Formation of metal-encapsulating Si cage clusters

We report the formation of a series of metal-containing hydrogenated silico n clusters using an ion trap. Mass analyses reveal that many types of trans ition metal ions M+ (M = Hf. Ta, W, Re, Ir, etc.) react with silane (SiH4) to form dehydrogenated MSin+ cluster ions (n = 14, 13, 12, 11, 9, respectiv ely) as an end product, indicating that the metal atom is endohedral and st abilizes the Si polyhedral cage. This finding is confirmed by our nb initio calculation that WSi12 is a W-encapsulatine Si-12 cage cluster, and is ver y stable owing to both the electronic and the geometrical shell closures.