Multi-TTFs

The solution electrochemical redox behavior of systems 34, 35, and model multi-TTFs has been studied. For compound 34 two redox couples typical of the TTF system were observed at and = 0.43 and 0.81 V, respectively (vs. 

Synthesis of TTF-phenanthroline macrocycles (e.g., 13) were accomplished in a simple multi-step sequence the macrocyclization procedure was from the 2,9-di(p-hydroxyphenyl)-1,10-phenanthroline with TTF-diiodide under high dilution conditions in the presence of CS2CO3 <00CC215>. 

Nakano Y, Balodis K, Yamochi H, Saito G, Uruichi M, Yakushi K (2008) Isotope effect on metal-insulator transition of (EDO-TTF)2XFs (X = P, As) with multi-instability of metallic state. Solid State Sci 10 1780-1785... 

Lorenc M, Moisan N, Servol M, Cailleau H, Koshihara S, Maesato M, Shao X, Nakano Y, Yamochi H, Saito G, Collet E (2009) Multi-phonon dynamics of the ultra-fast photoinduced transition of (EDO-TTF)2SbF6. J Phys Conf Ser 148 012001/1-4... 

This chapter provides an overview of recent syntheses, redox properties, and electronic structures of the multi-redox system of TTF or DT rings in cross-conjugation. 

Quite recently, fused TTF analogs having one or two [5]radialene unit(s) 40—42 have also been prepared (Figure 8.18), because the extended TTF moieties are of interest as multi-redox systems, components for molecular conductors, positive electrode materials for rechargeable batteries, and so on [48]. 

Almost a decade ago the first molecular superconductors based on the transition metal complex molecule (TTF)[Ni(dmit)2]2 was discovered (TTF = tetrathiafiilvalene, dmit = isotrithionedithiolate) [ 1 ]. Since then several M(dmit)2 superconductors have been found. Although most of the molecular metals currently studied are systems based on multi-sulfur (or selenium) 71 molecules, the first example of a metallic molecular crystal was a partially oxidized platinum complex. The discovery of the partially oxidized platinum complex is very old, about 150 years ago, but the physical meaning of the system had not been noticed until the crystal structure (by Krogmann and Hausen) revealed the existence of the extended linear Pt-Pt metal bonds [2]. The diffuse X-ray scattering experiments on this system (K2[Pt(CN)4]Bro.3 3H2O) by Comes et al. [3] convinced many people, who were interested in conducting crystalline molecular solids at that time, of the existence of one-dimensional metal electrons in molecular crystals for the first time, and so a new era of metallic molecular systems had been bom. 

As mentioned in Section 1, similar to BEDT-TTF, M(dmit)2 molecules are members of a family of multi-chalcogen % molecules. The concepts of the molecular design used in the development of the organic metals are also valid for the M(dmit)2 conductors. Owing to the resemblance in the molecular structures, M(dmit)2 molecules tend to form two-dimensional S S networks in the crystalline state similar to those of BEDT-TTFs. In the case of the M(dmit)2 complex containing peripheral chalcogen n donor molecules, such as TTF, even three-dimensional S S networks can be formed [18]. 

It has been more recently proposed, on the basis of band structure calculations including HOMO bands, that both the LUMO and the HOMO bands of the Ni(dmit)2 acceptor molecules are partially filled and also that the multi-Fermi surface of the TTF[Ni-(dmit)2]2 system exhibits some two-dimensional character at the F point of the Brillouin zone [19]... 

H NMR relaxation data and low- and high-resolution C NMR studies on TTF[Ni(dmit)2]2 have been reported [24]. The results confirm the occurrence of both HOMO and LUMO conduction bands. The CDWs above 160 K are associated with the LUMO bands. Thermopower studies show there is an inversion in the sign of the carriers, holes becoming the dominant carriers [25]. Usually the onset of a CDW state induces a metal-to-insulator transition in a molecular lowdimensional conductor. This is not observed in TTF[Ni(dmit)2]2, which remains metallic at ambient pressure down to low temperature. This is explained by the multi-Fermi surface system of the Ni(dmit)2 stacks consisting of HOMO and LUMO bands. The CDW instability could open a gap in only some of these bands, leaving the other bands unaffected, so some metallic bands will remain. 

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