Molecular conductors single-component

The coordination of redox-active ligands such as 1,2-bis-dithiolates, to the M03Q7 cluster unit, results in oxidation-active complexes in sharp contrast with the electrochemical behavior found for the [Mo3S7Br6] di-anion for which no oxidation process is observed by cyclic voltammetry in acetonitrile within the allowed solvent window [38]. The oxidation potentials are easily accessible and this property can be used to obtain a new family of single-component molecular conductors as will be presented in the next section. Upon reduction, [M03S7 (dithiolate)3] type-11 complexes transform into [Mo3S4(dithiolate)3] type-I dianions, as represented in Eq. (7). 

At the turn of this century it was realized that carrier generation was also possible between the HOMO and LUMO band even in neutral single-component materials assuming that there was a small HOMO-LUMO gap and conduction paths have been associated with the presence of large transverse intermolecular interactions. The most relevant examples of single-component molecular conductors are the mononuclear M(dithiolate)2 (M = Co, Ni, Cu, Au) complexes with... 

Molecular conductors at the first stage were single component systems. For example, the conduction band in KCP is a one-dimensional dz band. TTF-TCNQ has a HOMO band of TTF and a LUMO band of TCNQ, but both of them are one-dimensional pure -ir bands. Recently, however, increasing number of interesting systems which have two bands with different characters near the Fermi level have been reported for example, the DCNQI-Cu salt with tt and (itinerant) d bands, Pd(dmit)2 salts with a two-dimensional HOMO band and a one-dimensional LUMO band, the organic superconductor (TMET-STF)2BF4... 

The first molecular metal based on single component and electrically neutral metal complex, [Ni(tmdt)2] (tmdt = trimethylenetetrathiafulva-lenedithiolate. Figure 4.17) was reported in 2001. Details of this compound and some other single component molecular conductors are given in Section 4.3.4 and in several review articles. 

Figure 4.27 Schematic figures of the mechanism to generate conduction carriers in single-component molecular conductors...

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