Thermoanalytical Studies on the Double Complexes [M(NH3)6][M’(CN)6] and [MCl(NH3)5][Ni(CN)4] (M=Cr, Co, Ru, Rh; M’=Fe, Co)

Abstract

By means of thermal analysis, the titled complexes were shown to degradate in two stages up to 500°C. Through the first-stage decomposition of [M(NH3)6][M′(CN)6], 1mol of HCN gas and 4mol of NH3 gas evolved during a pronounced endothermic reaction (except for the complex with Ru-Fe as M-M′). Different combinations of M-M′ can reverse order of the two kinds of gas-evolution in the complexes; the loss of ligand leads to a di- or poly-nuclear complex in which the NH2 and/or the CN group has bridged; the electronic conductivity increased with the progress of bridging; the metal ion in complexes with Co-Fe and Co-Co as M-M′ was reduced. The complex [MCl(NH3)5][Ni(CN)4] also decomposed in two stages with the simultaneous gas-evolution of HCN and NH3.