4,5-tetrathiapentalene (9) have been reported and there is agreement between experimental and calculated 13C NMR data <84ZC418>. 

Generation of Alkyl Radicals. Murphy has utilized a closely related synthetic scenario for the nonreducing generation of alkyl radicals and, thereby, heterocyclic compounds as, for example, 29 (eq 5). In this sequence homolytic substitution at sulfur of a thioether 30 afforded an alkyl radical tetrathiafulvalene (TTF) served both as a source of electrons and, via its radical cation, as the initial radical trap (eq 5). 

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