Transition of the heterofullerene (C59N)Xto the monomeric phase of C59N

The stability of the azafullerenes of the type ( C 59 N ) X was studied by using infrared, optical and Raman experiments. X represents either hydrogen or an other cage of C 59 N . The solid phase of the dimer was shown to be stable up to 650 K followed by very slow degradation extending beyond 700 K. This is compared to our very latest results on the temperature stability of C 59 HN which was found to be stable only up to 540 K. A sudden change in the spectra at this temperature gives evidence for a transition to a new air stable phase which is claimed to be monomeric C 59 N . When heated in vacuum to about 700 K this phase dimerizes into ( C 59 N ) 2 .