Synthesis and Electrical Conductivity of a New Family of Pt Mixed Valence Complexes: Pt6(NH3)14Cl10X4 (X=ClO4, BF4, and PF6)

Abstract

Abstract A new family of Pt mixed valence complexes: Pt6(NH3)14Cl10X4 (X=ClO4, BF4, and PF6) was synthesized from the Magnus green salt (MGS) by the partial oxidation using an oxidant of H2O2 or by electrochemical method. On partial oxidation, the 1/6 of Cl− ligands in MGS are randomly replaced by NH3 ligands and simultaneously counter ions X are introduced. These complexes comprise of one-dimensional chains with direct contact between Pt atoms and consequently a quasi-one-dimensional band made up of 5dz2 orbital of Pt is formed. The average valence of Pt is +2.33 and the distance between Pt atoms along a chain is shorter than or comparable to that of K2[Pt(CN)4]Br0.3·xH2O (KCP). The electrical conductivity σ of these complexes was measured from 80 K to r.t. The σ(r.t.) is rather high in spite of the measurement on the powder pressed pellets. This suggests that σ along a chain direction may be as high as that of KCP if single crystals can be obtained. The conductivity data were fitted using a gap energy with various temperature dependence. In the complex with X=PF6, there may be a phase transition caused by ordering of PF6− ions at about 110 K.