Formation and structures of transition metal-C60 clusters

Transition metal (Sc, Ti, V, and CT)-C-60 binary clusters were produced in the gas phase by a two-laser vaporization method. In the mass spectra of cationic M-n(C-60)(m)(+), for M = SC, Ti, and V, clusters having the composition of (n, m) (1, 1)(+), (1, 2)(+), (2, 3)(+), (3, 4)(+), (4, 4)(+), and (5, 5)(+) were predominantly produced. The peaks having (n, n + 1)+ compositions are explicable in terms of multiple dumbbell structures, in which metal atoms and C-60 are alternately stacked. Clusters with composition (4, 4)(+) and (5, 5)(+) are presumed to be ring structures. For Cr-n(C-60)(m)(+), however, a Cr atom is surrounded by three C-60, forming a tricapped structure, and the structure acts as a unit for larger stable clusters of (2, 4)(+), (3, 4)(+), and (4, 4)(+). Ionization energy measurements for neutral M-n(C-60)(m) and a chemical probe method using CO, O-2, and C(2)H(4 )as reactants gave information concerning the geometrical and electronic structures.