Atomic nitrogen in C60:N@C60 : Special issue endohedral fullerenes

Endohedral N@C 60 (atomic nitrogen inside C 60 ) is produced by ion implantation. Two different production methods are employed: Kaufman ion source and glow discharge. After the bombarded material is dissolved in toluene or CS2 and is filtered, several milligrams of C60 containing N@C 60 in a concentration of 10 -4 to 10 -5 are obtained. N@C 60 gives a very clear hyperfine-split electron paramagnetic resonance signal. The most prominent features of N@C 60 are: (i) Nitrogen in C 60 keeps its atomic electronic configuration and occupies the on-center position. (ii) N@C 60 is stable at ambient conditions, the thermal instability starts at 260°C. (iii) The complex survives exohedral addition reactions and is a sensitive detector of cage distortions caused by addends. (iv) C60 and N@C60 exhibit slightly different retention times in column chromatography, thus permitting an enrichment of N@C 60 by this method.