Dithiolenes ligand formulas

Dithiolenes are best considered to be a resonance hybrid of the limiting structures (1)—(3). In both bis- and tris-dithiolenes the electron delocalization is not limited to the ligand, but includes the metals to give rise to cyclic delocalization ( aromaticity ). To symbolize this electron delocalization in dithiolenes, they can be represented, in a manner similar to that used for benzene, by formulas containing a ring inside the framework given by the metal, sulfur and carbon atoms. We will use this notation, shown in (4), throughout this chapter. 

In this chapter, the term dithiolene refers to a ligand of the formula R2C2S2, which depending on one s formalism could be described as an alkene-1,2-dithiolate dianion, a 1,2-dithione, or some oxidation state between these two extremes (Fig. 1). Benzenedithiolates, their derivatives, and analogues are also included. 

Several other tetranuclear iron-sulfur cluster compounds of general formula [Fc4S4X4]" ", in which X is a non-thiolate terminal ligand, have been studied in some detail. These include systems in which X = Cl, NO and dithiolene. The structure of the dianion [Fe4S4Cl4] " has been... 

A number of metal 1,2-dithiolenes, mainly corresponding to 1,3-dithioles of Class 0 (Table l),and selenium-, tellurium-, etc- anaIogs,have been described in refs [10]-[12] and refs therein. Recent work has been described in refs [48], [52], [54]. In this section we describe methods of preparation and properties of cation-rich salts of some metal 1,2-dithiolenes and selenium analogs, having ligands with additional heteroatoms (S,Se,N) to an additional ring or chain. These are compounds of the following formulas, ( QII)-(XXII),... 

---