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M(NH 3 ) 5 Cl][IrCl 6 ], M = Co, Cr, Ru, Rh, and Ir, were proposed as single-source precursors for bimetallic alloys. Their thermal decomposition in inert and reductive atmospheres below 700 1C results in the formation of nanostructured porous Ir 0.5 M 0.5 alloys. Salts decompose with a significant exothermal effect during the first stage of their thermal breakdown in an inert atmosphere above 200 1C. The exothermal effect gradually decreases in the series: [Co(NH 3 ) 5 Cl][IrCl 6 ] (1) 4 [Cr(NH 3 ) 5 Cl][IrCl 6 ] (2) 4 [Ru(NH 3 ) 5 Cl][IrCl 6 ] (3) 4 [Rh(NH 3 ) 5 Cl][IrCl 6 ] (4); [Ir(NH 3 ) 5 Cl][IrCl 6 ] (5) does not exhibit any thermal effects and decomposes at much higher temperatures. To shed light on their thermal decomposition and the nature of the exothermal effect, DSC-EGA, in situ and ex situ IR, Raman, XPS and XAFS studies were performed. A combination of complementary techniques suggests a simultaneous ligand exchange and a reduction of central atoms as key processes. In [Co(NH 3 ) 5 Cl][IrCl 6 ], Co(III) and Ir(IV) simultaneously oxidise coordinated ammonia, which can be detected due to a significant exothermal effect and the presence of Co(II) and Ir(III) in the intermediate product. The appearance of Ir-N frequencies demonstrates a ligand exchange between cations and the [IrCl 6 ] 2À anion. Salts with Cr(III), Ru(III), and Rh(III) show a much lower exothermal effect due to the stability of their oxidation states. Salts with Rh(III) and Ir(III) demonstrate a high thermal stability and a low tendency for ligand exchange as well as decomposition with exothermal effects.

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