Partially Oxidized Potassium Tetracyanoplatinates

Potassium tetracyanoplatinate may be prepared as described elsewhere in this volume,3 or commercial material may be used after chloride impurities are eliminated by two recrystallizations from distilled water. An aqueous solution at 

Available from Platinum Chemicals, Inc., P.O. Box 565, Asbury Park, NJ, 07712. 

When the above procedure is repeated with approximately 1 M KX (X = Cl, Br) 

In addition to the partially oxidized tetracyanoplatinates, bis(oxalato)platinate-(II) can be nonstoichiometrically oxidized by chemical oxidants13 to form highly lustrous needlelike crystals containing platinum in the 2.36 oxidation state. These complexes have not been characterized to the extent of the tetracyano-platinate complexes however, the oxalato complexes are reported to be highly conducting.13 The starting material is bis(oxalato)platinate(II), which can be prepared in 30% yields from hexachloroplatinate(lV) and potassium oxalate.9 

Potassium Bis(oxalato)platinate(II) (2 1) Dihydrate, K2Pt(C204)2-2H20 

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Partially oxidized tetracyanoplatinates contain nonstoichiometric ratios of either anions or cations. Potassium tetracyanoplatinates are prepared in the form of nonstoichiometric anions, e.g., K2Pt(CN)4Bro,3 SHjO, or cations, e.g., Ki.75Pt(CN)4 1.5H20 . The nonstoichiometric anion K2Pt(CN)4Bro,3 3H2O, can be prepared by chemical... 

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... 

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