Hydrogen storage in hydrofullerides

Highly reduced fullerenes containing nearly 5 wt.% of dihydrogen can be synthesized using readily available reagents. Hydrides prepared from C₆₀ by dissolving metal reductions give complex mixtures of unstable isomers of C₆₀H₃₆. High temperature syntheses using transfer hydrogenation reagents such as dihydroanthracene provide mainly two stable isomers of C₆₀H₃₆ that have been characterized spectroscopically. Dihydrogen can be removed thermally from these materials at 500 °C. The experimentally determined activation energy for the thermal removal of dihydrogen from C₆₀H₂ is 61.4 kcal/mol. This value is in good agreement with the value determined computationally for a multi step radical reaction. The 92 kcal/mol barrier determined computationally for the concerted loss of dihydrogen reflects the symmetry-imposed barrier to dehydrogenation. PACS 81.05.Tp; 82.30.Cf; 82.56.Ub