Atomic nitrogen in C60:N@C60

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 C-60 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 degrees C. (iii) The complex survives exohedral addition reactions and is a sensitive detector of cage distortions caused by addends. (iv) C-60 and N @ C-60 exhibit slightly different retention times in column chromatography, thus permitting an enrichment of N @ C-60 by this method.