Previous experiments have shown that the ionization/dissociation of iron pentacarbonyl clusters can lead to the formation of iron ions and iron cluster ions and that these species can further react with dopant molecules to yield chemically rearranged products. The present experiments characterize similar reactions with methyl iodide molecules and clusters. Heteroclusters of the form [Fe(CO)(5)](m)(CH3I)(n)Ar-p are created in an expanding supersonic jet of the component molecules. Following ionization by a 30 ps, 266 nm laser pulse, extensive dissociation, aggregation, and chemical rearrangement occur leading to ionic products which ate characterized by mass spectrometry. Cluster ions of the type FemIn+, Fe(CH3I)(n)(+), and FeIm(CH3I)(n)(+) are observed as products. The stability of the binary parent ion Fe(CH3I)(+) is demonstrated for the first time.