Ti 8 C 12 + -Metallo-Carbohedrenes: A New Class of Molecular Clusters?

Abstract

During the course of studying the dehydrogenation reactions of hydrocarbons by titanium atoms, ions, and clusters, an exceptionally stable and abundant cluster which contains 8 titaniums and 12 carbons was discovered. "Titration" reactions with ND₃ reveal the uptake of eight molecules, pointing to the fact that the titanium atoms are at exposed positions of similar coordination. A dodecahedral structure of T_h point group symmetry is proposed to account for the unusual stability of this molecular cluster. The Ti₈C₁₂⁺ dodecahedron has 12 pentagonal rings and each of the rings is formed by two titanium and three carbon atoms, where each titanium is bound to three carbons. Based on the model, it is expected that neutral Ti₈C¹² would be a stable metallo-carbododecahedral molecule and may comprise one member of a new class of molecules, namely metallo-carbohedrenes.