Synthesis and crystal structures of silver(I) and palladium(II) complexes of new bis(2-pyridyloxy)benzenes and methylene extended analogues

Four new ligands, 1,3 -bis(2-pyridyloxy) benzene II, 1,2-bis (2-pyridyloxy)benzene III, 1,4-bis(2-pyridyloxymethyl)benzene IV and I,4-bis(2-pyridylmethoxy)benzene V, have been prepared, and their complexes with silver(I) nitrate and palladium(II) chloride synthesized. The silver complex of ligand II is shown, by a crystal structure determination, to be a M2L2 20-membered macrocycle with close pi-pi stacking of the benzene rings of the ligands, similar to the analogous complex of the para substituted isomer of this ligand. The structure of the mononuclear palladium complex of ligand III shows the ligand co-ordinated to the metal in a nine-membered chelate ring, with evidence for a weak interaction between the metal and the central benzene ring. Structures of the silver complexes of ligands TV and V reveal that these are polymeric species, with the molecular packing controlled by pi-pi stacking interactions between aromatic rings. The crystal structure of the palladium complex of ligand V shows that it self-assembles into a M2L2 26-membered macrocycle, but without intramolecular pi-pi stacking.