Direct-current induced oxidation–reduction reactions in some partially oxidised cyano- and oxalato-platinate crystals containing platinum–platinum chains

Abstract

The application of d.c. fields of greater than 200 V cm^–1 to K_1·74Pt(CN)₄,1·8H₂O and K_1·64Pt(C₂O₄)₂,pH₂O (where p indicates an unknown number of water molecules) induces and oxidation–reduction reaction which commences at the anode and spreads through the crystal towards the cathode. The products of the reactions appear to be K_1·74H_0·26Pt(CN)₄,xH₂O and K_1·64H_0·36Pt(C₂O₄)₂,gH₂O (where g indicates an unknown number of water molecules). Mg_0·82Pt(C₂O₄)₂,5·3H₂O does not undergo this reaction at the anode up to 3000 V cm^–1. K_1·64Pt(C₂O₄)₂,pH₂O at 50 V cm^–1 and K_1·74Pt(CN)₄, 1·8H₂O at 500 V cm^–1 exhibit a colour change at the cathode. Evidence suggests that this is due to partial replacement of K⁺ by H⁺ ions.