Fluxional Behaviour of Isocyanide Derivatives of Dodecacarbonyltetrairidium

The fluxional behaviour of Ir₄(CO)₁₁(t-BuNC)] ( 1 ) and Ir₄(CO)₁₁(ArNC)] (Ar = 4-methoxyphenyl, 4-tolyl, phenyl, 4-chlorophenyl, 4-nitrophenyl; 2 – 5 ) has been investigated by 2D and variable-temperature ¹³C-NMR. These techniques give new evidence of the processes responsible for CO exchange, namely two successive merry-go-rounds causing Cotton-like scrambling and a CO rotation about one metal center.