The adsorption of molecular deuterium (D2 ) onto charged cobalt-fullerene-complexes Con C60 + (n=1-8) is measured experimentally in a few-collision reaction cell. The reactivity is strongly size-dependent, hinting at clustering of the transition metal 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, D2 is predicted to bind molecularly and for n=2 dissociative and molecular configurations are quasi-isoenergetic. For n=3-8, dissociation of D2 is thermodynamically preferred. However, reaching the ground state configuration with dissociated deuterium on the timescale of the experiment may be hindered by dissociation barriers.
Keywords: density functional theory; fullerenes; hydrogen adsorption; mass spectrometry; metal clusters.
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