Some new diatomic molecule containing endohedral fullerenes

Abstract

Several new diatomic molecule-containing endohedral fullerenes were prepared by heating C60 or C70 under high pressures of the corresponding gases. The species prepared are N2@C60, N2@C70, 13CO@C60, and 3He22Ne@C70. Their existence was demonstrated through high sensitivity, wide dynamic range mass spectrometry. Out of two thousand C60 molecules about one is observed to incorporate N2. The nitrogen molecule containing endohedral molecules are stable and the mass spectrometric signal is not lost even 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 C2 unit from the cage. The observation of 13CO@C60 by mass spectrometry opens up the possibility for future NMR studies of this molecule. The observation of 3He22Ne@C70 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 singly and doubly occupied fullerenes are in equilibrium but the empty and filled fullerenes are not.