Electrical properties metal-like behavior

Very few dithiolene platinum complex-based compounds have been reported and most of them exhibit poor electrical conductivity (9, 122, 123). The complex (Me4N)[Pt(dmit)2]2 does show metal-like behavior (RT conductivity = 10 S cm 1) but only >220 K (123). Another exception is (NHMe3)[Pt(dmit)2]3. This compound, which has the unusual 1 3 stoichiometry, behaves as a metal down to 180 K, with a room temperature conductivity of 140 S cm-1 (91). The Pt(dmit)2 units form pairs with an eclipsed overlap mode. Unlike the analogue Ni derivatives (see above) substituting one hydrogen atom for one methyl group in the (Me4N)+ cation leads to an improvement in the electrical properties. 

All suboxides and subnitrides described in the preceding sections are metallic. In the case of the alkali metal suboxides this property has been demonstrated by measurements of the electrical conductivity [58], CS7O, for example, exhibits a free electron like behavior in the temperature dependence of its resistivity rather similar to the element Cs itself. The characteristic colors of the alkali metal suboxides have been mentioned before, and spectroscopic investigations to be discussed in the following provide a more quantitative access to the metallic properties and the underlying chemical bonding. 

The electrical properties of an anodic oxide are found to depend on the formation conditions and subsequent treatments such as annealing. As-prepared anodic oxides show high leakage currents and a diode-like behavior known from anodic oxides of valve metals. A short high-temperature anneal, which removes the bound hydroxyl, reduces the leakage current to values typical of thermal oxides, as shown in Fig. 5.9. 

In addition to oxidation and reduction there is a change in the electrical properties between neutral state and metal-like conducting behavior. For investigation of the electrical properties electrochemical impedance spectroscopy is used. The principles of this method were described in Chapters 4 and 5. 

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