Electrical conductivity tetracyanoplatinates

The simple integral oxidation state compounds behave as either insulators or semiconductors. The tetracyanoplatinates of monovalent cations form anionic columnar stack structures with conductivities in the range 10-4—10-9 fi 1 cm-1 and a systematic variation of cry with 1 /electrical conductivity can be increased by as much as a factor of 104 by pressures up to 180 kbar.27... 

The electrical conductivity of several of these compounds has been reported.88 Compressed pellet four-probe measurements at room temperature are usually in the range 10 2-5 fl I cm-1 although a value of 150-500 has been reported for orientated polycrystals. Most of the compounds show semiconductor behaviour with activation energies of about 35 meV. Ko.6o[Ir(CO)2Cl2]-0.5H20 shows evidence of a transition to more metal-like behaviour near room temperature,88 It seems very likely that if good quality single crystals of these compounds could be obtained then they would exhibit conduction properties similar to those of the cation-deficient tetracyanoplatinates or bis(oxalato)platinates. 

Metal-chain complexes containing stacked square-planar tetracyanoplatinate groups, [Pt(CN)4]2", are currently of high interest because of their one-dimensional (very anisotropic ) metallic properties. Complexes of this type contain metal-atom chains and often possess a characteristic brilliant, metallic luster. They may be synthesized by oxidation using chemical or electrolytic techniques.1 Although these compounds often appear metallic, they may also be semiconductors. These complexes differ in their Pt-Pt intrachain separations, degree of partial oxidation of the platinum atom (Pt2-1 2 4), electrical conductivity, and metallic color.2 Compounds in this series which contain platinum atoms in a nonintegral oxidation state are known as partially oxidized tetra-cyanoplatinate (POTCP) complexes. Some complexes also possess a metallic luster but are not metallic, as is the case for Tl4(C03)[Pt(CN)4] (see below). 

The cesium [hydrogen bis(sulfate)] tetracyanoplatinate complex exhibits a room-temperature electrical conductivity (four probe technique) of approximately 113 ohms 1 cm 1, while that of the Rb analog (Pt—Pt - 2.83 A) is 1500-2000 ohms"1 cm 1. 

Earlandite structure, 849 Electrical conductivity metal complexes, 133 tetracyanoplatinates anion-deficient salts, 136 Electrical properties metal complexes, 133-154 Electrocatalysis, 28 Electrochemical cells, 1 Electrochemistry, 1-33 hydrogen or oxygen production from water coordination complex catalysts, 532 mineral processing, 831 reduction, 831 Electrodeposi (ion of metals, 1-15 mineral processing difficulty, 831 Electrodes clay modified, 23 ferrocene modified, 20 nation coated, 15 polymers on, 16 polyvinylferrocene coated, 19 poly(4-vinylpyridine) coated, 17 redox centres, 17 Prussian blue modified, 21 surface modified, 15-31 Electrolysis... 

One-dimensional metals of d -complexes with a quadric-planar surrounding are good electrical conductors (For a very recent review on polymers with transition metal chains see J.K. Bera, K.R. Dunbar, Angew. Chem. 2002, 114, 4633). Partial doping of tetracyanoplatinate (Kroogmann salt) with columnar stacks results in metallic-like conductivity [7]. A linear chain polymer containing Rh-Rh bonds has been obtained by galvanostatic reduction of... 

When a high potential field ( 50 V cm ) is applied across crystals of Ki.64Pt(ox)2(H20)a , a color change from bronze to blue-black commences at the anode (167, 259) and propagates along the crystal at a rate proportional to the electric field (167). A similar effect has been abserved for the partially oxidized tetracyanoplatinate system (165, 166, 167, 267,308,395). Concomitantly, the conductivity drops by four orders of magnitude, there is a decrease in pH (of the redissolved crystal), and droplets (pH > 7) appear on the cathode (167, 259). These observations have been rationalized as the replacement of protons for potassium ions in the lattices (167), Eq. 52, as well as reduction of the complex, Eq. 53 (167, 259). Consistent with the... 

---