Some new diatomic molecule containing endohedral fullerenes

Several new diatomic molecule-containing endohedral fullerenes were prepare d by heating C,,,, or C, under high pressures of the corresponding gases. T he species prepared are N-2@C-60, N-2@C-70, (CO)-C-13@C-60, and (HeNe)-He-3 -Ne-22@C-70. Their existence was demonstrated through high sensitivity, wid e dynamic range mass spectrometry. Out of two thousand C-60 molecules about one is observed to incorporate N-2. The nitrogen molecule containing endoh edral molecules are stable and the mass spectrometric signal is not lost ev en after several hours heating at 500 K. The corresponding endohedral ions undergo the Rice shrink-wrap mechanism; a mass-analyzed ion kinetic energy spectrum demonstrates the loss of a C, unit from the cage. The observation of (CO)-C-13@C-60 by mass spectrometry opens up the possibility for future NMR studies of this molecule. The observation of (HeNe)-He-3-Ne-22@C-70 is in accordance with the "promoter" mechanism of Thiel and co-worker [J. Am. Chem. Soc. 118 (1996) 7164 Helv. Chim. Acta 80 (1997) 495], whereby the sin gly and doubly occupied fullerenes are in equilibrium but the empty and fil led fullerenes are not. (C) 2001 Elsevier Science B.V.