Reactivity of cobalt-fullerene complexes towards deuterium.

The adsorption of molecular deuterium (D 2 ) onto charged cobalt-fullerene-complexes Co n C 60 + ( n = 1 - 8) is measured experimentally in a few-collision reaction cell. The reactivity is strongly size-dependent, hinting at clustering of the transition metals atoms on the fullerenes. Formation and desorption rate constants are obtained from the pressure-dependent deuterogenation curves. DFT calculations indeed find that this transition metal clustering is energetically more favorable than decorating the fullerene. For n = 1, D 2 is predicted to bind molecularly and for n = 2 dissociative and molecular configurations are quasi-isoenergetic. For n = 3 - 8, dissociation of D 2 is thermodynamically preferred. However, reaching the ground state configuration with dissociated deuterium on the timescale of the experiment may be hindered by dissociation barriers.