Findings of magic peaks corresponding to M(8)C(12)(+) (M = V, Zr, and Hf) formed from reactions of the respective metals with various small hydrocarbons, in conjunction with recent findings for the titanium system, establish metallo-carbohedrenes as a stable general class of molecular cluster ions. A dodecahedral structure of T(h) point symmetry accounts for the stability of these ionic clusters.

Evidence for the existence of metallocarbohedrenes [MacI2 (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,C, reveal the general mechanisms responsible for the formation of the prominent cagelike structure, M6C12, using a laser-based timeof-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 M6CI2 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 Th).

An unusual structural growth pattern has been found in the system of Zr m C n , in which multicage structures are formed. The experimental evidence shows that the first cage closes at Zr 8 C 12 . Surprisingly, subsequent cluster growth does not lead to the enlargement of the cage size as it usually does in the case of pure carbon clusters and water clusters, for example. Rather, multicage structures are developed, that is, a double cage at Zr 13 C 22 and Zr 14 C 21/23 , a triple cage at Zr 18 C 29 , and a quadruple cage at Zr 22 C 35 . This feature distinguishes the class of metallo-carbohedrenes from the regular doped fullerenes.

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