Figure 1 Molecular view of the cation with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are omitted for clarity. [Symmetry codes: (i) z, x, y; (ii) y, z, x; (iii) -x + , y, -z + ; (iv) -x + , -y + , z; (v) x, -y + , -z + ]