Dithiolene metal complexes

Keywords Donor type metal complexes, Metal dithiolene complexes, Molecular conductors, Organometallic complexes, Unsymmetrical metal complexes... 

General Features of Unsymmetrical Components Based on Organometallic Metal-Dithiolene Complexes... 

The nonplanar nature of 11 hinders intermoleeular contacts between the metal dithiolene complexes. Thus, there are few intermoleeular interactions between the anions within [Et4N][ll], although short C-H -S contacts of 2.906 A are observed between the pendent thiophenes of neighboring anions (Figure 13A). In contrast, the more planar structure of 12 allows significant jt stacking of the complexes to form columns with a face-to-face distance of 3.7 A (Figure 13B). ... 

A wide range of metal dithiolene complexes have been prepared and their electrical conduction properties reported.111-114 They include neutral, monoanion and dianion complexes with a variety of substituents on the ligand (R = Ph, Me, CN, H, CF3) and a variety of cations. The choice of cation has often been determined by the desire to obtain easily crystallized products and has resulted in the use of rather bulky substituted ammonium salts. The compounds behave as semiconductors with relatively low conductivities at room temperature. It has been shown that the monoanion complexes are considerably more conducting than either the corresponding neutral complex or the dianion, and Rosseinsky and Malpas have proposed that this is related to the ease of disproportionation.113... 

Similar processes are observed with transition metal dithiolene complexes, in which a range of formal oxidation states of metal ions may be accommodated. In reality, this is... 

Pilato, Robert S., Metal Dithiolene Complexes in Detection Past, Present,... 

Most of the compounds listed in this class (Table 7) are tetraalkylammonium (R4N+) salts of metal dithiolene complexes. These salts generally exist in a 2 1 or 1 1 stoichiometry. The 2 1 salts, such as [ra-Bu4N]2[Cu(mnt)2]114) and [Et4N]2-[Cu(mnt)2]115,116) can exhibit interesting properties, but they will not be considered here since the transition-metal components are isolated from each other (d(M-M) > 5 A). 

As has been noted previously81, the structural parameters of metal dithiolene complexes are relatively insensitive to the overall charge on the complex, and the monoanionic dithiolene complexes generally retain the mmm (D2h) molecular symmetry found in both neutral and dianionic dithiolene complexes. The only notable structural trend is a lengthening of the M-S bond as the overall charge on the transition-metal complex increases. 

This chapter discusses the synthesis of transition metal dithiolene complexes and is current to late 2002. Dithiolene chemistry has been reviewed several times previously, but this is the first review dedicated to synthetic aspects. Emphasis is placed on more contemporary methods, and the reader should consult the older reviews, especially those by Mueller-Westerhoff et al. (8) and McCleverty (9) for discussions of earlier literature. An effort was made to be comprehensive with respect to methods and the range of complexes examined, but the chemistry of metal dithiolenes is so vast that it is not practical to be exhaustive. 

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