A high pressure infrared spectral study of the reactions of dodecacarbonyltetrairidium with carbon monoxide and hydrogen

The reactions of Ir4(CO)12 under pressures of carbon monoxide and hydrogen have been investigated by following i.r. spectral changes in a high pressure spectrophotometric cell in attempts to obtain evidence for the existence of Ir2(CO)8 and HIr(CO)4. Although no reaction has been observed with carbon monoxide alone, the parent carbonyl is partially converted into HIr(CO)4 by reaction with carbon monoxide and hydrogen (1 : 1 mole ratio) at 430 atm. total pressure and 200°C; no evidence has been obtained for the formation of Ir2(CO)8. A convenient synthesis of Ir4(CO)12 in high yield is also described.