Figure 2 The crystal packing of (I). In this figure, a helical chain assembled along the a axis of (I) is shown on the left of the panel, while the N-H...[pi] interaction croos-linking the helical chains paralell to the b axis is displayed on the right. Hydrogen bonds are shown as dashed lines. [Symmetry codes: (a) (i) x, -y + [{3\over 2}], z - [{1\over 2}]; (ii) x + [{1\over 2}], y + [{1\over 2}], -z + [{3\over 2}]; (iii) x + [{1\over 2}], -y + 2, -z + 1; (iv) x + 1, -y + [{3\over 2}], z - [{1\over 2}]; (v) x - [{1\over 2}], -y + 1, -z + 1; (vi) x + [{1\over 2}], y - [{1\over 2}], -z + [{3\over 2}]; (b) (i) x, y + 1, z; (ii) -x + 1, -y + 1, -z + 1; (iii) -x, -y, -z + 1; (iv) -x + 1, -y, -z; (v) -x, -y + 1, -z + 1; (vi) x - 1, y, z; (vii) x - 1, y + 1, z + 1].  [article HTML]