Crystal Structure and Thermal Properties of Double-Complex Salts [M(NH)][M(CO)] (M, M = Co, Rh) and K[Rh(NH)][Rh(CO)]∙6HO.

Here, seven new double-complex salts, [M(NH)][M(CO)] (M, M = Co, Rh) and K[Rh(NH)][Rh(CO)]∙6HO types, are synthesised. The crystal structure and composition of DCS (double-complex salts) are studied by SCXRD, XRD, CHN and IR methods. The complex salts of the [M(NH)][M(CO)] (M, M = Co, Rh) type can be crystallised both as a crystalline hydrate [M(NH)][M(CO)]·3HO (sp. gr. -3) and as an anhydrous complex (sp. gr. -1) depending on the synthesis conditions. The process of [Rh(NH)][Rh(CO)] formation is significantly dependent on the synthesis temperature. At room temperature, a mixture is formed comprising [Rh(NH)][Rh(CO)] and K[Rh(NH)][Rh(CO)]∙6HO, while the [Rh(NH)][Rh(CO)] target product crystallises at elevated temperatures. The thermal behaviour of double-complex salts is studied by the STA, EGA-MS, IR and XRD methods. The complete decomposition of complex salts in helium and hydrogen atmospheres resulting in metals or CoRh solid solutions is achieved at temperatures of 320-450 °C.