METALLOCARBOHEDRENES AS A CLASS OF STABLE NEUTRAL CLUSTERS - FORMATION MECHANISM OF M8C12 (M = TI AND V)

Evidence for the existence of metallocarbohedrenes [M8C12 (M = Ti and V)] as a general class of stable neutral molecular clusters is reported. Studies of the formation and growth of metal-carbon clusters M(m)C(n) reveal the general mechanisms responsible for the formation of the prominent cagelike structure, M8C12, using a laser-based time-of-flight mass spectrometer. Investigation of the effect of the ionizing laser fluence over at least 4 orders of magnitude and studies at 1064, 532, 355, and 266 nm establish that the prominence of the M8C12 cluster arises due to its presence as a neutral rather than as the photofragment of clusters of large size. The unusual stability of this species for both Ti and V is consistent with the proposed cagelike structure being a pentagonal dodecahedron (point group symmetry T(h)).