Solid-State Thermal Transformations in a Mixture of Palladium Tetraammine Dichloride with Ammonium Chromate

Abstract

Solid-state transformations of a 3[Pd(NH₃)₄]Cl₂ + (NH₄)₂CrO₄ mixture at temperatures from 40 to 550°C in various media have been studied by thermal analysis and mass spectrometry. The results demonstrate that the solid thermolysis product obtained in an argon atmosphere consists of a single phase: palladium-based Pd_1 – xCr_x solid solution isostructural with palladium and having a unit-cell parameter a = 3.897(2) Å. Its formation proceeds through the formation of metallic Pd and Cr, as evidenced by the absence of chromium oxide phases in all of the solid intermediate thermolysis products. The solid thermolysis product obtained in air consists of the phases Pd and PdO. A model has been proposed for the transformations of the 3[Pd(NH₃)₄]Cl₂ + (NH₄)₂CrO₄ mixture through the formation of metallic palladium and chromium.