Coordination-directed one-dimensional coordination polymers generated from a new oxadiazole bridging ligand and HgX2 (X = Cl, Br and I)
Abstract
A new 1,3,4-oxadiazole bridging bent organic ligand, 2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole, C28H24N4O3, L, has been used to create three novel one-dimensional isomorphic coordination polymers, viz. catena-poly[[[dichloridomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgCl2(C28H24N4O3)]·CH3OH}n, catena-poly[[[dibromidomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgBr2(C28H24N4O3)]·CH3OH}n, and catena-poly[[[diiodidomercury(II)]-μ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgI2(C28H24N4O3)]·CH3OH}n. The free L ligand itself adopts a cis conformation, with the two terminal pyridine rings and the central oxadiazole ring almost coplanar [dihedral angles = 5.994 (7) and 9.560 (6)°]. In the HgII complexes, however, one of the flexible pyridylmethyl arms of ligand L is markedly bent and helical chains are obtained. The HgII atom lies in a distorted tetrahedral geometry defined by two pyridine N-atom donors from two L ligands and two halide ligands. The helical chains stack together via interchain π–π interactions that expand the dimensionality of the structure from one to two. The methanol solvent molecules link to the complex polymers through O—H...N and O—H...O hydrogen bonds.
