Direct solid-phase hydrogenation of fullerenes

Direct hydrogenation of C₆₀ and C₇₀ was achieved without the use of a catalyst by exposing solid-phase fullerenes to high-pressure hydrogen gas (500-850 bar) at temperatures ranging from 573 to 623 K. Efficient production of C₆₀H_x (x = 2-18) and C₇₀H_y (y = 4-30) was identified by laser desorption Fourier transform mass spectrometry. Temperatures above 950 K in the presence of H₂ resulted in complete degradation of the fullerene samples. Gas-phase studies of the C₆₀H_x⁺ ions revealed that these species will undergo proton transfer to pyridine, indicating that at least some of the hydrogens are bound exohedral to the fullerene cage and that the C₆₀H_x species have lower ionization potentials than C₆₀ itself.