Crystals of high conductivity

The simplest organic metals can in fact be produced starting from naphthalene and similar arenes such as pyrene, perylene, fluoranthene or triphenylene. 4-16 if these compounds are electro-chemically oxidized in an otherwise inert solvent containing a supporting electrolyte with anions of low nucleophili city, coloured crystals of high conductivity will grow at the anode. These crystals... 

Ionic Cations and anions Electrostatic, non-directional Hard, brittle, crystals of high m.t. moderate insulators melts are conducting Alkali metal halides... 

The precursor dithiocarbonates were also used to prepare mesomorphic derivatives of TTF (tetrathiafulvalene), a strong electron donor compound used in the formation of highly conductive charge transfer complexes. Attempts to prepare CT complexes between the mesomorphic dithiolenes as acceptors and these mesomorphic TTF donors showed that the electron acceptor strength of this type of dithiolene does not suffice to form strong donor-acceptor complexes mixtures of the two components form mixed crystals without any visible degree of charge transfer.208... 

Neutral square coplanar complexes of divalent transition metal ions and monoanionic chelate or dianionic tetrachelate ligands have been widely studied. Columnar stack structures are common but electrical conductivities in the metal atom chain direction are very low and the temperature dependence is that of a semiconductor or insulator. However, many of these compounds have been shown to undergo partial oxidation when heated with iodine or sometimes bromine. The resulting crystals exhibit high conductivities occasionally with a metallic-type temperature dependence. The electron transport mechanism may be located either on predominantly metal orbitals, predominantly ligand re-orbitals and occasionally on both metal and ligand orbitals. Recent review articles deal with the structures and properties of this class of compound in detail.89 90 12... 

As an example for the /3-(ET)2X family the crystal structure of the salt with X = Ig is shown in Fig. 2.14 [127, 128]. /9-(ET)2l3 was the second ambient-pressure organic superconductor (Tc 1.5 K) to be found [129]. The principal structure of most ET salts can be seen in Fig. 2.14. The ET molecules are arranged in columnar stacks within planes which are separated by anion layers. The 13-type structure is triclinic with the lattice parameters as given in Table 2.1. The ET molecules are stacked along the a- -b direction and are slightly dimerized. S-S contacts less than the van der Waals radii of 3.6 A are found in the ab plane only between the stacks and not within the stacks. However, due to their 2D connectivity (see Fig. 2.14b) the ET form sheets of high conductivity in the ab planes which are separated by insulating layers of linear Ig anions. 

A new family of high conductivity, mixed metal oxides having the pyrochlore crystal structure has been discovered. These compounds display a variable cation stoichiometry, as given by Equation 1. The ability to synthesize these materials is highly dependent upon the low temperature, alkaline solution preparative technique that has been described the relatively low thermal stability of those phases where an appreciable fraction of the B-sites are occupied by post transition element cations precludes their synthesis in pure form by conventional solid state reaction techniques. 

New complexes with DIP . or DIPS

Single crystals exhibit high conductivity along the needle axis at room temperature 40 (flan) 1 for J and 250 (Qcm) 1 for 2. X-ray analysis, temperature dependences of conductivity, susceptibility and relaxatio time for both complexes are reported. 

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