The reactions of hexachloro-cyclo-triphosphazene P 3 N 3 Cl 6 (1) with 1-aminoadamantane (amantadine, Ad-NH 2 ) and 1-amino-3,5-dimethyladamantane (memantine, Mem) were studied. New geminally substituted phosphazene derivatives, P 3 N 3 Cl 4 (NH-Ad) 2 (2), P 3 N 3 Cl 2 (NH-Ad) 4 (3) and P 3 N 3 Cl 2 (Mem) 4 (4), were prepared. The substances 3 and 4 were fully characterized by 31 P NMR and IR spectroscopies and elemental analysis. Molecular and crystal structures of 2–4 were determined by X-ray diffraction. The compounds are triclinic, space group P1¯. Compound 3 crystallized from dichloromethane as a solvate.