1,2-Dithiolenes, ligands

Figure 6 Metal complexes based on 1,2-dithiolene ligands...

Dithiolene Ligands and Related Selenium and Tellurium Compounds... 

Scheme 2 Selected 1,2-dithiolene ligands and commonly used acronyms. All ligands have been drawn in their 1,2-dithiolato form...

This makes it difficult to assign clearly separated formal charges to the metal and to the ligand, which would not be meaningful as a consequence of the noninnocent nature of 1,2-dithiolene ligands.53,54 In Scheme 5, the case of neutral diamagnetic square-planar Zw(l,2-dithiolene) complexes is illustrated. 

Finally, it should be noted that tellurium can act not only as ligand donor site in 1,2-ditellurolene ligands, but can itself be bound by 1,2-dithiolene ligands, as in the case of compounds containing [Te(mnt)2]2 and [Te(dtsq)2]2 dianionic... 

Figure 9-7. The various oxidation levels which are possible in a 1,2-dithiolene ligand.

Only in recent decades has it become clear that inorganic molecule-based compounds can possess remarkable physical properties. These properties can be electrical, magnetic, or optical. One of the first typical examples is KCP (kalium tetracyanoplatinat, in German), K2[Pt(CN)4X0.3] /1H2O X = Cl, Br), which was prepared as early as 1842 (1, 2). This complex was shown to be a metal-like conductor more than a century later (3, 4). Likewise, but within a shorter period of time, the use of metal complexes of 1,2-dithiolene ligands (Scheme 1), first... 

The dithiolene ligands considered in this chapter are depicted in Scheme 1. 1,1-Dithiolene ligands form complexes with four-membered rings, 1,2-dithiolene ligands form complexes with five-membered rings, and 1,3-dithiolene ligands form complexes with six-membered rings (Scheme 2). 

Pt disk electrode10,22. In contrast to the gold 1,2-dithiolene complexes, only one redox couple has been reported for the complexes containing dithiocarbamates. The monocations reduce at less negative potentials than the neutral, mixed complexes. The 1/0 couple for [Au(12)2]+ is irreversible and is fairly insensitive to the substituents bonded to nitrogen. Similarly, in the mixed 1,1- and 1,2-dithiolene complexes, the 0/1 couple is more sensitive to the nature of the 1,2-dithiolene ligand rather than to the substituents on the 1,1-dithiolene ligand. 

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