Synthesis and investigation of the thermal properties of [Co(NH₃)₆][Co(C₂O₄)₃]·3H₂O and [Ir(NH₃)₆][Ir(C₂O₄)₃]

Abstract

The complexes [Co(NH 3 ) 6 ][Ir(C 2 O 4 ) 3 ] and [Ir(NH 3 ) 6 ][Co(C 2 O 4 ) 3 ]·H 2 O have previously been synthesized and their thermal properties studied. The [Ir(NH 3 ) 6 ][Ir(C 2 O 4 ) 3 ] and [Co(NH 3 ) 6 ][Co(C 2 O 4 ) 3 ]·3H 2 O complexes considered here are the end members in a series of possible isostructural solid solutions based on the complex salts in the Co–Ir system. Their crystal structures and thermal properties are described in detail, including temperature-dependent in situ X-ray diffraction. During the thermolysis of these compounds, layered metal nanoparticles are formed. Close attention is paid to the details of the [Co(NH 3 ) 6 ][Ir(C 2 O 4 ) 3 ] synthesis. It has been shown that the formation of this complex salt is temperature dependent; upon heating, a new phase of the K 3 [Co(NH 3 ) 6 ][Ir(C 2 O 4 ) 3 ] 2 ·6H 2 O salt is formed, which incorporates the initial iridium compound into the crystal structure of the double complex salt. The target [Co(NH 3 ) 6 ][Ir(C 2 O 4 ) 3 ] product is obtained if the synthesis is carried out at room temperature.