Ammonium cations, dithiolene electrical

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... 

In spite of the large number of dithiolene complexes synthesized, 50 of their derived compounds exhibit a metal-like behavior at a temperature close to RT and within a significant temperature range. These compounds, listed in Tables I-IV, together with the relevant references and some details about their electrical behavior are either NIOS salts or D-A adducts. For the NIOS salts of dmit and mnt complexes, the associated counterions are mostly closed-shell cations such as alkyl-ammonium or sulfonium, or alkaline metal cations. For the D-A adducts derived from dmit and mnt acceptor complexes, the associated donors are TTF-like molecules and Per, respectively. The dddt complexes deserve special mention as the derived metal-like conductors involve M(dddt)2 v - cation radicals (instead of anion-radicals as in dmit or mnt systems). 

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