Formation and Structures of Transition Metal−C₆₀ Clusters

Abstract

Transition metal (Sc, Ti, V, and Cr)−C60 binary clusters were produced in the gas phase by a two-laser vaporization method. In the mass spectra of cationic Mn(C60)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 C60 are alternately stacked. Clusters with composition (4, 4)+ and (5, 5)+ are presumed to be ring structures. For Crn(C60)m+, however, a Cr atom is surrounded by three C60, 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 Mn(C60)m and a chemical probe method using CO, O2, and C2H4 as reactants gave information concerning the geometrical and electronic structures.