1.2- Dithiole-3-thiones conductivity

The donor-acceptor complex (TTF)[Pt(dmit)2]3 (dmit = 4,5-dimercapto-l,3-dithiol-2-thione) and its Group 10 congeners have been reported, and their electrical conductivities have been... 

Bulk crystalline radical ion salts and electron donor-electron acceptor charge transfer complexes have been shown to have room temperature d.c. conductivities up to 500 Scm-1 [457, 720, 721]. Tetrathiafiilvalene (TTF), tetraselenoful-valene (TST), and bis-ethyldithiotetrathiafulvalene (BEDT-TTF) have been the most commonly used electron donors, while tetracyano p-quinodimethane (TCNQ) and nickel 4,5-dimercapto-l,3-dithiol-2-thione Ni(dmit)2 have been the most commonly utilized electron acceptors (see Table 8). Metallic behavior in charge transfer complexes is believed to originate in the facile electron movements in the partially filled bands and in the interaction of the electrons with the vibrations of the atomic lattice (phonons). Lowering the temperature causes fewer lattice vibrations and increases the intermolecular orbital overlap and, hence, the conductivity. The good correlation obtained between the position of the maximum of the charge transfer absorption band (proportional to... 

LB films prepared from tridecylmethyl-ammonium Au-(dmit)2 and H2dmit = 4,5-dimercapto-l,3-dithiol-2-thione, transferred to hydrophobized glass substrates, and oxidized (by Br2 or electrochemicaily) Absorption spectra and temperature-dependent conductivity measurements... 

Ethylenedioxypyridino[4,5-fi]tetrathiafulvalene (561) has been prepared as an example of an unsymmetrical rt-donor capable of electron conduction. The compound (561) was prepared via crosscoupling l,3-dithiolo[4,5-fi]pyridin-2-one (560) with 4,5-ethylenedithio-3,l-dithiol-2-thione (559) by heating in triethylphosphite at 150°C for 5 h (Equation (51)). The reaction afforded the desired product (561) (6%) together with the self-coupled products (562) and (563) <90ZN(B)1216>. 

Coupling can also occur via a substituent, as for 1,2-dithiol-3-thiones, which are anodically oxidized to bis(dithiolyium)disulfides [48]. The related a-(l, 2 -dithioT3 -ylidene)acetophenones 16 are analogously oxidized to a di-cation (17) that de-protonates to give the uncharged dimer 18. When, however, the electrolysis was conducted in the presence of an oxidant such as DDQ, or by further oxidizing dimer 18, a new di-cation (19) was formed (Scheme 14) [49]. 

Many different chemical modifications have been carried out on the TTF skeleton to prepare building blocks for macro- and supramolecular systems of increased electrical conductivity. Direct selective functionalization of the TTF structure is usually a problem, because of its D h symmetry with four identical attachment sites. Therefore, versatile TTF building blocks have been developed and many problems concerning the selective functionalization of TTFs have been solved. For instance, the potential building block 673 was prepared in quantitative yield starting from the l,3-dithiole-2-thione 667 via intermediates 668-672 (Scheme 95) <1999S803>. 

The conductivity of a series of l,2-dithiole-3-thiones has been measured both in solution and in the solid state. Conductivities were found to be in the range of l(Tl4-10-15 ohm-1 reflecting an electronic tunneling effect. Dipole moments were given too.292... 

The complex [Ni(dmit)2](But4N)o,29 (292) (dmit = 4,5-dimercapto-l,3-dithiole-2-thione anion) has been obtained % the oxidation of the monoanionic complex with bromine. The conductivity of this compound is 10 S cm at 300 K. 

Amphiphilic TTF derivatives were easily obtained by either (1) cross coupling the corresponding thiones and/ or ketones of 1,3-dithiol compounds or (2) direct substitution of TTF skeletons. The LB films of these materials were prepared with or without matrix molecules and became conductive by doping with iodine or other oxidants. 

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