Figure 2.

(a) (0 -1 2) Plane in the crystal packing of L3 showing the chair-type conformation of L3 and the CH∙∙∙N contacts between parallel molecules; (b) infinite net ribbons formed by ligand molecules of adjacent planes in the (0 -1 2) family; (c) chair-type conformation of L4 in the crystal structure of the free ligand and infinite chains formed by head-to-tail connected molecules. Selected hydrogen bond contacts are shown.