An Open‐Cage Fullerene That Mimics the C60H10 (5,5)‐Carbon Nanotube Endcap to Host Acetylene and Hydrogen Cyanide Molecules

Treatment of the open‐cage fullerene C₆₃H₄NO₂(Ph)₂(Py)(N₂C₆H₄) ( 1 ) with methanol at 150 °C results in an orifice‐enlargement reaction to give C₆₉H₈NO(CO₂Me)(Ph)(Py)(N₂C₆H₄) ( 2 ). The overall yield from C₆₀ to isolated 2 is 6.1 % (four steps). Compound 2 contains a 24‐membered elliptic orifice that spans 8.45 Å along the major axis and 6.37 Å along the minor axis. The skeleton of 2 resembles the hypothetic C₆₀H₁₀ (5,5)‐carbon nanotube endcap. The cup‐shaped structure of 2 is able to include water, hydrogen cyanide, and acetylene, forming H₂O@ 2 , HCN@ 2 , and C₂H₂@ 2 , respectively. The molecular structures of H₂O@ 2 and HCN@ 2 have been determined by X‐ray crystallography. The ¹H NMR spectra reveal substantial upfield shifts for the endohedral species, such as δ=?10.30 (for H₂O), ?2.74 and ?14.26 (for C₂H₂), and ?1.22 ppm (for HCN), owing to the strong shielding effects of the fullerene cage.