One-dimensional coordination polymers generated from a new triazole bridging ligand and HgX₂ (X = Cl, Br and I): characterization and luminescent properties

The new 4-amino-1,2,4-triazole asymmetric bridging ligand 4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phen­yl]-4H-1,2,4-triazole (L) has been used to generate three novel isomorphic one-dimensional coordination polymers, viz. catena-poly[[tris­[dichloridomercury(II)]-bis­{[mu]₃-4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phen­yl]-4H-1,2,4-triazole}] aceto­nitrile monosolvate], {[Hg₃Cl₆(C₁₈H₁₄N₆)₂]·CH₃CN}_n, (I), and the bromido, {[Hg₃Br₆(C₁₈H₁₄N₆)₂]·CH₃CN}_n, (II), and iodido, {[Hg₃I₆(C₁₈H₁₄N₆)₂]·CH₃CN}_n, (III), analogs. The asymmetric ligand acts as a tridentate ligand to coordinate the three different Hg^II centers (two of which are symmetry-related). Two ligands and two symmetry-related Hg^II centers form centrosymmetric rectangular units which are linked into one-dimensional chains via the other unique Hg atoms, which sit on mirror planes. The chains are elaborated into a three-dimensional structure via inter­chain hydrogen bonds. The acetonitrile solvent mol­ecules are located in ellipsoidal cavities. The luminescent character of these three coordination complexes was investigated in the solid state.

3,5-Bis{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine and its one-dimensional polymeric complex with HgCl₂

The mol­ecule of 3,5-bis­{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine (L), C₃₀H₂₄N₈, has an antiperiplanar conformation of the two terminal benzimidazole groups and forms two-dimensional networks along the crystallographic b axis via two types of inter­molecular hy­drogen bonds. However, in catena-poly[[[dichloridomercury(II)]-[mu]-3,5-bis­{4-[(benzimidazol-1-yl)methyl]phenyl}-4H-1,2,4-triazol-4-amine] dichloro­methane hemisolvate], {[HgCl₂(C₃₀H₂₄N₈)]·0.5CH₂Cl₂}_n, synthesized by the combination of L with HgCl₂, the L ligand adopts a synperiplanar conformation. The Hg^II cation lies in a distorted tetra­hedral environment, which is defined by two N atoms and two Cl atoms to form a one-dimensional zigzag chain. These zigzag chains stack via hydrogen bonds which expand the dimensionality of the structure from one to two.

The structures of three Hg₂X₄L₂ macrocycles {X = Cl, Br and I, and L = 1,2-bis­[4-(pyridin-3-yl)phen­oxy]ethane} assembled from ether-bridged dipyridyl ligands

The new ether-bridged dipyridyl ligand 1,2-bis­[4-(pyridin-3-yl)phen­oxy]ethane (L) has been used to synthesize three isostructural centrosymmetric binuclear Hg^II macrocycles, namely bis­{μ-1,2-bis­[4-(pyridin-3-yl)phen­oxy]ethane-κ²N:N′}­bis­[dichloridomercury(II)], [Hg₂Cl₄(C₂₄H₂₀N₂O₂)₂], and the bromido, [Hg₂Br₄(C₂₄H₂₀N₂O₂)₂], and iodido, [Hg₂I₄(C₂₄H₂₀N₂O₂)₂], analogues. The Hg atoms adopt a highly distorted tetra­hedral coordination environment consisting of two halides and two pyridine N-donor atoms from two bridging ligands. In the solid state, the macrocycles form two-dimensional sheets in the bc plane through noncovalent Hg...X and X...X (X = Cl, Br and I) inter­actions.