The organic inclusion compound 2,4,6-tris-(4-bromophenoxy)-1,3,5-triazine was used to create an ordered arrangement of the endohedral fullerenes N@C-60 and P@C-60 in a crystalline host matrix. Two different host-guest structures were investigated by X-ray diffraction and electron paramagnetic resonance. In one of these, all axial deformation of the fullerene guests leads to a sizeable zero-field splitting of the quartet ground state of the encapsulated atoms. The small size of the zero-field strain leads to well-separated lines for all transitions, opening the possibility of transition selective pulses for future quantum computing experiments in these multi-level systems. (c) 2006 Elsevier B.V. All rights reserved.