Stabilities and dissociation reactions of the Irm(CO)n+ ions observed in TOF-SIMS of Ir4(CO)12 thin layer

The kinetic energies of Irm(CO)n+ ions observed in the high resolution TOF-SIMS of Ir4(CO)12 layer have been estimated using the post-acceleration electrode method. The observed kinetic energy of secondary ion depends on the number of coordinated CO molecules, but not on the cluster size of Irm+ shell. gnal of Ir5(CO)12+ ion is missing in the observed mass spectrum. The analysis of the uni-molecular dissociation reactions of the complex ions and DFT calculations have shown that this is due to the structural change of Ir5+ shell with the increase of the coordinated CO molecules.