Encapsulation of Formaldehyde and Hydrogen Cyanide in an Open‐Cage Fullerene

Reaction of C 63 NO 2 (Ph) 2 (Py) ( 1 ) with o‐ phenylenediamine and pyridine produces a mixture of C 63 H 4 NO 2 (Ph) 2 (Py)(N 2 C 6 H 4 ) ( 2 ) and H 2 O@ 2 . Compound 2 is a new open‐cage fullerene containing a 20‐membered heterocyclic orifice, which has been fully characterized by NMR spectroscopy, high‐resolution mass spectrometry, and X‐ray crystallography. The elliptical orifice of 2 spans 7.45 Å along the major axis and 5.62 Å along the minor axis, which is large enough to trap water and small organic molecules. Thus, heating a mixture of 2 and H 2 O@ 2 with hydrogen cyanide and formaldehyde in chlorobenzene affords HCN@ 2 and H 2 CO@ 2 , respectively. The 1 H NMR spectroscopy reveals substantial upfield shifts for the endohedral species ( δ =−1.30 to −11.30 ppm), owing to the strong shielding effect of the fullerene cage.