Thermal stability of the endohedral fullerenes N@C-60, N@C-70, and P@C-60 (vol B 63, art. no. 045421, 2001) - art. no. 159901

Nitrogen and phosphorus atoms enclosed in fullerenes keep their atomic grou nd-state configuration, and no charge transfer or covalent bonding to the c age occurs. These systems can be dissolved in organic solvents and reacted with addends without losing the atomic character of the guest atom. In this paper we present a detailed study of the annealing behavior of N@C-60, N@C -70, and P@C-60, and of some N@C-60 adducts. The disintegration of these sy stems, as recorded by electron paramagnetic resonance measurements, occurs in a temperature range between 400 and 600 K. The results are in qualitativ e agreement with potential-energy calculations, and confirm the proposed es cape mechanism which proceeds via bond formation of the trapped atom with t he cage. It is found that other combinations of group-V elements with fulle renes, e.g., N@C-84, P@C-70, and As@C-60, are not stable at room temperatur e. The escape mechanism and the possibility of disabling this path are disc ussed.