18-membered tetraimino macrocyclic complexes containing furan groups: stacking of two macrocycles and characterization of organic derivatives

The structures of the Na+ and Pb2+ complexes of a 18-membered macrocycle L- 1 which are prepared by the reactions of 2,5-furandicarboxaldehyde and o-ph enylenediamine in the presence of metal ions were studied by X-ray diffract ion. The Na+ complex has a methanol ligand and shows a stacking structure o f the two complex cations in the crystal. The sandwich-type structure was f ound for the Pb2+ complex. Two organic products obtained in the preparation s of the macrocycles containing other metal ions were also characterized by X-ray analyses. One (L-1a) is a derivative of the macrocycle in which addi tion of two methanol residues were found. The other product (L-2) has a rin g-contracted structure containing two benzimidazole residues. Structures of the macrocycles and sizes of the metal ions are discussed. (C) 1999 Elsevi er Science S.A. All rights reserved.