Abstract: | 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. |